Blimp Notes, Mar/97- - To the specification add a short bowline (1 m) to trail from the lower nose so that, in a stong breeze, the craft can be handled like a kite. -Immediate needs- (2) 9.6V 1000mah ni-cad packs jerimi, bill, mike, george, wan-yik, check servo angles w/ george -Trimble's credit card size GPS reciever, the Lassen-SK8, with RS232 interface, weighs 20 grams and sinks 150mA. The developers kit is 900 bucks, outside of current budgets, so discussions are underway to get sponsorship, i.e. carry a logo banner for use of the instrument. http://www.trimble.com/cgi/products.cgi/pd_om006.htm -Radio LANs have matured to a usefully affordable degree of lightweight performance. "Flying LANs" is a popular concept in APV/RPVs, allowing a robustness of redunancy and the ability to chain the aircraft, as communications repeaters, over long distances. The current prototype will fly a digital cellular phone/modem for local testing, until such time as a radio LAN or global satellite communications (i.e. Iridium) becomes needed.. -Envelope reinforcement has two aspects- As the airship drives thru the air at a slight angle of attack, the rear upper bag is the zone of highest internal gas pressure (lowest outside pressure) and is naturally stiff. A polyester tape spiral grid winding and seam reinforcement keeps this area from bursting. The lower nose experiences the opposite effect; high outside pressure cancels inside pressure and the nose becomes limp. Therefore a "rigid" nose shield of radiating aluminum stringers, spanned by ultralight sailmaker's mylar, maintains shape. This structure is more extentsive on the lower side where pressures are greatest and collisions (mostly with ground obstacles) occur. -Current Motors had to be retimed to work efficiently in a pusher prop configuration (no pusher props available). -Upgrade wishes- 14" prop, advanced motors (brushless cobalt) and batteries. Balloonet/ballast w/ controls. Thin film solar "panel" for extended missions. NREL's CuInGaSe2 prototypes have set the word efficiency effort at 17.7%. Commercial amorphous films are about have as efficient. (note: ask NREL (John Tuttle) for donation of material) -The varied pricing, features, performance, and availability of wireless communications means that multiple solutions are required for the broadest range of missions. 2.4Ghz video, 72.23 Mhz control- Inititial prototype configuration (add serial link to audio channel and GPS as payload allowance grows)/Digital Cellular- Broad geographic coverage with low bandwidth communications. Channels could be aggregated to build bandwidth. Full duplex audio (speakerphone mode) is a powerful feature./Wireless Ethernet- High bandwith communications with local base station. Satellite Digital- Global operations empower truly awesome missions. Dream On- Stratospheric solar cities- superpressurized and heated to human comfort levels, lifting gas in balloonets, ion engines restore ozone. -Toward a minimally adequate set of flight control primitives- Inputs- GPS/GIS data, fluxgate compass, operational commands, Outputs- LeftMotor/RightMotor/LeftTail/RightTail x hi/med/lo roll, pitch, yaw, throttle-hi/med/low, course/attitude/location circle holdStation holdCourse search land takeOff loop roll spin ================= Subj: HC11 microairship Date: 97-02-25 16:48:29 EST From: santos@88net.net (David Santos) To: faust22365@aol.com x86, radio lan, linux, HC11 microairship http://www-sgc.colorado.edu/people/siewerts/testbeds/floaters.html ==================== -Austin Centre will host trial flights of the new airship, requiring only that they be an additional insured party to the basic liabiity insurance. The American Modelers' Association provides 1.5 M coverage as part of its membership fee of $20. SXSW multimedia computer festival will be held at Austin Centre in the spring, providing a spectacular venue for the airship. -Skyride Balloons is eager to provide its six place hot air balloon for a trial cross country excercise were the airship would tag along with the balloon for good 2-way video. Thus chaperoned, the airship would be less prone to loss and the mission would benifit from the existing infrastructure of a chase vehicle and separate comm channels. -Every structural component of the airship is being leaned out to save weight. The weight grew enough to preclude carrying the serial data link and it was decided that downsizing batteries or motors would be a last resort. -George Parks cut some beautiful foam "wings" for the vee-tail control surfaces. Tom Lupton, of Lupton Machine, custom machined some small aluminum parts. -Extensive refinement of all components is paying off in a true work of art. -Bamboo stringers radiating from hardpoints have been replaced with aluminum tubes in sleeve sets for tapering spars. While the aluminum is more crumple prone, its a standard product easily replaced. -Barlett Sails has provided indispensible advice and materials for envelope details. Except for helium retention, the new materials that sailmakers use for light air sails are excellent fro micro airhip use. -An x-y positioning system for the heavy batteries has been developed that will allow versitile weight trim for best cruise and aerobatic performance. Only tiny amounts of trim ballast will be needed to precisely balance the craft. -Budget: An extra 1K has been spent out of pocket which, properly documented, should be applicable to our cash match requirements. A computer radio, as specified by George Parks, was the biggest new expense. -On Sept. 30 James Perez and David Santos visited Martin Jr. High on Austin's East Side to show off the airship work in progress. We demoed video capture using airship components and Web site creation using the Mobile LAN. -Mount propulsion units with a slightly splayed fore and aft stance so that at full cruise power they align at the most efficient angle. Provide for field tunability of the prototype to determine best splay factor. (7/14/96) -By locating the chord mounted elevon just above the propwash it avoids a high speed drag penalty but can still dip into the wash for aggressive maneuvers. Thus the tradeoff between agility and speed is substantially avoided. An elastic restraint will assist the high torque servos retrieving the leading edge from the propwash. (7/14/96) -Components are mounted on hard points of balsa and aviation plywood with sculpted foam fairings. A radiating structure of thin bamboo stringers spreads hardpoint loads across a large area .These stringers are arranged to follow stream lines and help to maintain operation with a limp gasbag. The blimp becomes semi rigid like a large rib cage is able to "breathe", that is adapt to varying gas pressure due to altitude change or leakage. Bamboo remains a unique structural resource that is usefully tapered, tough, stiff, light, and cheap. A more advanced substitute for the X-2 might be light carbon fiber fishing rod stock. (7/14/96) -The roller-keel serves several functions. It has a wheel for rolling along on smooth ground. It is a float for floating and skimming along smooth water. The ballast and baloonet system is housed within. Drop ballast provides most, but not all of the airships pendulum stability. (7/14/96) -New applications (7/14/96): Structural inspection, site inspection, employment and recreation for the mobility impaired, human rights witnessing, disaster assessment, hostage situations, lifeguard, photojournalism, education, specialized parcel delivery, livestock management, crop surveys, surveying,
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