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TakenIsUsernameThis t1_j6m6848 wrote

Reply to comment by Hypx in DARPA wants aircraft that can maneuver with a radically different method by Hypx

They are possibly talking about external moving parts. There have already been experiments with deformable wings, so the wings aerodynamic properties can be adjusted whilst maintaining a totally smooth, seamless skin.

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BoredCop t1_j6m7zw1 wrote

Which, oddly enough, is how the Wright Flyer controlled yaw. Warping wings are not a new concept at all, but doing it on a modern high performance aircraft without external wires and braces is quite new.

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TakenIsUsernameThis t1_j6mfp5p wrote

And without compromising stealth as well.

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Hot-Mongoose7052 t1_j6my46q wrote

Incidentally, the Wright flyer was rarely picked up by radar.

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xanthraxoid t1_j6ohu33 wrote

And even if radar had been invented then, it would have had a tiny radar signature, being mostly made of wood and cloth. The engine block would be pretty much the only bit that would show up more than a modern stealth plane.

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xanthraxoid t1_j6okdru wrote

While movable flaps are certainly a factor in providing a radar return, smooth wings aren't the ideal from a radar perspective - hense the distinctive Tesla CyberTruck^TM appearance of the [F117](https://en.wikipedia.org/wiki/Stealth_aircraft#/media/File:F-117_Nighthawk_Front.jpg].

If you have a flat surface, it'll only return radar waves in one direction (which is unlikely to be where the receiver is) whereas a curved surface will scatter it in lots of directions, meaning some is likely to end up going back where it came from to be detected.

The worst case scenario is something that forms a retro-reflector, such as a corner reflector or the radar equivalent of a cat's eye so they're careful to avoid those.

As a thought experiment (or a real one if you feel like it) have a friend hold up a Christmas tree bauble and a similarly sized compact mirror in a dark field. Shine a torch at them, and see which you can see more easily.

The ball will have a sharp spot of reflected light on it, and the mirror will (almost certainly) not reflect back toward you and be seen.

Of course, if you happen to angle the mirror just right, then it'll reflect a whole bunch of light back at you, but of course they don't use mirrors, they use the radar equivalent of VantaBlack so even the reflection you do get is minimised, but the difference between the flat and curved surfaces remains.

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Dohnakun t1_j6mtnnr wrote

> With “Active Flow Control,” aircraft can use plasma actuators or synthetic jet actuators to move air, instead of relying on physical surfaces. With plasma actuators, this is achieved through changing the electrical charge of air passing over the actuators mounted in the wing, in turn changing the flow of that air. Meanwhile, synthetic jets can inject air into the airflow over the wing, changing lift. In 2019, NASA patented a wing control system that combined both plasma and synthetic jet actuators, with the goal of creating actuators without any moving parts, and which were “essentially maintenance free.”

edit: removed offending "No." ;-)

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[deleted] t1_j6mvvgq wrote

Great information.

No need to preface it with 'No' however. Not everything you say has to be to prove you right and someone else wrong.

You could have said 'That's entirely possible, but they are for sure working on this other different thing: '.

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jjatoronto t1_j6ncbft wrote

No. :)

I believe Dohnakun was replying to Takenisusername comment on external moving parts.

So it was "No external moving parts". They were just being energy efficient.

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