Aircraft nose-up glide

Question

In the pilot's introductory book "Stick and Rudder" it claims that a nose-up glide is possible. It doesn't state how, why or when. It implies it's possible to do and maintain a constant forward velocity.

Is this possible? I really don't see how, unless the aircraft has what I assume would be an extremely unusual design, where the wings would have to have a reverse angle of incidence of the common designs.

Glancing through clancy's Aerodynamics, it seems that the force of lift acts upward, and slighly behind the normal of the chord. Given a glide has no thrust, I can't see how the net forces could balance with the drag to maintain forward velocity if the nose is up.

Thanks

Answer 1

The essence of a glide is that the aircraft is descending. Just like a car rolling down a moderate grade, it is trading potential energy to replenish the kinetic energy lost to drag.

Whether the nose points up or down only relates to the angle of attack, which only relates to speed. An aircraft traveling at slow speed has a higher angle of attack, so its nose will point up, compared to when it is traveling at high speed.

One of the things you learn in flight training is how to handle a loss of power. There's a mnemonic for that: ABC

• A: Trim for the Airspeed (65 kts in a C172) that gives you the best glide range. This is fairly slow and nose-high. (There is even a somewhat slower speed that gives you less range but more time aloft.)
• B: Look for the Best landing site, be it a field, road, or if you're lucky, an airport.
• C: Look in the Cockpit for what you can do, like trying to restart the engine, and Calling on the radio.

So, under A, you can see that a slow glide is relatively nose-up, even while the aircraft is descending.