[Tom Stanton] Builds An Osprey

The V-22 Osprey is an aircraft like no other. The tiltrotor multirole military aircraft makes an impression wherever it goes; coincidentally, a flight of two of these beasts flew directly overhead yesterday and made a noise unlike anything we’ve ever heard before. It’s a complex aircraft that pushes the engineering envelope, so naturally [Tom Stanton] decided to build a flight-control accurate RC model of the Osprey for himself.

Sharp-eyed readers will no doubt note that [Tom] built an Osprey-like VTOL model recently to explore the basics of tiltrotor design. But his goal with this build is to go beyond the basics by replicating some of the control complexity of a full-scale Osprey, without breaking the bank. Instead of building or buying real swash plates to control the collective and cyclic pitch of the rotors, [Tom] used his “virtual swashplate” technique, which uses angled hinges and rapid changes in the angular momentum of the motors to achieve blade pitch control. The interesting part is that the same mechanism worked after adding a third blade to each rotor, to mimic the Osprey’s blades — we’d have thought this would throw the whole thing off balance. True, there were some resonance issues with the airframe, but [Tom] was able to overcome them and achieve something close to stable flight.

The video below is only the first part of his build series, but we suspect contains most of the interesting engineering bits. Still, we’re looking forward to seeing how the control mechanism evolves as the design process continues.

20 thoughts on “[Tom Stanton] Builds An Osprey

  1. It’s not quite accurate though – the V-22 has a central gearbox that connects the motors to each other:
    –The V-22’s two Rolls-Royce AE 1107C engines are connected by drive shafts to a common central gearbox so that one engine can power both proprotors if an engine failure occurs.[75] Either engine can power both proprotors through the wing driveshaft.[Wikipedia]–

    Lego (and copies) have this down, so maybe build a flying Lego version?

    1. At model scale that is way too complex to make, probably too delicate to really survive use and definitely rather heavy – this is a great looking method for getting a cheap and probably very durable functional flying V-22 model.

      I’m surprised the acceleration based rotor tilt works so well with 3 rotors, really very cool.

    2. “one engine can power both proprotors if an engine failure occurs”

      Sure… but that’s because it’s carrying humans. There is no need to implement human safety features when you don’t have any humans to keep safe.

    3. Lego _had_ a V-22 Osprey but the kit was cancelled after they received complaints about it and pulled the release because it was claimed every purchase of the Bell Boeing-licenced product helped finance arms companies.

    1. No. This isn’t nearly as maneuverable as quadcopters, needs two servos, and requires complex control software. Additionally, the virtual swashplate seems to be a high stress component which needs to be made of metal.

      1. I’m not so sure on that – yes the swashplate is high stress enough he has made some of it in metal, but if you mass produce a high performance part it becomes cheaper, that swash plate is much simpler and smaller than high power brushless motors as are the servo, so it aught to end up cheaper, probably much cheaper. Replacing two motors with a basic bracket therefor could end up being the optimal choice, as its cheap and still does the job as well/better overall.

        Being able to transition to a normal(ish) flight profile also brings major advantages to range, plane are just way way more efficient in flight than helicopter, but the hovering and VTOL capacity of a helicopter are obviously beneficial, this is rather close to the best of both worlds…

        On maneuverability, I see that as very debatable as even without the tilt rotor the virtual swashplate isn’t all that far from conventional multirotor performance – its not up to the aggressive acrobatic flying but its perfectly sufficient, and in one axis it effectively is a normal multirotor. So flying this like a multirotor would work well enough, but then add in the tilt and it opens up a world of possibilities for movements in axis the multirotor can’t do nearly as well. Advantages and disadvantages to both.

        1. Oh also the control software is likely the exact same software a multirotor needs to fly, just with some of the parameters changed. It might not be, but both have similar complexity running PID loops often enough to not fall out of the sky and obey user input…

      2. The software doesn’t sound too complex, at least no more complex than ordinary quadcopters. It also requires fewer motors so it can probably run for longer. Maneuverability is overrated for consumer drones that often just want cinematic photos and videos.

        The virtual swashplate doesn’t necessarily need to be made from metal. It could have just been poor quality control left a stress riser. An injection molded part would probably be fine.

    2. It would be interesting to compare some metrics between this and a conventional drone of same size. I’m particularly thinking about the battery life, not maneuverability, since cine style video is possibly one of the most important functions of a drone.

  2. I wanna try something like a Rotodyne or a Gyrodyne for my VTOL but doesn’t burn a rainforest in cruise, type aircraft. Don’t know what would make a good fright controller for that though. (Yeah you read that right, it’s avionics that control how much the handling scares the pilot)

    1. Hmm intresting thought, and really I think depends on how you intend to control it – if its still going to have a swash plate (which some but not all of those type of machines do) then normal ‘fright’ controller for a helicopter aught to be just fine at take-off hover type stuff exactly as is, and will probably handle the normal flight mode too, as you don’t really need anything unusual for a heli but a throttle control for forwards…

      If its going to be entirely conventional aircraft control surfaces I doubt you even need a fright controller, the nature of auto-gyration seems to me self stabilizing enough you shouldn’t really need help, and even if you do the control surfaces are likely not experiencing enough airflow to bail you out, as the things tend to be rather slow…

      I’ve always wanted to try a tip driven rotor takeoff (and perhaps hover and landing) model, ever since I first saw one of those tiny CO2 canister. But as I’ve yet to actually even try to fly the last model aircraft and its been years sitting in a box on my wardrobe now… Leading me to wonder if my transmitter still works even, its been a while since I needed it for anything… it really should, but years of sitting around who can tell, may need some remedial work.

      1. I think basic STOL autogyros have even been flown on single channel one button gear, rudder only. Bit trickier if you wanna feed power to rotor and have some control authority at below the stall speeds of the rudder/elevators etc.

        1. Trickier yes, but not I think outside the realm of the normal fright controller now. The folk working on those have really created a seemingly almost idiot proof, very robust and customizable to the craft systems now, and a powered rotor with swashplate for control really is just a stock helicopter fright controller, with the one tweak to the settings so it doesn’t freak out and try damn hard to ‘help you’ fighting the forwards flying when operating like an autogyro – toggle the helper on and off in the software when you toggle on the power to the rotor…

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