Smokin Hole Posted July 25, 2012 Posted July 25, 2012 The P-51 feels far too efficient at cruise. I find that at 21,000 feet I can maintain 200 indicated with just 12-20" MP. That's 230+ true. This efficiency works with supercharger on or off. One notch of flaps at this altitude yeilds 150-170 with full power. (For all I know that could well be accurate but it also seems odd).
aaron886 Posted July 25, 2012 Posted July 25, 2012 No change with the supercharger? That sounds wrong at 21k...
Smokin Hole Posted July 25, 2012 Author Posted July 25, 2012 Not really. The supercharger just provides more air at altitude. If you are using a power setting below the "premium" yet get with boost on (say below 35") there should be little difference. To my simple mind, for a given altitude and temperature, power is nothing more than a combination of MP and RPM. If you are using the same MP in both cases, boost on or off, the thrust generated will be the same.
aaron886 Posted July 26, 2012 Posted July 26, 2012 Not really. The supercharger just provides more air at altitude. If you are using a power setting below the "premium" yet get with boost on (say below 35") there should be little difference. To my simple mind, for a given altitude and temperature, power is nothing more than a combination of MP and RPM. If you are using the same MP in both cases, boost on or off, the thrust generated will be the same. Well, at 21,000 feet if you're seeing no difference between with supercharger on and supercharger off and you're below the supercharger's critical altitude, that would be wrong. I suppose I should note I have no idea to what altitude the supercharger on the P-51 operates...
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