News

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]

Kitefoiler mast test – March 11

3/11/11

Today we tested the new kite-launching mast on the Kitefoiler for the first time. The setup includes the K1 winch with custom platform, two carbon windsurfing masts with extensions, and an intricate system of pulleys.
Don, Joe, and Dudu successfully launched the kite three times, but had difficulty transitioning from launch controls to sailing controls. Overall, the test went well, as each successive launch improved upon the last. However, they attempted a fourth launch, but the kite lost air after hitting a sharp carbon piece on the bow.
Today was also the first test of some of the new modifications to the boat, including steel reinforcements on the rail moldings and bronze bushings and smaller wheels on the […more]

New Logger Thermal Test

3/2/11

Jamie put the logger components in a new box (orange, on top) that is even smaller than the old box (silver, on bottom). Right now he is running a program on the Android phone to record the temperature to make sure that the electronics will not overheat in their new closer quarters.

The graph shows the temperature recorded by a Nexus S phone, using software that we wrote to log its battery temperature. (The PC either has no non-CPU temperature sensors or they are not visible to the OS.) The phone battery temperature is typically a few degrees higher than the ambient temperature. While the temperature did not fully stabilize during the 2.5 hour test, it appeared to be leveling […more]

Android + Bluetooth Servo Controller

2/11/11

We are exploring the use of our new Nexus S Android phone as a kite-based programmable wireless camera and pan/tilt controller. The first step in making this happen was to make a bluetooth connection to an RC servo controller and control it from the phone.
For extra fun, we mapped the phone’s orientation to its commands so that the pan/tilt unit tracks the phone’s rotations.

Next we will improve the app so that a user interface on a second phone or a remote computer can control the phone remotely over a socket connection. The final step will be to transmit both low-resolution, low-latency “preview” images and full-resolution images from the phone back to its client.

Kitefoiler Tow Test – Feb 10

2/10/11

We towed the Kitefoiler again today. We added a pulley system that allows us to adjust the J-foils from the steering position at the stern of the boat. These pulleys worked very well. The port foil was sticking and not moving correctly as it did yesterday, but due to the glassy bay conditions, this did not prove a problem for our very short test. Henry visited the shop today and rode on the boat with Don and Joe.

Three Kitefoiler tow points were tested, each with the powerboat pulling at at 45 to 60 degree angle. The graph shows the measured forces and speeds for each tow point. The 3rd point appears to have reduced the load over the 1st. […more]

Kitefoiler Kite Test – Feb 9

2/9/11

We took the Kitefoiler out today for a second test with a kite. We spent a bit of time hunting for wind, but found a reliable source east of Alcatraz and Angel Island. Dudu helped launch the kite, then left the Kitefoiler so Don and Joe could pick up speed. He later returned to the Kitefoiler to see if his extra weight would make it easier to steer at top speeds, which it did. We achieved the fastest speed yet for this boat, 27 knots. The kite bridle looked loose in one place, although it did not cause kite steering difficulties.