Dropping A Glider From 18,000 Feet

[Tarik and Kemal] have an objective in mind: to drop a home-made autonomous glider from a high-altitude balloon and safely return it to home. To motivate them, [Tarik] has decided not to cut his hair until they reach 18,000 feet. Given the ambition of their project, it isn’t surprising that his hair is getting rather long now.

While he grows increasingly hirsute, [Tarik] is working on the project from several angles, creating a device that will drop the 2.2 meters (7.2 feet) wide glider from the ballon using fishing line and nichrome wire. When the device reaches altitude, the nichrome wire is activated and heats up, melting the fishing line and dropping the glider. He has been testing this using a quadcopter at low altitude, with mixed results: often the glider falls in a nose-down profile, rushing into the ground at high speed. That might be less of an issue when they reach 18,000 feet, but from a quadcopter at 90 feet, it’s a problem.

[Tarik and Kemal] are taking a very honest and open approach to the project, documenting their missteps and failures in as much detail as their successes. That’s a commendable attitude, and they have made a lot of progress so far, creating a system that drops the glider in a more stable attitude and successfully landing several times.

Next, they want to start planning for a higher altitude launch, which means they need to look at controlled airspace and getting FAA permission to fly. So, they are looking for a partner who has a spaceport or something similar that they might be able to use. Does anybody want to help them out?

37 thoughts on “Dropping A Glider From 18,000 Feet

  1. They might want to contact TheRegister. Unfortunately the head boffin Lester Haines (RIP) has passed away, but they had a team working on releasing a rocket powered glider from high altitude, and had contacts at SpacePort America to do the actual launch there. The biggest hangup they had however was getting a permit from the FAA to launch something semi autonomous with the required size rocket motor from a balloon at high altitude over the USA.

    The whole saga can be found here: https://www.theregister.co.uk/Tag/lohan

    Also see their earlier PARIS project (Paper Airplane Release Into Space, yes they like backcronyms): https://www.theregister.co.uk/Tag/paris

  2. with a project like this you need to NOT drop it nose first

    at any altitude it will not work

    you need to drop it at just below horizontal

    don’t ask details of my reasoning, I live in Australia, there is no “statute of limits” on anything here

    this is where a gyrocopter would be a better choice

    a gyrocopter can glide, very well

  3. In 2014 there was a project “Stratocaching” here. The video is in Czech only but even just watching is worth:
    https://www.youtube.com/watch?v=s-rl8q9jezU

    It consisted of Dropion base on a stratospheric baloon which in some altitude released bunch of small light gliders with some electronics, construction inspired by maple winged seeds. The advantage was that no matter how you drop that object it always begins to rotate / glide so there is never free fall (and danger for people). Still needed a lot of permissions.

    they have many photos here:
    https://laborky.gymnaziumslany.cz/index.php/pocteni1menu/202-stratocaching-2014-ridici-stredisko-letu-laborky-cz

  4. Would make sense to add a parachute to control and orient the descent until you are at a safe altitude. Then do another hotwire release and glide back to base. The aerodynamics at 18,000 ft will make gliding difficult if it is not already factored into the design of the aircraft.

    1. The only difference between sea level and 18000 feet is that the air density at 18K is half of sea level. Lift and drag go up as the square of airspeed, so a glider will glide at a true airspeed about 1.4 times as fast as at sea level, but the glide ratio (which is determined by the lift/drag ratio, or L/D) will stay the same. When the glider is dropped, it will have to free fall a little longer to reach to reach the higher true airspeed that corresponds to whatever indicated airspeed it’s trimmed to fly at.

      When you start getting into the high 20Ks and above the true airspeed starts getting high enough that you may begin to experience mach effects and need to design accordingly.

      1. Yeah this is right, the 18k aircraft will be more stiff than this. The problem comes when we drop at 100k and there’s barely any air pressure to go around. We haven’t done the math for this at all yet and were hoping to get some HILSim testing in XPlane before finalizing anything for that alt.

        Also have no idea if the arduplane code will get confused by drop of pressure in that alt. But baby steps, we’ll worry about that when we get there.

  5. Bunch of places on the West Coast where you could do this, Mojave, Ridgecrest, black rock….. @18k ft, the stall speed is above the ailerons flutter speed so this won’t go well.

  6. How many feet keeps a man upright?
    Two.

    It disturbes me that you just can’t adapt to the rest of the world’s metric system.

    It must be easier using base 10 than divide inches?

    1. Sorry to disturb you, but there is nothing inherently superior about the metric system. But it sounds like your main objection is the use of fractions, rather than decimal arithmetic. Just tell me, honestly: in your metric purity, have you never referred to a half-liter bottle of anything? Do you really prefer saying “five hundred milliliters” to “half a liter”??

      1. As an American living and working abroad, i understand both camps.
        But the problem with fractions is that there is only a limited number of them anyone can rapidly calculate in your head. Sure half a liter is easy. 1/4 isnt that bad. But the difficulty compounds quickly. The fact that you have to calculate at all is a problem. And with a limited number of fractions for any given base measure which results in a whole number its difficult to be specific. Compound all of those problems by the fact that imperial is made up of a variety of bases and it becomes messy and time consuming rather quickly. A common base 10 system for EVERYTHING is simple. Fast. Easy to be precise. Fractions and all the baggage that comes with them is not needed.
        “1100 meters” or “1202 yards, 2 feet, 11 inches, and somewhere between 5/64th and 3/32ndth of an inch”
        Which is easier to say? Which is more precise? Those are the same distances. It took 4 different google searches to do the conversion without remembering the math from school. And several minutes of my time.
        “Half a liter” is only precise for 500 ml. You cant call 499 or 501 ml “half a liter” so what is the fraction for those? All you can easily say without a calculator is “about half”
        Fractions have forced much of Imperial engineering to stick to common rule of thumb measures that divide out nicely and play well with other scales in the system when precision is required and encouraging approximation wherever possible. In the 1100 meter example, someone might have chosen 1200 yards because its an easy number to workbwith even if it was not the ideal value for the project.
        To get anywhere with precision, machinists have to work in thousandsth of an inch, and then they call it mils(?) Sounds like a work around to “metricize” an impractical system.

        1. My point was that janostman was complaining about backwards American units, but he was really complaining about fractions. AT NO POINT IN MY LONG CAREER in electronics have I seen fractions of an inch used for anything smaller than 1/8″ multiples. No machinist works in 1/128ths of an inch, even if she is working in inches, and no PCB layout tools I’ve encountered showed my hole placements in powers-of-two fractions of an inch. I think we all came to the consensus EONS ago, that 43/64″ is a ridiculous thing.

          And while, yes, we do use inches for small and tiny things, we do tend to switch to feet for anything we’re going to be marking with chalk and cutting with an axe, and miles for things where we really couldn’t care less about a few feet. But tell me something: why don’t I hear any righteous indignation against astronomers around the world, who use units that are by no means powers of 10 of any S.I. units? Quick! How far is an A.U., in meters?

          I am actually a true believer when it comes to metric, but you know what? If I’m going to have to build something out of lumber, I really have to consider what sizes I can BUY. And I HAVE designed wooden things in mm, knowing I would be buying metric plywood, for example. But so much “imperial units” ranting is just completely without thought, and THAT disturbs ME.

        2. And by the way, you’re wrong about “half a liter” being not correct for 499 or 501 ml. It is common practice, when tolerance is not specified, for the number of significant (i.e., non-zero) digits to be a guide for the precision of a measurement, so saying “500 ml” can very well mean anywhere from 490 to 510 ml. This isn’t a metric thing, either.

        3. “Fractions have forced much of Imperial engineering to stick to common rule of thumb measures that divide out nicely and play well with other scales in the system”

          Says somebody who has clearly never seen wire or sheet metal gauges.

      1. “the design of the aircraft was in metric.” Are you sure about that? I mean, if a piece of sheet metal was specified as 0.8 mm, did that really mean 0.8 mm, or did it really mean 1/32″, which is 0.794 mm? I see electronic components all the time with lead spacings of 1.27 mm. Why would anyone design something with leads 1.27 mm apart? Is it at all possible that what they really meant was .05″, but they weren’t allowed to use inches?

        People design around what they can get, and if the customer requires metric, they’ll convert whatever they can get into metric.

        1. You know what, I’m not sure. Let me ask myself if I did mean to design and build the aircraft in metric or not.

          In all seriousness, that’s why I don’t like to take the metric/imperial debate too seriously because of living in the US. Every company has their own practices, while most of aerospace is imperial, some swear up and down on metric. It is what it is, but going from Imperial to metric is always easier than going from metric to imperial.

          I’ve found imperial is good for day to day measurements though. Especially the Fahrenheit scale, 0 is too cold to be comfortable, 100 is too hot to be comfortable. Celsius, 0 is too cold, 100 is too non inhabitable.

    2. 10 is commensurate with 2 and 5. 12 is commensurate with 2, 3, 4, and 6 and is much better for rational arithmetic – which is perfect. Besides, the inch is defined as exactly 2.54cm and I have a calculator. Would you want an oscilloscope with display gain of 1, 10, 100…? Why is 1, 2, 5, 10, 20, 50… so common?

      1. 1,2,5,10,20,50 is a common sequence on things like oscilloscopes because it is a logarithmic scale, not a linear scale. Much more useful over a wide range of possible values.

    3. Aviation tends to do things in feet even in otherwise metric places. It turns out that 1,000 feet is a nice amount of vertical distance to have between planes which happens to also be a nice number of feet. (also probably has something to do with aviation being slow to change and having a big influence from the US). Net result using feet for altitudes to describe a aviation related project seems rather applicable.

      1. hate to burst your bubble, but the internal system of the lunar lander computer was not in inches, feet and miles, only the displayed values were converted to them…

  7. It reminds me of a project much like this about 20 years ago. Some guy in Europe set up a glider. His main development was to record horizontal windspeeds as the balloon rose so that the return path could be better calculated. He had one flight where the drop caused a stall and the airplane autopilot kept the plane on course, but inverted, producing a poor glide angle.

    He had one camera that sent photos back in lo-res. His last flight photo was the plane not clearing a mountain top.

    I think the balloon was reaching 50k feet or higher before release.

  8. How about a small model rocket engine to kick the glider horizontal at release so it will definitely be flying flat instead of nosing down and taking a long time to recover?

  9. protip: either place the mic and plop shield more or less in frame. More so it covers the face completely, less so it is not the major thing in the frame. I’ts not cool to have a huge mic in frame, It only tells “Look, I’ve got a Big mike!!”. like its a f*ing penis or something.
    Movies have opted to place them out of frame completely and nobody ever complained about that.

    And to be on topic again, I like the way to use nichrome wire to melt plastic. the less movable parts you use, the better in that environment

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