Lift Forces On A Box Kite

by Des
(Ottawa, ON, Canada)

Q:

Can you explain how a box kite generates lift? I have trouble visualizing how it acts like a wing. It has a space in the middle that offers no resistance to the air flow.

I have read and think I understand your description of how a diamond shaped kite generates lift.

Thanks

A:

The key to understanding this is to consider the individual rectangular panels of the box kite cells. Each one, like a rectangular Korean fighter kite, is a 'wing' in its own right. Each one is held at an 'angle of attack' to the breeze, by the kite's bridle. So, you have 8 wings connected together, each of them subjected to the same forces as described for the Diamond kite example. Of course 'line tension' is a bit hard to compare, since the panels experience tension through the connections to the rest of the kite, rather than having individual bridle connections.

If you add up all these individual forces, they are equivalent to the same 4 forces described for the Diamond kite. Lift, Drag, Weight, Tension. The Box kite as a whole lifts a certain amount, drags at the air a certain amount, weighs a certain amount and pulls a certain amount of tension into the line.

A slightly simpler way of visualizing all those 'wings' is to consider each cell to have just 2 wings. A lower one, with 45 degree dihedral. Plus an upper one, with 45 degrees of anhedral. The 4 forces on each of the 4 wings would add to the same overall Lift, Drag, Weight and Tension.

A bit wordy, but I hope that helps!

Comments for Lift Forces On A Box Kite

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Oct 12, 2011
Forces On A Box Kite
by: Des

Thank you. The last paragraph was most helpful.

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