Page 6 of 6 FirstFirst ... 456
Results 51 to 57 of 57

Thread: Experimental eVTOL innovation

  1. #51

    Join Date
    Oct 2011
    Location
    WA
    Posts
    1,084
    Excellent article, thanks.
    I was flying a small RC evtol today, almost exactly like that Clark "Ava" configuration in the article. The model was easy to fly and transition to forward flight.
    So I don't see how my previous RC helicopter or full scale helicopter flight time would help at all much. The automation is essentially keeping these things upright and stable. Unlike the piston helicopters I flew, that require the pilot do everything including constant engine/rotor rpm control. But this automation reliability scares me. I would want a pilot take over control capability.

    I hope he stops at Air Venture on his transamerica flight.
    For my experiments, it would need to be much, much smaller and lighter, cheaper.
    Last edited by Bill Berson; 09-18-2019 at 09:47 PM.

  2. #52

    Join Date
    Aug 2019
    Posts
    15
    Quote Originally Posted by Bill Berson View Post
    ...I was flying a small RC evtol today, almost exactly like that Clark "Ava" configuration in the article. The model was easy to fly and transition to forward flight.
    Do tell. Is this your design or is there an RC community that has come up with some concepts or plans?

    Quote Originally Posted by Bill Berson View Post
    ...this automation reliability scares me. I would want a pilot take over control capability.
    Makes sense, but I'm just not seeing how it would be possible. I think just taking comfort in knowing (and requiring) redundancy of all parts of the powertrain from sensor/controllers to power to motor is the best option.

    I've done some coding on these microprocessors like we see in RC quad copters, and self balancing robots (like segway, etc). They have to "think" way faster than the human mind, or human reaction time. That is pretty much required for proper balance here. It really isn't possible for human perception to step in and handle the stabilization control. I for one do not view this as "auto-pilot" or automating the pilots responsibility. The human mind needs to focus on other things (flying, maneuvers, situational awareness, etc) than merely stability that can be left wholly to a computer.

    Now as for fully autonomous piloting, navigation, maneuvers... I couldn't agree more, I would want a pilot on board! It will be a loooong time before I can accept fully autonomous flight, or driving.
    Last edited by dapug; 09-19-2019 at 09:01 AM.

  3. #53

    Join Date
    Oct 2011
    Location
    WA
    Posts
    1,084
    I was flying this thing yesterday https://m.youtube.com/watch?v=CGN3LcosLZ4
    My friend brought it to the RC field. He said it was $100 but can be found for $50.

    I like the idea of a fully flyable glider when all the powered lift systems fail for whatever reason. The problem is getting to and from that safe glide height.
    Last edited by Bill Berson; 09-19-2019 at 09:26 AM.

  4. #54

    Join Date
    Aug 2019
    Posts
    15
    Quote Originally Posted by Bill Berson View Post
    I like the idea of a fully flyable glider when all the powered lift systems fail for whatever reason. The problem is getting to and from that safe glide height.
    Exactly my thoughts!

  5. #55

    Join Date
    Nov 2011
    Location
    Edgewood, NM
    Posts
    4
    I have learned a lot from this thread, and I am "cautiously optimistic". But back to the intent of the Original Poster: can we get some sort of "preliminary approval" from FAA? Several posts, mostly from Joda, say "build it and see what happens". But it would be a shame to make the investment in time and money only to discover that we wouldn't be allowed to fly our aircraft. Several contributors, including Joe and Mel, are DAR's. If YOU were presented with an aircraft like originally described (I will describe my concept aircraft in more detail below, but wanted to get this question at the top of the post), as a DAR, would you feel compelled to include a requirement for Power Lift category rating in the Operating Limitations? Or is there some possibility of a work-around? Is it possible to put this question to the FAA, prior to actual building? (As DAR's, you are the FAA, sort of).

    As for my concept aircraft, I would hope to start with a proven airframe, probably ultralight in nature, such as a Quicksilver. I would like to begin with a kit, to allow airframe modifications as necessary, and to avoid any questions about the 51% rule. I would add lift-and-control motors to nose, tail, and each wingtip, with these motors providing about half the lift needed for hovering, and pitch, roll, and yaw control while hovering. I plan on 8 of these motors total, two at each location, with sufficient lift to provide single-motor failure hover capability. I would add 4 tilting "main" motors on an axis near the CG, close to the fuselage. These motors would provide the other half of the hovering lift, and all of the forward flight thrust. During forward flight, the lift-and-control motors would be deactivated, and the aircraft would be flown in standard three-axis control mode. In the event of a major failure, such as a total battery failure, the aircraft would be glided to a landing, the same as the reaction to an engine failure in a conventional single engine aircraft.

  6. #56
    EAA Staff Joda's Avatar
    Join Date
    Jul 2011
    Location
    Oshkosh, Wisconsin, United States
    Posts
    183
    Quote Originally Posted by Bruce_H View Post
    If YOU were presented with an aircraft like originally described (I will describe my concept aircraft in more detail below, but wanted to get this question at the top of the post), as a DAR, would you feel compelled to include a requirement for Power Lift category rating in the Operating Limitations? Or is there some possibility of a work-around? Is it possible to put this question to the FAA, prior to actual building? (As DAR's, you are the FAA, sort of).
    I thought I described the process before, but just in case.... I, as a DAR, would not be able to make any specific determinations on my own. I would present the application to my FAA advisor, and he would work it through the system. I would not feel "compelled" to recommend ANY particular pilot qualifications. I would open a dialog with my FAA office and we would work the application. In a unique situation such as you describe, I am confident that my FAA guy would in turn talk to his manager, and they in turn would forward the application up the chain to wherever it would need to go for a final determination.

    Unfortunately, this gets us back to the "chicken and egg" thing. That is, I could not make ANY request for determination on this issue UNTIL I had an airworthiness application in hand. Anything that would be discussed before an application was presented would be non-binding by all parties.

    In any case, your investment wouldn't be lost. The aircraft would ultimately be certificated. We just don't know what the pilot requirements would be at this time.

    Sorry I don't have better news, but that's the state of affairs as it stands.
    Cheers!

    Joe

  7. #57

    Join Date
    Jan 2018
    Posts
    1
    I've been working on VTOL homebuilts for over 20 years, and have expiring patents on one. The advances in cheap controls and much more powerful electric motors drive a lot of the new developments, of course. However, I think Eric Lindbergh and his crew working on hybrid aircraft understand the crux of the problem. I'm a chemical engineer, and worked a lot in electrochemistry and energy technology before retiring. The energy density of current battery technology is not too far from reaching its theoretical limit on voltage per cell, which is about 5 volts. Using lithium has reduced the coulombs per pound to a minimum, too. Power density should continue to improve, with state of the art $ 2 MM hypercars using 150 pound batteries the size of a sofa cushion which can put out nearly 2000 hp. But not for very long! So electric systems can produce the huge VTOL lift power to get off, but the range will always be very limited, particularly for the designs which don't use wings. So the most reasonable solutions, in my opinion, will use electric motors for a short time to assist with takeoff, and then depend on an efficient combination of wings and internal combustion engines for cruise flight. None of these electrics will be able to have a long loiter time under VTOL conditions.

    There are an enormous number of developing eVTOL designs out there, as could be seen in the Innovations Tent at Airventure this year. The Boeing GoFly contest has brought everybody out, although I think the 8' cube volume restriction will limit the viability of the winning design. There is also an awful lot of money being poured into these designs, at last count hundreds of millions of dollars, which range from outright crazy to what look like very workable designs. Reminds me of the early days of MS-DOS and PCs. All of these things will be coming out of the woodwork long before any of us could start something from scratch, based on how long it takes homebuilders to complete their airplanes! I'm as guilty as any, with me and my partners taking nearly a decade to get a RANS S6 flying. Of course, maybe some of them will consider the kit route...........

    Anyone who would like to read up on the theory of lithium batteries and their limitations, drop me a line and I'll send you a copy of the article, which can be found in the archives of Chemical Engineering Progress, the flagship publication of the American Institute of Chemical Engineers. You can reach me at jyrodyne@comcast.net.

    Charlie Churchman, P.E.

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •