Sycamore,
You can start an engine and keep it in the feathered position until you are up and running, where you can then unfeather the prop and put it on load immediately.
If it decides not to unfeather then at least it’s in the right position.
Your ‘inference (there’s that word again) suggests that in restarting a feathered engine will immediately cause major drag problems, particularly where asymetrics are concerned.
But as I detailed above, engines can be re-started with no ‘significant’ problems and regardless of which position on a multi engined aircraft.
Bomberboy
Hummm, not quite sure where you are comming from here.
What you are actually talking about would be the airstart and unfeathering process of a free wheeling turbine, like the PT6, PW120 or something similar. They are, in the course of normal operation and during attempted airstarts, started with the prop in the feathered position. This is possible due to the fact that the prop is not connected to the gas generator turbine. On these engines, there are, say, three turbine discs at the rear. The two of them, that are nearest to the cans, are fixed together and are called, collectively, the gas generator turbine. The gas generator turbine runs the engine’s compressors located at the front end via a shaft. The rear most turbine would be called the Power Turbine, and that one would run the prop via a shaft running INSIDE the shaft powering the gas generator. As the prop and the compressor do not share the same turbine, it is possible to start the engine with the prop feathered.
Now lets look at a direct drive turbine like the Garret TPE 331. On that engine the Gas Generator Turbine and the Power turbine are one and the same. Two (IIRC) turbine discs at the rear driving one shaft, onto which are put the compressor and the prop (via a gearbox). Now, what would happen if you tried to start an engine like that in feather? The drag of the propeller rotating in feather, would either burn (set fire) to your starter motor, OR you would cook the engine itself when trying to spool it up to idle speed. All aircaft with direct drive turbine engines have UNFEATHERING buttons to be used before airstart is attemped from the feathered position.
All piston engines are direct drive engines, you can not turn the engine without turning the prop. If you try to start a piston engine in feather, one of two things will happen. Your starter will go up in smoke, due to the drag of the prop in full feather OR your engine will be ruined due dentonation (spelling). Dentonation is what happens if you put a lot of stress on your engine. A lot of heat will build up inside the cylenders and hot soot will begin to collect there. When the next portion of fuel/air mixture is put into the cylender the soot will set it alight and there will be an istantanious uncontrolled explosion as opposed to the controlled burn of normal operation. Very, very bad for your engine. So how do we start piston engines from feather? On a big thing like a Merlin, I think (without knowing for sure) that there would be an UNFEATHERING pump that would put the prop into fine pitch, and from there the engine (maybe with starter assist) would windmill till it was running.
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