Cambered leading edges

In article <13570@umd5.umd.edu>, jeffy@syrinx.umd.edu (Jeffrey C. Burka) writes:
|>In article <1992May28.151503.18650@e2big.mko.dec.com> sasaki@tle.enet.dec.com writes:
|>>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.
|>But does it stretch?

The double layer stretched a little, and the single layer looks like
it stretches the same amount. The low stretch is due to the fact that
the grain is more or less parallel to the trailing edge.

Along with the stretch, the double layer was to make the trailing edge
a bit stiffer. I also experimented with 1.5 ounce ripstop in that
area. On another design, I used a piece of 4 mil mylar along the
trailing edge.

The results were inconclusive. It seemed that the vibration was lower
frequency, but larger amplitude. Sometimes the kite flew slower
because of the larger amplitude.

|>>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.
|>I remember seeing that whisker on Darryl's Katana--was that before or after
|>you saw a Scorpion?  ;-)

Before and after. Like a lot of kite flyers I've experimented with
whiskers and battens and other things all along. The Katana was
designed with that extra whisker, so I didn't rip off the whisker. I
might rip off the way it is attached however... ;-)

|>Sort of.  Actually, out toward the very tip, there are _two_ layers on 
|>the Big Brother.  There's the trailing edge, which starts by the stand-off
|>and goes all the way to the wingtip.  Then there's another big triangular
|>panel at the wing tip.  I believe these overlap, creating two layers on
|>the trailing edge for the last several inches before the wing tip.  In fact,
|>I think the large triangle's edge falls roughly where your second set of 
|>whiskers does.

I'll have to take a look at my Big Brother...

This will probably lead to some experimentation with the overlap
again. Oh well...

|>The Pro actually has 3 layers out by the wing tip.  Dean has changed the
|>design several times (I've seen at least 3 different ones).  

Good to see that I'm not the only one who tweaks the design. I'm about
to make the third minor tweak and expect that when I change over to
Carrington that I'll have to make a few other minor tweaks...

It might be interesting to some folks to outline the history of the
Katana. It also might be increadibly boring. However, you've been

My other kites are slow flying and slow turning, although they are
capable of tight turns. They are very good team kites and are also
good for individual precision.

I decided that I wanted a kite that did the tricks that were popular,
a kite that would be good for individual ballet.

The first Katana prototype looked a lot like my other kites, but it
had a lower aspect ration (the nose angle was more acute) and it had a
higher cutout along the bottom. It flew just like my other kites,
although it was a little faster and had a little more oversteer.

The second prototype had the same general shape as the first, but it
had a curved leading edge and a curved trailing edge. The sail on it
was very tight, tight enough that in flight the spreaders didn't bend
much. I added the second set of whiskers and the double layer along
the trailing edge to this kite. This kite had more oversteer and could
float better.

The third prototype was smaller with a less pronounced curve in both
the leading and trailing edge, and the sail is much looser. It also
has a lower aspect ratio than the second prototype with much more
billow than my other kites.

This last proto is the kite that I now manufacture. As I said, I've
changed a few things, and expect to continue changing things as I go
along, but the basic sail and frame will remain the same.
Marty Sasaki                            sasaki@tle.enet.dec.com

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