ORCA MicroAirship Operations

Effective Payload Notes:

1. One must decide how much endurance and speed to trade payload against. One can design back from a hard payload goal.

2. Actual blimp design & construction varies and fudge factors are used to play it safe.

3. Variations exist in helium supplies, such as lower purity welding gas in the provences, lifting gas temp, weight from rain or condensation,

4. Shareware programs have long existed to calculate E-Flight parameters. I'll try to locate some.

5. Great variations exist in component quality. Fancy rare earth magnet brushless supermotors can be 50% + efficient (or weigh less for same eff.) than more common hobby versions. Advanced batteries are four times or more lighter than hobbyist ni-cads. We may presume DOD only specs the best, but for marginal civilian demining, who knows?

6. A blimp can be flown rather heavy (~20%) by maintaining an angle of attack to the wind, just as an airplane does, but this wastes propulsion energy.

7. Altitude of operations impacts payload. Previous notes were based on sea-level operations (best case). I think Denver is about a 12% or more penalty, but me memory is fogged. There is a table on net, which I'll hunt down.

Summary-

a) For small to medium microblimps payloads from 2 to 10 lbs. are typical.

b) A medium sized microblimp (20') might have a cruising speed of 12 mph. (25 top, 20 min endur.) with endurance of 1 1/2 hours, and a payload of five pounds. Advanced components could double these figures (except top speed), but quadruple cost.

c) A large micro blimp (30') could have about thirty pounds payload, and increased preformance specs., but at this scale costs and logistical req. start to skyrocket. We are counting on microelectronics to enable the smaller sizes to perform advanced missions with small payloads.

d) Fineness ratio of airship is commonly manipulated to reach a given bouyancy at a specific length. Multiple envelopes of different volumes can be supplied for operational flexibility.

Autonomous Flight-

Several approaches are of interest. One is to integrate an agent such as AirSoar with GPS/GIS based cross country navigation. Another tack is to do local exploration based on interpretation of proximity sensor data. A third approach undertakes complex mission level behavior as in Orca, the top level intelligence in the MSEL EAVE architecture.

A final option is to adopt innovative PC based "glass cockpit" aviation products. The processing and user interface would stay on the ground while the GPS unit, fluxgate compass, and attitude sensors would fly. A full duplex radio serial bus would tie together system resources.

Ultimate integration of the various schemes would allow varied missions with intelligent response to dynamic local changes within an absolute navigation framework.

Radio Line-of-sight-

Beware Fresnel Zone, where low level objects block radio line-of-sight while visual sight still exists.

Rapid Response-

For some applications, such as search and rescue, a rapid response capability is required. This aspect may long remain at the concept phase, but has interesting challenges. Obviously an inflated blimp taking up a lot of space and constantly losing helium is not good in a low usage rapid response mission unless instant operation is needed. A better solution is a suitcase sized package that stays charged and self-inflates and takes off automatically. Waiting for a volcanic eruption is a cool application idea.

Altitude Control-

As a rough goal, the design's lifting volume with proper altitude control gear should allow operation in excess of 3000 meters (stretched envelope if needed).

Balloonet system- Keeps blimp envelope taut at lower altitudes and enables climbing without venting helium. Sub issues: a) maintaining a constant relative pressure in the envelope. A photo or micro switch tensiometer mounted on the envelope could sense flaccidity and trigger air pump. and b) selecting a lightweight air pump to pressurize the balloonet. In one approach a ram air inlet may assist a fan pump. In another scheme a small piston pump or motorized "campers air mattress" pump provides the pressure. c) Size of balloonet up to about a third of total gas volume.

Drop Ballast System- Allows blimp to lighten for maneuvering or to balance helium loss, rain/ice/payload pickup. Plain water entails freeze risk. Other options include powder or mealy media or antifreeze liquids.

Legal and Safety Issues-

A comprehensive set of safety features and operational policies shall govern the use of the airship. Great care will be taken to follow applicable aviation law and best safety practice with this project.

Prop hazard- Props will be orange tipped and have a piano wire hoop to guard against contact with people and objects. Prop operation will only occur away from close proximity of third parties.

Plummeting hazard- All components of the blimp will be tied together. All high density components will be mounted on low density structures as shielding. Total loss of lift should result in a drop speed of no more than 30 mph.

Fire Hazard- No combustible fuels or ignition sources will be carried in normal use.

Navigation hazard- About half our team members are pilots and understand the regulations and issues involved. (most senior pilot/consultant is a retired 747 captain for United, others are already flying HTA RPV's under govt. contract)

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Thanks for flying PolyCosmos. Join us anytime.


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