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I am working on a throw glider and was wondering, How much lift would be too much lift, as in it causes the glider to stall (maybe thrust that causes this, but still). also, if I create a body that causes a large amount of drag, And then use an airfoil that causes an equal amount of lift, would they cancel each other and make the plane fly like a spear, or would one still be greater than the other? (not sure if I'm explaining correctly).

quiet flyer
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Hboi
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2 Answers2

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They do not. Lift and Drag do not directly oppose each other.

The opposite of Lift is Weight (gravity). The opposite of Drag is Thrust.

The performance of the craft will depend on how these two forces are balanced against their opposites.

Aerodynamic forces diagram

William Walker III
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  • That makes sense. thank you for your answer. – Hboi Apr 25 '22 at 14:47
  • Actually, for any given glider with an L/D ratio of 1:1, if you added enough weight it would fly fast, not slow, and likewise the stall speed would be high, not low. – quiet flyer Apr 25 '22 at 18:33
  • @quietflyer The OP has been edited, original language said "high lift...high drag" rather than 1:1. Editing now. – William Walker III Apr 25 '22 at 18:34
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    Yeah it's all a little tricky, the question does sort of imply that lift might be high in relation to weight but if we know it's a glider and we know L and D are equal then we know that Lift is about .7 weight. "High lift" really likely means "high lift coefficient" which does have implications for airspeed, but it 's not stated outright. All in all the question sort of blurs the concepts of "Lift" and "Lift Coefficient" and likewise for drag. – quiet flyer Apr 25 '22 at 18:42
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If Lift and Drag are equal and Thrust is zero, this simply means that -- at least in the case of steady-state flight at a constant airspeed in still air -- the glide angle will be 45 degrees.

For more, see these related ASE answers--

Can we show through simple geometry rather than formulae or graphs that the best glide ratio occurs at the maximum ratio of Lift to Drag?

Why is the L/D ratio numerically equal to the glide ratio? (all answers)

If you truly want the glider to "fly like a spear" -- i.e. to follow a completely ballistic trajectory-- then lift must be zero. But I doubt that this is actually your goal. Though especially in the world of paper airplanes, some models with rather dart-like properties have done rather well in distance competitions held on level ground (or the indoor equivalent).

quiet flyer
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