So I've been flying a bit.

Mooneymike

Mooneymike

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Mike
After about four hours I am finally geting back to feeling comfortable back in the saddle. One thing I always do when I fly is look around for the best place to land if the fan were to quite turning. So when I was walking on the shore of beautiful Lake Huron this AM I had about an hour to think about what configuration I would want on the prop control for a max glide effort. What say you, high pitch, or low pitch? I have not actually come to any conclusion yet so please say why you think one would be better than the other. Thanks in advance. Mike:dunno:
 
i say low rpm
reason: less drag.

that is, if i need less drag.
 
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Sac Arrow said:
Low pitch (minimum RPM, lever or knob fully back) for two reasons - one for less drag, and the other for additional torque to enable the prop to windmill better for a possible restart.
Click to expand...

Min RPM = High Pitch, which is the low drag configuration.

I thought about this too, and it only works if you still have oil pressure. If you lose oil pressure the prop will go to low pitch and high RPM (for single engine aircraft), which is high drag. Nothing you can do about it though.
 
For this case lets say you still have oil pressure. I think you would get more glide distance with the knob all the way out, high pitch, but than I get to thinking about push starting cars and how much extra effort it takes to get the engine spinning when you are in a higher gear with not much speed, as in best glide speed. Great comments so far, I am still thinking.:idea:Maybe I should quit thinking.:wink2: The nice thing about losing oil pressure is the engine will eventually seize up and then you will have less drag from the prop.
 
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Definitely pull the knob out to go to high pitch. I've done this in a simulate engine out and the plane almost 'lunges' forward when you go coarse pitch. Actually, it probably did lunge a bit for a second b/c I was still running idle, so I had enough oil pressure to force the blade coarse, but even after the initial surge, I could tell a definite difference in glide characteristics - especially with a 3-blad prop.
 
Mooneymike said:
For this case lets say you still have oil pressure. I think you would get more glide distance with the knob all the way out, high pitch, but than I get to thinking about push starting cars and how much extra effort it takes to get the engine spinning when you are in a higher gear with not much speed, as in best glide speed. Great comments so far, I am still thinking.:idea:Maybe I should quit thinking.:wink2: The nice thing about losing oil pressure is the engine will eventually seize up and then you will have less drag from the prop.
Click to expand...

Try this approach. The fewest revolutions per foot will provide the lowest drag (hold in airspeed constant).

Example:
Airspeed: 150 feet per second
RPM: 2700RPM = 45 RPS
Revolutions per foot: 0.3

Airspeed: 150 fps
RPM: 1500RPM = 25RPS
Revolutions per foot: 0.17
 
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