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More work to get the starter behavior right, without breaking David's

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work on the pa28 idle and without creating ridiculous side effects
(like being able to fly the aircraft with the starter motor, heh).
This one looks pretty good for now, pending work on the propeller to
get its low speed drag in line with reality.
This commit is contained in:
andy 2004-03-27 18:34:04 +00:00
parent 199aa53157
commit dc41cdb948
1 changed files with 16 additions and 11 deletions
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27
src/FDM/YASim/PistonEngine.cpp
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@ -130,7 +130,7 @@ float PistonEngine::getEGT()
void PistonEngine::calc(float pressure, float temp, float speed) void PistonEngine::calc(float pressure, float temp, float speed)
{ {
if(_magnetos == 0 || speed < 200*RPM2RADPS) if(_magnetos == 0 || speed < 60*RPM2RADPS)
_running = false; _running = false;
else if(_fuel == false) else if(_fuel == false)
_running = false; _running = false;
@ -191,20 +191,25 @@ void PistonEngine::calc(float pressure, float temp, float speed)
float power = _power0 * burned/_f0; float power = _power0 * burned/_f0;
_torque = power/speed; _torque = power/speed;
// Figure that the starter motor produces 60% of the engine's // Figure that the starter motor produces 15% of the engine's
// cruise torque. That sounds like a lot to me, but it's // cruise torque. Assuming 60RPM starter speed vs. 1800RPM cruise
// necessary to produce the right acceleration. Someone should // speed on a 160HP engine, that comes out to about 160*.15/30 ==
// find a good reference for this... // 0.8 HP starter motor. Which sounds about right to me. I think
// I've finally got this tuned. :)
if(_cranking && !_running) if(_cranking && !_running)
_torque += 0.60f * _power0/_omega0; _torque += 0.15f * _power0/_omega0;
// Also, add a negative torque of 10% of cruise, to represent // Also, add a negative torque of 8% of cruise, to represent
// internal friction. Propeller aerodynamic friction is too low // internal friction. Propeller aerodynamic friction is too low
// at low RPMs to provide a good deceleration. Interpolate it // at low RPMs to provide a good deceleration. Interpolate it
// away as we approach cruise RPMs, though, to prevent interaction // away as we approach cruise RPMs (full at 50%, zero at 100%),
// with the power computations. Ugly. // though, to prevent interaction with the power computations.
if(speed > 0 && speed < _omega0) // Ugly.
_torque -= 0.16f * (_power0/_omega0) * (1 - speed/_omega0); if(speed > 0 && speed < _omega0) {
float interp = 2 - 2*speed/_omega0;
interp = (interp > 1) ? 1 : interp;
_torque -= 0.08f * (_power0/_omega0) * interp;
}
// Now EGT. This one gets a little goofy. We can calculate the // Now EGT. This one gets a little goofy. We can calculate the
// work done by an isentropically expanding exhaust gas as the // work done by an isentropically expanding exhaust gas as the