I have been kindly lent an HQ example of Ralf Beutnagel‘s KAPfoil1.6 by Peter Blackmore and flew it today in a light South Easterly. For comparison I flew it alongside the Becotised Ultrafoil 15, this would be well short of an experiment in top end performance but should tell me something of how these new generation foils behave in the ligher stuff.
Wind-speed was between 5 and 12 mph (Bft3) which puts the smaller size of these kites at a disadvantage: they are not really going to develop useful power until Bft4. None the less the flight was instructive.
In Bft3 The 2 kites have very different flying angles, the KAPfoil flying at a lower pitch than the Ultrafoil.
Both kites are stable in this wind-speed but the real difference between them is lifting capacity, the KAPfoil generating useful lift at the expense of a great deal of down wind distance, it lifted a 700g rig happily although I was fortunate in having plenty of space to let it do this.
With something like 300m down wind distance and less than half that in height I was able to get a decent stitched panorama from the KAPfoil lifted rig. Things did not go so well with the Ultrafoil which, although flying at a steeper angle, failed to raise the camera much at all, looking at the photos I’d say between 5 and 15m AGL was achieved. Frantic line hauling was needed to keep the rig out of the water.
In lull the sink rate of the KAP foil is noticeably greater, it is of heavier fabric than the Ultrafoil, fortunately lull was brief and the loss of height quickly recovered.
I would not normally work with kites this small in Bft 3 but my impatience to fly the KAPfoil proved irresistible. My Sutton FF30 or Dan Leigh R8 would have done a better job but this exploration of soft kites needs to continue to find options for the next KAP workshop.
First impressions of the KAPfoil16 are that the kite is well made, set up true and shipped with a decent length of tail. It will lift 700g in Bft3 provided there is enough down wind space to do so. The KAPfoil is not prone to the weaving movements of the Ultrafoil but has some of the rocking movements characteristic of the ‘wider than tall’ aspect. I made no adjustments to the angle of attack which, unlike the Ultrafoil, the bridle will allow. The KAPfoil has the advantage of greater lifting power than the Ultrafoil.
It will be interesting to see how it fares in Bft4 and 5!