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Old 02-25-2014, 04:48 PM   #258 (permalink)
American Viking
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Quote:
Originally Posted by Old Mechanic View Post
Actually the WW2 engines used water injection for emergency power situations, where boost was a high as two atmospheres or more. I think it went to 35 PSI boost, which at sea level meant the engine would blow up in a matter of minutes, if not seconds.
War Emergency Power settings were for emergencies only, like in a B17 where you had two engines shot out and you needed to clear the coastline in order to ditch.
Heard once about a B17 that skipped itself over the channel and just cleared the cliffs of Dover on one engine.

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Mech
The B29's in WWII flying from Tinian, in the Mariana Islands, to bomb Japan need Water injection not to make max power but as a substitute for loss of air cooling on takeoff.
See, in order for the B29's to takeoff with a fuel load and a full bomb load, they really needed a longer runway, but that was not possible
Instead, the pilots were instructed to completely close all the cowl cooling flaps along with some other procedures to minimize the drag. That essentially meant no cooling for the engines, which made them overheat, detonate and in many cases catch fire.
Remember those engines would just about overheat while taxing in the tropical temperatures and they would easily spend an hour running engines while waiting with a hundred other bombers waiting to takeoff.
So the procedure was to close all cooling flaps at the start of the takeoff run, switch on the water injection at the 'point of no return' threshold on the runway, push the throttles through the "war power" gates (sometimes called the 110% power setting) to the final stops, click the stopwatch and hopefully climb to sufficient altitude to open the cowlings up before you had engine fire or engine failures.
That's extreme abuse, but it was war.
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