March 2011 Archive

Rokkaku & Android camera setup test – Mar 31

3/31/11

We took the “good” kite from the last two rokkaku tests out to the parking lot to compare its performance to that of the original carbon spar kite in very low wind.

Additionally, Jamie debuted his Android phone camera system by attaching one phone, in a padded cardboard box, to the kite line of the carbon-sparred kite and letting it out about 75m. In his hand he held another Android phone, which displayed the image taken by the lofted camera.

Meanwhile, Don and Dudu discussed weight differences in the two kites and experimented with bridle positions on the inflatable one. We also briefly attached a GoPro to the line of the inflatable kite to get an aerial view of the […more]

Kitefoiler Tow Test – Mar 30

3/30/11

We tried the side T-foils on the Kitefoiler for the first time today. They performed very well in the glassy conditions, demonstrating much more lift than the J-foils, and foiling stably with little spray on the crew. The boat also had no trouble foiling with five people on deck. Don’s parents, Sharon and Roland, and Erika came out to help round out the crew.

Kitefoiler tow test – Mar 29

3/29/11

We went out for a brief tow test today to check adjustments to side foils and to compare performance of original T-foil rudder to newly fabricated larger T-foil rudder.

The attached plot compares the speeds and loads with each rudder T-foil. The speeds are not identical in each case, and other factors such as the tow angle and acceleration may have varied between runs. However, there is some indication that the “new” foil requires a larger towing force at 20-21 knots.

Kitefoiler kite test – Mar 28

3/28/11

We tested the Kitefoiler today with the new rudder. Using the kite-launching mast, Don, Joe, and Richard successfully launched and transitioned to sailing for the first time and on the first try!
Thereafter, they sailed the boat to test the foils. Both Joe and Richard sailed with Don, but the wind was such that foiling was only possible with two crew members at a time. The foils worked but adjusted unevenly, causing the boat to jump a bit as it sailed. The foils tested were one original J-foil (starboard), and one new, modified from old quadfoiler, more steeply angled J-foil (port). We will test again shortly after further foil adjustment.

Rokkaku kite test – Mar 28

3/28/11

Dudu, Jamie and Renata tested two Rokkaku kites today, both with inflatable cuben fiber struts. Kite A was the best one from Friday (#4), which had 50% of the original curvature, 90% of the original diameter, and long battens. Kite B was a new one with the same tube diameter, 75% of the original curvature, and short battens.

From Dudu:
Both kites flew well with the same stability and held all gusts with no issue. The 50% kite still had better flying angle.
This test proved we can have smaller battens at strut tube tips and still spread the loads. This can save weight and storage.

Rokkaku kite test – Mar 25

3/25/11

We took four different rokkaku kites out to the parking lot today to compare their performances. Kite 1 (photos 1, 8, 12-15) was the original rokkaku with all-carbon spars. Kite 2 (photos 1, 8, 11-12) was similar but with a modified spine. We also hung a camera off the line of this kite to film Kite 3. Kite 3 (photos 1, 8-10) had an identical canopy to 1 & 2, but instead of carbon spars, it had inflatable spars made of cuben fiber. The inflatable spars had the same curvature as the original carbons spars. Kite 4 (photos 3-7) was also made from an identical canopy and also had inflatable spars made of cuben fiber. However, these spars were 90% […more]

Kitefoiler kite launch test – March 22

3/22/11

We took the Kitefoiler out again today to practice launching with the carbon mast. Joe added extensions to the mast earlier this week to accommodate a larger kite, and this time he, Don and Dudu used a brand new 25 sqm kite, instead of the 20 sqm one. The new kite is similar to the old 25 sqm high-aspect-ratio kite that we’ve been using with such success on the Trifoiler and Kitefoiler. The new kite, however, has some improvements, including a larger diameter strut base and a trailing edge canopy made of Dacron instead of the old, softer material.

During the test, we had trouble on the first couple of launches with an exposed bolt on the top of the […more]