Design Diffrents for lengths of main wing.

[blacksniper]

Angle of wing looks diffrent in the volocity then it does in the cozy. Plus the volocity has 3 feet longer wingspan then the cozy, anyone know the formula that reprensents this? The longer the wing span the less power is needed to keep at cruise speed, because the more wingspan the more lift that can be generated.

 

can anyone tell me if my assumptions are correct, because i am not a engineer.

 

thanks

scott.

[Steve Innova]

Angle of wing looks diffrent in the volocity then it does in the cozy. Plus the volocity has 3 feet longer wingspan then the cozy, anyone know the formula that reprensents this?

 

The longer the wing span the less power is needed to keep at cruise speed, because the more wingspan the more lift that can be generated.

NO. The longer the wings, the MORE power will be required to reach the same cruise speed (all other factors being equal), because longer wings = greater lift = greater induced drag (drag from lift) = slower speed.

 

Remember, you only need enough lift to lift the weight of the plane. The faster you fly, the more lift the wings produce. That's why fast planes use higher wing loading / smaller wings (higher wing loading, i.e. less wing area/lb weight).

[chasingmars]

NO. The longer the wings, the MORE power will be required to reach the same cruise speed (all other factors being equal), because longer wings = greater lift = greater induced drag (drag from lift) = slower speed.

 

Remember, you only need enough lift to lift the weight of the plane. The faster you fly, the more lift the wings produce. That's why fast planes use higher wing loading / smaller wings (higher wing loading, i.e. less wing area/lb weight).

Again, not quite. Induced drag varies with the square of the coefficient of lift and the span loading of the aircraft. So the original poster is correct if wing area is held constant (except it's more relevant at slower speeds than cruise, see below).

 

It's also not true that the faster you fly the more lift the wings produce. It's true that the faster you fly the more lift they produce for a given coeffient of lift, but in a given airplace, flying faster means more forward stick (or forward trim) to reduce the wing's angle of attack so that for level flight weight balances lift.

 

The consequence of this is that as you get going faster, the drag due to lift (induced drag) becomes small in comparison to parasitic drag. That's where the real speed advantage of smaller, more highly loaded wings comes in, lower wetted area makes for less parasitic drag at high speed.

[chasingmars]

Induced drag varies with the square of the coefficient of lift and the span loading of the aircraft.

On re-reading my post, it makes it sound like I'm saying it varies proportionally with these factors, while that's true for the square of the lift coefficient, it's not for span loading.

 

Lower span loading (and by extension, higher aspect ratio all else equal) gives you less induced drag. Don't remember exactly, but I don't think it's a proportional to the inverse relationship.