@Pumpkin:
Quote:
RC20,
Could use of WEP time have been limited to supercharger or boost temperature?
Possibly high exhaust valve temps, high inlet air temps surpassing the knock resistance given by the water injection?
Could you even hear detonation from inside the cockpit under such stressful full power conditions?
Apparently the connecting rods were Not the weak link being very robust.
If you just eroded the piston crowns necessitating replacement that's one thing, a hole in the piston would have been very bad. Better have kept your mechanic well lubricated
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Complex subject and I am no expert. EGT is used on aircraft for the lean function though when I was flying, you pulled back until a power drop off and then 1 inch forward past where it picked up again.
You did not want to spike the EGT. The complex and or FI engines, phew, many added EGT so they could protect their engines (costly things)
So its a dance between power needed with the prop speed and throttle and mixture all interacting.
Per Military historian, the FW-190 had an all in one control. Not separate levers. You could not maximize it in the air. But you also did not have to deal with EGT or Boost pressures in combat. I expect with interior lines you were not flying the long range missions the US and UK did (and Japan, phew, 700+ one way in a Zero)
So what I can tell you is Allison was far more rigorously tested than the Merlin. Maybe it was excess. They ran the 150 hours, tore it down, inspected everything and then adjusted parts build. Time consuming.
As I understand it, Merlin ran on the ragged edge of detonation and over. Never read a report of a pilot saying they hear it.
At least my use of lean, engine just fell off on power and you were very gentle on pulling that lever back. Once landed we killed the engine with full lean but it was idling.
Con rods from the Allison were used on the Merlin in air races.
Agreed on piston burn through.
And the time limit for WEP was a safe one but if you needed 30 minutes you would use it.
Keep in mind, in the UK you had the resources to do it per mfg (though I am willing to bet that was ignored during the Battle)
In the desert or the Pacific on the long end of a supply chain? Tough decisions and you may have just lived with being on that edge of failure.
Because I never flew constant speed aircraft, I never got into details per questions being asked. Just the general aspects.