Improve the P-47

[gripen]

Hm... Generally the ROF of the M2 is listed around 650-750 rpm (13 rps in Tony's site) so:

8 x M2: 8 x 13rps x 3s = 312 rounds/3s

2 x Hispano: 2 x 10rps x 3s = 60 rounds/3s

4 x Hispano: 4 x 10rps x 3s = 120 rounds/3s

Assuming as an example 10% hit probability for each projectile for both guns:

8 x M2:  31,2 hits/3s

2 x Hispano: 6 hits/3s

4 x Hispano: 12 hits/3s

Assuming that one firepower of a Hispano equals 3 x M2 (according to US Navy) ie as an example one second burst of 10 rounds from Hispano equals 39 rounds from three M2s. This gives ratio 3,9 for a Hispano round ie one hit from Hispano equals 3,9 hits from M2 so relative hit sum would be:

8 x M2:  31,2 hits/3s

2 x Hispano: 23,4 hits/3s

4 x Hispano: 46,8 hits/3s

So using US Navy rating, the 2 x 20mm would had been a downgrade while 4 x 20mm would had been an improvement. And if the ROF of the M2 had been increased to 1100 rpm, it would have resulted 44 hits/3s at same conditions ie very close the relative firepower of the 4 x 20mm, almost twice firepower of the 2 x 20mm and all this without large modifications to the airframe.

BTW US Navy rating might be well based on test shots on real airplanes and analysis of gun camera films. At least the Brits made such analysis so probably that was possible for the US Navy too.

gripen

[Captain Virgil Hilts]

I'd pretty much agree that given sufficient magazine capacity for each gun, having FOUR 20mm cannons on the P-47 would have been at least somewhat of an upgrade in armament. However, there's no way I'd think that TWO 20mm cannons would even be equal to the eight M2 50BMG gun set, nevermind any sort of an improvement.

As a side note, I would say that four 20mm cannons with around 250-300 rounds per gun would have been a serious step up compared to the standard gun set on a P-38, since Hohun brought it up. However, I do not think that the standard gun set on a P-38 is better than the standard gun set on a P-47, other than where the guns are located. So I still do not think that ONE 20mm cannon is an adequate replacement for FOUR M2 50BMG's.

Back on the actual subject of this thread, the gun set is the last thing I'd be looking at were I going to improve the P-47. And I would certainly NOT consider removing the turbocharger either. If anything, I'd likely increase the size of the turbocharger enough to eliminate the problem of over rev at higher altitudes. If you're trying to make a piston engine perform at maximum potential over a wide range of altitudes, it is near impossible to beat a turbocharger. Otherwise, the current generation of piston engine GA aircraft wouldn't have so many turbocharged versions at the top end of the scale performance wise. There wouldn't be so many high end turbocharger kits available as upgrades, either.

The truth is, the U.S. aircraft were just a little behind the curve in evolution for the early part of the war, mostly because of the USAAF/USAAC and their myopic lack of foward vision. They didn't really do a great deal to inspire innovation, and did a lot to stifle progress. Examples are scattered throughout the development history of many aircraft.

Merely accelerating the development curve for most of the aircraft in the inventory, the P-47 included, and removing the roadblocks brought on by ignorance and arrogance would have brought better planes into battle earlier. And don't forget that some really big improvements never saw production, but were shelved in the interest of cost and expedience. One need only look at the Sherman tank to see the Russians weren't the only ones to believe quantity has a quality all its own.

[Widewing]

Originally posted by gripen
Widewing,
Could you create similar presentation for the F4U-1C or the Typhoon because 4 x 20mm would have been practically only realistic alternative to the 8 x 12,7mm.

Thanks in advance.

gripen

As requested...

Typhoon, followed by the F4U-1C and the P-38L for good measure. I have included a rear view of a Fw 190D-9 in the P-38L image. Range was 991 yards. I transferred the same image, in red, to the target of the P-38.

 





My regards,

Widewing

[Debonair]

Originally posted by HoHun
Hi Debonair,

>giving the wings about 2-3 degrees of washout, vortex generators, winglets, outboard LE slats; setting the 'pit back a couple feet more to increase critical Mach number; Q-tip prop & adding a spinner over the prop hub would do a lot more for Thunderbolt performance than the few percent weight reduction thats been discussed for the last 100 posts

Good list, but are you sure all of them would actually have helped, or were 1943 technology at least? Washout for example would tend to reduce the wing's efficiency, and if you mount outboard leading edge slats anyway, you might not actually need it.

With regard to the "few percent weight reduction" though, you don't seem to appreciate the impact it would have had on performance. Just look at this weight comparison:

P-47D-25RE: ca. 14500 - 14700 lbs
Cannon Jug: ca. 13816 - 14016 lbs
P-47M: 13275 lbs

OK, the Cannon Jug would not have been equivalent to a stripped-down racer, but it would have benefitted both in performance and manoeuvrability. (Just one example:  At high altitude, the climb rate improvement would have been around 25%.)

If you still have the impression, that weight savings in the region of 5% are insignificant - we're talking about aviation here where 5% weight more or less is a big issue.

What do you think would happen in Aces High if the Cannon Jug loadout would be added to the list? 684 lbs saved, two Hispanos instead of eight Brownings ... which loadout would the players choose?

Regards,

Henning (HoHun)

washout done properly reduces induced drag, increasing wing efficiency.
important at high altutudes where indicated airspeeds are low.
even more so if you're interested in high altitude aerobatics.
i'd bet widening the low airspeed end of the flight envelope is a big deal for dogfighting up there.
shrinking the back side of power curve helps too

[Wolfala]

I've read over this thread in detail and wanted to bring in a POV from someone who uses the P-47 as his main ride. I'm not sure how many in responding to this thread fly in AH, besides Widewing and myself, but these are my thoughts based on the simulation fidelity HTC has allowed us to participate in.

1.  The notion of 8x50 being replaced with 2x20: I violently disagree with this and it would be a step backward.

2.  8x50 being replaced with 4x20: If you fly a F4U-C or Tempest on a regular basis, then there is some merrit in a mod like this. However - for me personally, I wouldn't be comfortable with the gravity drop of the 20mm over the distances I usually fire at.

I treat the P-47 like a paper shreader - my guns stagger from 400 up through 475 and overlap from banks 4 on inward to 1. I must be doing something right because according to the website my hit % hovers between 10 and 12 % fairly consistantly - but that should be considered and abbiration as i'm not a normal pilot by any means of the word. SLA Marshall and a few others post WW2 conducted a study and later wrote a book titled Men Under Fire: The Problem of Battlefield Command in which he wrote 25 % of soldiers engaged in direct action fired their weapons.

Now the correlation is this - when you consider the stresses of combat and the lack of experience you were dealing with in handling complex machinery - 10 % is a number which, in most estimations which is way up there in god territory. More realistic for your typical pilot is  1.5-3 % hit percentage, with the average creeping up to 5 %.

When I examine members of my squad, some of whom have been around a few years and others who are fairly recent - the average tends to be in the 7% range. With Shawk's group who has more pilots, on the higher range of 7% boardering 8 %.

The point which I am failing to make is this - the P-47 series is deadly enough without even considering 4x20's in the wings. I have very little issue with runs averaging 6-10 kills, and sometimes higher if fuel permits. For me, the sheer amount of lead going out - 103 rounds per second is staggering even in a virtual enviroment. Being in the Marines showed me first hand what a single BMG gun could do - you just don't want to be on the recieving end of 1, let alone 8 paired together.


S!

Wolf

[Knegel]

Hi,

regarding the armament hit probability so kill probability many dont seems to see that not only the armament is a factor!!

As long as a target fly strait or is very big and get attacked right from 6oc, a slow firing gun have exact the same hitprobability per ammoload like a fast firing gun, therfor i would tend to use cannons vs big targets(bombers), specialy cause the better penetration of the structure.

Interesting it get when the target roll/turn/dive/climb and if the attacker is forced to estimate a deflection.
MG´s in general tend to have a much longer time to shoot, therefor its good possible to adjust the aim while shooting, without to waste to much of the ammoload. Additionally many MG´s dont let a "open window" between each bullet, also this is very important, specialy while shooting with a high deflection.  
 
Imho the Tempest, HurriIIc and F4U-1c only are extremely danagerus in the H2H area with extended ammo load. In the other areas, with normal ammo load, the pilot need to be much more carefully not to run out of ammo.

Time to shoot is a big aspect of the armament hitprobability and MG´s in general could carry much more ammo!

P47D could shoot 32sec.

F4U-1c  23sec.

Tempest only 11,5sec.

HurriIIc only 9sec.

SpitIXc 12sec.

Of course the F4U-1c, HurriIIc, Typhoon and Temp had a extremely good firepower and vs not or slow moving groundobjects and bombers this is very good. But what is the firepower worth, if the pilot dont have enough ammo to adjust a bad calculated lead(the F4U-1c is almost a exception here, but still have 30% less time to shoot that the P47)??

While shooting to a smal fighter from a perfect attacking position(short range, 6 oc, enemy fly strait) or if the pilot was able to calculate a perfect lead, even 2 x MG17 + MG151/15 was good enough, like Mr. Marsaille and Mr. Graf did proof in a very impressive way.

Therefor i think with increasing distance and attackingangle, but decreasing pilot skill, the need of more guns or faster shooting guns with big ammoload, NOT more powerfull guns, was needed! (vs Bombers of course more powerfull guns was better, while the .50cal still was effective vs fighters on common shooting ranges)

At the end of the war and after the war, the computed gunsights did improve the hitprobability much, cause the pilot as influence got almost deleted. Therefor the need of a very long time to shoot wasnt needed anymore, so a smal number of cannons probably would have been a big improvement, cause they was effective vs fighters, bombers and groundobjects, on a longer range(with the computed gunsights long range hits got much more likely) and they was more light.

Greetings,

[HoHun]

Hi Hilts,

>However, there's no way I'd think that TWO 20mm cannons would even be equal to the eight M2 50BMG gun set, nevermind any sort of an improvement.

Well, the firepower would be equivalent - improvement really would be the weight saving (or fuel increase).

>However, I do not think that the standard gun set on a P-38 is better than the standard gun set on a P-47, other than where the guns are located. So I still do not think that ONE 20mm cannon is an adequate replacement for FOUR M2 50BMG's.

Hm, do you consider the gun set of the P-38 inferior (firepower-wise) then? In my opinion, it's about equal to the P-47's.

>If anything, I'd likely increase the size of the turbocharger enough to eliminate the problem of over rev at higher altitudes.

I think this was actually done throughout the life-span of the P-47, but it would be hard to rush this kind of progress to get a better Jug in 1943.

>Otherwise, the current generation of piston engine GA aircraft wouldn't have so many turbocharged versions at the top end of the scale performance wise. There wouldn't be so many high end turbocharger kits available as upgrades, either.

Well, but the general aviation aircraft are so slow that they can't reap the benefit of exhaust thrust anyway, and the turbo-supercharger is more economic which is important if you're paying for your own fuel. (And for range, too - my suggestion to delete the turbocharger is based on the idea that a lighter, smaller mechanical supercharger setup will allow more extra fuel to be carried than the more thirsty engine will drink :-)

>The truth is, the U.S. aircraft were just a little behind the curve in evolution for the early part of the war, mostly because of the USAAF/USAAC and their myopic lack of foward vision. They didn't really do a great deal to inspire innovation, and did a lot to stifle progress.

Hm, do you think so? In my opinion, there were many innovative aircraft helped on the way by the USAAC/USAAF, their weakness was just that they were not designed as accurately for their combat environment as the European types. (Might be a good spin-off thread :-) I see only one recurrent weakness of the US designs, and that's a habitual disregard of the impact of airframe weight.

Regards,

Henning (HoHun)

[HoHun]

Hi Debonair,

>washout done properly reduces induced drag, increasing wing efficiency.
important at high altutudes where indicated airspeeds are low.

Ah, I see what you mean. Did you mean this just as a general suggestion, or was the P-47 found lacking with regard to high-altitude wing efficiency? I'm asking because the NACA reports often provide this kind of insight, so if there's a good one on the P-47, well, I'd be interested :-)

Regards,

Henning (HoHun)

[HoHun]

Hi Widewing,

>I have included a rear view of a Fw 190D-9 in the P-38L image.

Thanks, that's a good benchmark! :-)

Regards,

Henning (HoHun)

[HoHun]

Hi Wolfala,

>1.  The notion of 8x50 being replaced with 2x20: I violently disagree with this and it would be a step backward.

Judging by Widewing's graphs, it seems that the Hispano has a bit more dispersion than the 12.7 mm in Aces High, while I believe the situation was the reverse in real life.

>I treat the P-47 like a paper shreader - my guns stagger from 400 up through 475 and overlap from banks 4 on inward to 1.

Interesting idea! In some other game that didn't allow such fine control, I used up to 600 yards with the P-47 (for all guns) and got good results, too, so I think I see your point.

>More realistic for your typical pilot is  1.5-3 % hit percentage, with the average creeping up to 5 %.

Certainly. It's the same with the errors in "precision bombing" - the average error in actual combat was far greater than what the man-machine combination would actually have allowed.

>The point which I am failing to make is this - the P-47 series is deadly enough without even considering 4x20's in the wings.

How would you feel about 2x 20 mm and 684 lbs weight reduction? (Or a fairer question might be, how about 4x 12.7 mm and 684 lbs weight reduction?)

From experience in Air Warrior, the Dora they had was quite effective despite being a bad lead sled, but in real combat I'd have considered it seriously handicapped. Just to point out that I don't mean to confuse online flying and reality - but your opinion on online flying would be interesting for me anyway! :-)

Regards,

Henning (HoHun)

[gripen]

Originally posted by Widewing
As requested...

Typhoon, followed by the F4U-1C and the P-38L for good measure.

Thanks, seems that at least in AH, the P-47 has very good concentration of projectiles around the target at long range.

Originally posted by Wolfala

Now the correlation is this - when you consider the stresses of combat and the lack of experience you were dealing with in handling complex machinery - 10 % is a number which, in most estimations which is way up there in god territory. More realistic for your typical pilot is 1.5-3 % hit percentage, with the average creeping up to 5 %.

I used 10% just as an example, the German data gives following values assuming steady about four engined  bomber size target (30m2) right behind at variable range 1000->300m:

Good shooter 15,9%
Average shooter 7,05%
Poor shooter 3,98% or less

In practice results are claimed to be more like half of these in real combat and other factors like deflection etc. might cause large difference.

gripen

[bozon]

Originally posted by Wolfala
The point which I am failing to make is this - the P-47 series is deadly enough without even considering 4x20's in the wings.  

The point HoHun is making and a few missed is that replacing mg with cannons is not a way to increase firepower but to save weight (while keeping about equivalent firepower).

I tend to agree with this, assuming the reliability of 20mm was sufficient. 684 lbs weight reduction? I'd take that anytime.

[gripen]

Originally posted by bozon
The point HoHun is making and a few missed is that replacing mg with cannons is not a way to increase firepower but to save weight (while keeping about equivalent firepower).

Well, keeping the about equivalent firepower would have been 2 x 20mm and 2 x 12,7mm according to US Navy rating (which is claimed to be based on somekind of real testing). There would have been still some weight savings and also some modifications would have been needed to airframe.

gripen

[Krusty]

In an plane as heavy as the P47, saving 600lbs wouldn't help. Somebody kept pointing out how the P47M weight was only about 800-1000lbs lighter and was such a great performer -- well the M had a different engine or rating than the D which is the real reason it was such a performer.

Take out 2 of the 50 cals. And their ammo. How much weight does that save? Take out half the ammo on the remaining guns. Now how much have you saved. You now have the same firepower as 2x20mm (6x50cal) at nearly the same weight savings. Nearly. Not the same, mind you. Cannon planes had their own problems, it wasn't a "magic bullet" solution, IMO. Putting 2x20mm in a plane and nothing else was just begging for complaints.

Besides, the P47 was/is so damn heavy that you couldn't really make it a turn fighter by removing the guns. You couldn't really add more fuel. You couldn't really do much without a major redesign (like the 47N's wing). Taking that weight out wouldn't have made it perform *that* much better, and wouldn't have allowed wing tanks (not much, at least) for extra gas.

Just my opinion.

P.S. I go into combat with my centerline tank sometimes in AH to keep the gas that much longer. If I'm in a D25 or later I'll drop the wing tanks first and keep the centerline. If I get in trouble I'll drop that one too.

[gripen]

According to Tony's site, there was plenty of problems in the developement of the American version of the Hispano so reliability might had been an issue too.

gripen