Glider question

1 1	A simple aerodynamic question. What makes a glider different than other aircraft? What allows the glider to remain in the air longer than a powered airplane? aerodynamics glider asked Jul 18 '10 at 17:21 wbeard52 2066●6●25●45

2 Answers:

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The key difference is the L/D (Lift to Drag) ratio. Gliders are designed to be able to stay airborne as long as possible as opposed to other airplanes which may be designed with other goals in mind, such as carrying passengers or cargo, or being sturdier (trainer). Gliders typically have long wings to generate more lift and are very light weight and super streamlined. They don't have things like props or jet engines acting like speed-brakes. Also, their gear is typically only two wheels and usually just barely hanging out of the fuselage.

According to the table on the Wikipedia article for Lift-to-drag, a glider has an L/D of around 70, a U-2 is around 28, a Boeing 747 is 17, and a Cessna 150 is 7.

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References:

Wikipedia - Lift-to-drag Article

answered Jul 19 '10 at 05:38

James 1
405●1●7●12

This is a good answer. In essence, the longer wings have a higher aspect ratio and become more aerodynamically efficient.

(Jul 19 '10 at 17:38) RichT 1

Nice photo of the USAFA

(Sep 15 '10 at 00:10) Tim

To expand a little on James' great answer, gliders can stay aloft longer by taking advantage of thermal columns, columns of rising air generated by uneven heating on the Earth's surface. Pilots can find these using experience, luck and variometers, devices that detect rises and descents.

answered Jul 20 '10 at 20:46

Patrick Pohler ♦♦
1337●18●41●117

I think it is safe to say that all aircraft can take advantage of thermals or orographic lifting. Due to the high aspect ratio wings, gliders are exceptional at converting the energy in the rising air to altitude. Most aircraft that are not gliders don't have variometers so locating thermals are a little more difficult.

(Jul 24 '10 at 00:00) wbeard52

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Asked: Jul 18 '10 at 17:21

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Last updated: Sep 15 '10 at 00:10

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