I can't say that I've ever shut my engine down to test glide, but I did find my glide testing very closely matches Marks with a 12:1 glide ratio with the engine at idle. ?I would submit that a significantly longer prop might create more drag when windmilling vs a stopped prop, but since my KR was windmilling at idle and my numbers very closely match Mark's, I would say that my longer prop didn't make a huge difference. ?I don't know of any KRs flying with a longer prop than mine, so I would conclude it is a non-factor on the KRs.
-Jeff Scott Los Alamos, NM > ----- Original Message ----- > From: Mark Langford > Sent: 02/20/14 11:08 AM > To: 'KRnet' > Subject: KR> Engine-out gliding > > I'd heard that there was a real difference in the glide ratio of a plane > with a wind-milling prop as opposed to one with a stopped prop, and thought > I'd test it to find what the story was for my KR...because I figured it'd be > good to know some day. So one calm morning I climbed to 10,000' and noted > altitude, compass heading, direction, speed (best glide being about 80 > mph), and then started a timer and pulled it back to idle. I glided all the > way down to 2000' maintaining 80 mph all the way down (pretty close, > anyway), and stopped the timer. Then I landed, replenished the two gallons > of fuel I'd used, climbed back to 10,000', took the same heading, started > the timer (same heading and altitude), and switched the ignition off to get > a dead prop. Because I have a high compression engine with a short, light, > prop, the engine doesn't windmill at any speed that I've tried, but > certainly not at 80 mph. Again I glided down to 2000' , stopped the timer, > and divided out the numbers. They were almost identical, and certainly > within the range of any kind of measurement error. I only mention this for > informational purposes, as it may come in handy someday for similar KRs. > Another useful tidbit is that the glide ratio for my heavy KR2S is just over > 12:1 (12 miles horizontal for every mile of altitude). > > I'm guessing that a low-compression O-200 with a larger and heavier blade > might continue to windmill with the engine off, but I've never tested that > scenario. I'm sure somebody else on the list has, however. > > Mark Langford, Harvest, AL > ML at N56ML.com > www.N56ML.com
