Personal Lighter-than-Air Flying Machines

The “age of the personal airship” always seems to be just around the corner. Hot air balloons have been around since 1783, but affordable personal airships that you can control and reliably fly from point A to point B in a reasonable time — even against the wind — seem to defy human creativity. Even just catching a ride on a blimp these days can be almost impossible.

Certainly a lot of people are working on the project. The “Small Blimp Community Wiki” discusses the basics of the problem, and the Small Blimps Chat and Discussion Group contains thousands of posts on hundreds of topics.

SkYacht Personal Blimp

Personal Blimp Alberto 2007 http://www.personalblimp.com/faq.html

Personal Blimp Alberto 2007
http://www.personalblimp.com/faq.html

A company called SkYacht has been flying the Alberto personal blimp since 2006, and was allowed to fly passengers in 2007 by the FAA. Recent news on the project has been scarce, but contact links are available on the web.

Cluster Ballooning

The quickest and cheapest way to build your own airship seems to be the “Cluster Balloon” approach.

Cluster ballooning is a form of ballooning where a harness attaches a balloonist to a cluster of helium-inflated rubber balloons.

__ https://en.wikipedia.org/wiki/Cluster_ballooning

Like hot-air balloons, cluster balloons are flown in the very early morning, when winds are calm. In some areas, it is also possible to fly in the evening, in the hour or two before sunset. Preparations for a morning flight flight start before dawn. The balloons range in size from four to seven feet; depending on the mix of sizes, anywhere from 50 to 150 balloons may be needed. It takes a crew of fiften to twenty people about an hour and a half to inflate the balloons. Special hoses and manifolds are used to inflate the balloons to the desired size, based on the volume of the helium tanks. The inflated balloons are sealed using tape and cable ties, and are tied with nylon twine.

… The pilot is in a harness designed for paragliding, which includes a rear-mounted emergency parachute. The pilot can stand up in the harness to take off or land; there’s also a little seat built into it, for greater comfort while flying. Bags of water ballast hang beside the pilot, and are used to maneuvering (see below). The pilot also carries an altimeter/rate-of-climb instrument, a GPS and a two-way radio.

http://www.clusterballoon.org/intro/intro.html

Cluster Ballooning Wikipedia

Cluster Ballooning
Wikipedia

In order to make your cluster balloon a true airship, you would need to add a means of propulsion with directional controls. Otherwise you are simply at the mercy of the winds.

Note that cluster ballooning is quite dangerous for those who do not respect the elements, and for those who have trouble focusing on what is happening in the moment — and on what is likely to happen soon. It is easy to get lost in the big sky, or alternatively, mangled or drowned by a bad landing.

A Goal in Need of Important Breakthroughs

Basically, the personal airship is a goal in need of some breakthroughs. Here are a few of the many considerations to be taken into account, when designing and building your own personal airship:

Airship Technology
Lifting Gases

  • Hydrogen – Density 0.08988 kg/m^3. It is also highly flammable. It can also be used as fuel. Allows for 1.202 kg of lift per m^3. Exists as diatomic H2 and leaks fairly quickly. http://en.wikipedia.org/wiki/Hydrogen
  • Helium –  Density 0.1786 kg/m^3. Allows for 1.113 kg of lift per m^3. It is monatomic and leaks very quickly.
  • Steam – Density depends on temperature.
  • Methane – Provides about half the lift of hydrogen. Methane is a larger molecule so it leaks more slowly. It can be used as fuel and has a higher volumetric energy density than hydrogen.
  • Hot Air – Air can be heated to reduce its density. Hot air provides about a third of the lift of hydrogen.

Airship Configurations

  • Traditional – Long, cigar shaped airship of fineness from 3-8. This type relies on buoyancy for nearly all of its lift.
  • Hybrid – This type of airship generates a significant portion of its lift through through non-buoyancy based lift.
    • Aerostat – This subset developed a significant portion of its lift through aerodynamic lift generated through forward flight.
      • Lifting body – This type uses the shape of the envelope to approximate a wing which generates lift.
      • Winged envelope – This type places wings on an otherwise traditional airship which generates lift.
    • Rotorstat – This subset places helicopter-like rotors on an otherwise traditional airship which generates lift.

Ways to vary lift

  • Aerodymanic Lift – As a body moves through the air, aerodynamic lift can be generated if the body’s longest axis is at an angle to the incoming flow or if the mean thickness line is cambered. Aerodynamic lift is very power efficient.
  • Powered Lift – A fan or rotor can be used to lift a craft up. This is the method helicopters and “jump jets” use to take off vertically. This method requires a lot of power.
  • Gas compression – Lifting gas can be pumped into a holding tank to reduce the airship’s volume and lift. It can also be expanded into the lift bags to increase lift.
  • Gas heating – Heat can be added the airship’s gas to increase volume and lift. Combustion, solar, and electric heating devices are all options for adding heat to the gas.
  • Reversible Chemical Reaction – Use chemical reactions to exchange gas with the atmosphere to change volume or mass. Example, regenerative fuel cell.

Power Systems

  • Internal Combustion Engines
    • Gasoline – Most common, engine is cheap. Fuel can be expensive.
    • Diesel – High efficiency. Can be heavy.
    • Methane – Can be converted from gasoline engine. Fuel is cheap and is a buoyant gas.
    • Hydrogen – High potential, not widely available. Fuel is a buoyant gas. Technology still maturing.
  • Electric
    • Internal combustion driven generator – Burns hydrocarbons to generate electricity. There is variety to choose from. They are relatively cheap and reliable.
    • Fuel cell – In development. Very high potential.
    • Battery – Electric energy is stored in batteries. Several choices in chemistry and performance. Can be heavy.
    • Solar – Electricity is generated during flight by the sun impacting a solar array. Can be expensive and heavy. Can only operate in direct sunlight. The technology still maturing.
Power Transmission
  • Electric – Electric motors are the obvious choice for an electric power system. The technology for these motors is increasing very rapidly.
  • Mechanical – Mechanical power transmission is common and well understood. Mechanical systems can be make of new lightweight composite materials to reduce the relatively high weight.
Propulsion
  • Prop – The standard in aviation. Widely available in many different sizes. Can be custom made fairly affordably. Larger sizes offer more low speed thrust.
  • Ducted Fan Difficult to design and manufacture well. Can have high efficiencies in low speed applications. Can have comparable performance to a prop, but in a smaller package. Usually operate at higher RPM than props due to smaller size

__ Airship Wiki for the Small Blimp

More ideas from the small blimp community

This fanciful account of one man’s adventures in his “poor man’s airship” contains some interesting ideas, although I suspect most of the tale is highly embellished, to say the least.

Problems:

  1. Helium is expensive
  2. Hydrogen leaks and is flammable
  3. Methane is less buoyant than H or He, and is explosive
  4. Good blimp-making material is expensive
  5. A large lifting body is needed to lift propulsion systems and to transport even small persons
  6. Gas compression and gas heating equipment adds even more weight
  7. Fuel is heavy and potentially hazardous to handle
  8. Ground crews for takeoffs and landings can be expensive and unwieldy to coordinate
  9. An airship designer and builder must make a large number of design decisions, based upon limited experience
  10. And so on . . .

A compromise between the cluster balloon approach and the small blimp approach might involve building an ultra-lightweight semi-rigid frame, with propulsion and directional control surfaces and with a compression and heating system all built in. The frame could be filled with individual balloons — such as weather balloons — for buoyancy. Buoyancy control might be achieved by alternatively compression or decompression + heating the balloons, for descent and ascent respectively.

The cost of helium has tripled over the past ten years or so, and will probably continue to rise at variable rates.

It appears that a safe way of using hydrogen buoyancy for personal airships is one of the top priorities for the cost-conscious personal airship pilot. I might be willing to try a mix of H and He, to save costs, but the cost-savings are likely to be minimal.

Using methane for buoyancy simply makes me nervous. I would rather use it for cooking, heating, and making hot water for baths. 😉

It is easy to despair of ever being able to fly your own personal airship, but for those who cannot resist the allure, it can be a difficult dream to abandon.

If one could make a craft safe for hydrogen buoyancy, a number of lower-cost possibilities would be opened up — including a hydrogen-filled lift body craft that combines buoyancy with conventional lift over a “wing” surface. Such crafts are being developed at much larger scales for military and freight-carrying uses. They may be difficult or impossible to scale down affordably.

Consider the “X-Prize” Approach

This project might benefit from the competitive effect of an incentive prize for a winning team. Such prizes have been successful in spurring advances in sub-orbital flight and human-powered flight. Pitting a number of motivated teams against each other can induce a lot of technological creativity.

By comparing the success of different approaches to solving the large number of problems involved, a savvy airship designer should be able to save a lot of time and expense in creating a workable plan.

This Kickstarter project may offer a model for how to finance a larger scale blimp.

Imagine island-hopping in the Caribbean or in the several island clusters of the South Pacific, in your personal airship. Difficult, but perhaps not impossible.

Think about it.

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