Over the past two weeks while recovering from the flu, I had some quality flying time on the multi-color PC31 versions of the Bird of Prey (BOP), which have wing spans of 48 and 62 inches. They are both dialed in and are a joy to fly. The new carbon tube frames were an enhancement. I also installed heat shrink tubing around the wing spars, at the point where they are inserted into the center joiner. There was a hard pressure point at the end of the white PVC center joiner tubing that was causing the prior hollow tubes to be crushed when too much force was applied to the flying line. The heat shrink tubing was carefully applied with a hair drier and made a better fit, while provided padded reinforcement around this pressure point. I have strongly pulled on the flying line for these two kites and havenít broken anything. The final static margin for these two kites is about 2%, which allows these glider kites to be responsive and have a nice flat glide for this style glider kite. During the trimming process, I tried a lower static margin of 1% (more nose heavy), but it made these two kites too stable due to the forward inertia from the higher sail loadings. The BOP 62 is majestic in the air, while the BOP 48 is very responsive and fun to abuse in the air. During one of the trimming flights, the BOP 48 got caught in a thermal and went straight up to 60 feet in my front yard, where I had to pull it down before it ended up in a tree. If the wind cooperates this coming weekend, I hope to shot some video of these kites in the air.
For the ultra-light versions of the BOP made with Cuben, I determined in the past that a static margin of about 1% was the best to this style glider kite, which makes the kite slightly more nose heavy than the PC31 versions. Due to the ultra-light sail loading of the Cuben versions, the lower static margin allows these glider kites to have more forward inertia for a flatter and longer glide, yet still be very responsive due to their low sail loadings. I did test the center of gravity a little more to the rear, with a static margin of about 2%. The result was a slower steeper glide angle, with the nose of the kite pointing a little higher in the air. The 2% static margin moved the point on the Lift to Drag (L/D) curve to the location of minimal sink, but not ideal to cover ground as a glider.
I am in the process of building a few more BOP-24s, one with 0.028 inch diameter carbon tubes. One of the BOP 24s will be for a young lady who will use it for a stage performance at the Eugene O'Neill Theatre in New York City, which is quite cool.
Someday in the near future I will get back to building the X-29 Canard Kite.
As indicated in the Kite Land Event section of this forum, on May 3, 2014 the Pocono Kite Symphony/Lehigh Valley Kite Society will be hosting their 24th Kite Day in the Park Event, at the Louise W. Moore Park in Easton, PA. I attended the event over the past few years and had a very enjoyable experience with other kite fliers. As in the past, my car will be loaded with at least three bags of kites (single line glider kites, single line kites and stunt kites), so I am prepared for whatever Mother Nature throws our way. I hope the wind will be light at some point during the day, so I can fly my glider kites discussed on this forum. Hope to see you there.