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Thread: Building of a manned copter with a gasoline engine.

  1. #21

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    The Curtis Wright Quadrotor crashed when a shaft broke, fortunately in hover. The outcome would be disaster at 50 feet.
    From my mini drone, I notice extreme vortex interactions that occur at near ground level. Much worse than a single rotor.
    The V-22 had some Vortex Ring State crashes. Almost all VTOL crashes are fatal.
    The power shafting might get extreme load variation. Would need expert design of shafting to understand torsional vibration.
    Last edited by Bill Berson; 03-09-2018 at 10:02 AM.

  2. #22
    rwanttaja's Avatar
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    Quote Originally Posted by DaleB View Post
    I don't think there would be time to deploy a parachute system if one (or more) rotors fail. The high CG and un-balanced vertical thrust will flip that thing over in a heartbeat. Just my opinion. You could use accelerometers to determine when to automatically deploy -- a risky approach, but in any case I doubt a 'chute would do a lot of good outside of one or two specific failure modes.
    I think an automated deployment system would work. Continuously monitor rates and power levels, and if a set of thresholds are exceeded, kill all power and fire the chute.

    Down low is going to be a bad part of the envelope, though. A conventional (Cirrus-like) ballistic chute wouldn't open fast enough to inflate until one gets several hundred feet high. Depending on the type of failure, in the interim, the aircraft may well get to a high deck angle.

    This basically needs the capability of a zero-zero ejection seat, which the Russian industries have done pretty well at. Explosive opening of the chute, rockets stabilize the body. It is going to run the price up quite a bit. May be some pushback from civil authorities regarding operating in urban areas...all the rockets and explosions might not be too good for the other cars in the Value Village parking lot.

    Finally, this system is going to require a lot of testing. As Dale says, you can operate it remotely easily enough, but I suspect you'll trash several very expensive vehicles by the time you get it right.

    Ron Wanttaja

  3. #23
    "...I don't think there would be time to deploy a parachute system if one (or more) rotors fail..."

    You are absolutely right! But my design is arranged so that the most likely failure is the loss of traction. The variant of asymmetric thrust is more likely when the blade is detached.
    But I will try to prevent this from happening.
    In the end, it's not an incredible task. Did someone often hear about the broken blade from the aircraft propeller?
    My propeller design is closer to the aircraft than to the helicopter. I do not have those hinges and dampers that are in the helicopter. My screw is practically an ordinary airplane. Only the step change drive is not through the hollow shaft, but outside. Like helicopter steering propeller.
    Reliable enough thing. Breakdowns are more common with long shafts or strikes about something.


    "...and the left front gearbox fails..."

    I have never described the design of the transmission.
    Therefore, I simply say (since the industrial design is not yet patented) - such a breakdown, which will lead to asymmetric draft - is almost unreal.

    "...load that sucker with sandbags instead of live bodies, and fly by remote control..."

    Of course! That's exactly what I'm going to do! :-) Suicidal tendencies are not in my nature! I love life! And I hope this is mutual!

    "...built to the same standards as Kamov..."

    Well ... Kamov started with this.

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    Do you see a big difference? :-)

    "...As Dale says, you can operate it remotely easily enough, but I suspect you'll trash several very expensive vehicles by the time you get it right..."

    I would not like that! With financing - and so it is not easy. That's why - I went to IndieGoGo!

    But seriously - I understand that there will be more problems and questions. Much will still appear during setup and setup. Then - during the tests.
    But not trying - you do not know! Is not it?
    In the end, the Wright brothers, Sikorski and others were in much worse conditions. We have experience of them and our new technologies.

    I understand that the greatest danger is asymmetric thrust. Therefore, in the design, I try to foresee this. It turned out or not - I can find out only by trying!


    Starting the campaign on IndieGoGo, I hoped that it would be interesting not only to me. But judging by the result on the Indies - everyone wants to give me only advice. And rudeness!
    But the support of the project - at least out of curiosity - "what will it do?" - NO!
    It's a pity!

  4. #24
    DaleB's Avatar
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    Quote Originally Posted by Ihor Nastashchuk View Post
    Therefore, I simply say (since the industrial design is not yet patented) - such a breakdown, which will lead to asymmetric draft - is almost unreal.
    OK... that just leaves me at a loss for words. "It can't break". Good luck with that, let us know how it turns out.
    Measure twice, cut once...
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    Flying an RV-12. I am building a Fisher Celebrity, slowly.

  5. #25
    rwanttaja's Avatar
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    Quote Originally Posted by Ihor Nastashchuk View Post
    In the end, it's not an incredible task. Did someone often hear about the broken blade from the aircraft propeller?
    The majority of aircraft propellers are solid pieces of metal or wood.

    Most of the remainder have a half-century or more of engineering history and operational experience.

    Even so, you occasionally hear of propellers breaking or shedding blades...even the ones that are solid wood or metal. It's a major event in a fixed-wing aircraft, but not necessarily catastrophic. The key is to shut down the engine quickly enough so that the vibration doesn't cause the engine to shake right off the airframe and ruin the balance of the airplane. If you can accomplish that, it's just a "normal" emergency landing. I knew a guy who added cables around his engine to hold it approximately in place if the prop broke.

    Of course, you rarely hear of helicopter rotors breaking...but, again, it does happen.

    With your design, loss of a blade will not only result in severe vibration but immediate, abrupt attitude excursions. As pilots, we would like to know what is being done to make such occurrences survivable.

    Ron Wanttaja

  6. #26
    I am constantly reminded of breakdowns.

    Let's figure it out.

    With the breakdown, which causes a drop in traction on all propellers - it is understandable. Decrease and landing or parachute.

    The failure causing asymmetric thrust can be of two types:

    - Drive failure to some propeller or propeller pitch changing mechanism.
    In this case, the reaction speed and the accuracy of modern electronics should be sufficient to maintain a stable position in the air.
    At least - such videos about flights of copters with variable pitch propellers give an opportunity to hope for it.
    The reaction time of the small copter is much smaller than that of the large copter. Nevertheless - the electronics are doing fine. (In the video - a small copter with variable pitch propellers).




    - Breakage of the blade and strong vibration from imbalance. In this case, the pilot of my copter will remain the same as the pilot of the helicopter, which broke the blade - to pray!
    But the pilot of my copter even has a small chance - a parachute. The helicopter pilot does not have this.

    But the helicopters are flying! And helicopters fly a lot of people!
    Last edited by Ihor Nastashchuk; 03-10-2018 at 01:18 AM.

  7. #27

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    You could get some comfort from a very large number of small props.
    Say 60 props. And have 6 separate autopilot controllers that are controlling 10 motors each.
    That would be super redundant. Sort of like the guy at Oshkosh that flew below 60 helium weather balloons.

    But 60 props driven by one engine isn't redundant. And heavy.

  8. #28

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    Parachutes are fine for one at altitude, but this thing just begs to be flown low and slow.

    I'd rather have a light roll bar and a four point harness, and if I had to chose between that or a parachute, still take the roll bar.

    I guess my hesitation with the whole variable pitch prop approach is that it adds a huge amount of cost to the end product.
    The opinions and statements of this poster are largely based on facts and portray a possible version of the actual events.

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