Avery Flies Sewed Pandora, a 27 Foot Blimp That Flies on Open Flame

Avery Flies spent roughly 200 hours sewing a nylon bag the size of a small bus, hung a barbecue burner under it, and flew the result around a park. The ship is called Pandora. Inflated, it runs 27 feet long and 11.5 feet wide, holds about 2,100 cubic feet of air, and leaves the ground on heat alone.

Lift is derived from the trick of a festival balloon, but scaled down and given a bit of power. When the burner is lit, the air within the balloon becomes lighter than the air outside, causing it to rise. The propeller, not the helium, decides where to travel, despite the burner appears to be a quite strong fire from the ground.

Sewing took up nearly the entire calendar, with Avery cutting and slicing 108 yards of 1.1-ounce silicone-coated nylon into 36 parts, tracing a modified version of a Geta Flug balloon shape, and sewing those gores onto the balloon itself using a home machine. The finished envelope weighs 8 pounds and required approximately 150 hours to complete. Three little fins sit at 120 degrees, one less than the typical number, because four would have required more stitching than the flight could manage. Each of those fins took around 20 hours to complete, and there are barriers within to keep them from blowing up like cushions. The rudder is sewed onto the bottom fin, which took an additional 8 hours to perfect, and it is inflated through tiny perforations in the main balloon.

There are roughly 40 odd ropes and stainless cables extending up from the gondola to patches on the envelope roof, so the cabin remains inside the balloon shape rather than being yanked flat. Pandora weighs 13.4 pounds and is ready to fly, powered by two 1-pound propane bottles. The gondola is made of bent aluminum bar, and it required another 50 hours of cobbled-together parts, retesting, and re-retesting before it was ultimately correct. The burner components are simply old 1/8-inch pipe fittings from the local hardware store, with a small servo controlling the blast valve and another valve metering out the pilot flame. The little green canisters are the same as those used on portable grills.

Pandora’s forward thrust comes from a brushless motor on an 18-inch propeller weighing more than 20 pounds. However, keeping the balloon from sagging is another issue. There’s a second 70 mm electric ducted fan in the gondola roof that blows air up into the balloon so the nose doesn’t cave in while she’s moving. It also helps keep the fins pressurized while she is flying. A 4-cell 8,000 milliamp-hour battery pack powers the system, which is controlled by an E-Flite 100 amp speed controller. Naturally, the propane is the last to go. A small winch servo from a model sailboat is used for steering, which operates this large fabric rudder that is roughly a meter tall. It behaves more like a sail in the wind than a typical airplane fin.

The first real flight didn’t happen until late September 2026, following some practice runs using a 2-foot miniature model created by Avery at the age of 12 and a line of smaller balloons. They took her to a pleasant park on a calm day, with family on the ropes, and Pandora flew off, holding steady in the light wind and performing a 180-degree turn inside a 400-foot perimeter. She isn’t very agile until she gets some airspeed going. Once she lands, the pressurization fan works hard to cool the burner and keep the nylon from melting on the way down.
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