Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Naudet on April 17, 2001, 11:28:00 AM
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Ok due to the intense debate i did today some testing with Mojack2 in the training arena.
Circumstances were the following:
Mojack2 flew a B17 as tgt plane
I made 3 sorties:
1. in D9 convergence 300 yrds
2. in A8 weapons, 2x13mm + 2x20mm, convergence 300
3. again in D9 with 300 yrds con
In my 1st sortie i flew the D9 in on the B17, and started firing at 750 yrds distance with the 20 mms only (distance Mojack saws was always about 200 yrds more, all distance posted below are from my point of few, for Mo's view add 200 yrds).
1st pings were noticed not before getting into 500 yrds range. The B17 did not have any notable dmg before atleast 20 pings from the cannons.
So i started the 2nd sortie.
At 1000 yrds i fired just for the fun, but Mojack answered "Hey i heared pings". So i throttled back and zoomed in as far as possible.
I was able to hold the distance between 990 and 1000 yrds. I started firing, with a small elevation above the tgt. And started firing with 20mm, and i scored hits, not randomly but regulary from all of my short bursts.
I than switched to 13 mm and yes no problem to hit a B17 at 1000 yrds (this were 1200 yrds for Mojack).
I than closed in, it was no prob to hit that B17, and before getting under 700 i killed the B17.
Now i switched back to D9, which should have the same guns as the A8.
I flew to 1000 yrds distance and fired with the 20mm only. Mojack was to report any ping he got, but nothing. I changed elevation above tgt, no hit. I startet a long 5 second burst and move the plane slowly through the elavation, till the B17 disappeared behind the nose. No hits were registered by Mojack.
After repeating this about 4 times. i Switched to 13mm and directly scored hits, without a huge elevation above the tgt.
Now i wanted to find out when the 20 mm would start to hit.
800 yrds: 2 pings from a long burst (4-5sec) with a high elevation.
600 yrds: regular hits with the same elevation used in the A8 for 1000 yrds shots and hits
up till yet Mo's B17 took about 20 hits without any dmg noticed in the dmg report
400 yrds: hits are more regular at 350 they still spray over the whole span of the B17s elevator
at 350 finally after about 30-35 hits the B17 lost both elevators (horizontal stabilizers) and was dead
This shows to me, that there is a difference between the MG151 on the D9 compared to other GE planes. It seems the Shells spray more and fall much shorter than in the other FW.
To me this proofed that the D9 guns are different. This will be my last comment to this discussion and my opinion will not be changed by any arguments u bring in. Test parameters were all the same. And the results can only be explained with screwed up MG151/20 on the D9.
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I made some training films last night, one platform I used was the Dora, had no problem downing this B17, this pic is the 3rd pass on him, he actually blew up before I flew into his flight path, but the film editor did not reflect this explosion (known bug)...I had convergence set at 500 for the 20mm's and used all guns in each pass. This is FYI stuff, not arguing your point.
(http://Ripsnort60.tripod.com/Angle2a.jpg)
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Naudet.
All you have to do is press alt-r to turn film on you know. It's really easy. Then we can all see instead of you having to convince us. You could also take screenshots of the film later to better illustrate your point.
FILM guys... it makes it so much easier.
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Sean "Lephturn" Conrad - Aces High Chief Trainer
A proud member of the mighty Flying Pigs
http://www.flyingpigs.com
Check out Lephturn's Aerodrome (http://users.andara.com/~sconrad/) for AH articles and training info!
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thats a pretty wide prop on the 190d9.
did you consider that the guns may have a lower ROF due to that vs the 190a8?
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Citabria:
Both the inboard guns on the A8 and the D9 guns are synchronized to fire through the propellor. ROF should be identical I believe.
Hooligan
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Well that leads to an interesting possibility...
The Jumo might effect the interupter.
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Originally posted by Hooligan:
Citabria:
Both the inboard guns on the A8 and the D9 guns are synchronized to fire through the propellor. ROF should be identical I believe.
Hooligan
A8 and D9 have different engines and propellors, so ROF should be different for both of this planes. But ultimately this is irrelevant to the way bullets fly, this only means either of this planes could put up more lead into the enemy at any given moment.
The only way for D9 to have bullets with worser trajectory is if it would have used different ammunition from the rest of the German planes. It doesn't...
mx22
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Originally posted by Citabria:
thats a pretty wide prop on the 190d9.
did you consider that the guns may have a lower ROF due to that vs the 190a8?
The BMW801 had a prop rpm of 2700rpm
the Ju213 had a prop rpm of 3200rpm
The blade is wider,yes, but the bigger rpm should make up the difference and even INCREASE the rate of fire, I think.
[This message has been edited by R4M (edited 04-17-2001).]
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Hmm somehow I doubt that planes with different engines AND propellors will end up giving same ROF. I remember someone posting a formula to calculate ROF, can anyone paste it in here? Would the wide blade account for a slower ROF or is it irrelavant?
mx22
Originally posted by R4M:
The BMW801 had a prop rpm of 2700rpm
the Ju213 had a prop rpm of 3200rpm
The blade is wider,yes, but the bigger rpm should make up the difference and even INCREASE the rpm, I think.
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A few days ago I was flying 190d9 and I just coulding hit a lancaster even at 300yards
Same convergence as the a5 wich is the 190 I regularly fly, and sames guns. With the a5 I regularly shoot down buffs from longer distances.
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Originally posted by Animal:
A few days ago I was flying 190d9 and I just coulding hit a lancaster even at 300yards
Same convergence as the a5 wich is the 190 I regularly fly, and sames guns. With the a5 I regularly shoot down buffs from longer distances.
This is not a prove of anything. Last week I flew Yak-9 and couldn't hit enemy from around 150 yards. Then day or two later I loged on and was killing enemies from way farther. I think it was me being too much trigger happy, then guns firing slower then usual.
mx22
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I will repeat the test and film it, my only prob is i find that the "movie player" isnt very good for taking screenshotsm cause it seems it has no picture-per-picture option.
But i will try to get a visual evidence of this.
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I'm a lousy shot but i have no trouble hitting with 190d9. i fire cannons only too.
your problems with the 190d9 guns are imaginary just as is my problem with getting shot down by flak every time i get in range.
It's Your imagination! (http://bbs.hitechcreations.com/smf/Smileys/default/biggrin.gif)
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I share your second problem Cit ...
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I made a gun sight just for the D9 and adjusted it downward until I got consistent hits at 300 yard convergence cannon only, after this was working satisfatorily I had to drop the MG's to 200 yards to get then to converge with the cannons at 300 yards so it looks like the at a normal 300 yard convergence the cannon have droped 100 yards below the MG's, with the convergence adjusted as described above it was very deadly at 300 yard convergence, not exactly a consumers report test but it sure does make me wonder how the D9 guns are modeled
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Naudet,
Check your keyboard assignments for film playback. There's an "advance frame" key which should enable you to take accurate pictures.
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And the MG151 isn't as effective as in R/L. Takes a hell of alot more then 20 rounds to bring down a buff, even if you hit all 20 in one wing.
The dammage modell isn't detailed enough, it only takes in account "hwat parts get blown off" so you can hit 10x20mm in left wing, 10 in right and 10 in fuselage and the plane still flies as good as long as no parts have been blown off, in R/L the plane would have been downed due to too many holes.
(http://saintaw.tripod.com/jg5wilbus.gif)
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Rasmus "Wilbus" Mattsson
III/JG5 Eismeer
"Only the spirit of attack, born in a brave heart, will bring success to any fighter aircraft, no matter how highly developed it may be."
Adolf Galland
[This message has been edited by Wilbus (edited 04-18-2001).]
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Originally posted by Wilbus:
And the MG151 isn't as effective as in R/L. Takes a hell of alot more then 20 rounds to bring down a buff, even if you hit all 20 in one wing.
The dammage modell isn't detailed enough, it only takes in account "hwat parts get blown off" so you can hit 10x20mm in left wing, 10 in right and 10 in fuselage and the plane still flies as good as long as no parts have been blown off, in R/L the plane would have been downed due to too many holes.
(http://saintaw.tripod.com/jg5wilbus.gif)
Same for Hispano..
Actually, 24 rounds was enough to bring down a buff if i remember correctly.
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Your test was interesting Naudet.
Could the cowl guns be mounted out of plane with the wing root cannons?
What we need is a gunnery butt to test the guns on. Something that lets up prop up the tail and see the pattern of the rounds at different ranges.
I personaly am finding the D9 good at snap shots but poor at long range 6 shots.
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same pongo
i have trouble hitting dead 6 shots, but snap shots no trouble, very wierd
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Okay concerning ROF:
If some sort of interrupter mechanism is used then the gun would fire at full rate with the firing simply being periodically suspended when a propellor blade was in the way. I don't know how to calculate firing rates for this situation. If the guns are synchronized by some mechanical means between the propellor and the electrical firing circuit of the 151s (and I believe this is the case) then the ROF should be calculable.
Making my best guesses for ROF.
In AH the unsynchronized guns fire at 700 rounds/minute, so the syncyronized rate would be somewhat less. The good sources I have seen on ROF for synchronized 151s usually quote a number between 600 and 650.
At 3200 RMP a propellor blade passes in front of the gun 9600 times a minute. A synchronized gun would fire at an integer divided subinterval of this so... this probably means 9600/16 = 600 rounds/minute or 9600/15 = 640 rounds/minute for the Dora.
For the A8 2700x3 = 8100. 8100/13 = 623 rounds/minute. (When I measured this with a stop watch I got 630 a while back and 623 is certainly within my margin of error for measurement accuracy).
Given the stated RPMs, my guess is that the a8 is firing at 623 and the dora is firing at 600 or 640. This is a 3% difference in ROF and I doubt it would be noticeable.
Hooligan
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Why you people connect ROF with this issue? Smaller or bigger ROF would have no effect in any way on the way bullet flies. The only way for bullets to drop more in D9 would be if it either had different guns or different ammunition. ROF will be of importance only if you were discussing how fast you can shot down enemy plane, given every bullet you shoot finds the target.