Setting Prop pitch RPM for best climb
in 912iS Technical Questions
9 years ago
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Re: Setting Prop pitch RPM for best climb
by Fred Northup » 7 years ago
How do you get the 5600 figure at WOT straight level when there is almost always some wind at altitude. Doesn't a tail wind flight tend to give you a higher rpm than a head wind?
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Re: Setting Prop pitch RPM for best climb
by Glenn Martin » 7 years ago
Hi Fred,
the answer is NO.
Wind aloft during flight does not make any difference as it is relative wind.
There is a difference if you do ground running a prop wind will increase or decrease rpm slightly.
But when flying no practical difference
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Re: Setting Prop pitch RPM for best climb
by Shawn Britton » 4 years ago
Sorry to bring this thread back to life.
I have an LSA with a 912is and a DUC prop. I have it set so my average cruise altitude (3,500) at WOT, I am getting 5520 RPM. On a 80kt climb I'm seeing around 5100 rpm (Vy is 72) and about 750 ft/min
My rationale, may be flawed but this is my thinking:
1. I do quite a few cross-country / long flights so speed is fairly important, but fuel efficiency is not that important to me.
2. I wanted a prop pitch so WOT I am right at or below the 5500 RPM max continuous for the engine. This way I get the best top continuous speed.
3. At level cruise, the engine likes to be at 5000rpm or less --OR-- WOT / out of ECO mode. Anything in between the EGT tends to get a bit hotter than I like.
4. If I pitch the prop to have a WOT at 5600/5700 RPM, I believe I will lose top-end speed and I will likely have heat issues because to get the engine into a full rich mixture I will be over the max continuous RPM.Thoughts?
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