KAi KITEBOAT. INSTITUTE (March 2011) PROJECT & KITE ASSIST UPDATE

Transcription

1 KAi KITEBOAT PROJECT & KITE ASSIST UPDATE INSTITUTE (March 2011)

2 Kiteboat Project & Kite Assist Institute Monthly Update March 2011 Kiteboat Development, Testing & Data...3 Kite Development & Testing...6 Kiteboat Electronics...8 Kite Assist Projects Lifting Kites...9 Electronics...10 Other Projects Hadal AUV...11 CONTRIBUTORS: Joe Brock, Richard Jenkins, Decimo Mazzocato, Don Montague, Betsy Pfeiffer, Ann Prenty, Jamie Schulte, Damon Smith

3 KITEBOAT DEVELOPMENT, TESTING, & DATA 1 Kitefoiler BUILD As discussed in the February report, we made two new sets of side foils for the Kitefoiler, J-foils and T-foils. Additionally, we modified a larger J-foil from the old Quadfoiler for trial on the Kitefoiler, and we improved the pivot point system by strengthening and replacing rolling components. 1.1 New Foils This month we finalized work on the J-foil molds and are nearing completion on the foils themselves; we also finished fabrication of the T-foils at the end of the month and tested them for the first time. Additionally, we completed a new, larger rudder T-foil and rudder control system. (top row from left): Jacob helps Damon fabricate the J-foils on the new molds; a partially-constructed J-foil; the J-foils mid-filling stage; one of the newly-glued T-foils; (bottom row from left): Damon inspects his sanding job on a T-foil; the final paint coat dries on the T-foils; Damon demonstrates the angle on the modified J-foil from the Quadfoiler; the modified J-foil mounted on the boat 1.2 Roller Modifications As noted after testing in January and February, some of the foil sticking we experienced was due to the roller mechanism by which the cassettes move against the rail moldings, allowing the foil to pivot. Point loading on the rollers destroyed the bearings on the first set of rollers, and eventually it also crushed the carbon rail molding. This month, we put steel plates on the rail moldings to provide a sturdier rolling surface. Later, we replaced the rollers on the cassettes. The bearings in the original rollers were made of 440 stainless steel, and before the March 11 test, Joe replaced those rollers with smaller ones that had Oilite bronze bushings instead of bearings. We had hoped that the bushings would perform better than bearings, which do not last well in salt water. However, while we towed back from the kite test, the foils consistently locked up at speed and caused the boat to jump unstably when it encountered waves. Back in the shop, we found that applying sideways force to the foils made it impossible to shift the position of the foils. We theorized that either the size of the new rollers or the way that the bushings meshed with the steel reinforcements was causing the problem. We subsequently replaced the bottom outside rollers with another model, one with bearings made of 316 stainless steel that are designed to endure salt water. These rollers work more smoothly, although we have not eliminated

4 near right, a steel reinforcement on the rail molding; far right, the three rollers: 316 bearings (left), bronze bushings (center), 440 bearings (right) 1.3 New Rudder This month we completed the new adjustable rudder for the Kitefoiler and tested the steering mechanism with both with the original T-foil and with our new, larger T-foil. (above from left): Joe assembles the pitch adjustor; the completed rudder stock; carbon uni-fibers attach the rudder to the boat layering the individual fibers is the best way to maximize the strength of the carbon; the rudder and tiller attached to the boat with the larger T-foil 1.4 Waterproof Components We manufactured waterproof containers in the hull that are made of carbon and customized to hold kitepumps. We are also making a waterproof box for the sensor elements. Small improvements like these that tailor the boat to our specific needs will help to streamline and improve the testing process by eliminating extra steps. (above from left): the mold for the kitepump compartment; the carbon kitepump compartment; Damon fits the lid on the compartment; the compartment installed in the port hull 2 Kitefoiler TESTING & DATA Testing this month consisted of kite-launching tests with the carbon A-frame mast, kite sailing tests of the modified older foils, and tow tests of the newest foils. 2.1 Kite-Launching Mast Tests Please see Kite Testing section for this information. the foil-sticking problem completely. As we continue to refine our foil options, we will address this on the foil side.

5 above left, Joe and Don experience foil jumping while sailing; above right, Don and Joe foil stably during the March 28th test 2.2 Kite Test After successfully launching the kite on the 28th, we tested the Kitefoiler with the new rudder and the new, longer T-foil. The wind was such that foiling was only possible with two crewmembers at a time. The foils worked but adjusted unevenly, causing the boat to jump a bit as it sailed. The side foils we used were the single, modified, steeply angled J-foil (port), and one of the original J-foils, so part of this behavior might have been due to unmatched foils. The new rudder adjustments worked well, and the larger T-foil seemed to lift the boat out of the water more quickly. Tow Tests We went out for a brief tow test on the 29th to check adjustments to the side foils used on the 28th and to compare performance of the original stern T-foil to the newly fabricated, larger stern T-foil. We compared the speed and load data for each stern T-foil to quantify relative performance. The speeds are not identical in each case, and other factors such as the tow angle and acceleration may have varied between runs, but it provides some indication that the new foil requires slightly a larger towing force at knots. On the 30th, we tried the side T-foils on the Kitefoiler for the first time. They performed very well in the glassy conditions, demonstrating much more lift than the J- this plot suggests that the new T-foil, which is larger, requires a larger towing force foils and foiling stably with little spray hit- ting the crew. Additionally, we put five people on deck for the first time, and the boat had no trouble foiling stably with the additional weight. (above from left): lowering the boat into the water with the two new side T-foils and the newest stern T-foil; Erika, Sharon, Don, and Joe demonstrate the stability of the foiling platform by going hands-free; the boat foils with five people on board: Erika, Sharon, Don, Betsy, and Joe

6 KITE DEVELOPMENT & TESTING 3 Kite development At the beginning of March, Dudu, Don, and Joe visited the kite factory in China in order to collaborate with the team there on developing new kites. In the later half of the month the new kites arrived and we have begun testing them in preparation for Dudu's return to China in April. Additionally, we have been developing and improving a kite-launching method for the Kitefoiler, and successfully launched and sailed the boat using our new kite-launching mast. 3.1 China Trip & New Kites We spent much of our time in China designing and testing new prototypes and kite parts in order to speed the design process. Our presence in China allowed us to test with the kite makers, in order to directly communicate our needs and to better understand their capabilities. It also enabled us to design a kite in the morning and test in the afternoon, as the factory was able to produce prototypes on a much faster turnaround than if they'd had to ship them to the US. Our kiteboat kite focus was on creating new 25m 2 kites that improved upon the old white-and-red highaspect-ratio kite that we used with such success on the Trifoiler and Kitefoiler between October and February. The four kites we ultimately requested are all 25m 2, with aspect ratios of 6. They feature variations in stretch, loading, and performance details that are meant to address inadequacies in the old kite. The new kites arrived in Alameda in late March, and we have so far used two of them. The first was a kite made entirely of Cuben Fiber, which is lighter and more durable than our usual materials. Until now, we had only used Cuben Fiber for portions of the kites, not the entire structure. We had hoped to use this kite on the Kitefoiler launch tests, but it failed during minor shop tests, due to poor seam construction. The kite will need to be repaired before further testing, but it may be that the Cuben Fiber material will need to be glued instead of stitched, or stitched in a new fashion. The second kite we have used in Alameda features a larger diameter strut base than the old high-aspectratio kite, and it has a trailing edge canopy made of Dacron. We used this kite with good results during the kite-launching tests on March 22nd and 28th. (clockwise from top left): some of the newly arrived kites from China; the Cuben Fiber kite on the kite-launching mast in the shop; a closeup of the leading edge and center spar joint on the Cuben Fiber kite; the second 25m 2 kite flying during a boat test; a drawing of that kite highlights the location of the Dacron details 4 Kite TESTING Mid-month, we completed the kite-launching mast and began launching tests using both a 20m 2 kite and

7 a 25 m2 kite. By the end of the month we had used this system to successfully launch and sail a kite on the Kitefoiler. 4.1 Kite-Launching Mast Tests The kite-launching mast setup is an A-frame built from two carbon windsurfing masts with extensions and a system of the pulleys to position the kite on the frame and release it from the frame. With it, we have been using the K1 winch and a custom winch platform. 20m 2 Kite On March 11th, we tested the new kite-launching mast on the Kitefoiler for the first time and used a 20m 2 kite. We were able to successfully launch the kite from the mast three times, but we had difficulty transitioning from launch controls to sailing controls and were unable to get the boat sailing. However, our technique did improve with each launch, and the kite recovery from water to mast was much simpler than without the mast. One problem we did have with kite recovery was that the mast did not eliminate the problem of kite lines tangling after a crash. Therefore, after the test we rigged up a new pulley system to prevent tangling and also to improve the speed of kite launch and recovery. top left, Joe, Don, and Dudu inflate the 20m 2 kite using the kite-launching mast; above left, the improved pulley system; above center, a view from the 20m 2 kite; above right, launching the kite during the March 11th test 25m 2 Kite On March 22nd, we took the boat out again to test the new pulley system and one of the new kites from China. Additionally, we added extensions to the mast to accommodate a larger kite. We successfully launched the kite, but again had trouble converting the launching position to a flying position. This time, the problem seemed to be, in part, due the line length we were using 80-meter lines, which make it more difficult to control the kite, particularly when learning a new process. We had lengthened them thinking that a higher kite would have more space to transition. Additionally, because the diamabove, a kite view from the March 22nd test; right, Richard, Don, and Joe sailing on the Kitefoiler after successfully transitioning from launch on the March 28th test

8 eter of the front lines was greater than the diameter of the back lines, depowering was uneven as the lines spooled around the winch, which proved difficult to compensate for. We addressed these line issues, and on the 28th again went out with the 25m 2 kite. We successfully launched and transitioned to sailing on the first try. KITEBOAT ELECTRONICS 5 SENSOR DEVELOPMENT In an effort to streamline our testing procedures, we are working on making our sensor suite more compact and easier for the crew to set up on board. 5.1 New Logger Thermal Test This month we made the logger components compact enough to fit in a new box that is even smaller than the old box. Before using this setup on the water, however, we recorded the temperature in the closed box over two and half hours in the shop, to ensure that the electronics would not overheat in their new closer quarters. The graph below 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 two-and-a-half hour test, it appeared to be leveling off with a likely asymptote at around low-to-mid 40 Celsius. This is good news, since the most sensitive component in the box, the lithium polymer battery, should be kept under 60 C. The logger PC itself uses a solid state disk, and should thus be able to exceed 70 C. This was also the first test in which we used a single small battery to power the PC, the radio link, and the N2K network for an extended time period. Extrapolating from the amount of charge used, we expect to be able to run these devices for at least six hours on a battery charge. (clockwise from above left): the Nexus S phone running the temperature software; the graph showing the temperature curve over the course of the test; Jamie closes the new, smaller sensor box (orange) below is the old, larger sensor box (gray)

9 1 LIFTING KITES This month s lifting kite testing centered around the four identical rokkaku canopies that we made in China and the carbon and inflatable spar systems we attached to them for comparison. 1.1 China Trip During our trip to China at the beginning of the month, we worked with the factory staff to develop several rokkaku prototypes for us to test back in Alameda. While in China, we focused on construction details and testing initial prototypes enough to be able to send good test kites back to the US. above left, Don, Dudu, and Joe work in the China office; above center and above right, manufacturing preliminary rokkaku prototypes in China 1.2 Rokkaku Tests March 25 Test After receiving our new kites late in the month, we took the four rokkaku kites out to the parking lot to compare their performances. All canopies were identical, and all kites featured carbon center spars, but the (clockwise from top left): Don, Dudu, Jamie, and Joe observe the flight of Kites 1-3; Joe, Jamie, Don, and Dudu launch Kites 1-3 using two spools and the kite-launching boom; Don and Jamie rig Kite 4; Kite 4 flying with minimal deformation; Kite 3 flying with additional deformation Kite Assist Projects KITE ASSIST PROJECTS

10 the cross-spars on each were different. Kite 1 was the control group, a kite with all-carbon spars. Kite 2 had a similar carbon structure but featured a modified spine. Kite 3 had inflatable cross-spars made of Cuben Fiber instead of carbon spars. The inflatable spars had the same curvature as the carbons spars on Kite 1. Kite 4 also had inflatable cross-spars made of Cuben Fiber. However, these spars were 90% of the diameter of Kite 3's spars, and their curvature was 50% that of Kite 3's spars. Kite 4 had the best performance overall, which was a surprise. Its general appearance while flying showed very little deformation, unlike the other kites. Additionally, Kite 4 rarely wobbled during flight, unlike Kite 3, the other inflatable kite, which constantly swooped while flying. It is likely that the less-curved spars were simply more resistant to deformation from compression than the more-curved spars. When we jerked the line very hard from the ground it was possible to make Kite 4 deform, but that did not occur when flying or winching. An additional measure of performance was the line angle of each kite. The line angle from the vertical of Kite 4 was around degrees, whereas for Kite 3 it was around degrees. The carbon-sparred kites had line angles closer to degrees. Kite Assist Projects March 28 Test The best kite from the previous test, Kite 4, featured carbon battens at the tips of the Cuben Fiber struts to help spread bridle loads. Despite the good results, we wanted to lighten the structure in the hopes that the inflatable rokkaku could surpass the all-carbon sparred rokkaku in performance as well as ease of operation. Therefore, we tested Kite 4 against a new kite setup, Kite 5, which consisted above left, closeups of the rear struts, respectively, on Kite 4 and on Kite 5; above right, the two kites shown with different batten lengths Kite 4 (behind) has a longer batten at the tip of the strut than does Kite 5 (front) of inflatable Cuben Fiber tubes of the same diameter as those on Kite 4. Kite 5 s spars, however, were 75% of Kite 1 s curvature, instead of 50%. Additionally, Kite 5 featured weight-saving battens that were shorter than those on Kite 4. Both kites flew well with the same stability and held all gusts with no issue, proving that smaller battens at the strut tips can still spread loads while saving on weight and space. The 50% curvature kite, Kite 4, still had better flying angle, suggesting that less curvature is desirable for the inflatable shape. March 31 Test On March 31st, we again took Kite 4 out to the parking lot to compare its performance to that of the original carbon spar kite, Kite 1, in very low wind conditions. At first, Kite 1 flew much better than Kite 4, but with some bridle adjustments their performance was again fairly comparable. Kite 4 suffered somewhat in the low wind when we tried to get it to lift a camera, likely because the kite still weighs more than Kite 1. During our April China trip we will work on adjusting materials and tube sizes to reduce weight. 2 ELECTRONICS Our electronics work this month has focused on improving aerial photography systems. In particular, using the Nexus S Android phones to transmit kite views in real time. 2.1 Android Phone Wireless Setup Early this month we succeeded in linking two Android phones together wirelessly so that one's screen shows a live feed of the other's camera. This is to be utilized on the kites in tandem with the pan/tilt camera app developed last month, so that one phone can serve as the boat- or ground-based control device for the other

11 phone, which can be mounted on the kite. At the end of the month, we debuted the 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 75 meters. On the ground, we monitored another Android phone, which displayed the image taken by the lofted camera. Kite Assist Projects above left, the phone in Jamie's left hand streams a live feed from the phone in Jamie's right hand; above center, Jamie monitors the ground phone with one hand and maintains the kite line with the other hand; top right, the temporary cardboard case that protects the camera and attaches it to the kite line; above right, a closeup of the ground phone showing an aerial view of Don walking across the parking lot