Thunderbolts and Mustangs versus the Jagdwaffe (split topic)

[Six Nifty .50s]

Originally Posted by Franek Grabowski

I have never heard pilots complaining on reliabilty of their Merlins

Well I've heard of it, right up until the Spring of 1945. Fouled spark plugs and rough running Merlins was a very common complaint, but a minor flaw next to its weak main bearings.

At least three Mustang Mk IIIs from 316 (Polish) Squadron crashed due to Merlin engine failure, within four months. An overall check of other squadron losses due to motor trouble proves what I suspected all along, the Allison engine was far more dependable than the Merlin:

65 Squadron: 7 Spitfires, and 1 Mustang Mk III
222 Squadron: 7 Spitfires
401 Squadron: 9 Spitfires
412 Squadron: 9 Spitfires
421 Squadron: 7 Spitfires

2 Squadron: 1 Mustang Mk I, and 1 Mustang Mk II
16 Squadron: 0 Mustang Mk I
26 Squadron: 0 Mustang Mk I
168 Squadron: 0 Mustang Mk I
169 Squadron: 0 Mustang Mk I
170 Squadron: 0 Mustang Mk I
241 Squadron: 0 Mustang Mk I
268 Squadron: 1 Mustang Mk I, and 0 Mustang Mk II
400 Squadron: 0 Mustang Mk I
430 Squadron: 1 Mustang Mk I
613 Squadron: 0 Mustang Mk I

The actual number of engine failures per squadron is probably 3x higher or more. From July 1940 through October 1940, No. 43 Squadron lost no less than four Hurricanes to motor trouble and it is probably safe to extrapolate that for the entire war.

The least reliable piece of equipment on the Allison was the automatic boost control. This was sometimes removed by the RAF and since they routinely overboosted the engines anyhow, the limiter was just an annoyance.

Originally Posted by Franek Grabowski

ORB of 309 Sqn notes frequent visits of Allison engineers trying to rectify experienced problems

I've read about this, but it seems that you misquoted the ORB.

No. 309 flew the Mustang Mk I from 1942 to early 1944. In November 1943, the radiators installed in AM211 and a few other Mustangs gave trouble, causing spark plugs to foul. This persisted for some time as they tried to fix the radiators with field modifications, but there was no problem with the Allison engine itself.

Originally Posted by Franek Grabowski

Note that air racing teams flying P-51Ds installed Allison connecting rods to prevent their Merlins from blowing up. Without this modification, the Mustangs could not compete with the speedy Bearcats at Reno.

Aircraft races are so specific matter, I do not think any experience applies here.

Rolls-Royce tried to market the Merlin engine for commercial airlines, but it was generally rejected because of poor reliability, and high fuel consumption for a liquid-cooled power unit. Many times I have read that Mosquito pilots reported that single-engine returns were very common.

Originally Posted by Franek Grabowski

One cannot escape common knowledge that liquid-cooling systems were easily knocked out with one bullet or shell splinter.

I talked to several Polish 2 TAF Spitfire pilots and I never heard them complaining a lot about the problem.

Maybe they were tired of complaining about it...