Originally posted by Angus
"Spitfire`s WEP time was restricted to one-half or one-third that of the WEP time of the 1944 German figters, try to live with that."
True,however not completely. Guaranteed 5 minutes without harming the engine, but nothing to stop you running the it at high WEP until it broke. There are reports of Merlins being run at WEP up to 30 minutes without any damage.
The MW would however gradually eat the engine with the side effect of power loss unless it would be overhauled frequently. That often was a hard task for the German engineers in the heat of war.
What eats engines is the load, and ruining effects of the fuel/mixtures used. The first one is easy to get, ball bearings will give it up sooner or later, pistons crack, crankshafts broke etc.
The other is the additional wear within the pistons from the fuel and mixture. Allied 150 grade was high on aromatics, and so were the German C-3 fuel, which means increased fouling especially of the spark plugs etc. MW had both good and neg effects for maintaince. The good one : it helped to keep the engine internals clean from the leftovers of burning such highly blended fuels, thus reducing the problems associtated with these fuels. The neg one was corrosion - though not that much of a problem, as 99% of these engines were aluminium alloy, but the engines needed to be checked for signs of corrosion more often - every 50 hours as Jane`s says so. But it`s not acid or something that it would eat the engine.. the greatest killer of all these engines was the extreme loads of the parts under their maximum outputs. As for the 'low overhaul time' problem, I doubt German mechanics would change the powerplants any more often than their Allied counterparts of +25lbs etc. Spits. First, statistically, the plane was already written off by the time overhaul was neccesary (ie. loss rate vs. sorties required to reach overhaul time). Second, engine swap was very quick on those German birds, being 30mins or so on the 109, not sure how much it did take on the 190, probably a bit more, given the size and dimensions. Thirdly, by the time those birds with MW engine eating acid
arrived, there were so many replacement a/c produced, that they didn`t even bother repairing damaged fighters. 'You broke it? That`s tough, go grab another one.' Literally.
As for the Merlin/30min at WEP/no damage, I am highly sceptical about that. All these prescribed periods are with a safety margin of course, but nothing like 6 times than allowed. And, take note that nothing prevented you from using MW50 as long as you wanted, as long as there was fuel in the tank to burn. Though I bet funny noises would come from the engine after a while. Not something you ask for in the winter, over the Ardennes with no place to land on..
