Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: LUPO on January 19, 2002, 12:15:09 PM
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Now in the CT "Stalingrad" the MC202 could find a practical use.
But the modelling of MG Breda is making useless this plane even in a setup like that.
It's a pity to have such a beautiful and glorious plane and be obliged to leave it into hangers.:(
So, please please, HT for next release look into the breda MG modeling !!!
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MC 202 vrs p40 (http://digidownload.iol.it/DgC/breda.avi)
Kinda like this?
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The Breda machine guns fire suffer from poor rate of fire and poor muzzle velocity. Furthermore C.202s carry a rather light armament of only 2 7.7mm and 2 12.7mm MGs.
For Comparison:
US .30 9.73g Projectile, 835 m/s velocity, 1200 rounds per minute
US .50 42.9g, 928 m/s, 800 rpm
Breda 7.7mm 11.3g, 730m/s, 800 rpm
Breda 12.7mm 36.7g, 760m/s, 575 rpm
The very poor rate of fire on the Breda 12.7mm especially hurts.
I would expect the full armament of a C.202 to be somewhat less effective that 2 US .50s.
Hooligan
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Cool Video Wotan!, Got any more? I'm hooked :)
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12.7mm Italian Breda-SAFAT Machine guns: they all were armed with the multi-effect "S.I.T." - "Scoppianti"(explosive)+ "Incendiarie"(...incendiary)+"Traccianti" (..tracer)- bullets (a variant of Vickers 12.7mm x 81Sr cartridge).
This round is not modelled in ah............
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Nobody had magic ammunition. British .303s used the DeWilde AP/I incendiary rounds. US .50s used M8 AP/I rounds. Except at the very beginning of the war, everybody used Machinegun projectiles with some incendiary or explosive content that were significantly more effective against aircraft than standard Armor Piercing rounds. There is nothing particularly unusual or wonderful about Italian ammunition
Hooligan
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Remember Dinger's gun lethality tests? Breda had a lot more destructive power than it should have based on kinetic energy. That "something extra" has to be chemical energy. HE Breda rounds are definitely modeled in AH.
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AP/I rounds are are a compleatly diferent beast than HE/I rounds, HE/I rounds are more efectave aganst defeating the aircraft as per say defeating the means by which it is able to fly. AP rounds kill engines, men and the such, HE/I rounds set it afire, tear pices off it ect, both are effectave, but for different reasions,The Italians, and the Japanese(and others) had HE/I rounds from the start of the war, The Japanese even adopted an Italian design for one of their own.The Breda 12.7mm is not exactely one of the better MG's of the war, the ammo it fires is howeaver a very effectave type.
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Originally posted by Wotan
MC 202 vrs p40 (http://digidownload.iol.it/DgC/breda.avi)
Kinda like this?
Uhm. This is the film that has been going around this BBS since the first time this particular issue came up, right? Well, this is the first time I bothered to download it and take a look.
Sooo... lots of small explosions and puffs as I would expect from small HE rounds -- but -- WTH are those few very big ones on the hurri about 1 - 2 seconds into the film? I can't believe they would be the HE rounds going off.
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In the video we can notice a lot of flying pieces, but no fire (from API). It seems the HE 13mm rounds were really effective.
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Brady, I would agree with you once you get up into true "cannon" rounds, say from 20mm and up.
But Hooligan is dead on. The HE component in both the Italian and Japanese MG rounds is very minute. And while it may very slightly increase its effectiveness, its not gonna make up the difference between them and the US .50's.
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i have parked a 202 behind a spit ix and zeke and those 2 planes eat most of the ammo.
Sure they "dont hit as hard as .50s" I dont think they were as ineffectual as in AH.
I go to the da and test umm.
I didn't say there was some magic bullet just that they are in my ah expierence ineffective. While definately under gunned the 202 from what I've read and seen wasn't as whimpy as in AH.
I have never seen dingers test.
And clearly you see the damage in that video and you can count most of the hits. Nothing rips off the plane so maybe its the damage model in ah.
Either way Lupo is right......... they are useless........
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"i have parked a 202 behind a spit ix and zeke and those 2 planes eat most of the ammo. "
I have to agree the 202 seems toothless, but how does the 202's MG's compare to other "ordinary" MG's, such as the RAF's 303's? Does the advantage of an explosive round show up there?
Am I right in thinking that if a Hurri pilot uses up his cannon and misses, then in theory at least, the 202 should out gun him?
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Wotan,
I can't see how that is possible.
I've blown the wing off of a B-17 in one pass using the 202, and that didn't take half of its ammo.
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Nice film. What are those flashes above the fuselage and right wing?
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Check out:
http://www.lvcm.com/jayb/ahgun102.htm
The information is a bit dated but nonetheless pertinent.
Hooligan
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I found different specifications for the gun used:
Company Calibre Weight Feed Rpm Mv
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Breda SAFAT 7.7mm 12.5kg Belt 900 730ms
Breda SAFAT 12,7mm 28kg Belt 700 760ms
Italian 7.7mm and 12.7mm Breda SAFAT machine guns were generally efficient and reliable, using a mix of solid, incendiary and tracers bullets. The 12.7mm gun outranged the machine guns of their opponents with a close punch as good as the US 0.5"
quote from COURAGE ALONE by Chris Dunning, Hikoki publications
(http://lupoweb.supereva.it/firma.jpg)
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BTW Wotan nice film.
I have the same film in VHS (the whole one) and you can definitly see there that the destructive power of Breda MGs is, if not impressive, effective and lethal against P40s, Spitfires and Blenheims.
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LUPO:
My rate of fire information is from Aces High (i.e. I measured it with a stop watch offline in AH). Part of the problem is that the 12.7mm guns are synchronized to fire through the propellor and this always results in a signifcant decrease in the rate of fire. In the few instances in which I have found Rate of Fire information from archival sources, the AH figures have always matched. I trust HTC's research much more than I trust Gustin's for example.
As far as they quote you gave us: US .50 rounds were significantly heavier and faster than the Breda rounds. There is no way that a 37g round going 760m/s is going to outrange a 43g round going 928 m/s. Simply put, Chris Dunning is wrong.
The C.202 is armed with 2 slow firing 12.7mm and 2 slow firing 7.7mm. This is very light armament, possibly the equivalent of 2 US .50s. By mid-war everybody felt the need to give their fighters 3 or 4 times this much firepower. Is it any wonder that the guns seem weak in AH?
Hooligan
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Hooligan wrote: Simply put, Chris Dunning is wrong.
This is possible. I'm checking out different sources in order to verify.
The C.202 is armed with 2 slow firing 12.7mm and 2 slow firing 7.7mm. This is very light armament, possibly the equivalent of 2 US .50s.
Nobody cannot admit it: IS a light armament.
But the comparison with 2 US .50s is quite opinable.
Is it any wonder that the guns seem weak in AH?
No wonder, but weak is quite different from useless...
You have to think about the whole damage modelling in AH, where gun effects are generally overmodelled. The feeling is that the only exception are just the poor Breda MGs. Consider besides that I'm not speaking about 202 armament in MA wich is a late war arena, but about 202 efficiency in CT Stalingrad!
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LUPO
TM 9-1985-6 Italian and French Explosive Ordnance (March 1953); 213 pages, 282 illus. Price 22.00 {Item No.2959}
Here is a document you can order that contains the hard data collected by the US on Italian armaments after the war. I own the Japanese, both Germans ones, a US one, and Hooli owes me the Brit one ;)
The Manual can be ordered from this link.
http://www.military-info.com/MPHOTO/P110.htm
They're very good. If you get it, I'll trade you copies of some of the others.
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I have the scans of the pages from the Manual he refers to that pertain to the debat at hand, namely the 202 mg ammo pages, with cross sections of the ammo, if anybody wants I can scan theam and post team hear.
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please do brady
one other thing elrkonig my squaddie was on an 8 kill sortie in a 202 when i logged off earlier
who'd a thunk it ............:eek:
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Originally posted by Hooligan
LUPO:
My rate of fire information is from Aces High (i.e. I measured it with a stop watch offline in AH). Part of the problem is that the 12.7mm guns are synchronized to fire through the propellor and this always results in a signifcant decrease in the rate of fire. In the few instances in which I have found Rate of Fire information from archival sources, the AH figures have always matched. I trust HTC's research much more than I trust Gustin's for example.
Hooligan
I'm very interested in this as I have found synchronised RoF information to be extremely rare. The only one I know of for certain is for the Soviet 12.7mm UBS, which fired at 800 rpm instead of 1,050 rpm for the non-synchro versions.
If you can publish or email to me what you have on this, and the sources, I would be very grateful.
Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://website.lineone.net/~a_g_williams
Gun and ammunition discussions at:
http://www.delphi.com/autogun/messages
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Thanks VERMILLION, this source is extremely interesting to me.
Unfortunatly they cannot ship orders to Italy anymore... :(
We are only shipping orders to customers in the United States, until further notice, because of the National Tragedy (09/11/01).
With the only exception is, that we will ship outside of the United States to United States Military personnel in military units at Military addresses (like APO's, and FPO's) (01/01/02). Note: Military personnel must send a photocopy of their ID card along with their order.
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Yep, Brady. I would be very interested to read that page.
Please if you can send me an e-mail or publish it here.
I greatly appreciate any new source about this argument. :)
Regards,
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Nobody cannot admit it: IS a light armament. But the comparison with 2 US .50s is quite opinable.
Sorry Lupo, it's a fact:
2 US 50 cals firing 43g projectiles at 800 rpm with muzzle velocity of 928 m/s deliver ordnace with 1062 kgm/s of impulse power per second (not sure what the proper english term is but it's "stopping power", mass x velocity). Combined impact of both 7.7 and 12.7 Breda guns would be just 904 kgm/s per second.
This, in turn, means that under ideal conditions (reported rate of fire/muzzle velocity) 2x7.7 + 2x12.7 Breda SAFAT MGs were just 85% as efficient as 2x US 50cal Browning M2 MGs. If you compare their kinetic energy (mass x velocity squared) delivered by each round Breda projectile gives only 53% of Browning one...
These are obviously just rough calcs omitting loads of factors but they give an idea of comparative gun efficiency...
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lynx, what about the explosive effect of Breda's HE rounds?
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Originally posted by MANDOBLE
lynx, what about the explosive effect of Breda's HE rounds?
The explosive content of a light round such as 30 or 50 caliber is not the destructive force as it is in a heavier round like 30mm-- heavy artillery. Comparitively, a light MG rounds kinetice energy bares the destructive force. The browning 50 cal is hard to beat in this category. Lots of muzzle velocity, heavy projectile, flat trrajectory...all this equals a very good AC gun platform.
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I will say it again:
EVERYBODY added explosive or incendiary effects to their MG ammo. In HMG ammunition this typically turns out to be about 1g of incendiary or explosive compound in a projectile (that is like 1/10 of a teaspoon, or .5ml). Everybody experimented with both HE and Incendiary rounds. Some preferred HE in their MG rounds and some preferred Incendiary.
There is nothing particularly unique about Italian MG rounds concerning their explosive content.
Hooligan
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I just got my main computer back up and working my hard drive went out on me and I am reloading everything right now if i do not get the pages scaned today i will do it tomarow.
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Originally posted by Hooligan
I will say it again:
EVERYBODY added explosive or incendiary effects to their MG ammo. In HMG ammunition this typically turns out to be about 1g of incendiary or explosive compound in a projectile (that is like 1/10 of a teaspoon, or .5ml). Everybody experimented with both HE and Incendiary rounds. Some preferred HE in their MG rounds and some preferred Incendiary.
There is nothing particularly unique about Italian MG rounds concerning their explosive content.
Hooligan
True enough. It is worth noting, however, that the Japanese were so impressed by the Italian 12.7mm HE rounds that they copied the design. (But then, the USA copied the Soviet design for the .50 API!)
Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://website.lineone.net/~a_g_williams
Gun and ammunition discussions at:
http://www.delphi.com/autogun/messages
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Tony Williams wrote:
True enough. It is worth noting, however, that the Japanese were so impressed by the Italian 12.7mm HE rounds that they copied the design.
So nothing is crystal clear, nothing is proved... :p
...we are just sure that, at the moment, 202 is quite useless even in a setup like Stalingrad :(
That's why Im asking: HT look into the modelling of MGs Breda :)
Perhaps the effectiveness is perfectly modelled in itself but is possible also that they didn't find a good compromise about realism (!) and playability (read: balance):D
BRADY:
Mate I'll wait until your computer will be ok.
I thank you very much.
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Hi LUPO,
the problem is strictly related to our late war plane set. I mean, if our gunnery model is built around heavy cannon armed fighters, it is normal to have very weak 2xMG fighters. I'm sure that a more balanced plane set would partially solve the problem.
In other words, and reasoning from an opposite point of view, if you give to the 2x12,7mm armed C.202 the right and historical hitting power (C.200s and C.202s were able to shoot down light and medium bombers) what will happen to the 4x20mm armed fighters lethality? They will be like laser armed space ships ... something like the F4U-1C or the other dweeb-hispanos-ships ;)
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GATT wrote:
I'm sure that a more balanced plane set would partially solve the problem.
Hi GATT,
absolutely agree with you. In fact the problem comes back to mind now that we HAVE a more balanced plane set. I'm speakin about CT Stalingrad, of course. The plane set there is quite balaced... Especially thinking that, you know, at that time most of the italian fighters involved in operations were MC200 and not 202... (open canopy, poor boyz).
In other words, and reasoning from an opposite point of view, if you give to the 2x12,7mm armed C.202 the right and historical hitting power (C.200s and C.202s were able to shoot down light and medium bombers) what will happen to the 4x20mm armed fighters lethality? They will be like laser armed space ships ... something like the F4U-1C or the other dweeb-hispanos-ships
Good question.
Now, thanks to the Hitechcreations and CT group, we have the chance to reflect more about how the gunnery is modelled in Aces High.
Of course the melting pot of fiters of early war and late war, all mixed thogheter in MA, called for some compromises. But when we build some quazi-historical plane set that compromises show their limits...
Perhaps the solution could be 2 possibility of settings for the gunnery lethality as we have in simulators like IL2: a "Main arena" setting end a "realistic" setting for historical planeset matchup.
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Hello all. This is very interesting thread. :cool:
I have a question regarding HE Machine gun rounds.
We all know the Browning gave the higher penetration value. If a Browning AP round hit a wing, and a Breda HE round hit a wing, would the Breda HE round make a slightly bigger hole on the surface?
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It depends Silo, there is no simple answer.
Did the HE MG round fuse/explode on contact outside the skin? Did it explode within the wing? Did it hit a wingspar? Did it just simply pass thru both sides of the wing without fuzing at all?
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I found another interesting opinion about Breda MG efficiency.
This is the testimony of an Italian ace, Lugi Gorrini. He shot down six B17 Flying Fortress :eek: and 13 more aircrafts (Hurricanes, Spitfires, Marauder, Mustangs, Thunderbolts etc.) flying with MC 202 and 205.:eek:
Gorrini wrote, telling about a fight against spitfires (Lybia 29 oct. 1942 ):
"Looking at the holes in the fuselage, wings and rudder of my 202 I considered I was lucky.
But the caliber of the 8 wing-mounted machine guns of the spitfire (7,69mm) isn't so much dangerous. After all I prefere my two Breda Safat, that can compensate their inferior volume of fire with superior power and better concentration of fire".
Of course this is just the opinion of a man, of a pilot, of an ace...
Sorry for the rough translation: I'm sure somone else can translate much better than me the expressions that Gorrini used: inferiore volume di fuoco- maggiore potenza e miglior concentrazione del tiro... Gatt or anyone else, any help is welcome... :)
After all nobody doubt about the fact that this armament was weak. Those man were heroes. But what I'm saying is that this armament was EFFECTIVE.
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LUPO, your english is IMHO good ;) Anyway, I think it is a lost war. Our plane set system, all togheter in the Main Arena that is, will always penalize 1940-41 fighter's lethality for the reasons I mentioned above.
Lets try to get more fighters ... like the incoming 109E, 110C and so on. Maybe something will change in the future ... who knows, maybe a Rolling Plane Set :eek: or weekly historical light scenarios.
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Hi Silo,
>If a Browning AP round hit a wing, and a Breda HE round hit a wing, would the Breda HE round make a slightly bigger hole on the surface?
Excellent question! :-)
The amount of explosive contained in the Breda shell was so small that it must have been fused to explode immediately on impact to do any noticable damage.
Let's assume all rounds hit a sheet of metal at a 90 degree angle. I'd expect these results:
Browning AP: Small hole.
Breda HE: Slightly larger hole with damage at the edges
20 mm AP: Slightly larger hole.
20 mm HE: Irregular hole, skin buckled
20 mm Mine: Slightly larger irregular hole, skin buckled.
Now let's assume a second sheet of metal is arranged 20 cm behind the first one. What would the damage to the second sheet look like?
Browning AP: Small irregular exit hole.
Breda HE: Some fragment damage, buckles, small irregular exit hole
20 mm AP: Slightly larger exit hole.
20 mm HE: Large area with fragment damage/buckling, perhaps small fragment exit holes
20 mm Mine: Large area buckled
(The buckling of the aluminium skin has a similar effect as tearing a hole into it as it's unable to carry loads in that condition.)
Next, let's see what happens if the two metal sheets are two surfaces of a small metal box, affixed by rivets, simulating the confined volume of an airframe's interior construction:
Browning AP: As before
Breda HE: As before
20 mm AP: As before
20 mm HE: Much larger ingress hole than before, skin torn and bent outwards, larger area of skin buckled
20 mm Mine: Even larger ingress hole, skin torn and bent outwards, edges of the metal sheet torn off the rivetting in some places.
(Boxes like these were actually used for ballistic trials in WW2.)
In short, the filling of the Breda HE projectile is too small to gain similar benefits as from 20 mm HE or mine shell rounds. Its destructiveness against the unprotected aircraft wing is probably similar as the Browning's, though the latter's higher kinetic energy might cause larger damage when it can be converted to damge fully, for example by striking a structural member of the airframe.
However, heavy machine guns (and even 20 mm AP rounds) weren't really effective against the wings of WW2 aircraft anyway - they were designed to attack critical components and could only achieve crippling airframe damage if a high number of hits was scored.
By contrast, 20 mm HE and mine shells were easily capable of destroying the airframe without hitting any critical components. The mine shells were designed to be much more effective than normal HE shells: Since they carried a much larger explosive charge, they could rip the aircraft skin off the rivets, creating a much more serious by weakening several cells of an aircraft's wing where a normal HE round would only have affected a single one.
This discussion of airframe damage is much simplified, of course, and the damage I described is an estimate based on what I've read on this topic. Don't take it as the last word, though I'm quite confident that my descriptions are fairly realistic :-)
Regards,
Henning (HoHun)
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Another interesting note that should be considered. Aces High models exterior ballistics well IMO. They take into account ballistic coefficients, drag, wind, etc.. They also attempt to model terminal ballistics well. Where I think the biggest improvement could be made is in the damage moodel, not the ballistics model. The 30 call birds like the early spit and hurri, the 202, the p-40B, etc all had 30 cals. They didnt create alot of structural damage, but they certainly were more effective than how they are in AH. Why? Because they affected the electronics, the Hydraulics, and other important systems within the AC. These system while not structurally related would certainly spell doom for a combat fighter. And all fighters were different. A watercooled AC would be in the same trouble against a Cannon armed AC as he would against a 8x 30 cal bird.
Just My Opinion. I have always wished for a very detailed damage model:) Wouldnt it be nice to see a few bullet holes in you instrument panel? Effectively taking out your instruments? Hydraulic fluid all over your windscreen (or in the pilots eyes).
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LUPO wrote :
Gorrini wrote, telling about a fight against spitfires (Lybia 29 oct. 1942 ):
"Looking at the holes in the fuselage, wings and rudder of my 202 I considered I was lucky. But the caliber of the 8 wing-mounted machine guns of the spitfire (7,69mm) isn't so much dangerous. After all I prefere my two Breda Safat, that can compensate their inferior volume of fire with superior power and better concentration of fire".
LUPO, I'm not sure which guns Gorrini is referring too (the 7.7mm or the 12.7mm) when he compares them to the British .303, but if he's talking about the 7.7mm light MG, he's mistaken.
The Italian 7.7mm round is identical to the British .303 round. It is in fact able to be used interchangeabley between the two guns, at least according to the documents that Brady posted today (I'm looking at the copies that Brady sent me, I'm not sure how many of the pages he posted on the BBS).
And your English is just fine :)
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Originally posted by LUPO
Gorrini wrote, telling about a fight against spitfires (Lybia 29 oct. 1942 ):
"Looking at the holes in the fuselage, wings and rudder of my 202 I considered I was lucky.
But the caliber of the 8 wing-mounted machine guns of the spitfire (7,69mm) isn't so much dangerous. After all I prefere my two Breda Safat, that can compensate their inferior volume of fire with superior power and better concentration of fire".
I read an account recently of a survey of the opinions on fighter armament of experienced RAF commanders (including Stanford Tuck) written in January 1942. This stated that many RAF pilots would have preferred the armament of the Me 109 because it was concentrated in the nose, even though it was much lighter than the armament of current RAF fighters.
The marked differences between the pilots which shot down aircraft and those which didn't was in their shooting accuracy. For the aces, concentrated fire was more useful than spread fire.
Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://website.lineone.net/~a_g_williams/
Military gun and ammunition discussion forum:
http://www.delphi.com/autogun/messages
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Vermillion,
Gorrini was referring to the nose mounted 2x12,7mm for sure. Italians were used to those weapons since the CR-32 and CR-42 biplanes (sic!) they used in the Spanish civil war during late thirties. Then they found the same armament on the G.50, C.200 and then C.202. Just a few C.202 mounted the 2x7,7mm on the wings, since those two 12,7mm were enuff to shoot down fiters and medium/light bombers.
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Yes, Vermillion, Gorrini was referring to the nose mounted 2x12,7mm.
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Ah! Then I would heartily agree :) 12.7mm MG's over a 7.7mm light MG any day of the week.
Was just sharing the info that the Italian 7.7mm was acutally the same round as the British .303 Which I didn't know until I read it yesterday, while looking up the info for LUPO.
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Tks Vermillion to share infos.
Tomorrow (jan 24, GMT+1) I sould have some new infos about Breda 12,7 and some interesting pics too. Of course I'll post it here.
Learning quite a lot thanks to this thread... :)
Anyway I'm not sure that HT will appreciate the effort giving to me a positive answer about what I'm asking for...
:rolleyes:
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Originally posted by Vermillion
Was just sharing the info that the Italian 7.7mm was acutally the same round as the British .303 Which I didn't know until I read it yesterday, while looking up the info for LUPO.
So was the Japanese Navy 7.7mm - but the Japanese Army's 7.7mm was different....
Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://website.lineone.net/~a_g_williams
Gun and ammunition discussions at:
http://www.delphi.com/autogun/messages
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Isnt it curious that AH has it reversed, wing mounted guns are much better then center mounted weapons.
Just compare any current Spit vs any Bf109 with only the 20mm engine cannon.......
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Originally posted by GRUNHERZ
Isnt it curious that AH has it reversed, wing mounted guns are much better then center mounted weapons.
Just compare any current Spit vs any Bf109 with only the 20mm engine cannon.......
I'd probably venture to guess that it is because dispersion is calculated by gun, not by mount & gun. I'm not sure if it is so but it would make much sense to me programming wise.
If the difference in dispersion between wing mounted and nose mounted (especially with the twins which don't have an engine on the nose) was significant in reality, then centerline mounts are penalized a bit perhaps.
Is the .target command available online? If it is, it would be simple to test the difference between a wing mount and a centerline mount. Take a Spit and a P-38 and get a GV or something to damage the spits other cannon. Then it's just firing a lot of rounds and comparing the results.
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Hi SageFIN,
this is another really intersting question. I'm becoming more and more passionate in understanding how gunnery is conceived and works in AH. So I want to put this question to HTC: Is dispersion in Aces High calculated just by gun, or by mount & gun?
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Dang I just wish one day our graphics will look like that guncam footage was.
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Just compare any current Spit vs any Bf109 with only the 20mm engine cannon.......
Anybody who does this will discover that much to their SURPRISE:
2 20mm cannon and 4 lmg are better than
1 20mm cannon and 2 lmg
Who would have ever guessed!
Hooligan
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Some news here!
First of all I have to say that I verified the data that Hooligan kindly provided about Breda MG:
Hooligan wrote:
Breda 12.7mm 36.7g, 760m/s, 575 rpm. [...]
The very poor rate of fire on the Breda 12.7mm especially hurts.
I asked to an expert (Piero Lomazzi, historic and journalist for "Aerofan", one of the best source of information about italian armament on planes). He sent me a lot of interesting infos and pics. So I discovered that... the rate of fire of Breda SAFAT wasn't 575 rpm, BUT 700 rpm!!!
Other data Hooligan posted were correct. I hope that my scanner will be ok soon and I'll post some nice pics here.
Second: I did a test. It's not a REAL test. I mean it's just a film that shows how effective the MG of the 202 are. If interested, have a look and try yourself. Second and third pass are... frustrating? I wait for comments.
(Don't look at my BFM skillz, I was typing and flying at same time :D )
Click here to download the film (http://lupoweb.supereva.it/202TEST.zip)
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LUPO please pay attention:
1) 575 is the rate of fire for the Breda 12.7mm IN ACES HIGH. Or to be more precise, when I measured it over a year ago it was then. This is easy to measure. Feel free to measure the rate of fire yourself in the current version and let us know what you discover.
2) The cowl mounted 12.7mm machine guns are SYNCHRONIZED to fire through the propellor disk. This slows the rate of fire. 700 is the rate of fire for an unsynchronized gun.
Perhaps Mr. Lomazzi has some information about the synchronized rate of fire for this gun. If you can come up with an archival document showing the the synchronized ROF for Breda's I am certain that HTC would love to see it. I know that I and Tony Williams would be interested also.
By the way I can't download your film.
Hooligan
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I remember in the C-hog days, I once emptied an entire c202 ammo on KBMAN's chog.. he only lost a flap. Was hilarious :)
One thing I do find very interesting though, is that the 202 in the MA really has no bite.. but in the CT, when I am whacked to TCP connection, they can smack a yak9t with 2 good bursts. Tried that in the MA, the entire ammo load on hits (all below d200 in both cases) on a yak, and it flew away unharmed.
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Trouble downloading the film - SuperEva not very willing today, I'm afraid...
:(
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Hmm.. I've killed a dhog or chog not sure which one it was with less than 1/4 ammo load of the 202. I only fly the version with the 2x7.7 only!
I've done a 4 kill sortie in 202 and still have ammo left..
I've killed a b17 with 202 although THAT took 3/4 ammo sprayed to the tail and wingtip at close distance. For some reason the pilot didn't bother to shoot me during the 20-30 seconds I hung there shooting his wingtip.
One pass kill in 202? Must have been already damaged part..
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Many interesting things here.
Rgr Hooligan. I thought you were speakin about REAL SAFAT rate of fire. It's nice from your side to specify this now. Of course I'll check the ROF in AH, even if I haven't any reason to doubt of the result of the test you already did.
But now, pay attention, this means they're using "syncronized ROF data" which are INFERIOR to the ROF data I found (non synchro?).
Now, OF COURSE real Breda-SAFAT guns were syncronyzed in order to fire through the propeller. As you know the two 12,7 were installed immediatly ahead of the cockpit. At the beginning, when mounted on the MC200 "Saetta" the SAFAT had provision for 310 rounds per gun with the unusual feature of an ammunition indicator in the cockpit wich registered the number of rounds remaining per gun. In the MC200 the capacity was increased to 370 rpg.
Early production series of MC202 retained the original Saetta armament of twin 12,7-mm Breda SAFAT guns, ammunition capacity being increased to 400 rpg, but later production series (e.g. Serie IX-XI) also carried a 7,7-mm gun with 500 rounds in each wing (non syncro), while one batch carried a 20-mm Mauser MG 151 cannon (with 200 rpg) under each wing (non synchro).
(I have a picture of the cannon-202 but my scanner doesen't want to work :( )
BUT... :rolleyes:
The data I found indicated a ROF of 700 for the 12,7 with a "starting velocity" (velocità iniziale) of 760 m/s (meters per second).
I'd be glad to find an archival document showing the synchronized ROF, even if all the document I found until now are indicating the ROF whitout any specification.
And of course I'd be happy to share it with the community.
So, it comes to mind another question for HT staff:
Do they have data for ROF of each gun based on synchronyzed and non syncronyzed guns? Are this data used in order to model simulated ROF different for guns shooting through the propeller or not?:confused:
If the answer is NOT, perhaps the current AH ROF for the SAFAT is uncorrect.
This also remind me the another questions I posed above:
Is dispersion in Aces High calculated just by gun, or by mount & gun?
Those question are posed because of a genuine interest both for historical data and for the complex simulated world HTC created.
The link works. But SuperEva is a naughty girl... Try again or, BETTER, just get a 202 and fly it in MA :D
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BTW this is a pic of the MG we're speaking about...
(http://lupoweb.supereva.it/Breda01.gif)
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Well, I've read almost everything about the C.202 and the C.205 and I've never ever seen something about synchronized rate of fire. However, whats interesting is what I've read on a plate fixed to the cockpit of a Series 5 fighter (dont remember if a C.205 or a G.55 cockpit): "Dont fire with MG when RPM are between X and Y".
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Hooligan:
From Tony Williams:
I read an account recently of a survey of the opinions on fighter armament of experienced RAF commanders (including Stanford Tuck) written in January 1942. This stated that many RAF pilots would have preferred the armament of the Me 109 because it was concentrated in the nose, even though it was much lighter than the armament of current RAF fighters.
But what would the actual Spitfitre pilots know, they were too busy flying the planes and fighting in them.....
The only people who know anything about WW2 fighters are people who play games. Right Hooligan?
:rolleyes:
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GATT wrote:
I've read almost everything about the C.202 and the C.205 and I've never ever seen something about synchronized rate of fire.
Neither did I! ;)
Do you think that somone could give us an answer to those questions, GATT?
GRUNHERZ wrote:
I read an account recently of a survey of the opinions on fighter armament of experienced RAF commanders (including Stanford Tuck) written in January 1942. This stated that many RAF pilots would have preferred the armament of the Me 109 because it was concentrated in the nose, even though it was much lighter than the armament of current RAF fighters.
The Italian ace Gorrini wrote exactly the same. He preferred his 12,7 to the spifires armament because of the better concentration of fire. That's the reason why I posted the question above:Is dispersion in Aces High calculated just by gun, or by mount & gun? (Repetita iuvant...) Nobody knows?
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Hi Gatt,
>Well, I've read almost everything about the C.202 and the C.205 and I've never ever seen something about synchronized rate of fire.
Let's assume that there's only one point during each rotation of the propeller where the gun is allowed to fire.
With the engine at continuous power at 2300 rpm and a gear ratio of 1:1.685, the longest possible delay (just short of one full revolution) would be 44 ms, extending the interval of 86 ms between 2 shots of the free-firing gun to a total of 130 ms - yielding a rate of fire of 460 rpm. However, on the average, only half a revolution would be spent waiting, so the interval would be 108 ms for a rate of fire of 560 rpm.
With the engine at 2800 rpm, the average synchronization delay would be 14 ms for a rate of fire of 600 rpm.
If the synchronization system was more sophisticated in being able to trigger each 120 degrees of rotation (between the 3 propeller blades, that is), the average delay would be down to 4.7 ms for a total rate of fire of 660 rpm.
I don't know about the Italian synchronizer gear, but the German weapons were electrically triggered and could have allowed multiple trigger actions for each revolution. I've got a picture here of a Me 109E on the factory range, with a cardboard disk mounted instead of a spinner that shows 3 sets of holes at 120 degree intervals. Unless the photograph was staged for propaganda purposes (which is a possibility), I'd believe that the Messerschmitt at least had "best case" synchronizer gear :-)
(The Macchi in Aces High on the other had seems to have the "worst case" synchronizer gear that's only capable of triggering once every 360 degrees.)
Another interesting aspect of the Messerschmitt photograph is that there are actually 2 sets of holes each 120 degrees that are about as far apart as the two machine guns on the cowling. Obviously, both guns were triggered simultaneously so that they hit the rotating disk in different places.
Regards,
Henning (HoHun)
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hohun can you post that pic or do you have a link?
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LUPO:
I believe the 7.7mm guns are mounted inboard of the propeller tips so they are also synchronized (accounting for their poor rate of fire also).
As far as whether or not the Breda's were synchronized: There is no question that they were. Machine gun rates of fire were not exact. If the specified rate of fire for a normal breda was about 700 then this really means something like a range of about 650-750 (depending upon any number of things). Propeller RPM could be theoretically be adjusted to for a given rate of fire, but without some sort of synchronization apparatus then there would be no way to prevent the guns from being fired at the exact moment when a propeller blade would be hit. Further, the variation in machine gun rates of fire would mean that there is no way to guarantee that machinegun would fire at the desired rate unless some sort of synchronization gear were employed. The Breda guns on the 202 must have been synchronized.
I have no reason to believe that HTC’s ROF information for Breda MGs is wrong. Do you?
If you use the target command offline and play with convergence settings I do believe that you will find that dispersion of center mounted guns is noticeably less than dispersion for wing mounted guns. This is easy enough to test.
GRUN:
You seem to be implying that something is wrong with the Geman guns in AH. And you are basing this on the rather ambiguous statement that some UK pilots stated that they thought they would prefer the centerline gun mountings of the 109 (pilots who did not in fact ever fire the 109 gun set against enemy aircraft). Have you ever considered just letting a gunnery thread go on without contributing your obligatory whine about LW gun modeling in AH? If you really think that center mounted guns suffer some disadvantage vs. wing mounted guns in AH I suggest you compare the 4 .50s in a P-51B to the 4 .50s in a P-38, particularly at longer ranges.
Hooligan
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Hi Wotan,
>hohun can you post that pic or do you have a link?
The picture can be found in "Me 109 - der siegreiche deutsche Jäger" by NSDAP-Reichsbildberichterstatter Professor Heinrich Hoffmann, München, 1941.
Unfortunately, I don't have a scanner so that I can't post the image.
Regards,
Henning (HoHun)
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Hi Hooligan,
>And you are basing this on the rather ambiguous statement that some UK pilots stated that they thought they would prefer the centerline gun mountings of the 109 (pilots who did not in fact ever fire the 109 gun set against enemy aircraft).
There's nothing ambiguous about the RAF pilots' statement. They saw a major advantage in having the armament concentrated close to the centreline of the aircraft, and considered this advantage to be large enough to overcome the disadvantage in weight of fire. Though they couldn't back up the latter point with combat experience, this comment was based on their estimate of the effectiveness of their wing guns and the difficulties associated with them. In short, I think they knew well what they were talking about.
It's interesting that the Luftwaffe pilots had the opportunity to compare wing cannon to nose cannon directly when the Me 109F was introduced. Mölders' comment "One in the nose is better than two in the wings" ironically mirrored the RAF pilots' point of view exactly.
(Though initially other Luftwaffe pilots had some doubts, this was because the first batch of Me 109Fs was delivered with a 15 mm cannon, not with the 20 mm that became standard later.)
Regards,
Henning (HoHun)
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Well, all Germans were not so sure about this, IIRC Galland stated something like "flying targets are usually shot with the shotgun".
gripen
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(Though initially other Luftwaffe pilots had some doubts, this was because the first batch of Me 109Fs was delivered with a 15 mm cannon, not with the 20 mm that became standard later.)
I thought the very first 109Fs had the MG FF 20mm in the nose.
I think the German pilots may have thought 1 MG151 in the nose was better than 2 MG FF in the wings.
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Originally posted by Hooligan
I have no reason to believe that HTC’s ROF information for Breda MGs is wrong. Do you?
There's no question that the cowl guns were synchronized. But as Ho Hun pointed out, the resulting ROF would vary depending on the method of the synchronization. Do you have any reason to believe that HTC would have exact info about the synchro capabilities of the MC. series? I don't think that such information is easily come by, as gatt's and LUPO's ventures with Macchi documentation have pointed out. Also, the planes are quite numerous (and some of them very exotic).
Sooo...
I would guess that each synchronized gun in this game has it's ROF reduced to a same set percentage, as it would probably be the most easily implementable way. This should be easily verifiable within the game. I remember that at least the ROF of synchronized Mg151's has been tested and compared to the unsynchronized values from books. Can't remember what the results were though, it was quite some time ago.
If I would care one bit about the way synchronized guns are implemented in the game, I'd probably test them all myself. However, I prefer planes with .50 and Hispano wing armament (or nose, as with the P-38 and Mossie), so for me it's a non-issue. LW enthusiasts might be interested.
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Hi Gripen,
>Well, all Germans were not so sure about this, IIRC Galland stated something like "flying targets are usually shot with the shotgun".
Galland's final reply to Mölders' "One in the nose is better than two in the wings" was "I'd rather have all three". Accordingly, Galland did not pull out the "one in the nose" when he flew his unique F-6/U conversion since he didn't actually oppose Mölders - but his real concern were bombers. Against fighters, accuracy had priority, against bombers, it was weight of fire.
Regards,
Henning (HoHun)
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Hi Nashwan,
>I thought the very first 109Fs had the MG FF 20mm in the nose.
You're right, but the pilots knew that the MG FF/M was an interim armament until the new MG151 became available. "First batch" was the wrong term, I was actually thinking of the first significant variant of the Friedrich.
Regards,
Henning (HoHun)
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Hooligan wrote:
I believe the 7.7mm guns are mounted inboard of the propeller tips so they are also synchronized (accounting for their poor rate of fire also).
Negative. You're wrong. During WWII the 7,7 mm SAFATdidn't found any application, as a synchronyzed gun for firing through the propeller disc . The 7,7mm were used in combination with the 12,7 mm. But 7,7mms were installed in the wings and firing OUTSIDE the propeller disc.
Hooligan wrote:
I have no reason to believe that HTC’s ROF information for Breda MGs is wrong. Do you?
Mate, try to understand. I don't believe neither that HTC information are simply wrong nor that there's a conspiracy against italian planes in AH. This is simply stupid.
Aces High was the first on line simulator wich modelled italian aircraft and, as an italian enthousiast of flighsims, I greatly appreciate their job.
I'm simply trying to understand if the gunnery of 202 in Aces High is historically accurate. If it was so weak in real life as it is in the simulation.
And, looking at number and the kind of planes the 202 was able to shoot down during WWII, I believe is possible that, becouse of the compromises due to the presence in the AH plane-set of aircrafts of different period of the war, the gunnery of some planes is exaggerate whilst the gunnery of others is less effective than it was.
Punt.
Sage FIN wrote:
I would guess that each synchronized gun in this game has it's ROF reduced to a same set percentage, as it would probably be the most easily implementable way.
Affirmative, SageFIN. I found a very intersting link about how different parameters of planes are modelled in CFS.
Click here to acces the site (http://www.avhistory.org/)
This site is about creating flight models for the computer that fly within 1% of the performance of their real world counterparts.
One of the infos I got there is that for the guns that fire through the propeller, they reduce the rate of fire by 15%!!!
This is perhaps historically accurate, altough 15% could be considered as a rough approssimation.
If Aces High use the same parameters our beloved 202 will remain, as it is, toothless. :o
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LUPO:
Concerning the 7.7mm:
I don't have access to much information about the c.202, so I can't tell for sure but those 7.7mm guns look pretty far inboard to me. Perhaps they are just past the spinner. However the ROF in AH is 800. This seems rather low for a non-synchronized gun (Gustin states a ROF of 900 for these).
Sage:
I am certain that HTC does not reduce ROF for all guns by the same percentage.
Mg151s in AH have an ROF of 700 normally and 630 when synchronized (inboard guns in the FWs). Presumably the Bredas would go from 700 to 630 also if all synchro guns were uniformly reduced. I also measured all the ROFs in HTC prior work (Warbirds) and synchro/non synchro ROFs there definitely were not proportional in uniform ratios.
I have looked into aircraft weapon information quite a bit and one of my conclusions is that HTC knows a lot more about it than I do. However they determined their ROF information I expect that it is quite accurate.
Also, I expect that if it is wrong they will quickly fix it if somebody comes up with data to show them.
Hooligan
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There's a lot of factors that go into how synchronization affects rate of fire. Just changing your engine RPM affects rof, but trying to create a real model of interruptor gear goes well beyond the point of diminishing returns. In AH, all synchronized guns are treated the same with a fire rate set to 90% of the weapon's unsynchronized rof. In AH, the unsynched 12.7mm Breda has a rof of 650 rpm. 650 * .9 = 585 which is the rate of fire for the synched installation you see in the Macchi's.
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I wonder if this post will break 100? hmmmmmmmmmmmmm
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HoHun,
IIRC Galland rated armament of the Bf 109E better than Bf 109F? One of the main reasons why Galland wanted to get more Fw 190s was much better armament and therefore much better possibilities to get hits (thats why he said shotgun). IMHO very few pilots were precision shooters like Mölders or Udet so generally more guns in the what ever position (wing or fuselage) was better for an average pilot.
gripen
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Well, Pyro, first of all thanks a lot for the quick and precise answer! I know this isn't a big issue so your answer is also a proof of the attention that HTC is tributing to his customers. Thanks again: now I'm starting to understand how the whole thing works... :)
I have to say that the data I found are slightly different from the AH data for the two Breda MGs (if, as Hooligan states, 7,7 rof in AH is 800). According to Mr. Lomazzi usynched 12,7 had a rof of 700rpm, and 7,7 of 900rpm.
Gustin's site report the same data, as follows:
Name Breda-SAFAT
Ammunition 12.7 x 81SR (36.7 g)
Rate of Fire 700 rpm
Muzzle velocity 760 m/s
Weight 29 kg
-----------------------------
Name Breda-SAFAT
Ammunition 7.7 x 56R (11.3 g)
Rate of Fire 900 rpm
Muzzle velocity 730 m/s
Weight 12.5 kg
I repeat, I know isn't a big issue, but please consider the possibilty to fix it. I'll be glad to send any info, if needed.
With regard,
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Hooligan wrote:
I don't have access to much information about the c.202, so I can't tell for sure but those 7.7mm guns look pretty far inboard to me. Perhaps they are just past the spinner. However the ROF in AH is 800. This seems rather low for a non-synchronized gun (Gustin states a ROF of 900 for these).
You're right, Hooligan: the guns ARE just past the spinner.
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Pyro:
Thanks a lot for clearing some of this up.
Hooligan
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Hi Gripen,
>IIRC Galland rated armament of the Bf 109E better than Bf 109F?
I've never read he actually stated this. What is clear is that he did everything in his power to increase fighter armament. He did never replace the engine cannon, but just added more firepower.
>One of the main reasons why Galland wanted to get more Fw 190s was much better armament and therefore much better possibilities to get hits (thats why he said shotgun).
The Fw 190 had two inherently accurate centreline cannon opposed to the single one of the Me 109. I think Galland's preference for the Fw 190 was due to their overall suitability as bomber destroyers, not merely due to their greater firepower.
>IMHO very few pilots were precision shooters like Mölders or Udet so generally more guns in the what ever position (wing or fuselage) was better for an average pilot.
The pilot had to spend much more effort to getting the burst in at precisely the right range with wing guns than with centreline guns. It was much easier with centreline weapons:
"I had previously flown the twin-engined P-38 Lightning where the nose-mounted armament made for an ideal gun platform. Ranging wasn't the problem it was with the P-51 and other fighters which had wing-mounted armament where the fire converged."
(Major Robert Riemensnider, USAAF, quoted from Roger Freeman's "Mustang")
I think with Luftwaffe, RAF and USAAF all in agreement, the case should be pretty clear :-)
Regards,
Henning (HoHun)
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...sorry, I meant the "synchronisation" post to be attached to this thread, but I hit the wrong button :rolleyes:
As one theme in this this thread is to do with optimum fighter armament, you might be interested in the long debate which took place here:
http://forums.delphiforums.com/n/mb/message.asp?webtag=autogun&msg=97.1
The first post expresses my views on the subject.
Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://website.lineone.net/~a_g_williams/index.htm
Military gun and ammunition discussion forum:
http://www.delphi.com/autogun/messages
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VERY interesting, Tony.
Thanks. Learning a lot :)
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HoHun,
AFAIK Galland keeped his Bf 109E long time because he rated it's armament better and he also got a special Bf 109F with wing cannons.
And I have not disagreed that centerline position for guns was best, certainly a Spitfire with all armament (2x20mm + 4x7,7mm) in the centerline would have been better than a Spitfire with wing armament (and not only because concentrated firepower but also for less inertia). But the comparison was between the Spitfire vs Bf 109F (or G) or the Bf 109E vs Bf 109F. And I believe that in the both cases an average pilot could get more hits with a plane with wing armament because most bullets miss anyway and therefore combination with better firepower is better.
I believe that only best shooters could really benefit from the centerline armament for others it was pretty much same if same firepower was available. Nowadays most quoted pilot's comments are from ace pilots (best shooters in other words) therefore it is a bit missleading to use their opinions for general conclusions. Galland's comment about flying targets and shotgun tells a lot about normal situation during WWII.
gripen
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Hi Gripen,
>AFAIK Galland keeped his Bf 109E long time because he rated it's armament better and he also got a special Bf 109F with wing cannons.
I've not read anything about Galland retaining a Me 109E. His special Me 109F variants included the Me 109F-2/U with the cowl machine guns upgraded to 13 mm calibre, though it would have been considerably easier to mount them in the wings (like the MG FF/M of his Me 109F-6/U). The F-6/U as the wing cannon aircraft you're referring to did not replace the engine cannon, but merely augmented it with more cannon that had to be mounted in the wings as they were unsuitable for synchronization (and wouldn't have fit into the cowling anyway).
Galland's quest for firepower included the addition of wing guns, but all his aircraft kept the accurate centreline guns. He certainly was aware of their advantages.
>But the comparison was between the Spitfire vs Bf 109F (or G) or the Bf 109E vs Bf 109F. And I believe that in the both cases an average pilot could get more hits with a plane with wing armament because most bullets miss anyway and therefore combination with better firepower is better.
You're talking about a quantitative difference, but in fact there was a qualitative difference between centreline armament and wing guns: While the former's cone of fire coincided with the sight line at any range, the latters' did so only at convergence range. This is the problem Major Riemensnider mentioned - wing guns don't just give you more firepower, but they introduce a new aiming problem.
If you look at the harmonization procedures, it becomes clear that the goal was, even with wing guns, was to keep the resulting pattern as small as possible. The desired result was dense fire, not a "shotgun effect". A "shotgun effect" could, after all, have been produced by suitable mis-alignment of a centreline weapons set, too - but instead, the weapons were set to fire parallel or to converge at very long range.
In short, the "shotgun" comparison is misleading. Galland's exmple of the "shotgun" (20 mm MG FF/M) may have illustrated his line of thinking when he compared it with a hunting rifle of greater accuracy, but smaller calibre (15 mm MG 151). However, he was advocating higher firepower, not simply a large and poorly centered pattern as you'd get from wing guns.
Regards,
Henning (HoHun)
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As I have mentioned I was in the PRO last week, and one of the files was a very comprehensive debate on the harmonisation issue. No space to go into all of it here, but it seems that in 1942, two years after deciding to harmonise RAF day fighter guns at 250 yards (night fighters at 150) a decision was taken to spread rather than concentrate fire, with the guns set to deliver a cone of just under one degree.
The reason was that deflection shooting was so poor that most pilots could hit nothing beyond a 5 degree cone behind the target. In fact, results of deflection shooting against the little 109 were so poor that most pilots didn't even bother to try. It was reasoned that with a wider spread of fire, pilots would stand a better chance of scoring hits in deflection. The lack of results at long range was put down to poor aiming rather than lack of concentration of fire.
Of course, British fighters then had a heavier gun armament than the German ones so could afford to spread the fire around a bit without losing effectiveness.
The plot thickens...
Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://website.lineone.net/~a_g_williams/index.htm
Military gun and ammunition discussion forum:
http://www.delphi.com/autogun/messages
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Originally posted by SageFIN
I'd probably venture to guess that it is because dispersion is calculated by gun, not by mount & gun.
It should be easy to test, 109G10 1x20 and then 109G10 3x20.
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HoHun,
IIRC Galland claimed that he keeped Bf 109E long time in his memories (or someone else famous german pilot).
And you don't need to prove advantages of the centerline weapons because I fully agree (how many times I should state this...). But this discussion started from a claimed claimed opinion by unnamed pilots who thought that 1x20mm + 2x7,9mm in the centerline was better than 2x20mm + 4,7,7mm in the wings. And I believe that for large majority of the pilots later combimation was better simply because better firepower, therefore shotgun example is also very valid.
gripen
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Hi Tony,
>No space to go into all of it here, [...]
Will we see it on your site then? :-)
>but it seems that in 1942, two years after deciding to harmonise RAF day fighter guns at 250 yards (night fighters at 150) a decision was taken to spread rather than concentrate fire, with the guns set to deliver a cone of just under one degree.
I've to admit that I'm surprised to hear that: With a cone of fire of one degree, the pattern at the 250 yards distance would have a 4 m diameter. Assuming the normal dispersion was 0.5 degrees, the bullet density - and accordingly, the lethality - would be just 25% of what it was before. Even comparing it to the Me 109F with half the number of guns, it would only be 50%.
To me, this order sounds like it was born out of desperation. Do you have any information on how long that order remained standard procedure?
Regards,
Henning (HoHun)
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Hi Gripen,
>IIRC Galland claimed that he keeped Bf 109E long time in his memories
Galland stated that he scored 28 victories in one particular Me 109E-4, but I didn't get the impression he stuck to the type after the Me 109F appeared.
>And I believe that for large majority of the pilots later combimation was better simply because better firepower, therefore shotgun example is also very valid.
The point is that the better firepower of wing cannon only materialized at convergence range, while at all other ranges, the firepower of centreline armament was superior. With the sight on target, wing guns could still miss the target to the left and right if it wasn't exactly at convergence range. Firing centreline armament with the sight on target, it was likely that the entire burst was on target, too. Centreline armament made shooting easier - that's what Riemensnider is referring to.
When Galland advocated firepower, he meant firepower - not wing guns. As far as I know he never opposed Mölders' "One in the nose is better than two in the wings", but he was neither content with one in the nose nor two the wings but wanted to get all of them, and heavier machine guns as well.
Regards,
Henning (HoHun)
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Hooligan:
Not german guns modeling at all. But I dont think the advantages of center mounted guns transfer well from RL to AH.
This gous for all the planes with central armament.
Why in gods name do you allieds always think its a german plane whine? :)
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Hohun,
In the Caidin's Messerschmitt book Galland states that probably Mölders was only one in the Luftwaffe who was happy about the change from 2x20mm MG FF to 1x15mm MG 151.
And for one reason or another you don't seem (or want) to understand my point (and actually Gallands point) that for an average pilot amount of firepower (in what ever position in the plane) was more important than concentration of the firepower because average shooting skills were quite poor (shotgun effect). Also it should be noted that centerline armament has advantage from short range but from long range it's pretty much same because shooting was very unaccurate anyway even in the case of the best shooter.
There were pilots who could shoot very well with the Spitfire like Beurling. Generally skill of the pilot and amount of the firepower are more important issues than optimal position of the armament in the plane.
gripen
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Hi Gripen,
>In the Caidin's Messerschmitt book Galland states that probably Mölders was only one in the Luftwaffe who was happy about the change from 2x20mm MG FF to 1x15mm MG 151.
Caidin states that several pilots, among them Mölders, preferred the new armament, while other considered it too light. As I mentioned initially, this opinion was formed by the comparison of 20 mm cannon to the lighter 15 mm cannon. Later this cannon was replaced by a 20 mm, and the only complaints about Me 109 firepower from then on concerned effectiveness against heavy bombers.
Remember that we were talking about the RAF pilots' view who said they'd have preferred the Me 109's armament over the Spitfire's. In January 1942, they were facing Me 109s armed with 20 mm cannon, and they reached the same conclusion as Mölders had reached before.
>And for one reason or another you don't seem (or want) to understand my point (and actually Gallands point) that for an average pilot amount of firepower (in what ever position in the plane) was more important than concentration of the firepower because average shooting skills were quite poor (shotgun effect).
Since Caidin quotes Galland's comparison as one of "rapier" and "broadsword", Galland's point was power even by that source. Galland's first conversion, the Me 109F-2/U, boosted firepower as well, and without relying on wing guns. Wing guns would have been easier to implmeent and would also have provided greater firepower since the MG17 cowl guns could have been retained, yet Galland had the centreline guns upgraded.
I'm afraid your point and Galland's point are not quite identical.
I know what you mean by "shotgun effect", but the problem is that not only the density of fire decreases, but that for most distances, the centre of gravity of each wing's guns is laterally off target. Luftwaffe pilots sometimes witnessed tracers missing their aircraft narrowly on both sides of the fuselage - that's what happened when the enemy had his sights on them perfectly, but wasn't exactly at convergence range.
Centreline armament made hitting easier even for inexperienced pilots as it eliminated the convergence-induced range problem entirely. This was quite valuable as an inexperienced pilot could close in to compensate for poor marksmanship without having to deal with lateral strike point offset and two separate centres of gravity for his fire.
Regards,
Henning (HoHun)
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Originally posted by HoHun
>but it seems that in 1942, two years after deciding to harmonise RAF day fighter guns at 250 yards (night fighters at 150) a decision was taken to spread rather than concentrate fire, with the guns set to deliver a cone of just under one degree.
I've to admit that I'm surprised to hear that: With a cone of fire of one degree, the pattern at the 250 yards distance would have a 4 m diameter. Assuming the normal dispersion was 0.5 degrees, the bullet density - and accordingly, the lethality - would be just 25% of what it was before. Even comparing it to the Me 109F with half the number of guns, it would only be 50%.
To me, this order sounds like it was born out of desperation. Do you have any information on how long that order remained standard procedure?
There was no indication of any change from that point on. However, it was a large and messy file, full of correspondence, diagrams and so on, and I was (as always) pressed for time at the PRO. So much to see, so little time!
Incidentally, some very interesting points were made about the sighting issue. One was that positive or negative G in combat also caused guns to shoot low or high. This was another reason given for widening the spread of fire. Diagrams showed the cones of fire from concentrated and spread guns in various circumstances. Reading between the lines, I guess that the RAF found the Hispano so devastatingly effective against fighters that two or three hits would usually do the job, so it was better to spread the fire and score a couple of hits than concentrate it and miss entirely.
Another interesting point of detail concerns harmonisation for range. It was pointed out that the guns could be set to fire "level", which means that the sights would be aimed downwards to harmonise with them, or the sights could be set level and the guns aimed up. The latter was recommended as more useful in dogfighting (although obviously not in ground attack).
Another point at random was that the harmonisation diagram for the Spitfire with two 20mm and four .303 had the Hispanos harmonised at different ranges; drawings at different ranges showed a vertical as well as horizontal dispersion. Then there were the early 8 x .303 diagrams - did you know that four different harmonisation patterns were being tried by different squadrons in early 1940? The problem was, as Dowding dryly observed in a note, that the Luftwaffe refused to cooperate in the experiment, as they would insist on crashing their planes into the sea so they couldn't examine the wreckage....
Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://website.lineone.net/~a_g_williams
Gun and ammunition discussions at:
http://www.delphi.com/autogun/messages
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HoHun,
I dug a bit and it's a Joe Christy's book (Luftwaffe Combat Planes and Aces) which contains Gallands and also Walter Oesaus views:
"But with only a single nose cannon and pair of rifle caliber machine guns, it (F) did not have the firepower of the E. Veterans like Mölders and Udet prefered that way. The F climbed well, turned tightly and was the last classic Messerschmitt dogfighter. This was fine, if one were an experienced ace, but Adolf Galland and Walter Oesau clearly saw that as the war progressed the number of veteran marksmen would dwindle, while the ranks of raw recruits, many of them product of accelerated flying school crash programs, would swell. These new pilots would know very little of unerring marksmanship. They would have their hands full just flying the airplane. They would invariably be outnumbered, and Galland and Oesau didn't want to be outgunned too. They demanded that the new 109s carry more firepower, at the expense of performance, and Oesau went so far as to refuse to fly the 109F for several months, even though his wing, JG 1 had already re-equipped with it."
Galland and Oesau certainly knew the advantages of the center line armament and knew that ace level pilots (like themselves and Mölders) could utilise these advantages (note that this had been my point right from the beginning). But for an average pilot (who certainly was not an ace) armament of the E was better because firepower was better and therefore possibilities to got hits were better too (because firepower is better then Gallands shotgun for the flying targets claim fits here well). I afraid that my points are quite identical with not only Galland but with Oesau too. Also I don't see any reason why Galland would have wanted centerline cannon removed from his plane when he got wing cannons (also for center of gravity reasons), he wanted firepower and he also saw firepower of the E better than the F's (despite better fire rate and muscle velocity of the MG 151, 15 or 20mm).
I remember well that we are comparing the Spitfire and Bf 109. Some good shooters in the RAF might have benefited from the 1x20mm + 2x7,7mm in the centerline at close range shooting but most would not. And at higher range there is not much difference, because then shooting is very unaccurate anyway. The firepower of the Spitfire was about twice as large than the F's or early G's so for an average pilot possibilities to get hits were therefore better.
Generally I see your views about accuracy of the air gunnery quite strange, even in the case of the best shooters accuracy was very bad, only small percentage of the bullets hit the target. In the Finnish Air Force main difference between the aces and average pilots was shooting range; the aces were good shooters and shot from very close range and therefore they could benefit from centerline weapons. Average pilots shot from higher range and and were not so accurate shooters, therefore higher firepower is better for them (despite what ever convergence). Also your claim about LW pilots witnesing bullets missing their planes on both sides is quite questionable; how about opinions of those pilots who witnesed hits...
I quess you can't never admit that you are wrong on this but lets try to hit 100!
gripen
I noted that Oesau served in the JG 51 or JG3 that time. He was KIA in the JG 1 at 1944.
gripen
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Hi Gripen,
the point you seem to fail to appreciate is that more weight of fire isn't equivalent to more firepower or easier aiming. Having the armament out in the wings creates an aiming problem, and this is the problem Riemensnider mentioned.
If we'd choose to ignore this problem, it would be a clear issue, and I'd have to agree with you.
However, at least Mölders, Tuck and Riemensnider thought it was a problem. Mölders and Tuck even thought it was worth sacrificing half the weight of fire to avoid it!
How about the other aces?
Galland didn't actually state an opinion on the matter. However, his Me 109F-2/U with increased centreline armament shows his preferences were not focused on wing guns.
And while Oesau favoured the Emil's armament, don't forget that its powerful 20 mm mine shells stood against the far less lethal 15 mm projectiles of the early Friedrich. As a result, Oesau's decision to keep the Me 109E is not particularly useful for comparing different 20 mm cannon arrangements.
Regards,
Henning (HoHun)
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Hi Tony,
>Incidentally, some very interesting points were made about the sighting issue. One was that positive or negative G in combat also caused guns to shoot low or high. This was another reason given for widening the spread of fire.
I'd guess this might result from the wings flexing under the loads. You wouldn't see that effect with centreline armement.
>Another interesting point of detail concerns harmonisation for range. It was pointed out that the guns could be set to fire "level", which means that the sights would be aimed downwards to harmonise with them, or the sights could be set level and the guns aimed up. The latter was recommended as more useful in dogfighting (although obviously not in ground attack).
Different settings with seem to have been common with the USAAF, too, greater elevation being used for air-to-air combat to improve the view over the nose, and alignment with the fuselage datum line to facilitate low-level strafing runs.
By the way, it's my impression that the British referred to "harmonisation" as the coincidence of sightline and trajectory in the vertical plane, and "crossover" as the coincidence of fuselage axis and trajectory in the horizontal plane. Unfortunately, the actual elevation of the sight line is seldom mentioned.
>Then there were the early 8 x .303 diagrams - did you know that four different harmonisation patterns were being tried by different squadrons in early 1940?
With the poor placement of the Spitfire's guns, I'm not suprised :-) I'd say you could still tell it was orginally meant to carry 4 guns only.
The Hurricane's firepower was acknowledged to be superior even with the same number of guns as they were concentrated right outside the propeller disk.
>Reading between the lines, I guess that the RAF found the Hispano so devastatingly effective against fighters that two or three hits would usually do the job, so it was better to spread the fire and score a couple of hits than concentrate it and miss entirely.
My way of reading between the lines is that they were considering the probability of hit being close to nil and widened the cone of fire just to get any hits, whatever the probability of kill might be :-)
Is there any information on how many hits the RAF considered as necessary to ensure a kill? I think the Luftwaffe arrived at 6 20 mm hits to kill a fighter. It was easier for them to find out, though as they weren't as hard pressed by the Dowding Syndrome as the British ;-)
Regards,
Henning (HoHun)
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HoHun,
Well, I have admited several times that aiming problem existed and benefits of the fuselage armaments were signifigant specially for a good shooter at short range. But also you should admit that for an average pilot firepower (in what ever location in the plane) was more important than concentration of the fire. And this is clearly the idea what Galland and Oesau were promoting.
And I fully agree that the MG 151/20 was a much better weapon than the 20mm MG FF. But again to really utilize these benefits (ie to substitute weight of fire of two MG FFs with one MG 151/20) the pilot should be a good shooter. Therefore quoting just aces is a bit misleading. The case of the Spitfire vs Bf109 armament comparison is easier because the HS 404 performed about as well as the MG 151/20 and in addition there were 2 mgs more in the Spit.
Just two posts more...
gripen
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Hi Gripen,
>Well, I have admited several times that aiming problem existed and benefits of the fuselage armaments were signifigant specially for a good shooter at short range.
The benefits of the fuselage armament was that it hit the aiming point no matter what the range is. You don't need to be a good shooter to exploit this - you can be an inexperienced pilot and just concentrate on bringing the sight on target and push the button.
With wing guns, you've to be aware of the range, how it translates into lateral offset of the strike points, keep the relative orientation of the aircraft in the rolling plane in mind, be prepared to aim next to the target to compensate for the lateral offset, or even to push the rudder to yaw one or the other wing's guns on target if you're close.
It should be obvious that this does not make hitting easier, it makes it more complicated. A good shooter might be able to consider all of it and act accordingly without missing his shooting opportunities, but for an inexperienced pilot, guns that hit the aiming point are a big advantage.
Regards,
Henning (HoHun)
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HoHun,
Once again: You dont need to prove advantages of the fuselage armament every time. The purpose of the weapons in the plane was to hit the enemy plane and this required good shooting (and flying) skills ie ability to maneuver the plane to the right position and ability to choose right target point. Shooting skills of the average pilots were quite poor and they tended to shoot from longer range than aces, thenefore it was better to have more firepower in the what ever location in the plane than less firepower in the optimal location.
Generally if the target point is not very accurate it is better to have more convergence and more bullets in the air for better hitting possibilities. At short range advantages of the fuselage armament are signigant ie the advantages can substitute firepower but at long range firepower is more important because shooting is unaccurate anyway (even in the case of the ace).
100!
gripen
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Hi Gripen,
>Generally if the target point is not very accurate it is better to have more convergence and more bullets in the air for better hitting possibilities.
You're neglecting that by spraying a large area, you'll only get few impacts in any part of that area, and accordingly the probability of kill drops.
Let's assume Gaussian distribution of the pilot's aiming error and homogeneous distribution of the bullet density within the pattern radius.
Let's have our pilot open fire at a range where he has a 67% chance of having aimed correctly. Additionally, let's assume that if he aimed correctly, bullet density will suffice to give him a 40% chance of a hit on the target aircraft for each bullet fired.
Firing 25 shots from a single accurate 20 mm gun, he'd score (long term average :-) 6.7 hits. That's a number the Luftwaffe considered high enough to kill a fighter reliably.
Now let's increase the pattern: At the range where the pilot can be expected to have his sights on target with a 67% chance only, increasing the pattern size might seem like a good idea. Doubling the pattern size will indeed give our pilot a 96% chance of being on target. However, bullet density within the pattern is down to one quarter of what it was before, meaning that with the pattern right on target, there'll be only a 10% chance of a hit for each bullet.
Firing 50 shots from his new twin guns of reduced accuracy, our pilot will now score (long-term average again) 4.8 hits only. That means by adding another gun and increasing the pattern size to increase hit chances, he's actually decreased firepower to just 72% of what he had before.
Of course, this is only a simplified example. It illustrates some of the factors whose combination determines firepower, though, and demonstrates how apparently logical measures to increase firepower can be foiled by numerical effects.
Regards,
Henning (HoHun)
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HoHun,
I thought that 100 was enough ;) anyway...
First it should be noted that normally wing guns were harmonized for most common shooting distance (say 100-200m depending on the AF or pilot or what ever) so in this range (and say 50m more or less) more armament in the what ever position will give more hits than less armament in the optimal position. Also this probably covers more than 50% of all combat situation shooting in the case of the average pilot.
Then it should be noted probability of correct aiming was probably much less than 50% specially in the case of the average pilot and at longer range the error was probably partially systematic ie it did not behaved like Gaussian distribution (also other reasons could cause uneven distribution); the gyroscopic gunsight improved shooting very much...
Anyway, if aiming is correct then centerline weapons certainly gives relatively more hits outside and inside above mentioned range (depending on the size of the target and number of guns) but more armaments in the what ever position give better possibilities to get hits.
BTW I checked Galland's book again and at least in the finnish version he states that he thought that two cannons in the wings would have been better than one in the fuselage despite he knew advantages of the centerline weapons.
gripen
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There's a parallel discussion about this going on in the Military guns and ammunition discussion forum (see below - "Ideal WW2 Fighter Armament" thread).
Basically, centreline guns were more efficient than wing-mounted ones. At short range, they provided concentrated fire, whereas wing guns could miss completely, with the two groups of fire passing each side of the enemy fuselage. At long range, it was possible to angle the cowling or wing-root mounted guns outwards a fraction to increase the hit probability if required; the natural dispersion of the projectiles due to gun/mounting inaccuracy could prevent any gaps in the pattern from forming. Wing guns only achieved a good distribution of fire within a certain range band around the crossover point. Beyond that, you have a dumb-bell shaped distribution with a hole in the middle. You can get around this by setting the pairs of wing guns at different convergence distances, but then you don't have concentrated fire at any range.
Of course, the RAF and USAAF did pretty well with wing guns, but they had to carry a lot more of them to make up for the lack of efficiency, with obvious weight and performance penalties.
Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://website.lineone.net/~a_g_williams/index.htm
Military gun and ammunition discussion forum:
http://forums.delphiforums.com/autogun/messages
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Hi Gripen,
>First it should be noted that normally wing guns were harmonized for most common shooting distance (say 100-200m depending on the AF or pilot or what ever) so in this range (and say 50m more or less) more armament in the what ever position will give more hits than less armament in the optimal position.
Wing guns work fine at convergence range. They don't work fine short of convergence range and beyond convergence range. Both estimation of range and the execution of the attack ("to aim at a piece of sky that will be full of aircraft when your bullets arrive there after you've fired from convergence range") are additional difficulties not present for centreline armament. This is the reason centreline armement is better for inexperienced pilots at any range.
>Then it should be noted probability of correct aiming was probably much less than 50%
The mechanism is the same for any hit probability. The poorer the aim of the pilot, the more you have to widen the pattern, the lower your bullet density becomes and the lower your probability of kill drops.
(Note the difference between correct aim and probability of hit in my example - random dispersion etc. lowered the probability of hit to just 27% for the centreline case.)
>BTW I checked Galland's book again and at least in the finnish version he states that he thought that two cannons in the wings would have been better than one in the fuselage despite he knew advantages of the centerline weapons.
How about a direct quote then?
Regards,
Henning (HoHun)
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HoHun,
Well, I think that I have admited several times benefits of the center line armamaments and problems with wing guns (ie aiming and convergence problems) but for one reason or another seems that you still can't admit that 2x firepower from the wing guns is better for an average pilot than 1x firepower from the centerline because they tended to shoot normally within optimal range of the wing guns.
Within the normal shooting range (say 100-200m) there is not much differences in the pattern size but bullet density is doubled if wing guns offer double firepower. So in the most cases 2x armament in the wings offer about double chance of hit and therefore much better possibilities to destroy target.
At shorter range advantages of the center line weapons are real as noted several times here.
At longer range shooting was more or less random ie possibilities for correct aim were were about same as for any point within large area around target. It is easy to use standard Gaussian distribution model assuming that average aim point was correct, but in the most cases the average aim point was not in the target (ie systematical errors) and even if it was near it then the variance was probably bigger than in the standard Gaussian (ie probably much less than about 68% of the aims were within about 33% of the whole range of the aims). Before gyroscopic gunsights pilots did not have much possibilities to estimate right deflection therefore aiming was more or less random.
Here is a translation, but you can probably find same from the original language version (actually I believe that you have read this several times but you just can't admit it).
Adolf Galland: Ensimmäiset ja viimeiset. WSOY 1956. German to Finnish translation by T. J. Kivilahti.
Chapter 24 p. 236-237 ("quick, poor and free" finnish to english translation by gripen, couple errors corrected)
"There was a question about armament. When there was just one 20mm cannon and two rifle caliber mgs in the Me 109F, they where not rated as sufficient for against four engines bombers. Also this armament meaned difficult to understand worsening in the Me 109F if compared to the E-series which went out of production previous year, which had two 20mm cannons and two rifle caliber mgs. The cannon of the new F-series was indeed more modern, faster firing, had better ballistic characters and most important it was arranged to shoot through propeller hub. Despite this there were discussion if this armament was a improvement or worsening. Mölders and Udet liked that one center line cannon was better than two in the wings. My opinion was that one cannon was not enough, specially when I had thought long time that mgs were outdated and meaningless "fireworks stuff". They had not much effect against enemy fighters and even less against four engined bombers. Of course I was aware about benefits of the center line armament, but if it contained just a cannon, then it looked to me - specially when schooling level of the pilots decreased when war continued - that it was still better to use two cannons even if dispersed to the wings. Not all pilots were "rifle shooters" like Udet or Mölders. Flying game animals are most commonly shooted with shot."
gripen
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A question for you, Mg/gun experts, we actualy have two kinds of wing mounted guns/Mgs: root mounted (synchronized) and wing mounted (unsynchronized). I haven't done any test with japanese guns, but in the case of 50", hispanos and Mg151/20 the result is clearly that 50" and hispanos (unsynchronized wing mouted) has less dispersion at convergence than root mounted Mg151/20. All of us know the trajectory and ROF advantages of hispanos and 50" over 151/20, but at short ranges the difference should be minimal. So, lets talk only about short distances (convergence up to 350 yards) where dispersion due ballistic differences is minimized. At these ranges, IMO, the main differences in dispersion will come from gun shake. IMO, these hi-ROF, hi-KEnergy weapons should have a clear disadvantage in dispersion compared to lo-ROF wing root mounted guns. They are (due ROF) almost doubling the recoil effect and they are mounted in a more flexible place. Is that statement correct?
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I don't know about German installations of the MG 151/20 but the Russians tended make their armament installations so that there were some built in dispersion in the gun mounting (not poor engineering but purpose built).
gripen
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Hi Gripen,
>Well, I think that I have admited several times benefits of the center line armamaments and problems with wing guns (ie aiming and convergence problems)
Don't forget these disadvantages actually mean something: Poorer firepower.
>Within the normal shooting range (say 100-200m) there is not much differences in the pattern size but bullet density is doubled if wing guns offer double firepower.
Bullet density is doubled at convergence range. Out of convergence range, bullet density decreases and soon reaches a lower value with concentrations off the boresight.
That's why Mölders, Riemensnider and Tuck thought centreline armament to be better than wing guns.
>It is easy to use standard Gaussian distribution model assuming that average aim point was correct, but in the most cases the average aim point was not in the target (ie systematical errors)
I'd like to see any facts to prove that point as I do in fact believe the opposite of what you state. I have to admit I can't prove it. My line of reasoning is that at long range, dispersion is much greater than bullet drop anyhow so that the systematic error due to this factor can be neglected. I also believe that long range shots are only sensible against non-manoeuvring targets from a stern aspect, eliminating most other opportunities for meaningful systematic errors.
>(actually I believe that you have read this several times but you just can't admit it).
Let me assure you that I only read "The First and the Last" once, maybe five years ago, and that it's not even on my bookshelf :-) Of course, there are several other books echoing Galland's thoughts, which might explain why you think I had the passage you quoted in front of me, but I didn't.
Anyway, there's a key remark in the quote: "not rated as sufficient for against four engines bombers"
Galland did not just leave it at that remark: He pressured for heavier armament, flew the F-2/U conversion that set the mold for the Gustav aramement, lobbied for the RLM's Me 109F-6 armed with wing guns, and actually set out to prove his point by making his personal F-6/U with 20 mm cannon in the wings. He personally told Hitler that he wanted a three-cannon Messerschmitt, and when he got Hitler's support, he finally managed to get fighters equipped with gondola cannons. Galland was quite disappointed when the gondola cannon turned out to make the Me 109 inferior in fighter-to-fighter combat, but he actually saw them as a means of providing the necessary firepower for bomber interception.
I think you'll probably see the key passage as:
"but if it contained just a cannon, then it looked to me - specially when schooling level of the pilots decreased when war continued - that it was still better to use two cannons even if dispersed to the wings."
However, in the light of Galland's campaign for powerful interceptors, I'm convinced this comment was at least partly aimed at bomber interception, too. His unit, JG26, was dealing with the very first Short Stirling the Luftwaffe shot down, and if I remember it correctly, the attacking Messerschmitt expert first silenced the defensive gun position, and then flew repeated attacks at the bomber until it went down.
Clearly, the hastily trained pilot he had in mind couldn't have done that, and more firepower, even as wing guns, would have been highly beneficial for him. However, I think this is an entirely different affair from fighter-to-fighter combat, which the Luftwaffe's Messerschmitt pilots continued to fight with a single cannon for the rest of the war.
Regards,
Henning (HoHun)
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Originally posted by MANDOBLE
A question for you, Mg/gun experts, we actualy have two kinds of wing mounted guns/Mgs: root mounted (synchronized) and wing mounted (unsynchronized). I haven't done any test with japanese guns, but in the case of 50", hispanos and Mg151/20 the result is clearly that 50" and hispanos (unsynchronized wing mouted) has less dispersion at convergence than root mounted Mg151/20. All of us know the trajectory and ROF advantages of hispanos and 50" over 151/20, but at short ranges the difference should be minimal. So, lets talk only about short distances (convergence up to 350 yards) where dispersion due ballistic differences is minimized. At these ranges, IMO, the main differences in dispersion will come from gun shake. IMO, these hi-ROF, hi-KEnergy weapons should have a clear disadvantage in dispersion compared to lo-ROF wing root mounted guns. They are (due ROF) almost doubling the recoil effect and they are mounted in a more flexible place. Is that statement correct?
Basically, yes, in that outer wing mountings will be more flexible than inner root ones, so other things being equal outer guns will suffer more dispersion. However, other sources of gun accuracy were not necessarily related to power or RoF but to the quality of the mounting and the basic characteristics of the gun. For example, the Browning was rated less accurate than the Hispano.
Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://website.lineone.net/~a_g_williams/index.htm
Military gun and ammunition discussion forum:
http://forums.delphiforums.com/autogun/messages
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Hi Mandoble,
>IMO, these hi-ROF, hi-KEnergy weapons should have a clear disadvantage in dispersion compared to lo-ROF wing root mounted guns. They are (due ROF) almost doubling the recoil effect and they are mounted in a more flexible place. Is that statement correct?
I think the rate-of-fire difference actually isn't that decisive. However, the forward spar of the Fw 190 near the wing root is probably the most rigid structure ever designed for a WW2 fighter :-)
The wing is much more flexible outwards at the wing cannon, and accordingly one should expect firing to induce more violent oscillations. In the case of unsynchronized machine gun batteries, it'll be a factor that they fire at random timing shaking the mounts badly. The Focke-Wulf's wing root cannon by contrast fired each round in the same instant, producing only a rearward-directed recoil and no lateral forces or moments.
It's important to realize that the dispersion was almost entirely mounting-induced. For example, when jacked up on the firing range, the MG151/20-armed Ju 87D-5 produced a 70 cm x 70 cm pattern at a distance of about 100 - 200 m when firing bursts. I think that's about the accuracy you should expect from a smoothbore musket, not from a modern 20 mm rifle ;-) Accuracy was better in the air than jacked up, but it still was far worse than the precision the barrel would have yielded in a truly rigid mounting.
In short, I think it would be safe to assume that the dispersion of wing-root or nose-mounted guns like featured by the Fw 190, Me 109 or P-38 should be appreciably lower than that of wing-mounted weapons.
The Me 109E's MG FF/M seem to be an especially interesting case - from what I know (most of it from Tony's book :-) it should enjoy a comparatively low recoil, which I speculate might give it a lower dispersion and accordingly better long range capabilities than one would assume from looking at its low muzzle velocity alone.
Regards,
Henning (HoHun)
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HoHun,
Once again: I have admited several times advantages of the center line armament but for one reason or another it seems that you can't admit that 2x wing armamment was better than 1x in the fuselage for an average pilot.
And once again: The problem with your Gaussian based probably theory is that there were no way before gyroscopic gunsights to get accurate deflection for shooting at long range so shooting was more or less random (ie variance in the "aims set" is huge and there is no clear concentration around correct aim). Also most pilots used too little deflection ie average target point was behind and under real target. This means that the average of the "aims set" is not correct aim (as you try to present ) but something else. Your theory is valid only in head-on and directly behind cases, in all other cases bigger dispersion is better because it gives better possibilities to hit. Anyway, at normal shooting ranges 2x wing armament is superior as noted several times.
And once Again: Galland rated two wing cannons better than one in the fuselage for an average pilot and he also thinked that armament worsened in the F-model if compared to the E. Also Galland and Oesau presented their critics long before four engined bombers arrived. Right from the beginning of this endless debate I have just pointed out that there were manykind of thoughts about armaments in the Luftwaffe.
gripen
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Hi Gripen,
>Once again: I have admited several times advantages of the center line armament but for one reason or another it seems that you can't admit that 2x wing armamment was better than 1x in the fuselage for an average pilot.
Ah, the good old times when there were records, and they had scratches ;-)
Well, the undisputed advantages of centreline armament are large enough to make them superior for an average pilot - the RAF in 1941 had no shortage of the latter, and yet RAF leaders like Stanford-Tuck considered the Messerschmitt's armament superior to the Spitfire's.
>And once again: The problem with your Gaussian based probably theory is that there were no way before gyroscopic gunsights to get accurate deflection for shooting at long range so shooting was more or less random
"Random" behaviour is a requirement for a Gaussian distribution. Note that you're talking about long range deflection shots, though, which have so low overall chances of killing the target that I consider them operationally insignificant anyway.
>Anyway, at normal shooting ranges 2x wing armament is superior as noted several times.
Wing armament is superior at convergence range. It's inferior short of and beyond convergence range, and as Riemensnider pointed out, getting the burst in at precisely the correct range is a problem by itself.
>And once Again: Galland rated two wing cannons better than one in the fuselage for an average pilot and he also thinked that armament worsened in the F-model if compared to the E. Also Galland and Oesau presented their critics long before four engined bombers arrived. Right from the beginning of this endless debate I have just pointed out that there were manykind of thoughts about armaments in the Luftwaffe.
Oesau compared his twin 20 mm Emil to the new 15 mm Friedrich. The 15 mm cannon was much less powerful than the 20 mm cannon were, so you're comparing apples and oranges here.
Galland was writing in retrospect and formulates his points as if the Friedrich was armed with 20 mm right when it came out - which it wasn't. You'll note that he criticizes MG armement for its low effectiveness against anything, but single-cannon armement only for its lack of effectiveness against bombers.
Regards,
Henning (HoHun)
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HoHun, if you are right (and I think so) about the wing root mounted 151/20s producing only a rearward-directed recoil and no lateral forces or moments, perhaps HiTech should take a look about the actual lateral displacements (small yaw displacements) produced by these guns inducting a clearly noticeable dispersion at short ranges.
Tony, can you confirm 151/20 HoHun point?
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HoHun,
As noted several times here, only good shooters and experienced pilots could really benefit from centerline armament, for all others 2x wing armament was certainly better than 1x center armament because much better firepower and better possibilities get hits within normal shooting range of the average pilots.
About Gaussian distribution it should be noted that you used it in it's standard form ie about 68% of all points of the set should be inside about 33% of the measured range and you also presented that the average of the set is same as correct aim. Both assumptions are wrong because without better gunsights there were no possibilities for accurate aim (except in the case where both planes are in the same flight path) and pilots tended to repeat their errors.
Yeah, I know that I have been talking about long range shots and please see my previous posts; I have stated several times that in the case of the long range shooting it was pretty much same where the guns were located, it was very unaccurate anyway but with better firepower there were more possibilities to get random hits. So are you changing your opinions...
And it is not "just" convergence range where the 2x armament in the wings is superior, it is the whole range where this combination has more concentrated firepower against target. And in the case of the average pilots, it is practically whole normal shooting range ie say 100-300m. Experienced pilots could benefit from centerline armament because they tended to shoot from short range. Anyway, you finaly admited that at convergence range 2x armament in the wing is superior, earlier you argued that: "centreline armement is better for inexperienced pilots at any range". So a little movement here too...
About Galland and Oesau: Well, in fact you are writing in retrospect and you try to bend their sayings and doings to fit on your own theories. What they did and wrote is pretty clear.
gripen
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Originally posted by MANDOBLE
HoHun, if you are right (and I think so) about the wing root mounted 151/20s producing only a rearward-directed recoil and no lateral forces or moments, perhaps HiTech should take a look about the actual lateral displacements (small yaw displacements) produced by these guns inducting a clearly noticeable dispersion at short ranges.
Tony, can you confirm 151/20 HoHun point?
I don't know about the firing arrangements for the synchronised guns so I can't comment.
I'm also not sure about the yaw effect of wing mounted guns; it depends on how many, their rate of fire and their power. For example, I would not expect any such reaction with eight .303 because each recoil kick was small, and there were so many of them that the effect would even out. Clearly, as guns become larger and slower firing, and there are fewer of them, each recoil impulse becomes more significant and is more likely to have small effects on aiming. I have no data on the likely extent of this with different armaments, though.
Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://website.lineone.net/~a_g_williams
Gun and ammunition discussions at:
http://forums.delphiforums.com/autogun/messages
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Hi Gripen,
since you seem to think we're caught in some kind of vicious circle, let me attempt to break out by concentrating on a single point :-) This doesn't mean you aren't wrong about the rest, too, but maybe we can solve them one by one ;-)
>About Gaussian distribution it should be noted that you used it in it's standard form ie about 68% of all points of the set should be inside about 33% of the measured range and you also presented that the average of the set is same as correct aim. Both assumptions are wrong because without better gunsights there were no possibilities for accurate aim (except in the case where both planes are in the same flight path) and pilots tended to repeat their errors.
Please suggest a dispersion example similar to the one I posted to demonstrate wing guns can indeed be better at long range.
I think you're going to find that any function that makes wing guns look better will include an element of avoidance of the correct aiming point, which implies knowledge of the correct aiming point, which you state is an impossiblity. You'd contradict yourself that way :-) I could be wrong, of course, but I'd really like to see some math now.
Good luck!
Henning (HoHun)
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HoHun,
I wonder what are you trying to say? You presented a theory without data so actually it's your problem to bring in some kind of data. Anyway, if we have a large random set of aim points and we assume that correct aim point is within set but not necessarily near average of the set, then it is more probable get hits with the armament which put out 2x more hits within set. Despite the area of the 2x hits set is a bit larger, there is more density inside the set.
Thanks, but I don't need luck for this.
gripen
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It's pretty easy to see what Gripen is describing if you try it in Aces High. There is a feature that lets you fire at a white target, and you can select the range of the target. You can see the pattern of shells at any range.
With a single nose gun you get one area of hits that grows with range.
With wing guns you get two areas of hits at close range. But as you get near convergence they become one large area of hits. But as range increases beyond the convergence distance, the dispersion of each gun becomes so large that the effect of the gun spacing is minimized. The two patterns are centered maybe 15 feet apart but their diameter is so large that they overlap for the most part.
Remember that dispersion is helpful for long range gunnery. It is unlikely that you will have the enemy perfectly centered in your dispersion pattern, so the aircraft with the widest pattern can get hits even if the aim is off. And at long range with low-time pilots and rudimentary WWII aiming devices I'm sure this was the rule.
The M61 Vulcan rotary cannon used in post-war jet fighters and AA units actually had to be modified because it was found that more dispersion increased the probability of a hit unless the pilot/gunner had perfect aim. They altered the gun so that each barrel was "off center" a little bit, giving a nice fat pattern.
Galland's alleged comment about shotguns will seem pretty accurate if you look at the patterns in AH or the gunnery simulation tool of your choice. Just use .target xxx where xxx is the range in yards. Try it for different weapons packages and convergence ranges. You will see some truth in what Gripen is saying.
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Yeah, dispersion is the reason why the Russians did that built in loosenes to their gun installations.
gripen
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Hi Gripen,
>I wonder what are you trying to say? You presented a theory without data so actually it's your problem to bring in some kind of data.
I was referring to the model I developed earlier:
Let's assume Gaussian distribution of the pilot's aiming error and homogeneous distribution of the bullet density within the pattern radius.
Let's have our pilot open fire at a range where he has a 67% chance of having aimed correctly. Additionally, let's assume that if he aimed correctly, bullet density will suffice to give him a 40% chance of a hit on the target aircraft for each bullet fired.
Firing 25 shots from a single accurate 20 mm gun, he'd score (long term average :-) 6.7 hits. That's a number the Luftwaffe considered high enough to kill a fighter reliably.
Now let's increase the pattern: At the range where the pilot can be expected to have his sights on target with a 67% chance only, increasing the pattern size might seem like a good idea. Doubling the pattern size will indeed give our pilot a 96% chance of being on target. However, bullet density within the pattern is down to one quarter of what it was before, meaning that with the pattern right on target, there'll be only a 10% chance of a hit for each bullet.
Firing 50 shots from his new twin guns of reduced accuracy, our pilot will now score (long-term average again) 4.8 hits only. That means by adding another gun and increasing the pattern size to increase hit chances, he's actually decreased firepower to just 72% of what he had before.
What I expect from you is a similar model demonstrating the superiority of wing guns. Be constructive: You've criticized my assumption of a Gaussian distribution long enough, give me something to criticize, too.
Regards,
Henning (HoHun)
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Originally posted by funkedup
With wing guns you get two areas of hits at close range. But as you get near convergence they become one large area of hits. But as range increases beyond the convergence distance, the dispersion of each gun becomes so large that the effect of the gun spacing is minimized. The two patterns are centered maybe 15 feet apart but their diameter is so large that they overlap for the most part.
Remember that dispersion is helpful for long range gunnery. It is unlikely that you will have the enemy perfectly centered in your dispersion pattern, so the aircraft with the widest pattern can get hits even if the aim is off. And at long range with low-time pilots and rudimentary WWII aiming devices I'm sure this was the rule.
The M61 Vulcan rotary cannon used in post-war jet fighters and AA units actually had to be modified because it was found that more dispersion increased the probability of a hit unless the pilot/gunner had perfect aim. They altered the gun so that each barrel was "off center" a little bit, giving a nice fat pattern.
A couple of comments:
The patterns achieved by wing guns depend on the harmonisation set. It was not uncommon to set each pair of guns at a different convergence distance. This would lead to a fairly distributed pattern at all practical ranges, but still tending towards the dumb-bell shape, with most bullets at any range striking to either side of the aiming mark.
It is true that increasing the spread of fire does increase the long-range hit probability. However, it really depends what kind of guns you were using, as the odd hit from a machine gun (even a .5") is unlikely to do much damage. The RAF's .303's had to deliver concentrated fire to stand any chance of a kill. Only a cannon shell stands a reasonable chance of inflicting serious damage with one or two hits.
The M61 is available with three different barrel clamps, which provide difference dispersion settings. However, I have the strong impression that the usual clamp provides a very tight group, as USAF pilots who have corresponded with me about this all praise the gun's very high degree of accuracy and limited dispersion.
Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://website.lineone.net/~a_g_williams/index.htm
Military gun and ammunition discussion forum:
http://forums.delphiforums.com/autogun/messages
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Hi Funked,
>It's pretty easy to see what Gripen is describing if you try it in Aces High.
Thanks for the additional information! However, I think Gripen and I don't necessarily disagree on pattern size etc., but rather on the conclusions to draw from it.
Regards,
Henning (HoHun)
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HoHun,
OK, as you wish. Let's assume first that aims set what we got from long range is with 99,9% probability within 20m (you can change this to degrees or what ever) from the correct aim (probably optimistic in the case of the average pilot) and let's use standard Gaussian distribution which is very probably untrue because we don't know if the correct aim is in the set nor how correct aim and average of the aims set are related. Then lets assume that target area is within 2m from the center of the aims area then the probability of the correct aim is about:
2/(20*0,33)=0,30 => 2*0,118= 23,6%
Then lets assume that dispersion is same for wing and fuselage guns (probably untrue but the difference does not affect results very much) so we don't have care about it and the hits set for the wing guns is 2m larger (due to convergence) than aims set so probability of the single hit drops to 21%. But when we ad twice fire rate ie 25 vs 50 then we got 5,9 hits with the 1x fuselage gun and 10,6 with the 2x wing guns. You can ad dispersion if you want...
gripen
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Ok... let me guess. Gripen and HoHun are actually siblings in RL ;)
Is Not !
Is Too !
Is Not !
Is Too !
Is Not !
Is Too !
Is Not !
Is Too !
Is Not !
Is Too !
Any thread that these two start debating in, eventually grows to 100+ in just a couple of days. ;)
Just kidding guys.
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Hi Gripen,
I'm not quite sure I understand your example yet.
What is your assumption for the bullet dispersion radius for centreline guns and for wing guns respectively?
Do I understand it correctly that your target is a disk of 2 m radius in the centre of the Gauss curve?
Regards,
Henning (HoHun)
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HoHun,
My example just counts deflection error ie it's a single dimensional model (real life situation is three dimensional and therefore error is much bigger then). Purpose of the model is just to show how the error caused by large variance (aiming error for deflection at long range) is much more signigant than error caused by location of the guns.
As noted the model does not count dispersion at all , I have no idea about the size of the dispersion of the HS 404 or MG 151(I'm not gun expert like Tony). If it's as large as Funkedup told and same for both guns then tthe wing guns combination has clear advantage at long range.
Otherwise model is just a bit of basic statistics ie standard one dimensional Gaussian distribution assuming that 99,9% range is about 2*20m and therefore average error is about 20/3 and the target set is 2*2m in the center of the aims set. I used traditional Z table from my old biometrics book for densityfunction; could not find that feature from the spreadsheet ;)
gripen
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Hi Gripen,
>My example just counts deflection error ie it's a single dimensional model
Hm, I still don't understand. Does that mean you increase target area size increases linearly from 2 m for centreline guns to 4 m diameter for wing guns?
>As noted the model does not count dispersion at all
Here's a comparison of available firepower from centreline guns and from wing guns based on the assumption of Gaussian dispersion.
Bullets travel left to right, yellow/orange denotes superior firepower for centreline guns, grey approximately equal firepower, blue superior firepower for wing guns.
(http://members.aol.com/hohunkhan/convergence.gif)
Poor quality rendering courtesy of Excel :-(
Regards,
Henning (HoHun)
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HoHun,
No, the target size is same (4m for both combinations) as well as the aims set only thing which changes is convergence caused by the guns locations which is about 2m from the center line in the wing guns plane and at shooting range (ie 2x convergence range, 300-400m) and this is modeled simply by increasing the size of the hits set to 44m vs 40m in the case of the fuselage gun (no anykind of dispersion modeled).
Seems that you have no much idea what gaussian distribution means. You model assumes that error of the aim is very small. Here is samples assuming 1m target and 5m error which is a very little error at long range (again no dispersion modeled):
fuselage gun
0,5/(5/3)=0,3 => 2*0,1179=0,2358 => 5,9 hits/25 shots
Wing guns
(2-0,5)/1,167=0,9 => 0,3159 => 9,205 hits
(2-2,5)/1,167=1,5 => 0,4332 => 3,34 hits
9,205 -3,34 = 5,865 hits/50 shots
Well, I needed to edit it couple times; long time since I've done these. Anyway, the samples should show effect of the accuracy at long range.
And if we assume that dispersion is as large as Funkedup claimed (ie dispersion circles cover each other above convergence range) and bullet density is even inside dispersion circles as your model assumed (which is not necessarily true) then the wing armament allways give better bullet density at the aim point at longer range than convergence range.
gripen
Ah, (edited again for formula error) I forget to ad effect of the smaller target to the wing guns (not really needed for 4m target).
gripen
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Hi Gripen,
Do I understand it correctly that you simulate wing guns by increasing standard deviation of the aiming error by 10% and then doubling the number of hits?
Regards,
Henning (HoHun)
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HoHun,
In my first example I did so , but purpose of the example was just to show effect of the increased variance (as noted and which is the one of the main problems of your model; you assume far too small aiming error) or in other words standard deviation ie square root of the variance. My other example includes ( after couple edits ;) ) calculation for error caused by location of the guns, still it does not include dispersion which actually favors wing guns.
Anyway, we don't know if the distribution of the aims set behaves like Gaussian distribution; so overall these are just speculations.
gripen
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Hi Gripen,
(Nonsense deleted. Staring at a copy until it makes sense again ;-)
Regards,
Henning (HoHun)
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Hi again,
I posted nonsense, please disregard while I fix it :-)
Regards,
Henning (HoHun)
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Hi Gripen,
OK, I understand both of your examples now. Let's work with your second example since it actually includes the off-centre placement of the wing guns.
(Under construction)
Regards,
Henning (HoHun)
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HoHun,
LOL... but please note that my second example is still a simplified single dimension model the like first one. Well, normally teachers get paid for their work :(
gripen
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Hi Gripen,
>but please note that my second example is still a simplified single dimension model the like first one.
I'm using your model because I'm a nice guy trying to help you break the vicious circle :-) I'm well aware of its limitations, though.
>Well, normally teachers get paid for their work :(
Glad you're trying to bring me up to speed for free :-)
However, you could have saved some work by using a more useful symbolic notation instead of some purely numerical scribbles which had me guessing about their significance.
Anyway:
Let's work with your second example since it actually includes the off-centre placement of the wing guns.
Further assumptions:
- Wing guns 2 m off centreline
- Convergence distance 200 m
- Aiming error is constant in angle
Results:
- 2x wing guns are inferior to 1x centreline gun below 110 m range,
- superior from 110 m range to 660 m range,
- inferior above 660 m range.
However, the example you picked is highly sensitive to aiming error.
Reducing the aiming error from 5 m to 2.5 m:
- 2x wing guns are inferior to 1x centreline gun below 130 m range,
- superior from 130 m to 330 m range,
- inferior above 330 m range.
Do we agree so far?
Regards,
Henning (HoHun)
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HoHun,
Well, not much reason to disagree; seems that your calculation results are closing my thoughts. Generally it is easy to manipulate the model changing aiming error and/or target size. But lets look at that aiming error.
So whats your estimate for aiming error of a average pilot in the case where his plane and target plane are at same flight path ie head on or directly behind case at range of 400m (meters or degrees)?
And what about the aiming error in the case of the deflection shooting in the case of the when flight paths differ say 20deg and distance is again 400m?
About notation it should be noted that you started to talk about Gaussian so I was under impression that you knew what you were talking about. My samples are pretty much basic stuff, pretty clear for anyone who has played with statistics . Sorry if lack of notation caused too much work (IMHO that's good; you certainly learn when you have to figure system out) .
gripen
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Hi Gripen,
>About notation it should be noted that you started to talk about Gaussian so I was under impression that you knew what you were talking about.
I knew what I were talking about, the problem was finding out what the hell you were trying to say. The math was simple enough - the problem were poorly defined assumptions and uncommented numbers as well as a typo in two lines of example 2 which you seem to have missed during your edits. I've to admit I did not immediately gain the impression you were knowing what you were talking about.
>Well, not much reason to disagree; seems that your calculation results are closing my thoughts.
The interesting thing is that even by your own single-dimensional model, the advantages of wing guns are at medium ranges, not at long range. Now compare this to the two-dimensional dispersion graph I posted earlier:
(http://members.aol.com/hohunkhan/convergence.gif)
(Yellow/orange denotes superior firepower for centreline guns, grey approximately equal firepower, blue superior firepower for wing guns.)
Regards,
Henning (HoHun)
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HoHun,
Well, you "gaussian" model assumes constant 67% probability for the correct aim point without claiming target size (this means that accuracy of the aim increases when range increases), the only conclusion I can draw from this is that you had not much idea how gaussian distribution works.
My first example shows actually my point ie aiming error at long range is much more signifigant than location of the guns in the plane. I purposedly used large 4m (ie same as distance between the wing guns) target to make example simple because most important thing is the variance caused by the aiming error.
My other exsample (after couple edits) is just for to show how small must target and aiming error be to make calculation to show advantage for the 1x armament in the fuselage at long range. If we set target and aiming error small enough, we can draw a conclusion that the fuselage armament is superior at all other ranges except convergence range and this is just what you did in your model. I see why you don't want to estimate real life aiming errors and how about the case of a larger (more realistic) target?
Anyway, adding third dimension will favor the fuselage gun , adding dispersion will favor the wing guns and so on... It can be modeled but I'm far too lazy to try. But good enough conclusions can be made with a bit of statistical knowledge; due to aiming error 2x armament in the wings is better than 1x in the fuselage at long range.
gripen
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Hey guys!!!
When I started this thread I could never imagined that would be so long and interesting...
...and, in a way, so far from the initial question:
are the 12,7 MG Breda-SAFAT undermodelled in AH?
What do YOU think, HoHun and Gripen, about that???
I guess this thread will reach 200 post now... :D
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Galland was quite disappointed when the gondola cannon turned out to make the Me 109 inferior in fighter-to-fighter combat, but he actually saw them as a means of providing the necessary firepower for bomber interception.
Gents - you're arguing apples & oranges. Center-mounted gun is ideal for fighter/fighter combat delivering ammo accuartely on a small target. More guns required to bring down a bomber. Also, the need to be as accurate disappears when you're facing a Lancaster - it's not manoeuvering and it's big. No need for deflection shooting. Just unload as many rounds as quickly as possible to bring it down.
and yet RAF leaders like Stanford-Tuck considered the Messerschmitt's armament superior to the Spitfire's
It is the same RAF leaders who set convergeance to 500 yards, right? And which Spitfire were they talking about here? Spit I or II wth 8 0.303s? Sure. Spit V with 2 Hispanos and 4 0.303s? Versus 1 15/20mm cannon and 2 x 7.7s? Of please... It looks like Peter's principle (everyone gets promoted up to the level of their incompetence) was working in RAF.
For example, when jacked up on the firing range, the MG151/20-armed Ju 87D-5 produced a 70 cm x 70 cm pattern at a distance of about 100 - 200 m when firing bursts. I think that's about the accuracy you should expect from a smoothbore musket, not from a modern 20 mm rifle ;-)
Hmmm let's see that smoothbore firing 800 rpm and check it's distribution pattern then;). 70x70 looks pretty good to me although my experience with automatic weapons tops at 14.5mm turret mounted MG...
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Since I started the Stanford-Tuck hare running, I had better clarify.
This came from a survey reported in January 1942 (so, not 8x.303 Spitfires!) of senior RAF fighter officers, of whom Stanford-Tuck was one (the others I didn't note, but I recognised his name). This is a direct quote from the report:
"In spite of our superiority of fire power over that of the enemy, many pilots would prefer the armament of the Me 109 with its one cannon firing through the air screw hub and two MGs mounted in the fuselage. They feel that despite its inferiority to our armament the concentration of parallel fire more than counterbalances our criss-cross pattern."
This is not attributed to any individual fighter commander, but was obviously a commonly (but not universally) held view at the time. You may debate till the Spitfires come home about what basis they had for such a belief - I merely reproduce what was reported at the time.
Tony Williams
Author: "Rapid Fire: The development of automatic cannon, heavy machine guns and their ammunition for armies, navies and air forces"
Details on my military gun and ammunition website:
http://www.quarry.nildram.co.uk
Military gun and ammunition discussion forum:
http://forums.delphiforums.com/autogun/messages/
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HoHun nice graph there.
One thing to remember is that the graph is not to scale (for good reasons), so one must consider that when getting a subjective impression.
Considering that, it looks very similar to the results I observed in Aces High.
Except near convergence range, centerline guns are better if the pilot has near-perfect aim. But if the pilot's aim is not so good, which becomes more and more likely as range increases, or if there is a snapshot or tracking deflection shot, then a pair of wing guns is much more likely to score. And I think that in WWII, poor aim and snapshots and deflection shots were quite common, making the number of guns more important than their distance from the thrust line.
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Hi Gripen,
>Well, you "gaussian" model assumes constant 67% probability for the correct aim point without claiming target size (this means that accuracy of the aim increases when range increases)
I approximated the complex shape of a real aircraft, the dispersion of fire and the effect of firing at a two-dimensional target by assigning a finite probability for hitting even with a correct aim. You assume dispersion to be zero, limit the problem to one dimension, and consider the aircraft's shape that of a short line. It's the nature of simplified examples to be imperfect.
I could ridicule your skills on the basis of your example just like you're ridiculing mine. Since that's not the kind of discussion I'm looking for, I won't.
>But good enough conclusions can be made with a bit of statistical knowledge; due to aiming error 2x armament in the wings is better than 1x in the fuselage at long range.
Here are some numbers from your own example situation:
Range [m]; Phit 2 wing guns, Phit centreline gun
600; 8,97%; 7,53%
650; 7,46%; 7,14%
700; 6,24%; 6,74%
750; 5,47%; 6,35%
800; 4,78%; 5,96%
850; 4,14%; 5,56%
900; 3,64%; 5,17%
In short, beyond a certain range, the wing guns in your example lose their advantage and become inferior to the centreline gun.
I assume this is a terminology problem concerning the definition of "long range". However, in your example, the longer the range, the greater the superiority of the centreline gun.
Regards,
Henning (HoHun)
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Hi Lynx,
>Hmmm let's see that smoothbore firing 800 rpm and check it's distribution pattern then;)
Great example :-)
I don't doubt dispersion is large, I just wanted to illustrate it's mostly a function of the mount, not of the weapon itself.
Regards,
Henning (HoHun)
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Hi Funked,
>One thing to remember is that the graph is not to scale (for good reasons), so one must consider that when getting a subjective impression.
Exactly. It also shows a case where the dispersion conce is smaller than the inward firing angle necessary for convergence. If you'd want to get overlapping convergence zones, you could widen the dispersion angle so that the outward dispersion boundary is parallel to the sight line. However, that would require a very large dispersion angle or a very long convergence range, and still leave the centreline gun with a long-range advantage due to the large dispersion as only a small fraction of the bullets actually hit the overlapping area.
>And I think that in WWII, poor aim and snapshots and deflection shots were quite common, making the number of guns more important than their distance from the thrust line.
Well, and I believe that in WW2, short-range fire was a quite important way to achieve kills, for the exact opposite emphasis :-)
But your post actually reminds us that we shouldn't forget that the weapons' capabilities determined the tactics, i. e. whether the pilots would go for a tracking shot or for a snapshot, or whether they would fire at long range or at short range.
Regards,
Henning (HoHun)
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HoHun,
I wonder what is the point of your correct aim based model in this discussion; I have agreed right from the beginning that in that case centerline armament is better?
You can certainly play with my simplified model and use it for purposes it was not made for; if the range is long enough, it will favor fuselage guns. But ranges beyond 500m are pretty unrealistic and if the dispersion is as high as Funkedup claimed and evenly distributed as in your model, then wing guns have advantage at very long range too.
BTW do you still disagree conclusion that the 2x wing guns combination is better for a average pilot than the 1x fuselage armament?
gripen
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Let's have a little look on progress:
HoHun 31.01.2002: "centreline armement is better for inexperienced pilots at any range."
HoHun 01.02.2002: "Wing armament is superior at convergence range. It's inferior short of and beyond convergence range"
HoHun 05.02.2002: "Well, and I believe that in WW2, short-range fire was a quite important way to achieve kills"
Well, not much to ad.
gripen
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Gripen, if you are trying to argue that those three quotes are somehow incoherent, I suggest that you look at them again.
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Sage FIN,
Well, all quotes are from 1x fuselage vs 2x wing armament discussion. Please see above, you can easily find them above and see connections. And all I see is progress... (siis edistystä ei ristiriitaisuutta)
gripen
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IMO, nose mounted guns are always better for air to air shooting than wing mounted ones, no matter the distance, no matter the quality of the pilot.
Look into the post war developed fighters, and prior to the guided missile era, most if not all the fighters had the guns mounted in the nose or wing roots.
With this placement you are gaining in precission at any range and plane performance. Obviously, the chances of hitting the enemy are reduced, but the chances of destroying the target if hitting are increased.
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MANDOBLE,
Postwar fighters tend to have advanced gunsights, actually radar assisted in many cases (range measuring). I have admited right from the begining that center line is best location for guns. But question is if 1x armament in the fuselage armament is better than 2x in the wing for a average pilot without advanced gunsight.
My pretty well founded opinion has been right from the beginning that at short range fuselage armament have signifigant edge ie is better (no aiming problems). At convergence range wing armament is better because more concentrated firepower. And at long range wing armament is better because aiming errors are much more signifigant than optimal location of the guns.
See my examples and note that the second example shows just about how accurate aiming should be (99,9% of the aims within 5m center of the 1m correct aim point at 400m range ie 2x convergence range) to give advantage for the fuselage guns at long range. Real world error was much more (probably more than 10m) and also target size was bigger.
Aces tended to shoot from short range and therefore they could benefit from the fuselage armament.
gripen
(edited for a error in the text)
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Is a centerline unsynchronized gun better than two wing mounted synchronized ones? IMO, yes.
Is a centerline unsynchronized gun better than two wing mounted unsynchronized ones? IMO, yes too.
Is a centerline unsynchronized gun better than six wing mounted unsynchronized ones? Probably not.
Here in AH you have a very good example in the 109G (1x20 unsynchronized) compared to 190A/D/F (2x20 wing root synchronized).
The Hit Percentage achieved by 109 is usually doubling the HP of the 190.
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Hi Gripen,
>You can certainly play with my simplified model and use it for purposes it was not made for; if the range is long enough, it will favor fuselage guns. But ranges beyond 500m are pretty unrealistic and if the dispersion is as high as Funkedup claimed and evenly distributed as in your model, then wing guns have advantage at very long range too.
Actually, adding dispersion increases the superiority of the centreline gun.
As explained above, to get overlapping fields of fire at ranges beyond convergence, it's necessary for the dispersion radius at convergence range to equal the the wing guns' offset from the centre. (That makes it 2 m @ 200 m for our example.) Assuming Gaussian dispersion, the 2 m @ 200 m should be our 3 * sigma value.
Here are the numbers for our example:
Range [m]; Phit 2 wing guns, Phit centreline gun
500 9,0% 8,7%
600 5,7% 7,2%
700 3,8% 6,3%
800 2,9% 5,5%
900 2,2% 4,9%
1000 1,8% 4,4%
The observations:
- The break-even range of centreline guns is shorter than without dispersion
- The superiority of centreline guns increases with range increasing beyond the break-even point
Regards,
Henning (HoHun)
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Hi again,
as it occurred to me while typing, the above numbers are with only half the necessary diversion to fulfill the overlap requirement.
Here are the numbers for full dispersion:
450 8,3% 8,2%
500 6,3% 7,4%
550 4,9% 6,7%
600 3,9% 6,2%
650 3,2% 5,7%
700 2,6% 5,4%
750 2,3% 5,0%
800 2,0% 4,7%
850 1,7% 4,5%
900 1,5% 4,2%
950 1,4% 3,9%
1000 1,2% 3,8%
It's interesting to note that more dispersion leads to poorer results for both weapons arrangement, but that wing guns are affected worse.
Regards,
Henning (HoHun)
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HoHun,
Wow, now you have found out that dispersion might not be homogenously distributed as you presented in your own model and which I BTW doubted. So why don't you carefully read again my text which you quoted.
And again, you are continously trying to use my second example model for the purpose it was not made for. The values in the model were setted to those just for to show how small aiming error and target should be at 2x convergence range if someone wants present 1x fuselage armament better than 2x wing armament. And you are continously using these values to show that I'm some how wrong on this. Real world values for the aiming errors at 400m range are much more likely closer to 10-20m and also target size is larger.
So, if you want to continue, please estimate real world aiming errors as I asked before and use also more realistic target size. Also ranges beyond 500m are irrerelevant.
gripen
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Hi Gripen,
>Wow, now you have found out that dispersion might not be homogenously distributed as you presented in your own model and which I BTW doubted.
Yes, and it easily lead to the conclusion that a centreline gun is superior to wing guns at long range. Thanks for your constructive doubts :-)
>And again, you are continously trying to use my second example model for the purpose it was not made for.
Not a problem, I'm continuously improving the model.
>Real world values for the aiming errors at 400m range are much more likely closer to 10-20m and also target size is larger.
I don't think you have any real-world records to prove that claim, do you? If you had, I'd be very interested, of course.
>So, if you want to continue, please estimate real world aiming errors as I asked before and use also more realistic target size.
I simply used the values you provided earlier. So what's your suggestion now?
>Also ranges beyond 500m are irrerelevant.
I'd tend to agree that they're academical :-) This doesn't mean I'm not interested in the answer, though.
Regards,
Henning (HoHun)
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HoHun,
Well, if the distrubtion is standard then 99,9% of the aims within 5m from correct target point means that about 68% is within 1,67m, so it is easy to see that at 400m range such accuracy is pretty much impossible even if planes are in the same flight path. I have seen some Finnish Air Force ground target shooting data and typical results for a good shooter were around 40-50% to 6x6m target from 100-300m range, much less in the case of a poor shooter and longer range.
In the case of the different flight paths deflection can easily be say 20-40m (several degrees) and without advanced sight aiming is very unaccurate so here error is much larger. Anyway, we know that gyroscopic gunsights improved shooting accuracy dramatically so poor accuracy is pretty well documented.
My estimate is that 10-20m aiming accuracy at 400m range might be something a very good shooter reached and realistic target size should be around 2-3m. So these are my suggestions.
But actually I am pretty sure that you won't do that. I think that you have known since you understood the model that I have been right. Your attitude is clear as seen in the way you use my second model (funny thing is that you proved it true). Oh well, I said long time ago that you won't never admit that you are wrong on this. But lets do 200, anyway I've got some fun.
gripen
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Hi Gripen,
>My estimate is that 10-20m aiming accuracy at 400m range might be something a very good shooter reached and realistic target size should be around 2-3m. So these are my suggestions.
OK. And what results do you get from these suggestions?
Regards,
Henning (HoHun)
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HoHun,
You asked suggestions and you got them, so it's up to you.. I got 8,3 hits with wing guns and 5,7 with fuselage gun at 400m assuming 20m error and 3m target. No dispersion again.
gripen
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Hi Gripen,
>No dispersion again.
Is there a special reason you left out dispersion?
Regards,
Henning (HoHun)
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HoHun,
Yes, no dispersion beacause I don't know size or distribution of the dispersion. In the case of the built in dispersion like in the Russian guns or the M61 the pattern might not be distributed as standard. It is very probable that similar practices were used elsewhere too.
But it's up to you, if you want to ad dispersion then help your self (assuming that you have good data on it).
gripen