Worlds first 'flapless' plane | Hacker News Reader

Worlds first 'flapless' plane

bbc.co.uk

36 pointsdchs29 comments

If I'm understanding this right, it's a similar idea to what several F1 racing teams have been using this year, a concept that's been dubbed the "F-duct". [1]

The idea is that downforce on the car is generally paid for by aero drag, and thus if you want grip in the corners, you have to sacrifice straight-line speed. But what if you could aerodynamically disable that wing on the straights, so you don't suffer from the drag? (mechanically movable wings are illegal)

They devised a completely passive system that routes some air from the front of the car back to the rear, dumping it out behind the engine intake, just in front of the rear wing. When the driver seals the duct with his knee (or hand, in the case of Ferrari), the air can flow through this path, thus stalling out the rear wing, significantly diminishing its aero effect both in terms of downforce and drag.

From the video, it sounds to me like the plane is doing sort of the opposite: directing air not to stall, but to cause an aero effect over the normal surface.

[1] http://www.suite101.com/content/the-mclaren-f1-f-duct-how-it...

Thanks for the explanation, I've been hearing about these F-ducts on Formula 1 cars (I follow F1 vaguely) and wondering what the hell all that was about. Is this the technology that Brawn pioneered last year?

No, this is new this year. It was first seen on the McLaren at the beginning of the season.

Last year's Brawn innovation was the "double diffuser" -- and I understand what the diffuser does even less than I understand this.

Ah, I see. Skimming an article on the double diffuser, it seems to just be a creative interpretation of the rules which allows an extra piece of wing to be attached by some means that the rulebook-writers didn't think of. It's not particularly interesting, since it's based more on legalese than on physics.

Personally I find the most frustrating thing about F1 to be the way they keep inventing new rules in an attempt to make the cars slower. Don't they know that people watch Formula 1 because they want to see fast cars race?

A friend of my dad's was really good at finding gaps in the rule books of dirt track speedway. Like, for instance, it might specify you could only have a radiator of a certain capacity in the car to cool the engine, but it didn't specify where it had to be mounted. If you can find somewhere with less mud being thrown at it or better air flow, then you've got a competitive advantage.

Eventually some Nascar teams became aware of him. He told them his time was worth a lot of money. "Money's not a problem!" "If you're serious you'll send me a blank check."

Two teams sent him checks. He filled in some unnamed amount, waited to see if it cashed and then ripped up the other one.

He spent a few months in the States, came back, and bought himself one of the biggest houses in town.

Sometimes chutzpah pays off. :)

I couldn't agree more. The teams have agreed not to use the F-duct next year.

I found the late 80's in F1 extremely interesting due to the technical innovation. By the end of that era, the cars were "active everything", completely reconfiguring themselves (aero and suspension settings, brakes, you name it) for every different turn on the track. As an engineer, I was just eating that stuff up.

The argument against it was that the proliferation of technology was leading to development budgets spiraling out of control. But the budgets haven't gotten any smaller since, AFAIK.

It seems to me that the cars of today are so similar, differing only in tiny details, that there is precious little difference.

Gone is the creativity of the 70s, like the Tyrrell six-wheeler [1] or the Brabham "fan car" [2].

[1] https://secure.wikimedia.org/wikipedia/en/wiki/Tyrrell_P34

[2] https://secure.wikimedia.org/wikipedia/en/wiki/Brabham_BT46#...

I'm reading a book all about the Wright brothers at the moment (and this story made me think about it), absolutely fascinating to see how unbelievably revolutionary they were.

And in a way this highlights just how much; (one of) their great innovation(s) was flaps and wing warping for control, it put them light years ahead of other inventors (who mostly were trying for "automatically stable" flight). It's fascinating to see that it is only now we are (in a sense) re-innovating their invention.

If you get chance to read up on the Wrights it is worth it; they were simply brilliant hackers. They were smart and creative, and had no concerns about disagreeing with established theory if they thought it was wrong (in fact going to great lengths to correct theories).

My favourite "story" about them, though, is that the propeller was an after thought - they spent so long perfecting the wings, flight control and the engine and had assumed a normal boat propeller would work. When they realised the error - just a few months before making their attempt they - they hacked something together using wind tunnel data collected for wing designs. And when they went to Kill Devil Hills in 1903 were simply confident "it would work", because they had calculated it to do so.

You may gather I'm a little in awe of them :)

(all of which is not entirely related to this story, but still seemed an interesting semi-relevant thing to share :))

EDIT: although as pointed out below I am assuming that by "flaps" they mean all flaps because Ailerons were not a Wright innovation (they used Wing warping) but a rudder and flaps were part of the Wright flyer and crucial to the control.

What's the name of the book?

The Wright Brothers: The Aviation Pioneers Who Changed the World by Ian Mackersey

http://www.amazon.com/gp/product/0751533688

Recommended read (it is a bit effusive in places but also relatively balanced)

Most people don't appreciate that the Wright brothers weren't just tinkerers who got lucky but were for all practical purposes research scientists at the leading edge of their field.

Minor nit: this is not the world's first flapless plane. The Wright Flyer used a technique called "wing warping," where instead of movable control surfaces, they flexed the wing to change its shape and lift properties.

NASA has a neat simulator to show how this works here: http://wright.nasa.gov/airplane/warp.html

Also, the article seems to refer all control surfaces - aileron, elevator, rudder, etc. - as "flaps." I have several hundred hours logged in Citabria 7ECA and 7GCAA aircraft, neither of which have flaps.

"Flaps" in aviation refers to movable panels that increase the wing surface area and angle of attack in order to produce additional lift at low speeds for takeoff and landing. Again, NASA has a pretty good explanation: http://www.grc.nasa.gov/WWW/K-12/airplane/flap.html

Was about to post exactly this.

The novelty here is a plane which does not change the shape of the wing in any way to attain maneuverability.

And you thought ice on wings was a problem now, de-icing would be an absolutely crucial part of this system. If any one hole is even partially obscured, the balance between both sides is off. Clearly this is computer controlled and can be compensated for, but it seems to me that there's quite a few problems to overcome before it comes back to the mainstream.

Off the top of my head: that plane had a jet engine, so they could just route their air lines near the engine for heat, or siphon air from the jet directly. Then just constantly 'leak' some warm air from all the holes on the wing surface when in icy conditions.

Or just electrically heat the metal around the holes, like is currently done for the pitot tube (speed indicator).

Large airplanes usually have electrically heated leading edge surfaces in addition to pitot tube and stall indicator heat. As you point out, something like that would work well in this application. There is something of a drawback, though.

On mid-size planes rated for icing flight, "ice boots" are generally used. Boots are a rubber surface over the leading edge of the wing that can be inflated on command. Once ice buildup is sufficient to warrant their use, the pilot engages the system, which compresses air and then inflates the boots violently, breaking the ice off the leading edge.

The reason this is more popular for smaller airplanes is because electrically heated wings take much more power than you can reasonably expect to generate on something smaller than business jet sized (e.g., Cessna Citation), especially on approach when engine output is reduced (and when icing can become the most problematic). Even medium-large twin turboprops like the Beech KingAir 350 rely on boots.

An alternative technology for smaller airplanes that's pretty unpopular is the weeping wing, wherein a deicing agent is pumped out through small pores in the leading edge. It's unpopular because you either have to carry a lot of weight in deicing solution or risk running out. My father flew a Beech Bonanza A36 that he had retrofitted with the weeping wings, and he's remarked on many occasions what a pain in the ass they were.

I assume they mean aileronless rather than just flapless?

Or is "flap" a general term for flaps, ailerons and rudder surfaces?

The three primary control surfaces on an aircraft are the ailerons(roll), rudder(yaw), and elevator(pitch). Flaps shouldn't be interchanged with any of these surfaces, especially the ailerons, since they perform different functions. Unfortunately the video is blocked for me so I can't see how it's flying, but from looking at this picture:

http://img.metro.co.uk/i/pix/2010/09/28/article-128566123826...

it seems that the wings are one solid mass(save for the silver tab on the mid-rear edges). I'm almost inclined to chalk it up to bad journalism, but I'll have to reserve that judgment till I watch it.

Edit: Looks like I'm partially right.. the jets replace all of the control surfaces. I have to admit that's some pretty cool technology. I feel the headlines don't do much justice, but it's probably a lot easier for the general public to understand something like "flapless" rather than trying to describe "a lack of moving parts."

The airframe is based on their existing UAV family, which means it is pretty small and so the plane may not have a full set of conventional control surfaces to start with.

It could also be a case of reporter-translation - anyway the film implied they had replaced all the moving control surfaces, including the ones in the tail. So it would have included ailerons etc if it had them.

(I used to work in this facility on a different project, and it was one of the most interesting jobs I ever had. Just a shame it's so far from civilization.)

Flap means something to pilots, but not to popular audiences, I guess. What I gather from the article is that jets of air replicate the forces that the ailerons, rudder, and elevators normally provide.

From watching the video, it also seems like it's missing flaps, because of the shape of the wing. Landing is something they can worry about later ;)

It could just be that the aircraft doesn't need flaps. The purpose of a flap is to change the wing geometry such that the aircraft can fly at a lower angle of attack. This allows the plane to fly slower without stalling the wing. If the aircraft can already fly sufficiently slow to land then it doesn't need mechanical flaps to adjust the wing geometry.

As for replacing the control surfaces with jets of air, I can't help but wonder how that affects airflow around the aircraft. I'd bet something like this doesn't scale well to larger aircraft.

I'd bet something like this doesn't scale well to larger aircraft.

I think you're right. I've seen people's model DC-10s that they build, and apparently at that small scale, they don't even bother with coordinating the turns. If you want to turn, you just jam the rudder all the way left or right, and then the plane goes there. In a real DC-10... that probably doesn't work so well.

(Tried this in X-Plane, and it doesn't really do anything. But the "edge cases" are poorly handled there; I can't even get a Cessna 172 to spin.)

I don't know that full rudder deflection is really a corner case! In fact, the roll orientation of a plane shouldn't affect the effacacy of the rudder so long as the plane isn't in a slip or spin. The whole purpose of a rudder is to correct for a difference in lift between the wings in a bank. If there is no bank, and therefore no difference, the rudder should cause one.

The airflow over the wings when stalling is the "corner case". The usual models don't apply; if they used a model that could handle any arbitrary airflow, then the sim would run at 1 frame per hour. So they make some assumptions for normal flight that are easier to calculate, then they make some other special assumptions for stalling, and switch between the models as necessary. I think.

But apparently they don't do anything special for spins or uncoordinated turns, so you can't try this in X-Plane and be confident that a real plane would perform well.

Anyone have a DC-10 they don't want?

While not exactly 'flapless', blown flaps have used compressed air as part of the flap system for quite some time (it's even had time to fall out of favor due to complexity and costs!)

http://en.wikipedia.org/wiki/Blown_flaps

(Though it does look like the article linked refers to ailerons and elevators, not flaps proper).

Didn't Orville and Wilbur's prototype steer by twisting the wings?

Yes, they called it wing-warping apparently - http://www.pbs.org/kcet/chasingthesun/planes/wrightfly.html

What do you do when it loses power and you have to land?

(and WTF is with the greenwashing statement that guy made?)

Presumably, the same thing that you do when the motors driving the hydraulic pumps that drive the control surfaces on a conventional aircraft fail -- control the plane with the other, non-failed control surfaces and with the engine thrust.

There have been a few cases of big airplanes losing all control surfaces but still being able to land:

http://en.wikipedia.org/wiki/United_Airlines_Flight_232

http://en.wikipedia.org/wiki/2003_Baghdad_DHL_attempted_shoo...

Figures that this is right on the heels of the news of the first (successful) human-powered flapping plane.

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