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Old 02-19-2017, 06:28 PM
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Default Flight idle vs ground idle - Sensenich FP

Can anyone give me a feel for your ground idle speed and the idle speed you see on final, and at what speed? I'm trying to figure out the relationship. Thanks.
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Old 02-20-2017, 06:21 AM
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Recently I've been investigating the same thing myself. My plane is powered by a high-compression 140 HP O-290-D2 and an Aymar-Demuth prop. At idle, I typically see 700 RPM on the ground, depending on the OAT. Just a few days ago, I was on final at 85 Kts and was seeing 1030 RPM at idle. I pulled carb heat and the RPM stayed the same, so at 85 Kts, the prop was driving the engine. I'm on a quest to find the speed where prop no longer drives the engine. It's somewhere between 75 and 85 Kts. Here's the video. The digital tachometer is clearly visible over the top of the iPad. In the very last frame of the video, you can see the RPM was 950 on initial rollout:

https://www.dropbox.com/s/3owgxgojg1...nding.mp4?dl=0
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Old 02-20-2017, 07:54 AM
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When I was flying behind a Sensenich, ground idle was between 700-750 rpm and final approach idle maybe 1050-1100. This on an IO360. Of course you can adjust the ground idle and approach idle will depend on your approach speed and angle.
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Old 02-20-2017, 10:03 AM
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Quote:
Originally Posted by Greg Arehart View Post
When I was flying behind a Sensenich, ground idle was between 700-750 rpm and final approach idle maybe 1050-1100. This on an IO360. Of course you can adjust the ground idle and approach idle will depend on your approach speed and angle.
The Tiger has a similar metal prop and a carb. O-360 engine.

It is spec'd at 500 to 650 for ground idle RPM.
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Old 02-20-2017, 04:29 PM
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Default more data points

Today I practiced landing slower. Previously I was seeing 1030 RPM at idle power and 85 KIAS. Today at idle power I saw:
  • 78 KIAS = 980 RPM
  • 75 KIAS = 960 RPM
  • 75 KIAS (with carb heat) = 950 RPM
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Old 02-20-2017, 04:40 PM
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Default Ground idle?

Snopercod, what is your warm ground idle speed?
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