Tuesday 31 January 2023

A century-old experiment

I guess most people interested in sport kites are aware of the Peter Powell Stunter and the Dunford Flying Machine which brought dual-line flying to the masses in the 1970s. But these were not the first kites steerable due to having two lines. In the 1960s, there was the Glite, which, although a single-line kite, included instructions on how to turn it into a steerable dual-liner. And going a bit further back in time, the Target kites date back to the 1940s.

Now look at this, which I recently stumbled across:

The figure comes from Charles Miller's book Kitecraft and Kite Tournaments, which was published in 1914. Yes, 1914! A dual-line bridle more than half a century older than a Peter Powell!

I was very keen to put this 100+ year old idea to the test, using a modern single-line diamond kite. So I ordered a Prism Vertex from kiteworld, and set about adding bridle lines as shown in figure 17 in the book.

Next step is of course to try it out in the field!

First of all, after some adjusting of the position of the two point, the kite readily went up after launch. 

And .... it was definitely steerable! Loops to the left and right, big or small, straight-line flying ... 

This 100+ year old bridle idea worked!

There was one issue, though, which I hadn't thought of: because the spine isn't connected to the flying lines now, the kite almost completely loses the dihedral shape due to the wind pushing against the sail, and the sail only being connected to the lines at the wing tips and tail. So the kite almost turns 'hollow', the opposite of a dihedral. Of course, with nothing pulling on the spine and the two steering lines pulling on the wing tips, that also means the cross spars bend a lot ...

I think I can resolve this by making use of the original single-line bridle (which I hadn't yet removed) and adding a V-shaped bridle line going from the single-line bridle to the two dual-line bridle legs. That way, the spine will be supported and can't be pushed back anymore. 

Watch this space ...