Cambered leading edges

In article <13552@umd5.umd.edu>, jeffy@syrinx.umd.edu (Jeffrey C. Burka) writes:
|>Hmmm.  I'll agree that the camber can really make _parts_ of the sail taut,
|>especially the trailing edge, but most of the kites I've looked at seem
|>to have a lot of billow in the belly.  Merrick (the local guy who made
|>the quad "Dragonfly" you saw at ODSKC) was looking at a friend's Pro
|>knock-off, commenting that it looked good but that the sail didn't seem
|>overly taut.  I then showed him the same friend's Pro, which has the
|>same sort of looseness.  You just don't expect it.

Actually, I've got some looseness in the Katana. It's there to allow
the kite to bow along the spreader to allow the kite to change shape.
This makes things like skate/helicopters easier. I noticed that new
Pros, as well as one of the Katana prototypes, don't change shape much
in flight and this made tunability of oversteer difficult.

|>It seems like several kites (including the Big Brother family and the Pro) 
|>use additional layers of fabric on the trailing edge, out toward the wingtip 
|>to deaden some of the noise.  Doesn't the Katana have a panel out toward the
|>end like that?  The modified Bantam of which I spoke is incredibly noisy,
|>but it still seems to have a good deal of low wind performance.

The first dozen or so Katana's had a double layer of fabric along the
trailing edge. This was done as an attempt to keep the edge from
stretching. The new Katana's don't have this double layer and seem to
fly just as well as the old ones.

The Katana has an extra whisker to help with vibration in this area
and the difference in performance with and without the whisker is
quite noticeable.

The Big Brother is single layer in this area, but the grain of the
fabric panel in this area is parrallel to the trailing edge. I suspect
that the Pro has a double layer in this area because the grain of the
fabric (without the extra layer) is not parallel to the trailing edge.
The extra layer helps with the stretch.

|>(the EFM is largely a Phantom with a curved trailing edge and a rather
|>neat innovation on the lower spreaders.  it also has a really strange
|>bridle--the outhaul is about twice as long as normal, and there's a single
|>line from the other part of the bridle that joins with the outhaul way
|>out from the kite; supposedly it increases the wind range of the kite)
|>(sheesh...where do these people come up with this stuff!  ;-)

It's obviously a sign of a fertile imagination with not enough work to
do. ;-)
Marty Sasaki                            sasaki@tle.enet.dec.com

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