"The case for the P-47 Thunderbolt being the greatest fighter of the Second World War "

[GregP]

Hypothetical, how would a P47 go head to head in a one on one dogfight after the merge with a 190A or MkIX LF at low altitude?, the Jug pilot would haul the big girl around only to find the other two already in a firing position, same for high altitude, at 30,000ft the Jug pilot would turn losing height only to once again look over his shoulder to see a TA152/Spit XIV bearing down on him from above, the P47 was a B&Z fighter which is fine if you are in a position to bounce your enemy but in a straight dogfight it's weight puts it at a serious disadvantage.

The likelihood of seeing a flying Ta 152 was very close to zero. They completed over 150 airframes but only delivered about 43 to combat units, not all at the same time, and there were never more than about 20 flying simultaneously over the entire war. That from Adolph Galland, who should know if anyone should know. It also was not a low-altitude dogfighting airplane. The Fw 190 was also not the best dogfighter due to the zero-warning stall, meaning it could roll rapidly, but most pilots could not pull it as hard as they wanted, especially at low altitude since the stall was known to be somewhat vicious. I'd bet it would still out-turn a low-altitude P-47, though.

The P-47 didn't have the no-warning stall issue and handled pretty well as well as conventionally. The P-47 was also generally the best high-altitude fighter that was built in any substantial numbers. The Ta 152 may have BEEN a bit better, but there weren't anywhere near enough to even be dangerous.

Their total victory count for the entire war was anywhere from 6 to 10 victories (depending on who you believe) balanced against 2 to 4 losses in air-to-air combat. Granted, that was mostly due to the war situation coupled with rushing the Ta 152 into production before it was ready, no training on them, and no spare parts for the units that flew them. Still, 6 to 10 victories from 43 airplanes gives the Ta 152 a HUGE numerical and kill-ratio disadvantage over the P-47, which doesn't have a bad war record at all.

By the way, my German claims file shows 1,102 claims for P-47s in about 2 years of combat flying, which is pretty much in line with, though a bit lower than, the P-51 claims.

 

[GregP]

Merlin Mustangs appeared in large numbers after most of the experienced Luftwaffe pilots had been killed. The Germans did not deploy two stage superchargers until the last few weeks of the war. Spitfires went up against a well equipped, battle hardened Luftwaffe fighting mostly at altitudes where they were effective.

The Merlin-engined Mustangs also flew in the heaviest aerial fighting of WWII, which was in 1944 escort missions and 1,000-plane raids. The Spitfires pretty much didn't, though they DID face better German pilots early-on in the war.

 

[GregP]

It was a low altitude engine.

It used the turbocharger to be able to work at high altitude.

The engine may have been low-altitude, but the power system wasn't, and that is what they operated with, the entire power system including the turbocharger.

 

[PAT303]

The Merlin-engined Mustangs also flew in the heaviest aerial fighting of WWII, which was in 1944 escort missions and 1,000-plane raids. The Spitfires pretty much didn't, though they DID face better German pilots early-on in the war.

Merlin engined Mustangs couldn't have flown those missions without the Spitfires Typhoons Tempests of 2nd TAF and P47's of the 8th AF giving them a clear run. The Mustang was an awesome aircraft but the best?, no chance.

 

[PAT303]

The P-47 was also generally the best high-altitude fighter that was built in any substantial numbers

Testing done in 1946 on a P47N had it all but destroying it's engine performing a high altitude high speed test it was famous for, it also rolled poorly and was longitudinally unstable when combat loaded so I'm not convinced. P-47N Performance Test

 

[GregP]

Merlin engined Mustangs couldn't have flown those missions without the Spitfires Typhoons Tempests of 2nd TAF and P47's of the 8th AF giving them a clear run. The Mustang was an awesome aircraft but the best?, no chance.

Yes, they could have flown those missions regardless of help from Spitfires. And the Spitfires didn't need help from P-51s either. They were both flying entirely different missions that were only slightly related in that both were in the air and fought against Germans.

 

[GregP]

Testing done in 1946 on a P47N had it all but destroying it's engine performing a high altitude high speed test it was famous for, it also rolled poorly and was longitudinally unstable when combat loaded so I'm not convinced. P-47N Performance Test

Fortunately, that doesn't change the results. Many airplanes broke during performance testing, including those from all nations and manufacturers. Few of the breakages meant more than but a return to the maintenance area, but a few resulted in crashes. The P-47N gave very good service when it was used. Many airplanes (including British airplanes) were somewhat challenged when they took off at long-range weights, but that didn't stop them from being good performers; P-47N included.

 

[PAT303]

Yes, they could have flown those missions regardless of help from Spitfires. And the Spitfires didn't need help from P-51s either. They were both flying entirely different missions that were only slightly related in that both were in the air and fought against Germans.

No they would've have, mustangs made it to Berlin because they could carry their tanks to the border without interference from the Luftwaffe, 2nd TAF and 8th AF aircraft made sure of that.

 

[PAT303]

Fortunately, that doesn't change the results. Many airplanes broke during performance testing, including those from all nations and manufacturers. Few of the breakages meant more than but a return to the maintenance area, but a few resulted in crashes. The P-47N gave very good service when it was used. Many airplanes (including British airplanes) were somewhat challenged when they took off at long-range weights, but that didn't stop them from being good performers; P-47N included.

The more they flew it the more things went wrong, reading between the lines it appears the engine couldn't meet it's rated performance.

 

[Shortround6]

It was a low altitude engine.

It used the turbocharger to be able to work at high altitude.

Put a smiley on the jokes.

As has been pointed out the power system worked the same on all versions of P-47. Different limits depending on exact model but there were no non-turbos built.
No cropped impellers or low gears in the superchargers.

 

[GregP]

No they would've have, mustangs made it to Berlin because they could carry their tanks to the border without interference from the Luftwaffe, 2nd TAF and 8th AF aircraft made sure of that.

We'll have to agree to disagree. But, hey, that's OK.

I have spoken with WWII veterans about that and they said no (I think they said "hardly any") German fighters challenged the escorted bombers over the UK because there were simply too many fighters in the air. They waited until the bomber streams crossed into flak territory and were over continental Europe.

 

[Shortround6]

The more they flew it the more things went wrong, reading between the lines it appears the engine couldn't meet it's rated performance.

Ok, what was the maintenance requirements or problems with running a Merlin at 18lbs of boost or above in extended testing?

The P-47M and P-47N were the first installations of the "C" series engines and were operating at different RPM than the older engines.
Also note that the WEP of 2800hp was 33% higher than the MP rating of the engine and was higher than the ratings used for the Centaurus engine in the Tempest II.
Interesting report.

Tempest II Tactical Trials

Tempest II vs Thunderbolt II (P-47D) without water injection.

 

[GregP]

The R-2800-57/73/77 engines were stretched to make 2,800 hp. They were not happy at that power level, and they only built 130 P-47M models. I doubt anyone actually ran them at 2,800 hp for long in any case except an engine test stand guy or a test pilot who was more or less over the runway.

Yanks Air Museum has a genuine P-47M. As far as I know, we have no plans to fly it, and we couldn't run it at 2,800 hp anyway since we don't have 150 PN fuel to run it with. On 100 LL you could probably get 1,600 hp from it easily enough. We DO plan to fly our P-47D after we overhaul the propeller and do an annual on it.

 

[dedalos]

The R-2800-57/73/77 engines were stretched to make 2,800 hp. They were not happy at that power level, and they only built 130 P-47M models. I doubt anyone actually ran them at 2,800 hp for long in any case except an engine test stand guy or a test pilot who was more or less over the runway.

Yanks Air Museum has a genuine P-47M. As far as I know, we have no plans to fly it, and we couldn't run it at 2,800 hp anyway since we don't have 150 PN fuel to run it with. On 100 LL you could probably get 1,600 hp from it easily enough. We DO plan to fly our P-47D after we overhaul the propeller and do an annual on it.

Greek air force recently restored in enland , a spitfire ix lf, that was sitting for decades outside the war museum. As a child i was climbing ,illigaly, on its wings
Recently i spoke to one of its 3 current pilots. Despite the fact , they say that the engine is better than new after the restoration, they use minimum power even for take off. They are very gentle with the aircraft even on the air. Of course the aircraft flies in a much lower weight than in its operational configuration. Propably they never exceed 1000 hp.
. it often flies in formation with f16s .

 

[PAT303]

Ok, what was the maintenance requirements or problems with running a Merlin at 18lbs of boost or above in extended testing?

Merlins were cleared to run 25lbs boost on operations as you are well aware,
(Quote) Maintenance. No difficulty was experienced in maintenance of the engine though most running was at high boost. In one case only an exhaust stub was burnt out and no plug troubles were encountered. The R2800 couldn't run to it's rating in testing,
(Quote) At high power settings considerable maintenance was involved because of oil leaks, cracked vacuum pump housings, exhaust collector rings burning out and oil leaks. At war emergency power these malfunctions become excessive and operation was restricted at this power. In military power climbs high oil and cylinder head temperature above 30,000 ft. were experienced and made it necessary to reduce power after ten minutes of operation to cool the engine.

 

[GregP]

Merlins were cleared to run 25lbs boost on operations as you are well aware,
(Quote) Maintenance. No difficulty was experienced in maintenance of the engine though most running was at high boost. In one case only an exhaust stub was burnt out and no plug troubles were encountered. The R2800 couldn't run to it's rating in testing,
(Quote) At high power settings considerable maintenance was involved because of oil leaks, cracked vacuum pump housings, exhaust collector rings burning out and oil leaks. At war emergency power these malfunctions become excessive and operation was restricted at this power. In military power climbs high oil and cylinder head temperature above 30,000 ft. were experienced and made it necessary to reduce power after ten minutes of operation to cool the engine.

Not true. SOME Merlins are cleared to run at 25 psi of boost. Not all of them by any means. Merlins definitely DID required extra maintenance when operated at consistently higher boost. They still do today. Ditto big radials.

Ratings were established in performance testing. They were not assigned by the marketing department.

The Planes of Fame Museum operates R-2800-powered airplanes and they are extremely reliable. I worked the Planes of Fame airshow for 10+ years and we had R-2800-powered airplanes flying frequently every day of the airshow. There was one-single R-2800 airshow failure on an R-2800 in that time and only one takeoff was ever cancelled due to engine issues for R-2800-powered aircraft. It was a Tigercat and it had fouled a spark plug. It flew later in the day after the plug had been changed. All the aerobatic displays were flown at high power settings, with absolutely no evidence of what you suggest. My overriding impression after 10+ airshows was surprise that the old engines were so reliable. We flew about 50 sorties per day for 3 days for 10 years. That's 1,500 sorties with about 5 aborts. 1 was a flat tire. 1 was a Corsair that couldn't get one wing to unfold (hydraulic valve). 3 were engine-related; 1 was an R-1820 in Grumman F3F (backfired on landing and blew a gasket), 1 was the Tigercat, and the other one was a P-40 with a Curtiss-Electric prop that needed the brushes changed. That is, the issue was the prop rpm governor, not the Allison.

Here's a Tigercat at one of those airshows. The engines in the clip below aren't being babied.


View: https://youtu.be/TJxpUgeCWk0


Do R-2800s require maintenance? You bet. But nothing unusual. Normal maintenance wasn't too bad and engine changes weren't, either, relatively speaking. That is, all engines were a bit of a pain to change, but the big radials weren't any more difficult and actually could be easier since there were no coolant lines to deal with.

The old pilots who give talks tell us how reliable the R-2800 was, often being dispatched for several missions per day with no maintenance required between mission except refueling and topping up the oil tank(s).

All piston engines of that vintage required high, or at least higher, maintenance when operated at high power settings. If you used WER, there was mandatory maintenance and mandatory inspections required, regardless of whether the engine was a radial or an inline. Break the throttle wire and you triggered automatic maintenance. Break it too often and you triggered an automatic engine replacement.

 

[PAT303]

ot true. SOME Merlins are cleared to run at 25 psi of boost. Not all of them by any means.

Merlin 66 engines were tested with 150 PN fuel and 25 Psi boost in late 1943, by mid/late 1944 ALL Merlin engines were cleared to run 150 grade/25Psi as were the V1650-7's, that was after completing the 7 1/2 hour rating test at WEP.

 

[GregP]

Perhaps you mean all 2-stage Merlins were cleared at some point.

Not too sure single-stage Merlin ever got cleared for that MAP level. A Merlin 45 engine, for instance, was limited to +16 psi for it's entire operational life, IIRC. Now, they well might have taken all the single-stage units out of service at some point, certainly not right when the first Merlin 60 series was released, but I'm not too sure they CLEARED them for +25 psi boost, ever.

Do I think they'd operate there OK? Yes. That doesn't mean they were cleared to do so.

 

[PAT303]

A Merlin 45 engine, for instance, was limited to +16 psi for it's entire operational life, IIRC

It was obsolete by the time 150 PN fuel and 25 PSI boost was available, saying that the Merlin 50 was approved for 18 Psi mid 1943.

 

[ThomasP]

The following war-time Merlins were officially cleared for use of 150 grade and +25 lbs boost:

Merlin 24/224/25/225/26/27/66/266/70/71/76/77/100/101/113/114/130/131 and V-1650-7

All are listed in the respective airframe Pilot's Notes, and/or mentioned in Air Ministry/USAAF dispatches, as cleared for use of +25 lbs boost