Personal Aerial Vehicle (PAV) to take your commute into the third dimension

Discussion in 'Aircraft Design / Aerodynamics / New Technology' started by Kingfisher, Aug 4, 2016.

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  1. Aug 4, 2016 #1

    Kingfisher

    Kingfisher

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    Since it has now been proven by Volocopter and perhaps Ehang that it is feasible to carry a human with an electric multirotor, here is my stab at the topic. Please feel free to comment and criticize to your hearts content.

    The PAV was modelled in Solidworks.
    I want to experiment with the wings freely pivoting during hover and transitioning to forward flight. Since a multicopter is capable of considerable forward speed even with the rotors still facing up, the wings could be allowed to align themselves with the relative airflow. This way they won't interfere with the control effect of the motors, whose varying thrust controls motion around and along all three axes during hover. Once the wings reach their end-stops on the fuselage during fast forward flight, they then start to generate lift. The rotors tilt forward, and once they reach their fully horizontal position, the motor nacelles interlock with the wings. Pivoting the motors slightly will then move the wings as well, and control inputs should have the same effect as the controls on a canard airplane, plus the effect of vectored thrust on each wingtip. The manoeuvrability of such a machine should be quite incredible, given the need for enough thrust to exceed the weight of the whole aircraft.
    In addition, there will be a motor to drive the rear wheel and everything folds up into the parking space of a car. I can’t wait to try it…
     

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  2. Aug 4, 2016 #2

    Victor Bravo

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    Oy Gevalt...

    I'm inventing a new internet shorthand abbreviation, specifically for HBA on this kind of topic: HWGA, for "here we go again" :)

    All kidding aside, that configuration looks a lot less hopeless than most others. IMHO, keep studying this configuration, solving the problems, refining it, etc.
     
  3. Aug 4, 2016 #3

    henryk

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  4. Aug 4, 2016 #4

    bmcj

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    Cool, but for pivot-wing craft like these, I still wonder how you hold the fuselage level as you rotate the wings upward from forward flight without ending up flying through the air like this:

    image.jpeg

    :gig:
     
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  5. Aug 5, 2016 #5

    Aerowerx

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    Didn't the Marines try something like this?

    I remember about 15 or so years ago some guy in California was working on an aero car that used 4 ducted fans. It got at least as far as tethered flights, but I haven't heard anything about it since. It was all computer controlled for the "ordinary" person--- no pilots license needed.
     
  6. Aug 5, 2016 #6

    Topaz

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    My thoughts exactly. A very long way from being a "design" (right now, it's artwork), but at least with a lot of work, this one seems like it might have a ghost of a chance. Some of the HWGA we get is... "interesting" to say the least.
     
  7. Aug 5, 2016 #7

    Jon Ferguson

    Jon Ferguson

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    If you are going to have two wings that fold why reinvent the wheel, just put your little motors on a flying flea...
     
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  8. Aug 5, 2016 #8

    Riggerrob

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    Every sketch gets us closer to a viable flying car/road able airplane. Quad rotors look like the best approach today, considering how much software has advanced recently.
    Speaking of software, that is what keeps the fuselage level as you transition from vertical to horizontal flight.

    Once in horizontal flight, you can probably shut down two engines because most planes only need half power for cruise. Alternately, you could idle two engines, slow enough to reduce power drain, but still fast enough not to create drag.
     
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  9. Aug 5, 2016 #9

    Dan Thomas

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    Not Moller, maybe? more than 40 years and $100 million spent so far? Lots of lost investor cash.

    But I think that electric motors and advanced battery technology might eventually make it possible. Maybe not practical. Moller had to use a bunch of gas-guzzling Mazda rotaries to drive his fans, and even all that horsepower (something like 800 HP?) didn't lift it too well. Small fans or rotors aren't too efficient.

    Model airplanes fly well on electric power or tiny gasoline engines. But when you multiply the size of the aircraft, its weight goes up by the cube (I think) while its wing or rotor area only goes up by the square. So toy drones fly, but man-carrying machines have a lot harder time of it.
     
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  10. Aug 5, 2016 #10

    StarJar

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    Free wing/s + rotor/s is a tremendous possibility IMO. Think it all the way through folks.
    Adding a free wing or two, to a helicopter or quad is a harmonious combination.
    I'm taking note of all the nay sayers who I think will eat their words in the next few years. ;-) (I been fantasizing about a related concept for a few years now.)
    Remember; the free wing will automatically compensate for rotor downwash and flight path (simultaneously).
    Dan's point is true, however it can work in the concept's favor when you need less continuous power; just short bursts of high power for verticle TO's and landings.
    To address bmcj's question, I believe the tilt would be controlled by the rotors just the same as on a conventional quad.
     
    Last edited: Aug 5, 2016
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  11. Aug 5, 2016 #11

    Victor Bravo

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    :) :) :)

    Then there will have to be a whole lot of engineering and aero calculations to ensure that the "Free Wing" will do what you are saying, and yet can still provide some usable lift instead of just being an expensive weathervane.
     
  12. Aug 5, 2016 #12

    StarJar

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    Hey, sorry. I deleted the calcified crack. That's called 'violent communication" and I'm trying to stop that.
    BUT I think you just need ballpark calculations, at first. Everything would be copesettic if you had power for vertical manuevers, I think.
    There's a lot of other possibilities though. Such as linking all the surfaces to allow controlled forward flight, in case of power loss. You'd need a tail though, and some weird TO and landing safety habits. A TO run to stall speed may be the prefferef takeoff when avsilabe.
    BUT put a free wing on a conventional helicopter, and you could gain some serious range advantages I think.
     
  13. Aug 5, 2016 #13

    Victor Bravo

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    Oh no, the calcified crack is completely appropriate.

    Absolutely necessary to keep some of our "creatures of habit" dinosaur brains in motion.

    Put the calcified crack back in, and keep it there.

    And while you're at it keep a fire lit under my arse at all times. There needs to be something to offset the inertia and complacency of saying "this is the way it's done, pay attention children". As often as I like to think I'm the innovative and outside the box guy, it's also equally as often as I tend to behave like I've learned everything there is to learn and it's up to me to put it on stone tablets :)

    Can't speak for anyone else....
     
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  14. Aug 5, 2016 #14

    StarJar

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    You da' man VB, seriously.
     
  15. Aug 7, 2016 #15

    Kingfisher

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    What's "calcified crack?" I think I get the idea..
    Agree, basic calculations need to be to size the motors and propellers and ESC for enough thrust for vertical take off, everything else will be experimental. Volocopter guys made a very good and self-critical presentation. Unfortunately it's in German, otherwise I would post it. Some parts are quite funny if one understands engineering sense of humour. The guy goes something like "we put in lots of redundancy, and all the mechanical complexity of a helicopter is now in the software, but if the whole battery fries, well, that...that's bad."
     
  16. Aug 7, 2016 #16

    Kingfisher

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    Agree, the wings may need damping to prevent flutter, or it may be just a question of where their pivot point is. At the least, one would think they'd reduce drag over a "pure" multirotor, which usually has some sort of tubular beams or other structure that supports the motors. For fast forward flight, the rotors may still point up to some degree, to assist the wing in lifting. Obviously, the wings as I drew it would be too small to sustain any reasonable approach speed for a safe gliding landing. However I think for cruising it should be beneficial to have them. In case of full or partial loss of power, I'm thinking the BRS system should be a steerable parachute, and two handles would simply drop from the ceiling, and the whole vehicle would turn into a paramotor.
     
  17. Nov 21, 2016 #17

    Derswede

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    image.jpg Want a flying car? Here ya go!
    Comes with a trailer for the wings. The guy at the museum said that it had been flown as well. I will stick to my Triumph and no wings for ground transport.

    Derswede
     
  18. Nov 22, 2016 #18

    Victor Bravo

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    PAV commuter?

    Been there, done that 50 years ago, it works: https://en.wikipedia.org/wiki/Canadair_CL-84

    It works: "Despite the fact that the CL-84 was very successful in the experimental and operational trials carried out between 1972 and 1974, no production contracts resulted."

    It works: "There were two main reasons for the technical success of the CL-84 design. Aerodynamic considerations were given a very high priority, and the controlling of power was kept as simple and direct as possible. The propeller disks extended slightly beyond the wingtips, so the whole of the wing (except for the portion above the fuselage) was immersed in the propeller slipstream. This, together with full-span leading edge and trailing edge flaps which were programmed with wing tilt angle, ensured that the wing was never stalled. Trim changes were minimized by programmed tilting of the tailplane. All programming was based on extensive testing in the wind tunnel and on an outdoor mobile test rig. The power of both engines was controlled by a single "power lever" in all flight regimes. To provide crisp thrust control during hover, movement of the power lever caused a direct adjustment of blade angle, analogous to the collective pitch control of a helicopter, with the propeller cpu governor making a follow-up adjustment of blade angle to maintain the selected rpm. The direct adjustment of blade angle was faded out automatically as the blade angle increased with increasing forward speed."

    It works: "The CL-84-1 performed flawlessly, demonstrating versatility in a wide range of onboard roles, including troop deployment, radar surveillance and anti-submarine warfare. It could perform wing transition from zero airspeed and accelerate to 100 knots in 8 seconds."

    It works: "In the face of gale storm conditions, the "84" performed magnificently in tasks such as ferrying troops and "blind-flight." Phase 3 and 4 trials proceeded immediately after, but, despite rave reviews from over 40 pilots, the CL-84-1 did not land any production contracts."

    Now... take that well proven and demonstrated viable aircraft configuration and control model, and use modern electric motors to eliminate the majority of power system complexity. One main configuration and control computer (with two backup systems) should be able to manage all of the previously complicated mechanical control linkages, mixers, and modulated hydraulic systems. Today these computers would be the size of an iPad.

    Make it smaller and lighter than the military prototype, use modern materials where advantageous.

    Having a more efficient forward flight mode will extend the range and speed of the "cruise" portion of your commute far better than a PAV helicopter or lift-fan-only design. The Canadair prototype was a 300 MPH aircraft; scaling back the cruise speed requirement to 125 MPH would permit large reductions in required power, battery and structure weight, complexity, etc.

    Making a thicker, slightly larger, and higher lift wing (taking advantage of the reduced speed requirement) will also create the ability to have some amount of power-off glide. Not great by any means, but a lot better than some of the tinfoil hat ideas. Using the computers to their best advantage, and using a rapid wing tilt emergency mode, in a total power failure you might be able to glide fast and steeply downwards, putting energy into the rotor/propellers, tilt the wing upwards at the bottom of the glide, and use the kinetic energy in the rotor/propellers to have five or eight seconds of vertical landing capability just like the last few seconds of a helo autorotation.

    OK, let me have it with both barrels... flame away :)
     
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  19. Nov 22, 2016 #19

    bmcj

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    And it does an excellent knife-edge maneuver.
     
  20. Nov 22, 2016 #20

    BBerson

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    Tilt props need more power than helicopters. And electric hasn't worked for helicopters.
    The Sikorsky electric helicopter I saw at Oshkosh was cancelled without a test flight.
     

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