Quote:
Originally Posted by MadBlaster
the example works better for me if you assume the 'sudden' drop in efficiency for the bad prop happens at the margin of the csp peak envelope at/near Vmax/level. And to make it even more emphasis, the efficiency drops from .85 peak to 0 no thrust when 1 more kph is added above Vmax/level in 1 second, as soon as you enter the 45 dive. also, drag force just kicked you back into the peak envelope. okay, yes the bad prop now has excess negative thrust. because in that 1 second you went from max thrust to no thrust from the prop and drag force pushed you back and not enough time has elapsed for excess thrust from 45 weight vector to overcome the momentary loss from the prop. I'm probably missing something.
Now, we know there are no 'sudden' drops in these curves. they have slopes and they are a functions of TAS, RPM, reduction ratio, blade diameters...etc. this example, rigged.
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Good prop and bad prop share same diameter, same rpm, same advance ratio@same TAS. Their DIFFERENCE IS THE SHAPE OF AIRFOIL SECTION.
TAS Mach / good CSP / bad CSP
0.6 85% 85%
0.61 84% 83%
0.62 83% 80%
0.63 82% 77%
0.64 82% 73%
0.65 81% 70%
0.66 81% 67%
0.67 81% 64%
0.68 80% 60%
0.69 80% 56%
0.70 80% 52%
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Your TempestMKV equipped with bad propeller, my Tempest with good propeller.
If I drag you into a high speed dive, around 0.7 Mach TAS for 40 seconds, what is your energy loses?
To simulate this sharply efficiency drops for bad propeller, you can simply use il2 4.11m, quick mission, spawn @ 5000 m with Tempest mkv, you intently decrease your throttle to 60% during 0.6-0.7 Mach 45 degree dive and 45 degree zoom.
You will feel the energy loss.