Octocopter Will Someday Kill Someone

Above you can see Doctor Wily a Chinese hacker starting up one of the propellers on his octocopter. It seems that the man is using a collection of eight motorcycle engines, each with its own wooden propeller to create an eight-bladed helicopter. We were able to locate some video footage of his experiments, which you’ll find embedded after the break. As you can see, this is perfectly capable of flight, but we’re not quite sure if we’d call it controlled flight just yet.

The video starts off showing all kinds of hack-ity activities, like tightening the bolts on the propeller and priming the gas lines by sucking on them like a straw (mmmm….. high-octane!). Coke bottles serve as the gas tanks, and you’ll want to keep your hands inside the vehicle because there’s no cages to keep them out of the hand-started propellers. Although we don’t speak his language, we did understand the demonstration of the controls that the man gives, showing an earlier model with rings of fabric around four of the propellers meant to help direct the downward thrust as a steering mechanism. We don’t think this will be viable until there is some type of PID system that predicts the performance of each motor and makes quick adjustments to keep the craft balanced. None-the-less we were glued to the screen hoping that this turkey would fly.

[Thanks KillerBug via BoingBoing and DIY Drones]

104 thoughts on “Octocopter Will Someday Kill Someone

  1. Ordinary helicopters are NOT inherently stable. And for a device like this, the CG height is not that significant, because at slow airspeeds, the thrust is always aligned along the airframe’s down axis, even if that tilts with respect to gravity (unlike a balloon or parachute where the lift is always globally up.)

    Fixed pitch props mean it’ll be a near thing whether they can vary their thrust quickly enough – and also relying entirely on human control could be a limiting factor. The larger scale may help, though.

    That said, those spinning blades, with each engine and the cockpit all in plane, is scary! Also I’d keep the synthetic fabric away from the hot exhaust pipes.

    1. A real helicopter can be imagined as hanging by the rotors. If it’s tilted, gravity tends to pull it back level. This device, if it’s tilted due to a small imbalance in thrust, will move horizontally and the tilt will not correct without adjusting thrust, in fact the tilt will continue to increase. If it’s tilted beyond a certain point, it will very quickly flip over.

      The tethers and the way they are attached hide this. They also hide that he has no control over rotation, and 8 rotors all spinning counterclockwise will do the same as in a helicopter with no tail rotor, spin the vehicle the opposite direction. Reversing half the rotors would slow the spin he’d get on untethered flight, and spin would be controllable if you varied the speed of the left and right rotors as groups.

      A helicopter does require attention to 3 sets of controls, a stick that controls forward/back and left/right, pedals that control turning on it’s axis, and a lever like an automobile handbrake that controls height. This is why better than toy grade helicopter models need 4 channels of control.

      Real helicopters are made with mechanical controls, but the stick controls the tilt of a swash plate, the lever controls the height of the swash plate, and the pedals control the blade angle of the tail rotor. It’s doable with cable or hydraulic control. With 8 engines to control speed to try to balance a craft, electronics and faster than human responses to keep balance is going to be required, just as with newer planes like the B2 bomber, it is an inherently unstable design, computer adjustment of the diagonal control surfaces is the only way it can stay in the air.
      Look up how helicopters work, and also look up the B2 bomber’s controls.

  2. A real helicopter, if it has engine failure, autorotates, falling through the air the air moving past the blades forces them to turn, slowing it.

    One reason this octocopter has no central drive, no electronics to control, no real fuel tank to power it for more time, no seat, etc, is weight. It barely gets into the air with ground effect even with the blades starting just off the ground. Lifting the blades above the pilot’s head would reduce the ground effect, and make it that much harder to get as far off the ground as he has.

    For this to work, he needs a significant increase in thrust to weight, possibly a different kind of engine, turbine etc, lightweight blades, possibly as others have said variable pitch, a central engine might be best, but if you go to that, it would be easier to build something more recognizable as a helicopter. You can see in the video the difficulty of balancing the thrust of the engines, needs to be fly by wire system, with realtime tilt sensors and engine control, with quick enough response on the engines to recover from tilting. Then with this minimal frame, clean data from the tilt sensors would be hard.

  3. Didn’t anyone else see the fuel tanks he’s using:- old cola bottles with pipe shoved through the lids?

    Awesome, but I can’t help feeling that whatever the Chinese equivalent of the FAA is will be having strong words with him.

    Also, someone send him some lighter propellors.

  4. Kudos for him for pushing something past a paper design and building it, but eeesh, deathtrap.

    I’ve no experience with aircraft at all, but even I wouldn’t put 8 individual small engines (carb ones at that) on a craft like that.

    If I was considering something like that, I’d go for a four prop drive train design coupled to two engines. At least then if one engine fails, you should have one more powering everything (ideally each engine is powerful enough to lift the entire thing).

    Also, cages man. cages.

  5. i love that control box were you can see
    the meters are fake only the i think the kill button are have a real function the exhaust passes through a plastic cover smart idea but whit fast pitch rotor how do you control it

  6. I have to give him credit because there was lift but I think he knows the limitation of the craft or he would have taken off and he wouldn’t have shut it off. He may have high hopes but until he takes off, it is just for show.

    He didn’t fall out and he didn’t flip over so he hasn’t done anything dangerous yet so give him credit. He is getting his 3 minutes of fame so it is just for show as far as I’m concerned.

  7. What a riot – you have to love what people come up with given a little extra income in a country that spews every kind of component in the world – from zip ties to silicon wrap and scooter engines – out by the shipload on the cheap.

    That used to be us…

  8. While I give this guy full props for his “inventive spirit” as it were, am I the only one that sees this and thinks of the guy that attached a bunch of helium balloons to his lawn chair and ended up at 14,000 feet in LAX airspace ?

  9. Most of you are just complaining.

    How about you come up with something that this guy can use to make his project work?

    There would not be airplanes if wasn’t for people like him that keep trying.

    Same thing when the Wright Brothers have to deal with, people saying that is impossible just to give a crappy opinion.

  10. “imagine that frame collapsing in on it self and all blades rush in toward the operator. It would look like a seen from that movie hostel.”

    That is quite probable. He just needs a hard landing on the side to buckle the frame and send the props in his general direction.

    He must weld up a second tier of braces (spokes) to hopefully avoid certain death.

  11. Maybe its a idea to add servo control to the throttles and let a microcontroller with gyro control fly the thing. I think it’s to unstable to fly by hand. Time for a cheapo fly by wire system! :)

  12. The following will happen:
    Craft lands too hard,
    prop hits frame
    blade breaks off
    blade ziffs past pilot’s ear, shattering on wall
    pilot shits pants
    pilot goes back to playing with scale copters.

  13. Instead of having 8 engine with 1 prop each, why not have 4 engines with 2 variable pitch props on either side? that way, if one engine is going slower (or not at all) then it would still have a balanced thrust from either side, and with the help of the vpitch, control would be much more precise than varying throttle.

  14. Well, first off, I hope many of you don’t engineer as well as you spell. Grammar, shmammar, but spelling is actually kind of basic. Second. Put a person well above the CG, well above the CP, on an inherently unstable vehicle and someone is going to hurt. That’s why we ride motorcycles. And, as a couple of people have pointed out he has, at least, built something. Whether it is safe, or sage, is irrelevant. F-104 fighters, designed by the ‘best minds of the day’ had, as I recall, a well-earned nickname; Widowmaker. This guy has a middle-school education – meaning, judging by the signs of prosperity – that he can probably calculate the odds on dying.

    And, finally, to steal the punch-line from a 1970 (?) Playboy cartoon; “isn’t time you graduated from two strokes?”

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