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-   -   Flight idle vs ground idle - Sensenich FP (http://www.vansairforce.com/community/showthread.php?t=146851)

rjcthree 02-19-2017 07:28 PM

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.

snopercod 02-20-2017 07:21 AM

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

Greg Arehart 02-20-2017 08:54 AM

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.

az_gila 02-20-2017 11:03 AM

Quote:

Originally Posted by Greg Arehart (Post 1151586)
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.

snopercod 02-20-2017 05:29 PM

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

rjcthree 02-20-2017 05:40 PM

Ground idle?
 
Snopercod, what is your warm ground idle speed?

WAM120RV 02-21-2017 08:11 AM

O-320 Sensenich metal prop and approach speeds.
 
I have set up ground idle to 630 approach at 70mph is about 1000

Approach speeds above 70 mph often leads to an extended ground run. I am pulling back to 60 mph over the fence with all power off then gliding in the last 10 feet to thre point the aeroplane.

JSOliveira 02-21-2017 04:11 PM

Idle Speed
 
I have IO320, Sensenich 70/79 Metal Prop. I have ground idle set at 525-550.
I fly final at 60 knots 1200 rpm until I have runway made. Then back to idle. At that point I am not looking at the tach. I know that if I idle faster it sure floats a long ways. Usually touch down at 49-51 knots.

snopercod 02-21-2017 06:09 PM

700 normally
 
Quote:

Originally Posted by rjcthree (Post 1151735)
Snopercod, what is your warm ground idle speed?

Normally around 700 after runup but after flying today, just before shutdown it was 650 RPM. It really seems to vary a lot with temperature. In cold weather I've seen it as high as 850 RPM. It's a mystery...


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