Oh and yes, in the original Bellifortis it says:
“This flying kite may be made of leather on the head,
The middle of canvas, but the tail of silk,
The colors are different. At the end of the head there is a three-part rotating body,
Assembled from wood, with a blown in the middle.
The head will be directed against the wind, and when it stands”
May two lift their heads, a third may carry the blower. Follow him on horseback, the movement of the leash determines the flight,
Up, down, right and left.
Let the head be painted and reproduced with red paint,
In the middle of lunar silver color, different at the end.”
As is typical, he doesn’t explain that much about what it’s for, just how to make it and how to use it.