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Handy tip I learned this week The Garmin GPS 196 has a "glide ratio required" function. You can pick an airport and the little gadget will tell the necessary glide ratio required to reach it AND tell you the glide ratio you are actually getting. So, you KNOW whether you can make it or not. This looks to me like a smart emergency drill to do. Dave Winters N2797H -----Original Message----- From: Ed Burkhead [mailto:[EMAIL PROTECTED] Sent: Saturday, April 08, 2006 5:13 PM To: Ctech Subject: RE: [COUPERS-TECH] power off descend ----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]---- Hartmut wrote: > I then took the time to measure the actual sink that happened > over one minute and the altimeter measured merciless 800ft. > > It turns out that my best glide speed is between > 60 to 70 Miles indicated on my airspeed meter and that it is > around 800ft/minute. Maybe less with some luck, more if you > hit a downstream. > > At 4000 ft altitude above ground I would have 5 minutes glider > time until I touch ground. At 60 Miles/hour, I would have 1 > mile/minute, giving me a radius of 5 miles (8 km) to find a > suitable spot for landing, provided no wind condition. Hartmut, As I understand it, you tried several airspeeds to find which one gave you the minimum sink rate - i.e. the longest time in the air. I think you will find that the best glide ratio and best glide range will happen at a higher speed. At 75-85 mph, I think you will find that you have a higher sink rate but you will also have higher forward speed. Based on your 800 fpm sink rate at 65-70 mph you get 5 minutes, as you said. During that time, at 60 mph, you could travel 5 miles, as you said. That's 5280 * 5 = 26400' of forward motion. Dividing by the vertical drop of 4,000', you get a glide ratio of 6.6. That's not very good, as we all know. As I recall from ground school, the best duration glide speed usually gives a far shorter glide than does the best range glide speed. Sometime when you can fly again, please try it at higher speeds. You only need to measure the sink rate (via altimeter and stopwatch) at each speed and record the airspeed and temperature. Then, using your whiz-wheel you would correct the indicated airspeed value to be the true airspeed. With that data, we'd compute the glide ratio and glide range again. When I did it with my old, inaccurate airspeed indicator, I was surprised how good the glide ratio seemed to be at the higher airspeeds. Thanks for providing real, hard data with which to calculate. Ed Burkhead http://edburkhead.com ed -at- edburkhead???.com (change -at- to @ and remove "???") ======================================================================== ====== To leave this forum go to: http://ercoupers.com/lists.htm ============================================================================== To leave this forum go to: http://ercoupers.com/lists.htm
