Dynamic Spar: the mods begin

In no time after the last post I managed to upset the balance of the spar by a gentle side slip into a waiting tree. I tugged the kite free but the force was enough to stress the fragile duct tape work. The kite would not sit straight on the wind as the double tube slipped along the spar. The magic had gone.

Some helpful words from Mike LeDuc suggested I stiffen up the bond in a number of ways..one of which I jumped at: zip ties!

Stabilising the twist between the 2 tubes is one part of the problem. The next is how to prevent the assembly moving off centre. Mike proposed a pre-tensioned loop line which has worked well for him on test. I like this but it looks like a tricky thing to get right. I pondered on the problem as I placed the zip ties carefully….how do you centre the motion?

And then with a mighty clunk the penny dropped:

The force is balanced by using 2 bands linked to the centre of the guide…with zip ties of course! I left the tail of the centre tie on so you can see the reference point, its clipped off and will be replaced with something tidier as the concept is proven.

Oh the thrill of invention!..now to fly it and see…… flies well in 12mph but test stopped by rain…

DSBV_In peak flow of 12 mph the action of the spar is visible, getting the centring of the guide right was not simple as the rubber-bands, despite being new and unused, are not of equal elasticity. As wind-speed increased the tendency to heel increased too.

Fine tuning the balance of the elastic force at the CoG of the spar is the next task….





About billboyheritagesurvey

Heritage worker
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