"Altitude and Loss of Engine Thrust" Topic

Any aeronautical engineers or ex-pilots out there?

I'm interested in the loss of thrust due to battle damage, and its effects on the ceiling of the aircraft and speed, both WWII bombers (might as well ask about fighters too, I suspect), as well as Cold War and Ultra-modern bombers and fighters too.

Not sure if the ceiling and speed will be affected in a linear manner, or not, but that would seem to be easiest, say perhaps a loss of 25% of max ceiling and speed if you lose one out of four engines, and 50% if you lose two.

That would seem to be easiest in game terms, but perhaps, especially for modern, multi-engine jets, that might not be the case at all.

Obviously, I don't want to get into Reynolds numbers, and they didn't really cover this in aviation class, so……

Thoughts?

From what I have read of crew experiences – 4 engine bomber, one engine out – mission kill, dump bombs, probably fall out of formation, sitting duck for fighters – Two engines not on same side, loose height, dump the rest of the loose gear such as guns, ammo, loose radios, consider bail out – remaining engines likely to fail from being run at maximum – look for a nice paddock/field. 3 engines or two on one side – bail out if you are lucky. 2 engine bombers may go straight to bail out, some may have enough power to stay in the air for a little while but most will descend more or less abruptly. Single engine aircraft its straight to glider mode, there has been some suggestion that radial engines could function for a while even with a cylinder or two shot off, but that's more powered brick than anything.

If you lose any part of the system you loose power. Recently the B-17 (Collings Foundation 909) that crashed in Connecticut, was a civilian operated B-17, she lost at least one engine completely. A 17 should fly fine with one windmill stopped. Imagine taking a ew rounds of 13.7mm or 20mm in your turbo or supercharger in the P-47 or Corsair.
Excellent breakdown here.
rwebs.net/avhistory/opsman/geturbo/geturbo.htm

Also something as simple as Heat in the air can affect aircraft engines. Aircraft are built with a cushion regarding horsepower and basic flight, but any critical damage or failure of part of the system means you loose power usually quickly. Great example if you own car, when it seriously overheats the engine looses power before sizing.

Game wise Id picture a saving roll if damage after a hit.
IE:
1-2 No effect
3-4 Power loss lose 25% of move range
4-6 Control Loss (cant make hard turns)

Hope this is what you were looking for.
Having restored a FG-1D Corsair the sheer number of systems that are vulnerable to a 50cal is frighting.

Hi Thresher01,
There is an excellent little book entitled "Fighter Facts and Fallacies", by John Lee, Asst Director of Research, United Aircraft Corporation, published 1942, which discusses the important aspects of aircraft performance in terms intelligible to the layperson. There is a handy summary in the appendix, entitled "FACTORS AFFECTING PERFORMANCE OF A TYPICAL FIGHTER AIRPLANE" which may be of use -

It states in brief that a 10% increase in "power loading" (i.e., an increase of 10 pct in the number of pounds to be borne per available horsepower) will affect performance approximately as follows -

3 pct loss of top speed
13 pct loss of climb rate at sea level
3 pct loss of service ceiling

If the logic follows for a damaged multi-engine B-17 …

> one engine out (loss of 25 pct horsepower) -
Top speed – lose 8-10 pct
Climb rate – lose 30-35 pct
Service Ceiling – lose 8-10 pct

> two engines out (loss of 50 pct horsepower) -
Top speed – lose 15-20 pct
Climb rate – lose 65-70 pct
Service Ceiling – lose 15-20 pct

Because the book addresses single-engine a/c, it does not speak to the effects of asymmetrical thrust, added drag from feathered props, etc. So I am guesstimating on that stuff.

FWIW.

B

Thanks for the info, and replies.

I appreciate them.

I can see where jets might/should be less affected by minimal/partial engine thrust loss, up to a point, given at least there are no wind-milling props to add drag.