Jim Wilson wrote:
> What should I look for then when mucking with the cruise numbers from
> the prop definition?  Or is there some way to just remove them?

One thing to try would be to remove the variable pitch settings
entirely and nail the prop down at your specified cruise setting
(which should generally be low rpm, long range values).  Verify that
you get the desired performance in that configuration, then add the
min/max settings back in to check that they don't break anything.
Doing it this way, the variable pitch tuning shouldn't be far off from
1.0 in your cruise configuration.

> I've tried to get a little more thrust of this prop and haven't had
> much luck.  One thing that just occurred to me, does this formula make
> any assumption about the number of blades?  The P51D prop has four
> blades and I'm not clear on how that is accounted for.

Doesn't matter.  The big advantage to doing the modelling with an
efficiency curve is that you don't worry about details like this.  The
engine provides input power, divide by current speed to get output
thrust.  Plausibly perfect performance in all conditions.  But hard to

What thrust are you looking for, btw?  You can get an actual value in
pounds out of the property tree.  With some unit conversions, you can
multiply this by the true airspeed and divide by the engine power
output to work backwards manually to an efficiency value (maybe a
Nasal script would be good for this).  If you are seeing something in
the range of 75-85%, then your problem is more likely engine power
than prop thrust.


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