Took the boat out today to use the new 25 sqm version of the 18 sqm red kite. The 25 sqm kite is the first to arrive of the quiver of new kites that we made using this same design (KW-18, 20, 25, 30, 40). We launched the kite off Alameda Point and searched for wind on the western side of the bay near the ballpark. After having little luck there, we towed out north of Treasure Island and got some good runs in between Alcatraz and Albany. The kite did not perform as nicely as the 18 sqm version; it tended to pull to one side, so we we will measure all of the bridles tomorrow and check for […more]
We took K2 out early today to test the new sensor gearing adjustors. Initial towing went well, so we continued on to Treasure Island to launch the 18 sqm kite. We kited at mid-twenties speeds northeast of the island for a couple of hours before heading to the west side to check out the America’s Cup races. We, along with many other boats, watched Oracle’s amazing comeback, and then returned to the back side of Treasure Island. The wind began to pick up, and our best speed of the day was 32+ knots with 4 crew. Overall, the sensor gear adjustors were very effective in creating a smoother, although lower, ride. We did have some trouble on the tow home […more]
Good test today, kiting between Treasure Island and San Francisco in gusty conditions. We took the 25 sqm v10 kite, which we haven’t used in about a year. This kite creates about the same amount of force at given wind speed as the 18 sqm red kite, but it is a measurably lower-performance design, enough so that the boat moves forward faster with the smaller kite. We’re currently working with the kite factory to create a quiver of larger versions of the 18 sqm design, and Dudu will travel to China next week for that purpose. For now, Dudu is in Alameda, and we used his helicopter during the test to capture aerial photos and video.
We are now recording the foil actuator positions during tests. Looking at tow and kiting test data from last Thursday, we’ve plotted the relationship between the T-foil setting and the boat speed. The T-foil is controlled by the helmsman and is used in conjunction with the J-foils to control the pitch and ride height of the kiteboat. A relatively simple relationship between the two (as we see here) suggests that we may be able to automate the boat’s pitch stabilization, which would free the crew to concentrate on other tasks.
Another great test today. T-foil position adjustment was successful, and boat performance was excellent with 18 sqm kite. We initially tried to kite off Alameda Point, but the wind there was too low to foil reliably, so we packed up the kite and towed to Treasure Island, where the wind was better, and we hit a top speed of 28 knots near the San Francisco waterfront.
After the successful tow tests this morning, we took the boat out again for a test with the 18 sqm red kite. Boat performance was good, and we hit a top speed of 30 knots off Alameda Point. The T-foil position was set so it was slightly biased toward more positive angles of attack, so tomorrow we will move its attachment point to shift the angle of attack range to a better position. Jerry Shalhoob, Earle Alldredge, and Nico Rousselon joined us again for this test.
The new electronics for the foil actuators are now boxed and ready for installation. This design is a major advancement, in that we can now measure and record the foil offsets. The controller can also receive commands from the boat network, which opens the door to multiple control inputs, and eventually assisted or fully-autonomous foil control.
