Back in January of this year an American hack group, Quelab, from Albuquerque inadvertently launched a self built solar balloon in the shape of a tetrahedron. The Quelab blog picks up the story.
On Sunday morning in January 2015, a member’s project finally took flight from Quelab, and caused a bit of a stir. Gonner was test-flying his solar balloon, and it managed to get away from him. The tetrahedral contraption (known as a Tetroon) broke free and floated free in the skies above Albuquerque, prompting local residents and a news-team to call the United States Air Force and the Federal Aviation Administration. KOAT-7 (ABC) came by to interview the creator, and put the story on the 5pm and 10pm news on 18 January.
Gonner’s Tetroon project was inspired by a seeing a black tetroon flying through the New Mexico skies back in the mid-seventies. He constructed it as a thin-plastic shell in a tetrahedron configuration (a shape made from four triangles), and the lift is provided by solar heating of the air inside the balloon.
His two previous balloon-constructions proved to be too heavy and/or too small to fly, and even this envelope had its problems. Previous attempts to inflate and fly the balloon had only managed a flying-height of about 14 feet, and a lot of that was lift caused by the wind. This attempt was to see if he could get continuous lift if he started with colder ambient air. Side note: this is why most conventional propane driven hot-air balloons launch in the very early morning, to take advantage of the cold air. The last few tests indicates that solar does not work as well in the very early morning, so the test didn’t start in earnest until about 11:30am.
This design was roughly 20′ on a side, with a clear plastic top to allow for both side wall heating and greenhouse style heating. It was made with very thin 5mil plastic sheeting and a sewing machine.
The plan was to reel it up with a GPS-enabled cell phone attached which would function as a sensor package to determine altitude and to take photos from the air. Unfortunately, the tetroon jumped the leash and got away. The attached GPS stopped responding about an hour later as the balloon had headed off out of town, so recovery is not expected. The payload phone does have a card with our name and address on it, so if you find the Tetroon, please get in touch! Talking with the maker, he is going to be more careful with any future tests, as this was more of an adventure that had been planned.