FP Prop that has stopped in-flight

[sailvi767]

I was wondering the exact same thing. Your having a really bad day if your engine quits and the starter fails at the same time.

George

[Snowflake]

If your engine quits you're already having a bad day.

The question is what do you do when your engine quits and it can't be re-started... No fuel, ingested valve, electrical gremlin, etc. obviously if you can re-start, do that first.

[TThurston]

Just curious... probably a silly question.

I believe a stopped prop is is mostly quiet. I assume that a windmilling prop is still making noise, since it's spinning the engine and pumping air in and out, and beating the air as it turns.

So...

The difference in the sound of a windmilling prop is the lack of the sound of the burning fuel/air mixture. Is this combustion that noisy? Is the sound of a windmilling prop that different from the sound of a engine at idle with a spinning prop?

Or to put it another way... If my engine stops will it be obvious to me by the sound, without looking at any instruments?

[gasman]

Originally Posted by TThurston

Just curious... probably a silly question.

I believe a stopped prop is is mostly quiet. I assume that a windmilling prop is still making noise, since it's spinning the engine and pumping air in and out, and beating the air as it turns.

So...

The difference in the sound of a windmilling prop is the lack of the sound of the burning fuel/air mixture. Is this combustion that noisy? Is the sound of a windmilling prop that different from the sound of a engine at idle with a spinning prop?

Or to put it another way... If my engine stops will it be obvious to me by the sound, without looking at any instruments?

You will notice the sound is gone. And the aircraft will slow down right now if you maintain level flight. It will be VERY obvious........

[Neal@F14]

Originally Posted by Snowflake

What diameter and pitch were the wood and metal props? All identical?

Aymar Demuth wood prop on an RV-4 (68x74)
Sterba wood prop on an RV-6 (?? x ??)
Sensenich (74 x 58) on a Cherokee.

[Snowflake]

Originally Posted by Neal@F14

Aymar Demuth wood prop on an RV-4 (68x74)
Sterba wood prop on an RV-6 (?? x ??)
Sensenich (74 x 58) on a Cherokee.

So a prop with a coarser pitch on a faster airplane has an easier time getting started than a prop with a finer pitch on a slower airplane. I agree, that's exactly what should happen. Doesn't matter if it's wood or metal. Put a 68x74 metal prop on the RV-4, and it will start turning at the same speed as the wood one.

[n5lp]

Originally Posted by TThurston

...
So...

The difference in the sound of a windmilling prop is the lack of the sound of the burning fuel/air mixture. Is this combustion that noisy? Is the sound of a windmilling prop that different from the sound of a engine at idle with a spinning prop?

Or to put it another way... If my engine stops will it be obvious to me by the sound, without looking at any instruments?

If the engine quits at a high power setting it is very obvious. At idle the difference between engine running and not running is not noticeable at all.

[Neal@F14]

Originally Posted by Snowflake

So a prop with a coarser pitch on a faster airplane has an easier time getting started than a prop with a finer pitch on a slower airplane. I agree, that's exactly what should happen. Doesn't matter if it's wood or metal. Put a 68x74 metal prop on the RV-4, and it will start turning at the same speed as the wood one.

Actually the metal prop on the Cherokee with the finest pitch was by far the easiest to air start (began to turn and restarted at about 125 MPH). The Aymar-Demuth wood prop on the RV-4 was the hardest (took almost 160MPH before it started to turn again). The Sterba on the RV-6 was somewhere in between. The engines on both the Cherokee and the RV-4 were fairly new and tight with good compression. The O-320 on the RV-6 was approaching TBO and was "loose" enough the owner could hand-prop it without much trouble (until he finally bought a new starter )

[Bad Sheila]

Back to my original question? I have an RV6 and
1) The engine has stopped at a decent altitude
2) The prop has stopped because I got too slow
3) My electrics have failed.

I want to attempt an air re-start so what speed could I expect the prop to start windmilling? 120 kts? 130 kts?
Go for it. LOL

[Ron Lee]

Originally Posted by Bad Sheila

Back to my original question? I have an RV6 and
1) The engine has stopped at a decent altitude
2) The prop has stopped because I got too slow
3) My electrics have failed.

I want to attempt an air re-start so what speed could I expect the prop to start windmilling? 120 kts? 130 kts?
Go for it. LOL

Go try it under suitably safe conditions.