How to calculate the angle of the strings of a kite in relation to a balloon


What? Does it sound like the forces of the ball? OK, it looks similar, but there is a big difference. For the ball, there is this buoyancy force pushing upwards, and that’s just one value. It does not change as the wind speed increases. For the wing, the upward push force is lift, and it depends on the wind speed. So it’s not the same. Just consider the case where there is no wind. The drag force will be zero, which means the lift is zero. The kite does not fly – it just falls and it is sad.

Again I get two force equations that I can use to eliminate the unknown value of T. With this I get the following expression for the angle of the kite (θk). I actually put a k index on a bunch of stuff so you can see it’s different from the values ​​for the ball. Oh, the air always has the same density for both objects.

Illustration: Rhett Allain

OK, I’m about to do a plot of the flight angle of the balloon and a kite at different wind speeds. But before we do that, let’s think about the minimum speed to fly this kite. To take off from the ground, the lift force must be at least equal to the weight of the wing. I can then solve this problem for the wind speed. Anything less than that and you won’t get a kite.

Illustration: Rhett Allain

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