I recently read the following paper in which the author details his automated optimization for finding laminar flow airship profiles for certain Reynolds Number ranges:

Drag Reduction and Shape Optimization of Airship Bodies, T. Lutz and S. Wagner, University of Stuttgart, Journal of Aircraft, Vol. 35 No. 3, May-June 1998

The principal author has kindly provided the profile coordinates of the optimized airships and thus I have seen it necessary to size a laminar airship using a rendering software (Cinema4D) and to see how it would look to fly a laminar-flow zeppelin.

For a laminar body of rotation to be effective, the surface of the body must be free from imperfections, smooth, and have no wrinkles and have no dimples. These requirements reminded me of the two aluminum airships which flew more than 50 years ago. One of which was the ZMC-2:

It seems necessary to use a thin composite shell with gelcoat on the exterior. The gondola requirement poses a problem, so I propose to use a harness like that of a parachuting student to his instructor. The 100m3 airship is essentially a large buoyant backpack, with a shaft extending from the flyer’s feet through the gas-cell to the propeller.

The prone cycling position has been proven on land-vehicles:

And also on one human-powered blimp…. This is an appropriate harness for the aerial canoe.

A number of unknowns exist, including:

1. Is a rudder necessary, or can a swashplated or vectored propeller suffice?
2. How much would the exposed pilot disturb the otherwise laminar flow around the airship body?
3. Does the pilot need to be enclosed?
4. Can a composite hull be made gas-tight and how?

An RC model will answer some of those unknowns. Here are some renderings which I have done in my first day of Cinema4d usage:

The pilot will likely NOT fly with his arms extended like the stick-man in these images.

The pilot faces forward, side-to-side, and predominantly downwards.

This picture exposes the drive-train from the pilot’s feet to the propeller.

The renderings show an airship with a lifting volume of 100m3, a 3m prop and a 1.83m stick-man for sizing reference. The resulting airship is 16.76m long and 3.6m wide at largest width. The next steps are to build a spherical composite balloon, ensure that the finish is smooth, test the balloon’s gas-tightness with air and with lifting-gas, and learn and refine manufacturing techniques.

I was lucky enough to be able to talk with Bryan Allen the other day about his experiences flying the White Dwarf and also the Gossamer aircraft. He lends a large dose of reality to those wishing and wanting to float over the trees in nearly silent, propelled, lighter-than-air vehicles.

Bryan mentions “Apparent mass” which I had to look up: Apparent Mass=Force/Acceleration. This term was used in reference to the fixed-wing Gossamer aircraft, which had large aerodynamic surfaces and low mass. Just because those airplanes weighed around 30 kg each, lifting or moving them by hand would have been hard because the force required to accelerate them (overcoming drag on their large lifting and control surfaces) would have been higher than simply “mass times gravity”. Apparent mass!

It is also quite illuminating to do as Bryan recommends, to compare cost-to-performance ratios of small powered flyers, from 0.25 up to 20 HP. At the lowest-power end of the spectrum, around that of human-power, a blimp is actually pretty competitive. Slightly increasing the size and the power, from the human’s 0.25 HP up to 1-2 HP, then fixed-winged aircraft start to get better. Afixing a 20HP to a fixed-wing aircraft can make you go 120mph (see Rutan’s Quickie), so having a blimp at that power-range is not really sensible to go from a to b.

(UNLESS you need the advertising space, need to crawl along the rainforest canopy, need to break the FAI world record for that class of airship, need to build the first “microlift airship”)

Filmed on March 21, 2010. Thanks to Aerovironment for permitting use of the image of Gossamer Albatross in the film.
Thanks most of all to Bryan Allen for the inspiring doses of reality!

I want to find a low-cost lifting-gas barrier for use in our flycycle. I obtained some 3-mil polyethylene painter’s tarp material which i then folded in half and whose edges i welded together with a clothing iron. i covered the edges with 3″ masking tape to protect the iron from molten polyethylene. For the nozzle I cut a plastic funnel (and my middle finger) and attached it to an open corner using hot-glue from a crafter’s hot-glue gun. Then I test-inflated the bag at Gemeinschaftszentrum Bachwiesen. What follows are a series of photos from that successful air-inflation test. No perceptible leaks were observed. The 4×5m painter’s tarp material worked out to give 16m3 of volume (idealizing the shape to a right-angled cylinder), and thus approximately 16kg of lift if filled with lifting gas.

The air compressor from GZ Bachwiesen was a custom built number consisting of a motor and piston pump.  The rubber tube fit perfectly into the funnel-nozzle of the gas-bag.

Mu ha ha ha ha it’s alive!

It gets more air….

Fully Inflated. Ready to rock and roll.

Getting the kind assistance and motivation from 8hourcustom, we proceeded to start a fabric 1/50th mock-up of the piloted craft in order to plot our our envelope-attachment points, et, cet, tera. A four-gore, canvas model of the same aspect-ratio (or close) of the end-design has been started (marked, partially cut, sewn). Next week it will be ready to assist us with the fine-planning.

Marking the gores with #2 pencil on canvas (or similar – bedsheet material).

Sewing gores.

Stay tuned. Wait till we unfurl our self-correcting ballast system for free-flights over water.

In the following interview with Stephane Rousson, we find out about the challenges of human-powered airship flight outdoors, the construction techniques used in his airships, geographic differences in helium pricing, and the time-scale in which new airship projects can go from scratch to flight.

Thanks to Stephane for sharing his insight. Interview recorded on December 24, 2009.

Before any lighter-than-air undertaking is commenced, a sure and inexpensive source for a lifting-gas must be located. Helium, Hydrogen, Coal-Gas, Hot-Air, all of these come to mind. Let’s neglect Hot Air and Coal-Gas for more performant Helium and Hydrogen. Helium is expensive, and Hydrogen is inexpensive to obtain from water using Electrolysis. For the unmanned prototypes of the Aerial Canoe, we will use cheap Hydrogen, made at home.

This is a post I am contributing to Airshipworld. It is an interview with a present-day Aviator-Engineer in the sense of Glenn Curtiss and Alberto Santos-Dumont. Eric Raymond has built and flown one of the world’s first practical solar fixed-winged aircraft, and is setting his sights on Lighter-than-Air vehicles with his Sunship Project.

Eric Raymond is the head of Solar Flight, a world leader in manned solar powered aircraft.

Solar Flight’s Sunship Project will be the first zeppelin-class rigid airship constructed since 1939, the next chapter in his scalable approach which has been used successfully on Solar Flight’s fixed-winged Sunseeker Aircraft.

In this interview, Eric reveals how the Sunship can be kept small – 125 feet long – using modern materials such as Vectran cables. Another intriguing aspect is the use of a rocket-fired land-anchor for use in emergency moorings. And finally, he advises any newcomers with convincing ideas to start work on their ideas rather than leave projects on paper, and to assemble a high-powered advice-network of doers and creators in the field in which the big idea is relevant.

This interview was recorded on October 14, 2009.

Thanks to Kenneth Deacon, Airship Heritage Trust, and Solar Flight for use of images in the film.

Thanks to George Raymond for setting up this contact.

Thanks to Airshipworld for publishing this interview.

Thanks most of all to Eric Raymond for his time and insight.