Shape changing
Shape changing
(OP)
Would a wing that could change it's shape in flight have any advantage over other wings? e.g. go from deep chamber to low chamber...
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RE: Shape changing
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RE: Shape changing
RE: Shape changing
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FAQ731-376: Eng-Tips.com Forum Policies
RE: Shape changing
In the 1950s Gus Raspet at Mississippi state university
Fabricated an all fiberglass aircraft with a camber changing wing.
In the 1980s I helped take that wing off and install a conventional wing with flaps.
That aircraft is now in the flight museum in Birmingham Alabama.
Here is a press release from the aircraft dept at Mississippi state.
h
The university may have performance details of the old airfoil in their archives.
B.E.
RE: Shape changing
RE: Shape changing
RE: Shape changing
Bees do it ----
Maybe we cold learn a thing or two ---
RE: Shape changing
RE: Shape changing
You people "engineers" really amaze me. Most of you could figigure out how to get blood from a turnip the other half could\would get more blood from a smaller turnip.
The reason for my question isn't airplane design\construction. But more layman's understanding of wings,airflow and lift.
So, whith that said, let me delv a little more into my project.
"Forget about size and weight for a moment".
As I understand it a plane/wing with a deep chamber needs less air speed and runway to take-off "Glider compared to fighter jet"?
If a plane has a shallow chamber it wil use less fuel to climb "Kinda like a bullet shot straight up"?
Is this a correct assumptions? If so then a fly by wire control of the wing shape along with flaps would give the best of both worlds, would it not "Yes wing shape and flaps for precise control"?
My current computer model gives me a 35% savings in fuel if what I stated is correct.
RE: Shape changing
I'd like to comment one little difference that might be overlooked here on the flaps.
If you form flaps by means of a kneadable geometry the result is not the same as a "real" mechanical flap. In case of a normal flap there's an open space to re-energise the boundary layer on the suction side with air coming from the pressure side. (In fact normal flaps can be considered a variable geometry as well).
BTW:
Your question made me think about another question... ...what's more effective for the airfoil's glide ratio, a bit of camber increase or an increment in the angle of attack? I never checked that... If angle of attack is the answer, cambering your wing is an expensive solution to vary the aerodynamic properties. It all depends on your design angle of attack and your take off and landing boundary conditions I think.
BTW2:
I think that the speed range that you need will give you the answer whether it's worthwhile to build a kneadable geometry. The F-14 and the swift (I mean the bird,not any airplane type) are extreme cases, but for normal applications it's not necessary to overcomplicate life a s the swift does.
BTW3: (lots of BTW's BTW)
Fly by wire has only been invented because of the extreme dirigibility that seemed necesssary in fighter aircraft. For commercial aircraft, at least as far as I know, it's not necessary at all to fly stable.
RE: Shape changing
camber ... planes use camber (L/E slats and T/E flaps) on take-off (and landing) to increase CL, reduce ground speed of the plane. previous post is right about the effects of the open slot (to reenergise the boundary layer).
i just googled "F111 variable camber" and came across the project i thought about at first. called "mission adaptive wing", NASA Langley did some research with an F111 lifted with a smooth upper surface (instead of discrete flaps). judging by the lack of follow up, maybe it isn't worth it.
RE: Shape changing
> Ability to use "command" the flight computer to make a manuever and have it provide the necessary high-speed commands to compensate for aircraft instability
> Elimination of a considerable amount of mechanical weight, since the mechanical linkages need redundancy, hydraulics, supports, reinforcement, etc.
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RE: Shape changing
The reason the wing was removed from the aircraft at Miss state was, that although you could increase the CL of the wing, you could not increase the area of the wing.
The flapped wing fitted, had offset hinges that allowed the area of the wing to increase as the flaps were deployed.
B.E.
RE: Shape changing
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RE: Shape changing
There are a lot of interesting concepts that have even been tried out at large scale but typically don't go far because of the mass penalty. I thought the MAW was one of them, suction on wing surfaces to reduce drag was I thought another.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Shape changing
One may also think of using variable geometries to enhance the maneuverability of a plane (birds do that).
In fact the flaps and slats that are being used during landing and take off are variable geometries as well.
I can also imagine a drag reduction for supersonic airplanes, because after all they have to take off subsonic. Maybe the moving nose of the Concorde is an example of something like this, but I'm not sure whether drag reduction was the goal there, I don't know, but it's what I suspect. Maybe someone can confirm that.
RE: Shape changing
boundary layer suction, from Keant's last post, is another way to improve a wing's performance at the cost of weight, engine power; it did a good job on the Buccanneer, so it probably fits in special applications but not generally.
any thoughts newton ?? anything helpful ??
RE: Shape changing
RE: Shape changing
Concordes nose was for visibility, though arguably it was also to reduce drag as a more conventional stepped nose configuration to give visibility would have had more drag.
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Shape changing
You must always design a wing to be best at what it's role will be, and the tradeoffs you get from such extreme wings can significanly affect the handling of the airplane in all other flight envelopes. Two examples:
The U-2, a wing that gives so much lift that the airplane can't land unless it's fully stalled.
The F-104, a wing made so fully dedicated to speed that blown flaps were needed to get landing speed slow enough to make landing at all possible. The F-104 killed a great many pilots because of this wing.
So yes, a variable geometry wing can be made, but the cost will always outweigh the benefits.
RE: Shape changing
When the plane takes off the plane has a thick airfoil cross section, but as fuel is consumed the foil thins out as the bladders empty. The wing surface settles down onto a frame defining the minimum thickness profile.
This alows the plane to carry more fuel than a thin wing section would alow, and provides added speed and efficiency as the reservoir empties. It also seems like it is not to costly to impliment, although the wing shape is not constantly varied to increase performance as some of the things mentioned above.
RE: Shape changing
http://www.gano.name/shawn/papers/mdo02.pdf