Airbus tests 'flapping' wingtips

[Smythe]

Well, this is direct from Airbus, so the press didnt misinterpret anything...free- flapping wingtips?

Filton, 13 June 2019 – Airbus engineers have developed a scale-model aeroplane with the first in-flight, flapping wing-tips that could revolutionise aircraft wing-design.

The aerospace giant has drawn on nature to develop its ‘semi-aeroelastic hinge’ concept to reduce drag and overall wing weight, while combating the effects of turbulence and wind gusts.

Known as AlbatrossOne, the remote-controlled aircraft has already taken its first flights to prove the concept and the team will now conduct further testing before the demonstrator, based on the manufacturer’s A321 plane, is scaled-up further.

“While hinged wing-tips are not new – military jets employ them to allow greater storage capacity on aircraft carriers – the Airbus demonstrator is the first aircraft to trial in-flight, freely-flapping wing-tips to relieve the effects of wind gusts and turbulence,” explained Airbus engineer Tom Wilson, based in Filton, north Bristol, UK. “We drew inspiration from nature – the albatross marine bird locks its wings at the shoulder for long-distance soaring but unlocks them when wind-gusts occur or manoeuvering is required.

“The AlbatrossOne model will explore the benefits of unlockable, freely-flapping wing-tips – accounting for a up to a third of the length of the wing – to react autonomously during in-flight turbulence and lessen the load on the wing at its base, so reducing the need for heavily reinforced wing boxes.”

Jean-Brice Dumont, Airbus’ Executive Vice-President of Engineering, said the project showed “how nature can inspire us”. He said: “When there is a wind gust or turbulence, the wing of a conventional aircraft transmits huge loads to the fuselage, so the base of the wing must be heavily strengthened, adding weight to the aircraft. “Allowing the wing-tips to react and flex to gusts reduces the loads and allows us to make lighter and longer wings – the longer the wing, the less drag it creates up to an optimum, so there are potentially more fuel efficiencies to exploit.”

https://www.airbus.com/newsroom/press-releases/en/2019/06/how-the-albatross-is-inspiring-next-generation-of-aircraft-wings.html#media-list-document-document-all_ml_0

[Peter H]

Freely accessible video of test flight at https://www.youtube.com/watch?v=1xNg6XewjMM

[MarkerInbound]

It’s a bird, it’s a plane, it’s .... uhm, I don’t know.

[Smythe]

Thanks for the video...I mean it makes sense in some respects..

Always wondered why variable winglets, angle optimized for the phase of flight, havent happened.

[Airmann]

Well just wait until the 777X folding wingtip mechanism fails and you'll have the first ever commercial flight with the use of a flapping wingtip.

[capngrog]

I assume (I hate it when I do that) that the flapping wingtips on the full scale aircraft will not be moving about so much in calm conditions those shown on the model. They look kinda useless on the model, but I'm sure that further arithmetic will be done so that the tips only "flap" when encountering certain g-loads/aerodynamic forces. If these "flapping" tips provide any significant lift at all, they will involve some (significant?) fore-and-aft shifts of the center of lift (swept wing planform). As far as I know, the wings of all modern transport category aircraft flex ("flap") to a certain degree.

Anyway, an interesting concept and a very cool model. Oh my, what am I saying? It's a drone being flown in close proximity to an airport! Where's a dronecop when one is needed?

Cheers,
Grog

[msbbarratt]

At a guess I'd say it's going to reduce the roll stability of the airframe. Roll to the right and instead of providing lift to correct that the right wing tip will just flex up a touch more. I'm sure they've thought about that though! Interesting idea.

[Peter H]

A couple of related papers are available at
https://www.researchgate.net/figure/AlbatrossONE-Semi-Aeroelastic-Hinge-Demonstrator_fig13_328137723

[billybone]

Although one can argue they dont flap- watch the B52 wings bend upwards on takeoff. Depending on fuel load at the wingtip tanks , the wing can relatively easily be moved up and down by hand ... and that was over 50 years ago .

[EEngr]

Always wondered why variable winglets, angle optimized for the phase of flight, havent happened.
Ahem ...

https://cimg0.ibsrv.net/gimg/pprune.org-vbulletin/1024x768/xb_70_2_76b1615dc60e4b8e28221e3afde65280587b52ff.jpeg
Different flight regime and control laws. But it's been done.

[UltraFan]

I'm just thinking of a "worst case scenario". This structure has to be pretty light to "flap". An airliner descends from high-altitude cruise through rain. Cold fuel in the winds causes the "flapping" mechanism to freeze in the raised position. The plane lands. A refueller, who knows nothing about this technology and thinks those are just regular winglets, walks under the wing tip. And at that very momend the ice melts and BOOM, "refuelling technician wanted".

But jokes aside, if it helps improve airplane behavior in turbulence and cross winds, it'll be brilliant. What really makes my day is that they don't ever stop research even on the basics. Behind all those accountants and marketing people there are real engineers at work.

[tdracer]

Ahem ...

https://cimg0.ibsrv.net/gimg/pprune.org-vbulletin/1024x768/xb_70_2_76b1615dc60e4b8e28221e3afde65280587b52ff.jpeg
Different flight regime and control laws. But it's been done.

There is a popular myth that the XB-70 did the drooped wing thing when supersonic to 'trap' the shock wave and create lift. However I read a rather good book on the XB-70 a while back ("VALKYRIE North American's Mach 3 Super Bomber" - I recommend it if you share my fascination with XB-70). According to the book, while the wing design did in fact create lift from the shock, the drooped wing tips were related to improving high speed stability, not the trapped shock wave lift.

[billybone]

There is a popular myth that the XB-70 did the drooped wing thing when supersonic to 'trap' the shock wave and create lift. However I read a rather good book on the XB-70 a while back ("VALKYRIE North American's Mach 3 Super Bomber" - I recommend it if you share my fascination with XB-70). According to the book, while the wing design did in fact create lift from the shock, the drooped wing tips were related to improving high speed stability, not the trapped shock wave lift.

RE your fascination with the XB-70. As a relatively new engineer working for a possible subcontractor on the Alert Pod - I suggested a simple switching mechanism ( based on a pushbutton car radio ) for doing several things. The requirement was as I recall a 10 minute or less time from alert to takeoff roll. So a turbine powered pod with ' landing gear' was to be attached to the underbelly. What it did was to power startup of all engines, power up flight hydraulics, run control checks, etc. And at completion as brakes released, would drop off on its landing gear .

Never found later much publicity about that part of the ' rapid launch' capability ..
As part of that wound up with one push button on front gear to activate the whole sequence. Another issue was to figure out how to pressurize with nitrogen the hydraulic system reservoirs- which used a then special hi-temp hydraulic fluid while allowing for heat expansion and zip oxygen in the ullage at any time as fluid was used/leaked.

But for standby checkout - each of a half dozen systems could also be activated by ground crew via panel pushbuttons with certain mechanical/electical linkages to prevent inadvertent activation of other systems. We did not get the contract, and the division which was also closing down its other missile related work shortly closed, thus I came to BA ;)