On the p51d fdm configuration, it looks like the substantial change was
actually increasing the turbo multiplier from 2.0 to 5.5, and not reducing the
cruise speed as stated in the CVS log of March 23. The cruise speed change
does have an effect, but it is fairly small.
The problem with putting the turbo multiplier up in that range is the manifold
pressure output is directly multiplied by that number. So full throttle
produces an output of 164 inHG manifold pressure. We should be seeing about 61
inHG at sea level for this engine.
Setting this multiplier lower to get the correct manifold pressure with turbo
at sea level should reduce the maximum flight level for the aircraft since the
second stage turbo cannot currently be modeled. On the other hand, using this
lower value should NOT produce incorrect lower altitude performance since all
the data I'm using is for below the 20,000 ft altitude where the second stage
kicks in. The drag numbers calculated by YASim should be more or less correct
up to at least up to 20,000 ft where the second stage would be kicking in.
If there is a problem that setting the multiplier to 5.5 fixes, I suspect it
is in the FDM design and not the P51D configuration. Any ideas how we can fix
or work around this?
Flightgear-devel mailing list