XP-39 and the Claims

[varsity07840]

the Bf109K-6 had a new wing which is what I'd call a major redesign as I noted earlier. In the 190, excluding the MG 151 wing root guns, there was never a variant that carried more than one internally mounted wing gun. In most cases the outboard cannon primarily the MG FF was deleted. As far as podded underwing guns, I don't consider them to be wing guns, as for the P-39 and P-63. They were underwing because they wouldn't fit in the wing.

 

[drgondog]

the Bf109K-6 had a new wing which is what I'd call a major redesign as I noted earlier. In the 190, excluding the MG 151 wing root guns, there was never a variant that carried more than one internally mounted wing gun. In most cases the outboard cannon primarily the MG FF was deleted. As far as podded underwing guns, I don't consider them to be wing guns, as as for the P-39 and P-63. They were underwing because they wouldn't fit in the wing.

Bf 109K may have had a new wing but was named and identified as 'Bf 109'. As to the Fw 190?
Fw 190A5/U9&10 4xMG151/20 in wings
Fw 190A-5/U10 2xMG151/20 plus 2xMk 108 (outboard) wings
Fw 190A-6 4xMG151/20; Fw 190A-6/R2 2xMG151/20 plus 2xMk 108
Fw 190A-7 4xMG 151/20 wings 2xMG131 cowl

Fw 190D-10 2xMG 151/20 plus 2xMk 108

Fw 190A-8/R1 2xMG131 cowl, 6x MG151 wings -
To name most of the variants that had the much more powerful MG 151/20 and Mk 108 in the wings.

 

[varsity07840]

Bf 109K may have had a new wing but was named and identified as 'Bf 109'. As to the Fw 190?
Fw 190A5/U9&10 4xMG151/20 in wings
Fw 190A-5/U10 2xMG151/20 plus 2xMk 108 (outboard) wings
Fw 190A-6 4xMG151/20; Fw 190A-6/R2 2xMG151/20 plus 2xMk 108
Fw 190A-7 4xMG 151/20 wings 2xMG131 cowl

Fw 190D-10 2xMG 151/20 plus 2xMk 108

Fw 190A-8/R1 2xMG131 cowl, 6x MG151 wings -
To name most of the variants that had the much more powerful MG 151/20 and Mk 108 in the wings.

You're digging too deep into '109 minutiae. The P-51 didn't need a new wing to accommodate an all .50 cal battery, four then six guns. The two nose guns P-36A evolved into the two wing gun P-36C and P-40 to the six guns P-40E without a new wing. The F4U evolved from a 2 wing gun prototype to a six .50 cal or four 20mm battery with the same wing. They all retained the same designation. The FW 190A8/R1 had four of its guns UNDER the wings not in them. Why was that?. The rest of the 190s you list had two of the guns (synchronized) in the WING ROOTS not in the WINGS. The original wing gun in the 190 was an MG 17. They were never able to increase the NUMBER of guns in the wing. Change in caliber was the best they could do. The P-39 wing could not accommodate a modern gun battery in the wings, hence the under wing guns as per the 109 and 190. The drag induced by the underwing guns on the 109 and 190 made them easy meat for Allied fighters. As far as the P-39Q goes, it didn't really matter. It was already a dog before the Q was introduced. Even the Soviets realized that and removed the gun tubs. Even Bell caught on and produced a batch of Qs without them.

 

[tomo pauk]

Lo and behold, a Fw 190 with MK 108 in the outer wing: link.

 

[varsity07840]

Max speed of the P-39N at 25000' was 370-375mph depending on the test. Competitive with the 109G and 190A but certainly well below the two stage P-38, P-47 and P-51.
Radius of action at 25000' was about like a Thunderbolt when each plane had the 110gal drop tanks available in the ETO at that time, on the order of 350-400 miles at about the same speed 280mph TAS. Please remember that the P-39N had completed its production run before the P-47 got into combat in May '43.

Regarding armament, the 37mm cannon wasn't nearly as bad as most people think. Trajectory drop was within 21" of the twin .50s at 400 yards and that was about the outside limit for air-to-air. There were separate buttons on the stick for the .50s and the cannon so you could use just the cannon beyond 400 yards. Rate of fire at 2.5 rounds per second wasn't bad considering the destructive power. One hit was enough to bring down most anything with two engines or less. Reliability was spotty until the L model in mid '42 introduced the little exit vents just aft of the reduction gear. These exhausted the warm cockpit air that was ducted up from the rudder pedal wells onto the breeches of the cannon and twin .50s. This kept the guns from freezing at altitude which was the main cause of jams/interruptions.

According to what I have read AAFpilots were pretty evenly split between preference for the 37mm and 20mm. Biggest problem with the 20mm was only 60 rounds in the drum which was about 6 seconds of firing time. Spitfires held 120 rounds per gun and an increased magazine for the American 20mm would have been the ideal solution but that was not to be.

The Russian solution was to delete the useless .30 caliber wing guns and the IFF radio using the weight savings to further improve performance. They maintained that the 37mm cannon was much more reliable than the 20mm cannon. They also reportedly used the twin .50s against fighters and the 37mm cannon against bombers. Four of the top five Russian aces and scores of 20+ victory aces flew the P-39 and were enthusiastic proponents.

So, we're in agreement that the Russians used the P-39 effectively in a low altitude environment. What hasn't been discussed is the victory to losses ratio for them against German fighters. I don't pretend to know what it was, but the number of kills achieved by German aces that were of the same or higher caliber than their Russian ace counterparts might give us an indication. Certainly their scores were much higher. In North Africa, German pilots were quoted as saying they shot down P-39s like flies.

 

[XBe02Drvr]

So, we're in agreement that the Russians used the P-39 effectively in a low altitude environment. What hasn't been discussed is the victory to losses ratio for them against German fighters. I don't pretend to know what it was, but the number of kills achieved by German aces that were of the same or higher caliber than their Russian ace counterparts might give us an indication. Certainly their scores were much higher. In North Africa, German pilots were quoted as saying they shot down P-39s like flies.

Do reliable, credible statistics even exist for specific types fighter vs fighter kill ratios? Since varying percentages of kills on both sides were non-fighter aircraft, raw kill score comparisons are hardly valid. Also, many of the Experten laid the groundwork for their impressive scores early on against poorly trained Soviets in obsolete aircraft, while VVS pilots who survived to run up their scores mostly date from later times when higher performance Soviet fighters became available. Apples to apples? Hardly.
Cheers,
Wes

 

[Kevin J]

Do reliable, credible statistics even exist for specific types fighter vs fighter kill ratios? Since varying percentages of kills on both sides were non-fighter aircraft, raw kill score comparisons are hardly valid. Also, many of the Experten laid the groundwork for their impressive scores early on against poorly trained Soviets in obsolete aircraft, while VVS pilots who survived to run up their scores mostly date from later times when higher performance Soviet fighters became available. Apples to apples? Hardly.
Cheers,
Wes

The VVS had something called 'group area fighting tactics'. IIRC, 4 pairs of fighters stacked between 8 and 12 thou feet. The bottom pair were the shooters, those gifted enough to be able to hit their target, those above, assigned to protect them. I imagine they lost a lot of novices that way although it would have enabled their 2 shooters to rack up quite big scores.

 

[drgondog]

You're digging too deep into '109 minutiae. The P-51 didn't need a new wing to accommodate an all .50 cal battery, four then six guns. The two nose guns P-36A evolved into the two wing gun P-36C and P-40 to the six guns P-40E without a new wing. The F4U evolved from a 2 wing gun prototype to a six .50 cal or four 20mm battery with the same wing. They all retained the same designation. The FW 190A8/R1 had four of its guns UNDER the wings not in them. Why was that?. The rest of the 190s you list had two of the guns (synchronized) in the WING ROOTS not in the WINGS.

In what universe is an inboard wing gun requiring synchronization Not part of the WING?? The Fw 190A8/R1 did have 1x20 in the wing and two 2x20pods under - so what? what about the other half dozen variants I mentioned - all with either 20mm and/or 30 mm two gun batteries internal to the wing.

By the way the Wing on both the Fw 190 and the P-51 originate at the Centerline where the Root Chord is located. You unbolt that and the entire wing (intact) may be removed without confusion regarding "Gee, did I remember to get the Wing Root"?

The original wing gun in the 190 was an MG 17. They were never able to increase the NUMBER of guns in the wing. Change in caliber was the best they could do. The P-39 wing could not accommodate a modern gun battery in the wings, hence the under wing guns as per the 109 and 190. The drag induced by the underwing guns on the 109 and 190 made them easy meat for Allied fighters. As far as the P-39Q goes, it didn't really matter. It was already a dog before the Q was introduced. Even the Soviets realized that and removed the gun tubs. Even Bell caught on and produced a batch of Qs without them.

Not digging 'too deep'. You made a bold (and incorrect) statement that Bf 109 and Fw 190A didn't expand inner wing 20mm beyond the 1xFF for each wing. Simply wrong - own up to it rather than flail around comparing design changes from G to K as dismissive of the airframe designator.

For example - the Mustang airframe went from 2x30cal plus 1x50 cal in each wing and two (synchronized) in the cowl - then to 2x20mm in each wing, then the 2x50 cal in each wing plus two 50cal (Synchronized) in the cowl Plus dive brakes Plus external pylons with removable racks for bombs and fuel plus internal pluming for fuel transfer - then removed the dive brakes but retained the additional wing structural improvements required for dive bombing - to 2x50 cal with Completely new engine and further beef up for increased deflection of ailerons - to 3x50cal in each wing. That said, ALL of the Mustangs from P-51-1-NA through A-36 through P-51A/B/C/D/K were capable of easy mod to install 2x20mm in each wing as well as the intended P-51F in interceptor role (never ordered but design performed).

So why, in your mind,do you consider that the 109K should have a different designation from generic 109? Wing modifications? Lol.

 

[varsity07840]

Not digging 'too deep'. You made a bold (and incorrect) statement that Bf 109 and Fw 190A didn't expand inner wing 20mm beyond the 1xFF for each wing. Simply wrong - own up to it rather than flail around comparing design changes from G to K as dismissive of the airframe designator.

For example - the Mustang airframe went from 2x30cal plus 1x50 cal in each wing and two (synchronized) in the cowl - then to 2x20mm in each wing, then the 2x50 cal in each wing plus two 50cal (Synchronized) in the cowl Plus dive brakes Plus external pylons with removable racks for bombs and fuel plus internal pluming for fuel transfer - then removed the dive brakes but retained the additional wing structural improvements required for dive bombing - to 2x50 cal with Completely new engine and further beef up for increased deflection of ailerons - to 3x50cal in each wing. That said, ALL of the Mustangs from P-51-1-NA through A-36 through P-51A/B/C/D/K were capable of easy mod to install 2x20mm in each wing as well as the intended P-51F in interceptor role (never ordered but design performed).

So why, in your mind,do you consider that the 109K should have a different designation from generic 109? Wing modifications? Lol.

I said that with the 109 and 190, they were never able to expand beyond one gun in the wing. The wing itself not the wing root and not under the wing. Is that true or not? As for the P-51, you've made my point. The wing was adaptable to different gun batteries. It didn't need add on gun tubs for increased fire power. Same with the P-40 and F4U. That was not the case with the 190 and 109.

 

[Reluctant Poster]

Greg, please go over the time line for the P-38. There are two different issues with fuel at different times.

The early US fuel had little or no aromatics, this was in 1940 or so, If you want 100/125 or 100/130 you have to use aromatics. At least if you want to make fuel on a large scale.

When the Americans started to use the 20% (max it could be less) fuel there were all sorts of problems, including dissolving rubber parts in the fuel systems and self sealing tank liners, Jetting may very well have been a problem but the other problems were bigger. ALL of the problems were eventually solved. This is in regards to the early 100/130 fuel.

Early 100/130 fuel was limited to 3.0ccs of lead per US gallon and while there could be 20% aromatics in the fuel the types of aromatics may have been restricted. Use of aromatics is also restricted by the standard of BTUs per pound of fuel (18,700?) and most or all of the aromatics are lower than that so if you use too much of the aromatics in the blend you have somewhat lower than requirement heat value per pound.

At some point in 1942 (early?) they decide that if they use 4.0 cc of lead per US gallon they can get a lot more 100/130 fuel from the same amount of base stocks so that is approved (after testing to see about lead fouling) and in late 1942 or early 1943 they decide they need a lot more 100/130 fuel and the way to do that is to allow 4.6cc of lead per gallon and allow more of the heavy aromatics but still not exceeding about 20% total. everybody knew that this "new" 100/130 might cause problems and the engine makers began testing it with the engines at the beginning of 1943. Allison found they did have troubles under certain conditions and started working on a new intake manifold in the spring of 1943. It was being fitted to engines and P-38s in either November or December of 1943 but since it takes weeks to get a P-38 From California to Europe all the planes in theater had the old manifolds.

As Shortround notes the US started producing and using avgas with high aromatic content in 1942, however his chronology is slightly askew:
4 cc of tetraethly lead was allowed in November 1941 (Others sources say December)
125 PN was called for in May 1942. (Other sources note that it was mandated after July 1)
130 PN was required in December 1942.
This from AAF Historical Study No 65 "Aviation Gasoline Production and Control" which I believe I have posted previously but I am attaching here.

The US began introducing aromatics into their fuels produced in the l USA in May 1942 with the production of the aromatic cumene (Isopropyl benzol). In addition all 14 of the catalytic crackers existing in the US were converted to the production of Avgas.
To quote Sam Heron from his book Development of Aviation Fuels
"In lieu of suitable straight run gasolines, aromatics and the sensitive cat cracked gasolines (which largely owed their sensitive and rich mixture properties to aromatics) became desirable material for making Grade 100/130 in maximum quantity."

An excellent book for those who are interested in the actual production of Avgas (and every thing else related to petroleum):
Amazon product ASIN 1410221954
I purchased this book about 5 years ago but it has since been digitized and is available via Google Books for free.
A History of the Petroleum Administration for War, 1941-1945
This book says the following about cumene and its importance:

The above figure from the same book illustrates the importance of the aromatic cumene and cat cracking in enabling the production of massive quantities of high octane avgas.

 

[ssnider]

Are you seriously saying that German engineers could not design a wing for the FW 190 to add more guns if they wanted to? The pod packs of 2-2o mm guns were field kits that could be quickly added or removed as needed. The Germans saw merit in the Russian view that wing guns were MUCH less effective than centerline guns. The British and Americans seem to have valued cowl streamlining more and added guns to the wings instead. Its a matter of design priorities and preferences.

 

[drgondog]

I said that with the 109 and 190, they were never able to expand beyond one gun in the wing. The wing itself not the wing root and not under the wing. Is that true or not? As for the P-51, you've made my point. The wing was adaptable to different gun batteries. It didn't need add on gun tubs for increased fire power. Same with the P-40 and F4U. That was not the case with the 190 and 109.

Varsity - you REALLY need to pick up some good books about Fw 190 - there are tons of Internal (to the wing as defined below) four gun 20 and 20/30mm combinations from variances of the A-5 all the way through Fw 190D. The Fw 190 A-7 and A-8 variants had more internal firepower on board than any primary Allied fighter with 2xMG131, 4xMG151 - all under the skin - before adding pods- and before swapping a Mk 108 for MG 151/20mm.

What they sacrificed was range when compared to say a P-51-1-NA with 90 gal fuel cell in each wing.

You seem hung up on the definition of wing root versus wing. The Root Chord, wing root (as defined by the fuselage-wing interface) and the wing all the way out to the tip. Anything from the wing tip to the wing root chord is part of the wing. Any gun mouted internally between the upper airfoil surface and the lower airfoil surface is internal to the wing.

 

[varsity07840]

Are you seriously saying that German engineers could not design a wing for the FW 190 to add more guns if they wanted to? The pod packs of 2-2o mm guns were field kits that could be quickly added or removed as needed. The Germans saw merit in the Russian view that wing guns were MUCH less effective than centerline guns. The British and Americans seem to have valued cowl streamlining more and added guns to the wings instead. Its a matter of design priorities and preferences.

I'm sure they could. But, and I'm speculating here, perhaps there was concern about interrupting production. That was the case with the P-38K which though vastly superior to the J, would have halted production for retooling for revised cowlings. There were some Germans who did not agree with the Russian approach, notably Adolf Galland who thought the centerline guns on the Bf-109F was a step backwards.

 

[Shortround6]

This argument goes round and round. What we have for "evidence" is a few quotes from different aces. Not to be disregarded but they are their opinions. Unless back up by facts or firing tests we do have room for reasonable doubt.

We also need to acknowledge the intended target. Shooting at an He 111 is rather different than shooting at a 109.

We also get stories about how big the groups were from wing mounted guns fired on the ground, way bigger than any gun would have passed a test at the factory so the problem is not the gun or the ammo. However you have more than the wing left, you have the mounting system to wing that allows for the gun/s to aimed in slightly different directions so you can get all guns to hit in spot if you want. Some mounts allowed for slight movement against springs to dampen recoil.
And we are to believe that the wing which can keep from breaking while pulling a high speed 5-6 G turn on a 3-6 ton fighter somehow flops around like a wet noodle under the recoil of the guns? Or one wing bend one way and the other wing bends the other way when turning?

We have diagrams for British guns with dispersion that is truly huge. An order of magnitude worse than any inspector would pass either ammo or gun for at the factory. I have no explanation except deliberate policy in setting up the gun mounts?

 

[Reluctant Poster]

I'm sure they could. But, and I'm speculating here, perhaps there was concern about interrupting production. That was the case with the P-38K which though vastly superior to the J, would have halted production for retooling for revised cowlings. There were some Germans who did not agree with the Russian approach, notably Adolf Galland who thought the centerline guns on the Bf-109F was a step backwards.

The K was not vastly superior to the J. Unless you have some new data that supports this.

 

[varsity07840]

The K was not vastly superior to the J. Unless you have some new data that supports this.

My understanding is that at the same altitude, the K was 40mph faster than the current production J. The service ceiling exceeded 45,000 feet and the full loaded climb rate in military power was 4,800 FPM. That information comes from Warren Bodie. I'd say that's a vast improvement.

 

[drgondog]

I'm sure they could. But, and I'm speculating here, perhaps there was concern about interrupting production. That was the case with the P-38K which though vastly superior to the J, would have halted production for retooling for revised cowlings. There were some Germans who did not agree with the Russian approach, notably Adolf Galland who thought the centerline guns on the Bf-109F was a step backwards.

Galland objected most to losing the 2xFF 20's in the wing- IIRC he had especially modified F to accept the twoxFF plus the CL 20mm.

The K never flew in ops and the only version was a J modified with larger prop and gear ratio change - that said the only comparison test flown between the K and J was stacked from the beginning when the K Gross Weight at Take Off was 600 pounds lighter than the 'competing J' - the difference in climb was about what you would expect. Additionally, when that test flight was made, P-51B and C production was in full stride and the P-51D was in serial production. There simply wasn't enough difference to slow down J/L production to even think about the K.

 

[varsity07840]

Galland objected most to losing the 2xFF 20's in the wing- IIRC he had especially modified F to accept the twoxFF plus the CL 20mm.

The K never flew in ops and the only version was a J modified with larger prop and gear ratio change - that said the only comparison test flown between the K and J was stacked from the beginning when the K Gross Weight at Take Off was 600 pounds lighter than the 'competing J' - the difference in climb was about what you would expect. Additionally, when that test flight was made, P-51B and C production was in full stride and the P-51D was in serial production. There simply wasn't enough difference to slow down J/L production to even think about the K.

I realize the K was not operational. I don't think it was ever contemplated that P-51 production should be halted, even though Bodie says the K tested a Eglin showed superior performance to the P-51 and P-47. The extant of the performance advantages of the K is probably a moot point considering it was still powered by an Allison that didn't like Northern Europe, had compressibility issues and a cockpit that was a nightmare for an inexperienced pilot.

 

[Reluctant Poster]

I realize the K was not operational. I don't think it was ever contemplated that P-51 production should be halted, even though Bodie says the K tested a Eglin showed superior performance to the P-51 and P-47. The extant of the performance advantages of the K is probably a moot point considering it was still powered by an Allison that didn't like Northern Europe, had compressibility issues and a cockpit that was a nightmare for an inexperienced pilot.

The tests were by Lockheed not by the airforce.

 

[varsity07840]

The tests were by Lockheed not by the airforce.

According to Bodie, the tests at Eglin were conducted by AAF.