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First eVTOL flight in US

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First eVTOL flight in US

Old 31st Jul 2021, 15:52
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First eVTOL flight in US

Volocopter demonstration flights at Oshkosh.

https://www.autoevolution.com/news/v...us-166268.html

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Old 31st Jul 2021, 16:35
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What happens in the event of a main power bus failure?
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Old 31st Jul 2021, 17:29
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Very clever, but is it any better than a traditional rotor driven by an electric motor and battery? I would have thought that the energy needed to keep the ship airborne would be the same, whether delivered through multiple rotors or just the one?
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Old 31st Jul 2021, 18:20
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This flew also:
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Old 31st Jul 2021, 18:51
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Originally Posted by MLH View Post
What happens in the event of a main power bus failure?
I would be remarkably similar to running out of fuel in a twin. Only I guess these things don't autorotate that well. (Correct me if I am wrong: they have fixed pitch rotor blades, and hence don't autorotate at all.)
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Old 31st Jul 2021, 18:59
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Originally Posted by old,not bold View Post
Very clever, but is it any better than a traditional rotor driven by an electric motor and battery? I would have thought that the energy needed to keep the ship airborne would be the same, whether delivered through multiple rotors or just the one?
I cannot answer your question regarding efficiency (other might be able to do so).

The key advantage of a multicopter is that the rotor system can use fix pitch propellers. So no need for any articulation. No collective pitch change, let alone cyclic pitch change.

Control about the roll and pitch axes are produced by differential variation of motor speeds across the propeller plane, while yaw control is via appropriate combinations of motor torques.
https://vtol.org/files/dmfile/08Evolo2.pdf

Presumably also no need to accommodate for lead, lag or dragging or hunting. That makes the whole system much less complex.
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Old 31st Jul 2021, 20:50
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I wonder if it does energy recovery in autorotation?
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Old 31st Jul 2021, 21:12
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Originally Posted by MLH View Post
What happens in the event of a main power bus failure?
  • Battery Energy can be distributed around the airframe and divided between the motors with no need for a main power bus.
  • Each motor can have sets of independent stator coils.
  • Each set of motor coils can have its own, independent Electronic Speed Controller
  • Redundant flight control computers can be provided
  • Vehicle can descend safely despite losing one or more motors.
Lack of redundancy is not a problem for multicopters.

Battery capacity, battery life and certification are problems for multicopters.

Electric passenger aircraft development is where fixed wing was 100 years ago, when all sorts of strange aircraft appeared in the sky with various numbers and configuration of wings and engines.

Similarly, there's no real consensus at the moment of what the final shape of an electric aircraft will turn out to be.

The controllability, stability and performance of the current crop of quadcopter drones, with just four moving parts, hints at what electric aircraft might be able to achieve.

It's interesting times.




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Old 31st Jul 2021, 22:40
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Visibility from the Blowfly in the hover isn't all that flash...
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Old 1st Aug 2021, 01:27
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Originally Posted by Ascend Charlie View Post
Visibility from the Blowfly in the hover isn't all that flash...
Seems like it would save you the expense of an inversion table for stretching out your back, though.
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Old 1st Aug 2021, 11:47
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Neither appear able to achieve any meaningful forward flight - they're just hovering or pretty much hover taxiing. Then drag of all that framework would cripple the Volocopter's ability to achieve, let alone sustain any significant speed, to say nothing of the form drag of the pod as the pitch angle increased to provide a thrust vector.
Will certification really be posible with no ability to glide (autorotate) in the case of total loss of power? To date I don't belive anything with zero engine-off flying capability is certificated.
Essentially both are simply very large drones from what we've seen here, and thus of very limited use and capability indeed. I can't see any innovative or new capabilities here, just size.
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Old 1st Aug 2021, 12:02
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Here's a flight of fantasy.

One wonders whether there are any "Osprey meets slide wing" designs knocking about and whether they are feasible.

Such a design might be able to accommodate VTOVL, STOVL, as well as normal aircraft flight characteristics and be able to reach a higher forward speed than a helicopter. And, in the event of power failure it might be able to glide.

A restricted movement slide wing like NASA's AD-1 comes to mind.

Wing mounted multiple small tiltable/swivelable motor nacelles, possibly ducted fan, possibly partially enclosed in the wing per flying wings - the top and bottom of the tiltable nacelles forming part of the wing surface to reduce drag on fast forward flight.

For take-off and landing, the "Slide wing" would rotate to 90 degrees to the fuselage and lock, the motor pods would be swivelled fore-aft and tilted upward, as required to achieve the correct degree of take-off/landing lift. Obviously this would change in transition to normal aircraft flight. In flight the "Slide wing" could be rotated so that one wing tip or the other was leading, with the engine pods swivelling on their mountings to maintain correct position to the direction of flight.

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Old 1st Aug 2021, 15:47
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Nairobiís, what you are describing very much sounds like the Lilium. Which has its own thread here in prune where it is being dissected.
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Old 1st Aug 2021, 23:11
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I think I counted 18 motors/props, some seemed contra rotating so I guess half of them contra rotate. Wonder how it flies if one prop or motor fails? I think some 8 rotor drones can fly with one failure.
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Old 2nd Aug 2021, 01:07
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Doesn't save anything on hangar space either.
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Old 2nd Aug 2021, 09:15
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Originally Posted by ChrisJ800 View Post
I think I counted 18 motors/props, some seemed contra rotating so I guess half of them contra rotate. Wonder how it flies if one prop or motor fails? I think some 8 rotor drones can fly with one failure.
There's a ring of 12 round the outside and an inner ring of 6.

Most likely configuration is that the motors spin -L-R-L- as you go round each ring which gives 9 motors in each spin direction and motor pairs on opposing sides of the ring have the same spin, giving an approximately balanced lift to the centre of gravity.

Yaw is achieved by providing more power to the motors spinning in the opposite direction to the desired yaw and reducing the power to the others so that lift is maintained but there is an unbalanced rotational torque.

If a motor fails the simplest algorithm to maintain control would be to spin down the opposite motor to maintain lateral stability and increase the torque on the 7 remaining motors spinning in their direction to maintain lift and yaw stability. A cleverer algorithm would probably be able to generate lift from all 17 remaining motors. You could help by asking any passengers to move the side of the cabin away from the failed motor .

Last edited by netstruggler; 2nd Aug 2021 at 09:18. Reason: Can't subtract 1 from 18 correctly
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Old 2nd Aug 2021, 10:00
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The Electric Robbo

https://cleantechnica.com/2019/01/26...rthest-flight/

https://electrek.co/2016/10/05/first...ed-helicopter/
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