Goat Page        by Mike Sandlin

Last Update: April 28, 2010

The Goat is an airchair, essentially a garden chair with a wing. This is Goat4 in March of 2007.

Like the Bug biplanes, the Goat does not foot launch, but is either towed into the air or else launched by rolling down a hillside. My rolling launches are usually made at a site shared with hang gliders and paragliders. This glider has proved to be a worthy soaring aircraft, flying very much like a hang glider and readily adapting to hang glider techniques and procedures. The Goat1 has made a cross country flight of more than sixty miles, reaching an altitude above 13,000 feet.

This is a home built glider, made with a low level of technology (no welding, no special machining, no molds or jigs, no spray rig) from readily available materials (mostly aluminum tubing, steel cable, aircraft bolts and heat shrink fabric). The Goat is a noncommercial project, with no product or plans for sale now or later, but I have posted complete descriptive drawings of the Bug4 and Goat1 through Goat4 on the Web. These drawings are freely available for whatever purpose the user may desire.

Goat1 on the left, Bug2 on the right, are both carried on truck top hang glider racks.

My idea of an "airchair" is that it flies like a hang glider or paraglider but with improved stability, control, comfort, and crash safety. The glider can be kept at home and transported to the flying site on a simple car top rack. It can be assembled by one person in about 20 minutes. With a wing loading about the same as a hang glider, it flies and soars like a hang glider, making it compatible with many existing hang glider operations, using rolling launches, ground tows, or ultralight aerotows.

 

A careful pilot knows his glider and checks it out before flight.

 A high flying airchair pilot must be versed in sailplane procedures such as assembly, ground handling, preflight inspection, three axis mechanical flight control, emergency procedures, flying regulations, airspace restrictions, and the effects of wind and weather.

Coming down to the Landing Zone, Bug2 is already there

Goat1 makes a rolling takeoff  from a gravel  hang glider launch ramp

Goat1 in Flight

The Goat1 made it's first flight on February 1, 2003, and since then has been flying as a weekend soaring glider. It has proven to be a pleasant and practical glider for slope launching and local flying. It is easy to tow behind an ultralight airplane. The struts fold onto the wing for transport. As of  december, 2009, Goat1 has new fabric and removable, folding main struts,and is now called the Red Goat.

The biggest drawback to the Goat1 design has been the large size and heavy weight of the main wing panel with regard to loading or unloading it onto a car top rack. I make a point of carrying each wing panel by myself most of the time, and I find it stressful. The folded wing half weighs 42 pounds, which is about my upper limit for something big and bulky that has to be lifted and carried in the wind. The primary reason for the Goat2 design was to have a lighter wing panel to reduce the burden of assembly and loading.

Goat2, with a cable braced wing and tail, attracts attention from future pilots (February 2005).

Goat2 is a simpler, lighter version of Goat1 with almost exactly the same significant dimensions. In contrast to Goat1, the wing and tail boom are cable braced (no struts) and a 14" diameter ground roll tire is used instead of a 16" tire. The elevator control lines now run directly to the elevator control arms without any push rod mechanisms, and the removal of the tail plane for storage and transport has been simplified. The video clips "Airchair Thermalling" and "Landing in a Small Field" were taken from Goat2.

Goat2 was light and eliminated the bulky struts, but all those long cables created their own transport and assembly problems. This led eventually to the creation of Goat4, which retained the cable braced wing but simplified a lot of the assembly mechanics.

Goat3 high in a desert thermal

Goat3 in flight, (May 2006)

Goat3 has a smaller wing than the other Goats, with a fancier, sailplane style airfoil. The struts are removed for transport, and the wing does not have folding panels on the trailing edge. The seat back and shoulder belts are fixed in place on the nose section and do not require attention during assembly.

The reduced wing area of Goat3 forces me to fly faster, and the new airfoil doesn't seem to be producing any dramatic performance improvement. As it stands, it looks as if the larger wing with the simpler airfoil (as used by Goat1 & Goat2) may be a suiperior combination for an airchair. Goat3 probably won't stay up in light conditions as well as the others, which leaves me ( body weight 155 lbs., an average weight pilot?) wanting the larger wing.

Goat Features

The varioius Goats have these features:

• Five or six major separable parts, the heaviest being the the wing panel at 35 to 42 lbs.
• Emergency parachute, hang glider type, hand deployed 22 gore round canopy PDA, with bridle & swivel
• 16" or 14" diameter wheelbarrow or ultrlight aircraft wheel, tube tire
• nose skid for braking (no wheel brake), tail skid at rear (or wheel)
• drogue chute, hang glider type, 5 ft. diam. (flat octagonal) canopy, attached to main struts or flying cables, 27" outboard from centerline on left side
• tow hookup with weak link loop, to break at about 110% gross weight
• Altimeter/variometer mounts on nose tube or strut, hang glider type
• Quick assembly pins, handles & tapered ends for "drift pin" assembly, all fasteners attached to airframe
• Flap panels in fixed position, or fixed trailing edge.
• Four point seat belt
• Conventional stick and rudder controls
• There are no formal values established for performance, pilot weight, or maximum speeds or loads, because no rigorous tests have been performed to measure these values. There is, however, discussion of these factors on this page and on the

Unfortunately there is no commercially manufactured glider that can do all of what the Goat does. Homebuilding is fun, but people who just want to fly gliders should be able to "buy and fly" instead. Maybe home built airchairs like the Goats and Bugs will help generate enough interest to allow commercial production of an airchair someday. Whoever might choose to develop and sell airchairs would be in a position to set new standards and make a great contribution to ultralight soaring. I don't yet know of anyone doing this, nor would I be a part of that effort, but I will encourage any moves in that direction.

Author in Goat1

Drogue Chute Landing

 

Climbing on a static line, truck tow

Bug2 and the Goat1 on the airchair flight line, preparing for truck tows.

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