Beta technologies Ava

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Andy_RR

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I am a doubly big fan(s) of the tiltrotor idea, a la V22, V280 et al, for the aerodynamic advantages it offers a potential eVTOL, although I do also recognize the presence of loads of single points of failure. I was surprised to discover the XV-3 from a Youtube feed video - quite remarkable and upbeat as it is. The Wikipedia page suggests it was not all trouble free with some vibration and aeroelastic coupling phenomenon on some of the earlier versions. Anyway, I thought I'd share.

https://www.youtube.com/watch?v=WL2SeFy2Czs
 

jedi

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Wait, you want ornithopters...? :whistle:
What if there was an uncommon or new way to combine thrust/lift with small diameter propellers and relatively large span wings in a STOL aircraft instead of relying on large tilting propellers or vertical thrusters in a VTOL. What if that system had sufficient thrust to do a vertical or near vertical climb.
 

Aesquire

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All in all, I like Victor Bravo's preference for jump Gyros, and I wish I could get plans & some of the proprietary parts for a Gyrhino.
 

Andy_RR

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What if there was an uncommon or new way to combine thrust/lift with small diameter propellers and relatively large span wings in a STOL aircraft instead of relying on large tilting propellers or vertical thrusters in a VTOL. What if that system had sufficient thrust to do a vertical or near vertical climb.
You are alluding to a Lillium-style system with a tilt-wing to augment the vertical lift? Similar to the channel-wing concept of Hopflyt? Where the flow induced over the top surface of the wing generates wing lift which, given it is tilted at a positive angle can generate a substantial vertical lift component and the horizontal component being cancelled by angling the powered lift vector?
 
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Andy_RR

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I used to think that the full flap applied by the Harrier on vertical operation was to minimize drag but I'm beginning to wonder how much lift thrust this actually generates...? Same on the V22 et al
 

jedi

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You are alluding to a Lillium-style system with a tilt-wing to augment the vertical lift? Similar to the channel-wing concept of Hopflyt? Where the flow induced over the top surface of the wing generates wing lift which, given it is tilted at a positive angle can generate a substantial vertical lift component and the horizontal component being cancelled by angling the powered lift vector?
Sorry, I am not all that familiar with the Lillium-style system. Goggled it and it appears to be a blown wing with multiple small electric thrust units and a balancing lift fan.

That might be a start but no it is missing the basic concept. The Lillium is like putting tip thrusters on a helicopter and then not allowing the rotor to turn.
 

jedi

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Yes interesting aerodynamics that no one was ever been able to get quite right. I wonder if they will manage to make it work. Again, the transition is the kicker and the wing tips may be a solution.

I suggest further Custer Channel Wing and related discussion on other vehicles be continued on the Tailless Aircraft - Reflex and other design issues list or let's start a new thread to include forward sweep pros and cons as a carry over from the George Wilbur Cornelius flying wings, etc.
 
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Andy_RR

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The channel-wing idea is not so much the point here but rather that the fan inflow generates wing lift without forward airspeed. I assume with distributed propulsion at the trailing edge you could achieve the same effect.
 

Sockmonkey

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The channel-wing idea is not so much the point here but rather that the fan inflow generates wing lift without forward airspeed. I assume with distributed propulsion at the trailing edge you could achieve the same effect.
Ah, instead of having fans along the wing, the wing is along the fan.
 

jedi

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Re: Tailless Aircraft - Reflex and other design issues

Moderator Note: After talking with Jedi, and re-reading through the two threads, I've moved this post (and the following one by henryk) back into this thread where this discussion began, from where it was forked into the Tailless Aircraft - Reflex and other design issues thread. I think this location here is the better, less-confusing location for the discussion to continue.

----- End Note ------

From Beta Technologies Ava Thread

"I fear I'm missing what the jedi master is trying to teach us here...?"

Discussions were about the pros and cons of tilt rotors versus lift fans. Discussion to continue here.

Summary: Tilt rotors are to complex and have transition issues in going from vertical flight to high speed forward flight. Lift fans are power hungry and do not have high forward speed.

I am not implying I have all the answers but suggesting that we stop beating our head against the wall and step back and take a fresh look at the problem and broaden the search for solutions. Overwing blowing helps as does the Custer Channel Wing. A free wing should eliminate the problem of rotor wash impacting the fixed wing in the downwash from a lifting tilt rotor or quad copter configuration.

All of the above is premature until the problem to be solved is clearly defined. Is it a more useful GA aircraft, an inexpensive sport plane, a traffic avoidance commuter, a longer range roadable aircraft or all of the above.

The "Beta Technologies Ava" and many of the current crop of electric lift fans tend to be towards solving the "traffic avoidance commuter". As has been frequently pointed out in other threads this can be and in fact is done with current technology helicopters. There should be a detailed discussion of how the proposed electric lift fans will solve the helicopter problems of limited landing areas, operations in existing airspace structure, and high cost including fuel burn/electric/battery limitations.

I am not convinced that any of us on HBA are interested enough to seriously discuss many of these issues.

Any volunteers want to step in and narrow the discussion to specific areas? I obviously like the above post which is far from the lift fan/tilt rotor VTOL solutions and more in the area of "inexpensive sport plane" that solves operational and performance issues.

As for the prior posts on the "Beta Technologies Ava Thread" others are working on a system that solves the problem of combining the large span slow flow thrust required for efficiency with the rotary propeller/fan high speed low volume characteristics. Some of their work is not public so I can not give all the details. There is a lot to learn about low speed fluid dynamics and aircraft stability and control. There are also some very knowledgeable individuals on HBA. I hope we can work together to advance flying activity and solve the ground bound transportation issues.
 
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henryk

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Re: Tailless Aircraft - Reflex and other design issues

-the all today knowing propeller thrusters have very low SPECIFIC THRUST,
not moore then 10 kG/kW...

+noise,dust generation.

-it is possible to get one order moore,but with very low specific propeller surface loading (f.e. ATLAS HPV...)

Iff I know,the air transport problems solution is to go to the NONSTATIONARY aerodynamic (oscillating,flapping thrusrers)...

in that case we can got anihilation of drag, tremodeus specific thrust (experimentally achived 200 kG/kW !!!).

+safe,low noise,simple construction.

BTW=the first attempt to involve this technology we see in VOLERIAN project.
 
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