VTOL On Demand Mobility

sferrin

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LowObservable said:
An autogyro is actually the least crazy solution for urban VTOL, with few noisemakers, a reasonably efficient cruise mode and inherent power-off vertical recovery.

But there's one big issue - rotor diameter. You're going to need a lot of take-off-and-landing space to handle the traffic volume that the system needs to function economically, let alone make a dent in urban congestion. (I don't think any conceivable system will actually do the latter.)

Also, note that the optimum cruise speed is in the conventional autogyro range, rather than being much faster as Carter originally planned.
And they either need a runway or motor/tip-jets to run up the rotor.
 

AeroFranz

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Some kitplanes have hydraulic motors. I suspect the high inertia rotors require quite a bit of torque to spin up.
 

mboeller

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another interesting eVTOL Aircraft with fixed wing economics:

https://www.pterodynamics.com/transwing/

 

yasotay

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Brings new meaning to the term "tilt-wing"
 

AeroFranz

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the wing hinge is going to be quite something.
 

Arjen

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It should be similar to the Grumman hinge:
Many laborious hours were spent over sketches and with models trying to figure out a way to twist the wings to a vertical position and then fold them back along the fuselage. Finally, Roy Grumman, a fine engineer, found the steps. He saw in all probability that the solution revolved around a pivot. So he took a soap eraser, such as those used in drafting, and used that to represent the fuselage of the plane. Then he took two paper clips for the wings and bent out the short end of each of the clips so that it was normal or perpendicular to the body of the clip. Then he began sticking these short ends into the eraser until he found the proper angle and position at which the clip, when twisted to a vertical position, would also fold back snugly against the eraser. Eureka! It was as simple as that. Once the principle of the “STO-Wing” (as it came to be called) was established, all that remained was some hard engineering work by Grumman’s fine team of engineers to make the mechanism strong and fail-safe.
The STO-Wing was applied to the Wildcat, the Hellcat and the TBF Avenger. The Grumman foldingwing is still in use today, notably on the larger carrier-based aircraft built by Grumman.
https://www.asme.org/wwwasmeorg/media/ResourceFiles/AboutASME/Who%20We%20Are/Engineering%20History/Landmarks/238-Grumman-Wildcat-Sto-Wing-Wing-folding-Mechanism.pdf
Award found here:
http://heroicrelics.org/info/grumman-paperclip/paperclip.html
 

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Jemiba

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Came to my mind, too, but I think, that relatively few Grumman aircraft ever folded
their wings back in flight .... B)
 

Arjen

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Not intentionally ;D
 

harrier

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LowObservable said:
An autogyro is actually the least crazy solution for urban VTOL, with few noisemakers, a reasonably efficient cruise mode and inherent power-off vertical recovery.
Yes. I once gave a talk at RR Bristol. I asked if train or car was best to get there. They said the speaker last month flew himself in his own autogyro..... :-[
 

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Zootycoon

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With all the gyroscopic’s, airloads etc calculating the hinge loads & moments (both static and dynamic) will be fun, not impossible but extremely unforgiving.
 

galgot

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Video of the rc model with transitions e all, very cool.
https://www.youtube.com/watch?time_continue=85&v=YcXCCLrB7Ss
 

AeroFranz

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Indeed, many things that are "demonstrated" at the RC level do not scale up.
Even full scale vehicles can fly when carrying smaller amounts of batteries, and have very little range.
 

Foo Fighter

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In my humble opinion, pure battery electric vehicles are a blind alley. Developed on the back of a knee jerk reaction mostly by politicians and dreamers. Hydrogen and fuel cell tech would reduce the weight of battery components and provide a real solution for car, planes, anything. Why we continue to faff with pure battery tech I do not know. Question, how are we going to deal with recycling the number of batteries required for this failure to think in a joined up manner? Will we have to deal with environmental disasters like we potentially could with nuclear waste?
 

AeroFranz

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Rhetoric question - How long have hydrogen fuel cells existed for, and how many successful airplanes are flying them?
 

Machdiamond

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Foo Fighter said:
In my humble opinion, pure battery electric vehicles are a blind alley. Developed on the back of a knee jerk reaction mostly by politicians and dreamers. Hydrogen and fuel cell tech would reduce the weight of battery components and provide a real solution for car, planes, anything. Why we continue to faff with pure battery tech I do not know. Question, how are we going to deal with recycling the number of batteries required for this failure to think in a joined up manner? Will we have to deal with environmental disasters like we potentially could with nuclear waste?
(aero engineer working on battery powered airplanes here)

As far as cars are concerned, hydrogen is not a viable alternative to battery powered vehicles from practical, economical and environmental standpoints. I recommend you check this excellent documentary: https://youtu.be/f7MzFfuNOtY

Hydrogen cars are already dead (or as Trump would put it, they are a total disaster). You still see a few around because of politics and lobbies. Some groups of people really don't like the idea that you could refuel your car almost (comparatively) for free at home each night.

For airplanes, battery technology is not quite there yet except in some special cases - like VTOL on demand mobility (hey we are staying on topic!) and short range small aircraft such as trainers. While it is only a matter of a few more years before it gets to short haul regionals and freighters - it will be a very long time before it gets to medium to long haul carriers.

As aircraft fuel, Hydrogen has been promising and beaten to death for 30-40+ years and all engine and aircraft manufacturers have given up.

As far as recycling is concerned, you are misinformed. Well designed batteries such as those manufactured by Tesla are 100% recyclable and economically self sustaining due to the high cost of raw materials and due to the original design intent for recycling (unlike many recycling industries). They are also designed to last many years, unlike cellphone batteries.
 

Foo Fighter

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Thanks for that, always willing to find out what I am missing. Not an entirely balanced view but much food for thought. It is interesting to note that the orator suggests hydrogen may make sense for aircraft.
 

Zootycoon

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There’s a widely held belief that the automotive sector will push battery technology to the point that a high energy/power density becomes available.

But this belief is flawed.

The U.K. ATI battery technology road map (as presented at Warwick Uni in May) highlights the flaw. It shows a near term push for a lithium battery technology which will enable a 450-500 mile charge range for a car (base on the max expected while awake) and a six hour recharge time. Once achieved, the target becomes reduceing cost and the imperative will be moving away from lithium because there’s simply not enough of it. Presently the favourite for a lithium replacement is sodium which is inherently at a lower energy density, but greatly improved availablity and much lower cost.

Of course there maybe be a breakthrough but equally the high energy/power density battery but it could become the next cold fusion.

I too was recently involved in a full size electric twin seat TMG, and it’s very different doing the real thing compared to CGI and model aeroplanes;- just where did all that extra weight come from? the drag is much more than the vsaero predict, even “safe” battery chemistry suddenly have AD’s for random fires, just how do I protect the occupants from all that lithium in the event of a drama?

As to current batteries being ok for e-vtol? Wingless proposals, not a snowball in ....chance. Winged proposals;-well it’s strange I can only make the claimed performance match the best case weight/optimistic drag is to use a 2d range flight profile;- even a modest assumption for delta altitude during the profile burns the claimed performance to ash.

E-vtol jet with wings = highly loaded fans =megawatt motors/PE/battery power density in an exceptionally lightweight airframe = fraud.

And finally when I look at Uber’s specified day to day useage profile, with current battery C rating, the thing will need a brand new 100k$ battery every month...... like that’s going to be practical.
 
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