How to properly design a VTOL/ADAV helicopter-plane?

[Christophe]

30 minimum glide ratio is good...a paramotor is 5!

A Dragonfly is a little better...

[Remundo]

we are talking here about wing finesse, and again about idealized wing (without the induced drag).

the glide ratio of the real aircraft is generally much lower. There are many other frontal surfaces, little or no lift, which create more drag, yes which can degrade the lift of the wings by vortices/turbulences.

everything is in interaction, in mutual and reciprocal influence, like the famous site http://inter.action.free.fr

[Christophe]

How without the streak of nerve? It's not included in the Cx?

On a paraglider, the wing alone counts for a lot... The best competition paragliders are at 12-13, maybe 14 now... and a paramotor (classic) will degrade the glide ratio by a good 40%...

In short, no paramotor has more than 7 overall glide ratio...although a Dragonfly can be ...but hush...everything in its time!

[Remundo]

I do not go into the details of the different trails, the proportion of which can vary very greatly with the Reynolds number.

I take the wings with their overall Cx

for the global aircraft, it would have to be run on your finite element mecaflux software.

[Christophe]

The VTOL Lilium is not badly designed (even if I would have done it a little differently personally...) but requires a lot of regulation:



We talked about it a few years ago on the forum...I don't know if a human has ever flown in it though...

[Christophe]

This one is better...but still at the scale model stage:

[Remundo]

Thank you Christophe for the videos.

The Lilium does not inspire me with great confidence in its conversion phase, but it must be recognized that it is getting there. By design, this aircraft is unstable at low speed when changing helicopter-airplane mode.

The transwing with its 4 rotors is stable and the tilting of the wings seems to be a success on this scale model. However, the connecting rods and the pivots of the wings undergo high stresses. In addition, the wing spar does not anchor in the cabin. To make a ladder 1, you will need weight, and this weight will not be load-bearing.

[Remundo]

just for the record...

If the Americans have indeed developed an ADAV with tilting rotors (the tiltoror OSPREY), the original concept was German in 1938, in any case earlier, it was the project WESERFLUG P1003/1, who according to wikipedia was never built due to the complexity of its tilt-rotor wings

Das Flugzeug wurde jedoch aufgrund der Komplexität des VTOL-Systems nie gebaut, das Projekt nach Rohrbachs Tod im Jahr 1939 nicht weiter verfolgt.

some images

weserflug_P1003p1.png (388.51 KiB) Accessed 660 times

Source: luft46.com

The Weserflug is still sold as a realistic model...

amusing-maquette-avion-48a002-weserflug-p1003-148.jpg (497.5 KiB) Viewed 660 times

Source: oopsmodel

the American V22 OSPREY bears a striking resemblance to it.


A modernized version which has passed a test flight: this is the e-VTOL from DUFOUR Aerospace

Image-2-Dufour-aEro-2-VTOL-Aircraft.jpg (18.65 KiB) Viewed 656 times

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if I'm not too convinced by this large tilting wing and the stability with only a lift line (with 4 rotors here), instead of a polygon, the fuselage on the other hand is very well designed, inspired "tadpole" forms which I had already mentioned.

[Christophe]

Great research, I was unaware of this 1938 project...but when you see the difficulties and deaths during the development of the V22 more than 40 years later...I think it would never have seen the light of day at the time...

[Remundo]

I think the lift line is delicate for the stability of the aircraft.

Especially in the airplane/helicopter conversion phase. And maybe in 1938, it was the "electronic control" that ruined the case. Rotating a wing is not mechanically hard. But guaranteeing the balance of the aircraft is another!

Because as we have seen, we can still get there. The algorithms and servo-control must be strong to maintain the balance... I imagine that there are on-board accelerometers + gyroscopes, and "real time" instructions to the rotors to correct any drift.

Boeing's OSPREY V22 had several accidents. DUFOUR Aerospace's small plane is not doing too badly, no doubt with the progress in automation.