It has obviously been a long time since anyone here flew pistons!
Originally Posted by john
...as you appear to be suggesting, a magical low drag system ?
virgo isn't suggesting this at all, john - merely pointing out that a constant speed prop is just that. The control range of the pitch is relevant however.
Originally Posted by no-hoper
The prop has to go to feather position otherwise the drag will be too high.The engine will not turn anymore-means no more indications.
The prop is feathered by the pilot. The question is about what happens
before the prop is feathered (and the engine is thus still turning.)
Originally Posted by Micky
Secondly no piston engine will keep on windmilling due to the internal forces of turning the engine (try turning a big six cylinder engine on the ground...)
Sorry,
Micky - the air we fly through can provide a lot of force (enough to lift the entire aircraft into the air
). All piston engines keep windmilling after a failure (discounting mechanical lock-up) until the pilot feathers the prop.
Originally Posted by Micky
And when the engine is not working no supercharger will work or turbocharger.
Superchargers are directly geared to the drive train. If the engine is windmilling, the supercharger is turning, and thus doing it's job to compress the intake air. Turbochargers are powered by the extra energy in the exhaust, if the fire isn't burning, a turbocharger will stop working - but that isn't the question here.
Originally Posted by Micky
And as the engine is not working Oil pressure would be 0psi,
After the engine has stopped (after being feathered by the pilot) yes, this is the case. While the engine is windmilling, the oil pump is still being driven, so oil pressure is still normal.
Originally Posted by Deltabravowhiskey
Constant speed propeller systems regulate a positive torque output from the motor and convert that torque into a regulated speed.
Sorry, absolutely incorrect. You are confusing torque sensing (for auto-feather systems in turbines) with prop governors. Prop governors sense prop RPM, and adjust the pitch to compensate. If the RPM drops, the governor commands a finer pitch - if the engine is running, this reduces prop angle of attack, and thus prop drag and the RPM increases back to the governed level. If the engine is not running, the RPM drops, the governor commands finer pitch, this
increases angle of attack (relative wind is striking the front face of the prop in a windmilling situation) and the relative wind thus drives the prop faster.
So, back to the original question:
Supercharged engine, with a non-mechanical engine failure. Prop governor maintains prop RPM. Supercharger & oil pump is mechanically linked to the crankshaft so they still operate normally.
Indicated RPM, oil pressure & manifold pressure all indicate the same after the failure as they did before, and this will continue until the propeller gets to the fine pitch stop, the point of which depends on the airspeed of the aircraft.
The fire has gone out, so Cylinder Head Temp. reduces rather quickly, oil temperature reduces less quickly and (as the prop is now being driven by the airspeed) the aircraft yaws into the failed engine and the airspeed reduces. It gets a bit less noisy as well.
[anecdote: check captain checking new pilot on a
Heron arrives in the cruise. Check Captain reaches over and pulls all four mixtures out to the same point - as a demonstration of "efficient" engine management. Pilot under check thinks something is wrong - so pushes mixtures back in - and with the surge of power realises that the
Check Captain had shut down two engines without realising it!
[True story, that.]