ORIGINAL: IFlyEm35
ORIGINAL: Beavis
One of the benefits of having an aft CG is a lower stall speed so that would make sense.
Could you please elaborate on that basic concept (for the non-aerodynamicist)? I always thought that, with regard to weight, the stall speed was affected only by the overall weight and not by the CG as well. Of course, it appears that I thought wrong...
Thank you in advance.
I'm writing from my phone so I'll give you the Cliff's Notes version and update it once I get to a computer.
You are correct. Weight affects stall speed. Your CG is in front on your center of lift. This is why the nose drops when the wing stalls. So when in normal flight, to offset the nose dropping the tail produces a tail down force. This force adds to the overall weight the wings need to support. So move the CG forward and an increased tail down force is required to offset it. This results in the higher wing loading and increased stall speed.
To expand:
Stalling is a component of reaching the critical AOA (Angle of Attack). AOA is increased with a forward CG because the increased distance between the center of pressure (lift) and the CG. This requires the tail to produce more downforce to keep the nose from dropping. That downforce then has to be overcome with more lift. To create more lift AOA is increased.
Think of a teeter totter. One end is the nose of the aircraft, the other is the tail and the pivot point is the center of lift. If your CG is is ON the center of lift, the pivot point, both ends of the teeter toter or very light and easy to move. This would be unstable in the world of aviation. But would have the slowest stall speed. So the CG has to be moved towards the front of the plane. (So when the aircraft is in a stalled state the nose drops so the aircraft can recover.) This causes the nose side of the teeter toter to come down. To combat that we have the horizontal stabilizer. This creates the taildown force to lift the nose.
As that CG moves closer to the nose end of the teeter toter it take more and more pressure on the opposite end to counter act that. As pressure is added the more force is being applied as the pivot point (i.e. lift). So in a nustshell, the more weight the wings have to support the higher the AOA, the higher the stall speed.
