1942: the best fighter

[tomo pauk]

In 1942, the Bf-109F-4 was far more reliable than Fw-190, the BMW-801D engine being restricted in manifold pressure and RPM (so performance was similar to the earlier 801C) for the better part of the year. The 109G-1 and G-2 were also available, yet to experience the issues with engines themselves. The 2-stage Merlin in Spit IX had no problems back then IIRC. So perhaps 109F-4 and Spit IX would be battleing it for the 1st place as pure interceptors? The Spit having perhaps twice the firepower than 109.

 

[davebender]

How many Spit IXs were in service during 1942? I'm under the impression Britain produced Spitfire Vs like hot rolls, making it the most common Spitfire variant prior to 1944.

 

[tomo pauk]

They are battling for the 1st place of the best fighter in service, in 1942. While Mk.V was more numerous, it still lags behind the Mk.IX.

 

[Glider]

Re the P38, Compressability was the item that sprang to mind, I understood that the P38 had problems at altitude in Europe due to the cold, ammunition was limited (I think) in the F to 60 rounds for the 20mm, agility was not impressive and loss's were high. In the Middle East the general opinion (from Fighters over the Desert) on the Allied side was that the Spit IX was the allied best fighter followed by the P38 for its speed and range and the Spit V for its agility.

Re the Spit IX vs the 109G until the addition of the various power boost options for the Me109 the SPit IX had it beaten for climb and the Spit had eaten away at most of the advantage the 109 traditionally had over the Spit in the dive, apart from a small initial advantage, the Spit always maintained its advantage in agility.

The Me109 G2 also had some serious limitations applied to its dive speed due to wing failures.

Two quotes from
Johannes Steinhoff, Sicily, Commander JG 77 (July 1943):

The Malta Spitfires are back again... They're fitted with a high altitude supercharger and at anything over twenty-five thousand feet they just play cat and mouse with us.

At 28,000 feet the Spitfire could turn in an astonishingly narrow radius. We on the other hand, in the thin air of those altitudes had to carry out every maneuver with caution and at full power so as not to lose control.

As I said before the Fw190 and the Spit IX I consider to be a draw.

 

[tomo pauk]

How the compressibility affected other planes (aside the P-51)?
I agree that it took a lots of time to solve the cabin heating, also agree that the cannon was drum fed (=60 rds). OTOH, the ammo for .50 cals was of great capacity (500 rpg), so both firepower it's duration were sufficient. The agility was not something to write home about, ditto for roll rate, though the turn rate (due to Fowler type flaps) was excellent. Losses sustained speak more about the LW USAAF pilot's experience, than about their mounts.
I can readily agree that Spit, 109 or 190 were excellent fighters, but when tasked to do something 300 miles (even 200?) from their air base, they were speechless. Unlike Ki-43, Zero, P-38 or Mustang.

 

[Vincenzo]

Spit IX had not best climb rate over 102G-2 also with this limited a combat&climb boost, had not real advantage in speed. thanks to higher FTH is best for him encounters over 8km, but it's in disadvantage from 5 to 8 km to altitude (after M.S. supercharger heght and before of F.S supercharger height). What altitude was most commonf for encounters over 8km or 5/8 km? Spit superior in dive of the 109??? what's the source of that?

 

[oldcrowcv63]

How the compressibility affected other planes (aside the P-51)?

It may have been a matter of degree since virtually all modern fighters must have been flirting with the effect as you suggested earlier. Apparently the P-38 was prone to losing its tail when suffering compressibility in a high speed dive. That'd be pretty hard to ignore and probably created a very bad impression among those pilots who were slated to fly it.

 

[tomo pauk]

If you could point me to a source that can prove that P-38s were loosing their tails at a greater rate (compared with other fighters) when experiencing compressibility in a high speed dive, that would be very good. It would be cool to know just how fast P-38s were diving (both controllably and in compressibility), and then to compare the values with other fighters.
The tail flutter issue was pretty early solved via installation of wing fillets.

The reputation of P-38 in Pacific units was pretty high, since Gen. Kenney was clamoring for more of those.

 

[oldcrowcv63]

If you could point me to a source that can prove that P-38s were loosing their tails at a greater rate (compared with other fighters) when experiencing compressibility in a high speed dive, that would be very good. It would be cool to know just how fast P-38s were diving (both controllably and in compressibility), and then to compare the values with other fighters.
The tail flutter issue was pretty early solved via installation of wing fillets.

from wikipedia:

On 4 November 1941, Virden climbed into YP-38 #1 and completed the test sequence successfully, but 15 minutes later was seen in a steep dive followed by a high-G pullout. The tail unit of the aircraft failed at about 3,000 ft (900 m) during the high-speed dive recovery; Virden was killed in the subsequent crash.

The same source quotes the P-38 as suffering violent tail vibrations at mach .68. That sounds like a fairly low mach number to be encountering such a problem to me. I believe advanced fighters, (certainly the 51) were able to do much better in this regard. I would expect the compression problem would appear in a smaller aircraft at a relatively higher mach number. The problem thus may have been simply one of size perhaps?

It's been too many years since taking my dynamics course but it seems to me that long booms tend to be more problematic in this regard than shorter, structurally tighter bodies

The reputation of P-38 in Pacific units was pretty high, since Gen. Kenney was clamoring for more of those.

Yes, I think he saw it as the answer to his prayers.

 

[tomo pauk]

Stating that P-38s were prone to loose their tails since the prototype was lost because of that is quite an exaggeration, won't you say?
As for Mach .68 being the limit, the Mach .65 equals to 440 mph at 30000 ft, and 460 mph at 20000 ft, true air speed (TAS). Think we can agree that at such speeds only P-51 was non problematic of all operative WW2 birds; eg. the dive speed limit for P-47, acclaimed diver, above 25000 ft was only 400 mph TAS. All figures from 'America's hundred thousand', but you can check out the respective manuals available for download in the Manuals sub-forum here.

 

[oldcrowcv63]

Stating that P-38s were prone to loose their tails since the prototype was lost because of that is quite an exaggeration, won't you say?
As for Mach .68 being the limit, the Mach .65 equals to 440 mph at 30000 ft, and 460 mph at 20000 ft, true air speed (TAS). Think we can agree that at such speeds only P-51 was non problematic of all operative WW2 birds; eg. the dive speed limit for P-47, acclaimed diver, above 25000 ft was only 400 mph TAS. All figures from 'America's hundred thousand', but you can check out the respective manuals available for download in the Manuals sub-forum here.

This is really interesting Tomo! I just came across the Basic airframe max dive limit for the P-38 as 0.73 which again seems low to me.

P-38 by Ray Wagner - Page 3

(I don't have America's 100,000 and am definitely handicapped for that deficiency!)

I have to reconcile the numbers you quote to a long accepted hearsay-based belief that diving WW2 aircraft were frequently reaching Mach numbers closer to 0.85-0.90. Something is wrong with this picture.

 

[oldcrowcv63]

For me, anything below mach = 0.8+ is not a high mach number and not close to the speed of sound. It suggests to me we are dealing with something other than the basic airframe limit.

from wiki

Sound barrier - Wikipedia, the free encyclopedia

No mention of losing the tail but once again, it seems to me that perhaps we are looking at a situation of vibrational distress that was only different in magnitude not kind.

Propeller aircraft were, nevertheless, able to approach the speed of sound in a dive. This led to numerous crashes for a variety of reasons. These included the rapidly increasing forces on the various control surfaces, which led to the aircraft becoming difficult to control to the point where many suffered from powered flight into terrain when the pilot was unable to overcome the force on the control stick. The Mitsubishi Zero was infamous for this[citation needed] problem, and several attempts to fix it only made the problem worse. In the case of the Supermarine Spitfire, the wings suffered from low torsional stiffness, and when ailerons were moved the wing tended to flex such that they counteracted the control input, leading to a condition known as control reversal. This was solved in later models with changes to the wing. The P-38 Lightning suffered from a particularly dangerous interaction of the airflow between the wings and tail surfaces in the dive that made it difficult to "pull out", a problem that was later solved with the addition of a "dive flap" that upset the airflow under these circumstances. Flutter due to the formation of shock waves on curved surfaces was another major problem, which led most famously to the breakup of de Havilland Swallow and death of its pilot, Geoffrey de Havilland, Jr.

OC

 

[Glider]

Spit IX had not best climb rate over 102G-2 also with this limited a combat&climb boost, had not real advantage in speed. thanks to higher FTH is best for him encounters over 8km, but it's in disadvantage from 5 to 8 km to altitude (after M.S. supercharger heght and before of F.S supercharger height). What altitude was most commonf for encounters over 8km or 5/8 km? Spit superior in dive of the 109??? what's the source of that?

As to what height the combats normally took place that would vary and I don't pretend to know the real facts. I do know that at this time SPit IX's were used as top cover for the other fighters so high altitude would be more normal with a Spit IX than other fighters. Whatever the facts certainly point to the Spit havng the advantage over the 109G2 at altitude.

As for the dive speed its a comparison of the Spit IX Pilots notes with the German instructions for diving the 109G2


Flying Limitations of the Spitfire IX (from Pilot's Notes)
Maximum speeds in m.p.h I.A.S.
Diving (without external stores), corresponding to a Mach No. of -85:

Between S.L. and 20,000 ft. -450
20,000 and 25,000 ft. -430
25,000 and 30,000 ft. -390
30,000 and 35,000 ft. -340
Above ..................35,000 ft. -310


Flying Limitations of the Me 109 G (from: Technical Instructions of the Generalluftzeugmeister, Berlin, 28th August 1942.)

Reference Me 109 - wing breakages. Owing to continually recurring accidents caused by wing breakages in Me 109 aircraft attention is drawn to the following:

(1) The maximum permissible indicated airspeeds in the different heights are not being observed and are widely exceeded. On the basis of evidence which is now available the speed limitations ordered by teleprint message GL/6 No. 2428/41 of 10.6.41 are cancelled and replaced by the following data:

Up to 3 km (9,842 ft.) 750 km/h. (466 m.p.h.)
At 5 km (16,404 ft) 700 km/h. (435 m.p.h.)
At 7 km (22,965 ft) 575 km/h. (357 m.p.h.)
At 9 km (29,527 ft) 450 km/h. (280 m.p.h.)
At 11 km (36,089 ft) 400 km/h. (248 m.p.h.)

These are significant differences. However it should be noted that air tests showed that the 109 held the initial advantage in dive speed and in combat that can be a priceless advantage is cover is around, or just buy a few seconds of time.

A lot more information is available from the following link.
Spitfire Mk IX versus Me 109 G - Flight Testing

 

[Glider]

How the compressibility affected other planes (aside the P-51)?
I agree that it took a lots of time to solve the cabin heating, also agree that the cannon was drum fed (=60 rds). OTOH, the ammo for .50 cals was of great capacity (500 rpg), so both firepower it's duration were sufficient. The agility was not something to write home about, ditto for roll rate, though the turn rate (due to Fowler type flaps) was excellent. Losses sustained speak more about the LW USAAF pilot's experience, than about their mounts.
I can readily agree that Spit, 109 or 190 were excellent fighters, but when tasked to do something 300 miles (even 200?) from their air base, they were speechless. Unlike Ki-43, Zero, P-38 or Mustang.

Going in reverse order I cannot disagree that if you are going 300 miles plus in 1942 then the P38, P51 and Zero were the kings of the roost. I would not be quite so sure about the quality of the pilots. The Germans had a number of very experienced pilots would were deadly, but they also had a lot of relatively poorly trained pilots. The USAAF probably had fewer experienced pilots but their rookies were much better trained so it could have been more equal that it might look at first glance.
I also agree that my concern about the 60 rds for the 20mm were overdone as the 4 x 0.5 concentrated in the nose were more than sufficient for most combats.

 

[tomo pauk]

Re. pilot quality in 1942: maybe we should need a new topic that could cover those issues? It took time for all air forces to climb up the learning curve, so I see USAAF as no exception. Question is at what time German pilot training got reduced that new pilots were at disadvantage, maybe that process started to take it's toll even as early as 1942.

 

[wuzak]

from wikipedia:

On 4 November 1941, Virden climbed into YP-38 #1 and completed the test sequence successfully, but 15 minutes later was seen in a steep dive followed by a high-G pullout. The tail unit of the aircraft failed at about 3,000 ft (900 m) during the high-speed dive recovery; Virden was killed in the subsequent crash.

The same source quotes the P-38 as suffering violent tail vibrations at mach .68. That sounds like a fairly low mach number to be encountering such a problem to me. I believe advanced fighters, (certainly the 51) were able to do much better in this regard. I would expect the compression problem would appear in a smaller aircraft at a relatively higher mach number. The problem thus may have been simply one of size perhaps?

It's been too many years since taking my dynamics course but it seems to me that long booms tend to be more problematic in this regard than shorter, structurally tighter bodies



Yes, I think he saw it as the answer to his prayers.

It wasn't to do with the size of the aircraft, but the size and the shape of the wing.

The P-38 had a thick wing - not sure what it was in thickness:chord ratio, but I believe it was higher than a P-51.

The compressibility effects were due to local airflow exceeding the speed of sound. It also occurred in the Hakwer Typhoon - which had extemely thick wings.

Kelly Johnson had the solution to teh tail flutter problem very early on - but was not allowed to apply it because they didn't want to stop/slow production. So Lockheed was instructed to install the external mass balances on the elevator - which Johnson knew did nothing to alleviate the problem. Evenually Johnson's solution was implemented - and that was wing root fillets to tidy up the airflow at the wing fuselage interface and reduce the turbulent wake.

FWIW, the Spitfire wing, designed in 1934/5, had a higher critical mach number than the laminar flow wing of the P-51 (designed in 1939/40), and its thickness to chord ratio was lower.

 

[wuzak]

Re. pilot quality in 1942: maybe we should need a new topic that could cover those issues? It took time for all air forces to climb up the learning curve, so I see USAAF as no exception. Question is at what time German pilot training got reduced that new pilots were at disadvantage, maybe that process started to take it's toll even as early as 1942.

There was a website comparing the training hours per pilot for British, US and German pilots. From memory the LW pilots stated the war with the best training, but as the war progressed their training time shortened, while the opposite was true of the allies.

 

[davebender]

Stating that P-38s were prone to loose their tails since the prototype was lost because of that is quite an exaggeration, won't you say?

We are discussing 1942 fighter aircraft. That P-38 lost it's tail during November 1941. I doubt the problem was fixed and a new model P-38 mass produced before 1942.

 

[tomo pauk]

The P-38E and later all featured the wing fillet, the small addition that cured tail buffeting. The 'P-38' that crashed was the YP-38, far earlier model, without the fillet.

 

[Vincenzo]

Glider the speed limit is an other thing to actual combat dive performances, so a few second of initial advantage that also the much best LF IX, "the Me.109 can leave the Spitfire without any difficulty" Spitfire LF.IX vrs. Me.109G Tactical Trials.
Also the altitudes where they fightning are facts