![[Avery] standing inside the inflating envelope of his airship](https://hackaday.com/wp-content/uploads/2026/10/thermal-airship2.jpg?w=800)
We’ve had a lot of flying hacks here over the years, and that includes just about any way to get airborne you can think of — but very few of those have been airships. Fewer still have been 27-foot thermal airships, like the one [Avery Flies] designed and put together recently.
A thermal airship, in case the name doesn’t give it away, is a dirigible hot air balloon. Like a hot air balloon, it gets its lift from the density difference between hot air and the regular atmosphere. Unlike a hot air balloon, it has control surfaces and an engine so it goes where you tell it to. The craft uses good-old-fashioned radio control, and except for the nylon envelope he spends the first 15 minutes of the video below designing and sewing up, the technology mostly comes from be from the world of R/C aircraft.
The big exception is of course the a propane burner used to generate heat, said propane being supplied by a pair of small green tanks such as you might use on a portable barbecue. Everything that moves is electric, though: there’s a 70 mm (about 2¾“) electric ducted fan acting to push the air up into the balloon so it keeps shape, and a great big brushless DC motor pushing an 18” (about 457 mm) prop for thrust. The steering servo is actually a repurposed winch servo from an R/C sailboat, rather than anything from the world of model aircraft. But it makes sense, as the meter-scale fabric rudder is more like a sail than the control surfaces of most R/C aircraft.
You might expect a blimp to be the biggest flying machine we’ve featured on Hackaday, but some truly giant-scale R/C aircraft have come our way in the past. We’ve also seen some pretty teeny blimps.
The title of this one reminds me of the time that my wife and I were at a concert. It was crowded and my wife had her vape in the requisite clear plastic purse. The crowd had pushed in enough to hit the button and her purse was full of smoke. The girl behind us tapped her on the shoulder and asked “Excuse me, is your purse supposed to be on fire?”
They’re still friends
Did it become an impromptu airship and fly away
A smoke screen might be just what is needed to hide when spotted be a camera during a concert with ones extra-marital affair.
The title of this one reminds me of the time that my wife and I were at a concert. It was crowded and my wife had her vape in the requisite clear plastic purse. The crowd had pushed in enough to hit the button and her purse was full of smoke. The girl behind us tapped her on the shoulder and asked “Excuse me, is your purse supposed to be on fire?”
They’re still friends
This reminds me of Dan Nachbar’s personal hot air zeppelin project http://www.personalblimp.com/ — that was a project that captured my imagination for many years before I decided that it was ridiculous to consider such a pursuit for myself (and also I became a dad).
Site not found, unfortunately.
I actually pulled some inspiration from that, namely the bulbous shape. Knowing it didn’t need to be slick to work was a big relief.
Does the “250 gram max weight of an unlicensed drone” rule apply to something like this?
Not if it’s tethered
Can you bypass the rule with lighter than air gasses? For example will a several kilo heavy, but filled with helium to weigh -1kg blimp be legal?
They must’ve thought of that right? I guess dry weight only then?
“I guess dry weight only then?”
Just put your helium through a gas dryer then! There’s a loophole for every rule! 😜
It absolutely does, just because it is buoyant does not mean it does not have to abide by FAA rules. They also list weight requirements for ultralight balloons in FAR 103, which is 154 lbs, despite the balloon being lighter than air while flying. Pandora carries an FAA registration number and AMA number on the gondola.
What’s neat is that no one actually cares about drone laws unless you’re doing something really dumb.
Go fly a 200lb craft and people (cops included) will just watch and say “oooh that’s a big one”. Ask me how I know.
Drone certification is like getting those online religious certifications to marry your best friends or registering firearms. Pointless beurocracy to make idiots sleep better.
Thanks for the kind words! This was a fun project and it’s a real trip seeing it posted on Hackaday. More blimp projects in the works :)
“The steering servo is actually a repurposed winch servo from an R/C sailboat, rather than anything from the world of model aircraft. But it makes sense, as the meter-scale fabric rudder is more like a sail than the control surfaces of most R/C aircraft.”
Reading ‘Slide Rule’ by Nevil Shute (his autobiography that includes working on the British R100 airship) he describes how the competing R101 used a large servo to control the rudder, but the R100 found that it was easily controlled with unassisted manual steering gear.