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8 Answers

Glide ratio

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Hi, I am a relatively new private pilot. I was flying right seat the other day with a friend in his Piper Lance. We were coming back from the Bahamas so naturally the subject of glide ratio came up. He told me his Lance has a glide ratio of 16:1 . For every 5280 feet of altitude it would glide 16 miles. Later when I got home and started thinking about it I started to doubt it . What are the facts here? Thanks

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8 Answers

  1. Eric Gideon on Aug 22, 2010

    I don’t have a real answer for you, but the Cessna 400 (LC41-550FG) has an L/Dmax of 13:1, and the Piper PA28R-201 Arrow has an approximate L/Dmax of 9.6:1. From what I recall, the Lance weighs about as much as the LC41, with the airframe of a PA28R. It’s highly unlikely that it would have a glide ratio better than either airplane.

    If you’ve got access to his POH or a PIM for the Lance, check out section 3 and look up the expanded power off landing procedure. Piper states a per-1000ft glide distance in the details.

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  2. Best Answer

    Paul on Aug 23, 2010

    You probably already know but the glide ratio represents the distance an airplane will travel forward, without power, in relation to altitude loss.  So your friend says his Piper Lance has a glide ratio of 16:1.  That means the airplane will travel 16,000 feet horizontally for every 1,000 feet of altitude loss.  So yes, 16 miles horizontal for every 1 mile vertical or 84480 feet to 5280 feet or 16:1.  

    BTW, I have a call to Piper to verify the glide ratio on a Lance.   Will update this comment when I hear back.

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  3. Eric Gideon on Aug 24, 2010

    Also, note that usually glide ratios are in nautical miles, meaning that for every 6000 feet of altitude he is claiming 16 nautical miles of horizontal travel.

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  4. Brian on Aug 25, 2010

    “Also, note that usually glide ratios are in nautical miles, meaning that for every 6000 feet of altitude he is claiming 16 nautical miles of horizontal travel.”

    Ratios can be defined using any units. A 16:1 glide would is 16 nautical miles forward to every 1 nautical mile down. It is also 16 millimeters forward to every 1 millimeter down. Both statements are equally true. Arguably one is more meaningful to the pilot than another, but neither is wrong.

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  5. Eric Gideon on Aug 26, 2010

    What I meant is that many manufacturers (Piper, for example) provide glide performance only in miles per thousands of feet, which could be left open to interpretation: statute, or nautical?

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  6. Padge Dorne on Aug 27, 2010

    I was just reviewing the POH for the Cessna skyhawk I fly and it has a glide ratio of about 8 to 1 . I cant imagine the Piper Lance would be twice that? What am I missing here?

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  7. Jeffrey Peterson on Aug 30, 2010

    As with so many questions, the answer is – it depends.  If you want to get the best glide ratio out of the Lance, of course you would start clean (gear and flaps up) but also you would make sure the throttle is full open (it makes a difference) and the prop is full aft (this makes an even bigger difference).  Finally, you would make sure you are gliding at L/D max which varies with weight (92 CAS at max gross, which you will probably not be at, so something slower)  Doing everything right you should be able to get about 1.25 nm (7500 feet) per 1000 feet at stp (standard pressure and temperature) and no wind.

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  8. Steve Reed on Oct 28, 2010

    The glide ration on a Piper Lance is about 9:1 – at best. That’s with gear up, best glide speed of 106 mph and prop full back.

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