Originally Posted by Rainbird
My 2c on the matter. Drag is proportional to velocity squared... so.. for a specific configuration you can increase drag and loss of potential energy(altitude) by keeping the speed up.
This is for a specific configuration only.. putting out flaps/gear and spoilers will increase the drag above the clean configuration. A faster speed in those configurations will improve descent rate/energy loss as well.
Sounds reasonable to me.. feel free to poke holes in my thinking!
Drag is proportional to velocity squared - but so is lift. If you keep the speed up at a specific configuration, your lift will increase above your weight, so the plane will accelerate upwards and lose rate of descent!
As long as the plane keeps a constant rate of descent, lift has to stay equal to weight. Therefore, you can only change your airspeed if you simultaneously change your lift coefficient, e. g. by changing the angle of attack.