h a l f b a k e r yThe word "How?" springs to mind at this point.
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Aerodynamic pipes AHEAD of wing, blowing air above and under wings at flight pressures and speeds
or vacume input IN BACK of wings creating same effect,
to emulate air flow on wings during forward flight.
Aircraft can elevate horizontally, or slow down without stalling.
Fan Wing
http://www.fanwing.com/news.htm
similar concept, pictures farther down [FarmerJohn, Oct 17 2004]
Some thrust-to-lift conversions
http://www.theaviat...factsheets/amst.asp
Two examples [lurch, Oct 17 2004]
Fan on sail in boat
http://www.youtube....watch?v=0CrXvOKPymk
works! [pashute, Dec 05 2012]
mythbusters confirm fan on boat powered sail
http://www.youtube....watch?v=uKXMTzMQWjo
[pashute, Dec 05 2012]
[link]
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This has been done, boundary layer air injection, but only to improve the low speed flight characteristics by keeping the airflow laminar at large angles of attack and not in an attempt to generate flight force relative wind. |
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maybe wings can be made smaller because of this, and runways shorter... |
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I think this is the same thing as sitting in a sailboat with an electric fan and blowing it on the sail for propulsion. |
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Cedar Park: I'm not so sure about that. A helicopter generates list by rotating wings (blades) through air. Surely moving air over an aerofoil isn't that different. |
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Hold the aircraft still and instead move the atmosphere doesn't seem right does it. |
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No, but neither do helicopters. |
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Oh you want an argument, do you? |
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Helicopters do seem unlikely. If I had never heard of them before and I saw one sitting on the ground, I would just laugh. There is no way something like that could ever fly. |
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AO: I've no problem with helicopters going up and down. They're very graceful when they hover, too. It's just when they try to go forwards that I start laughing. |
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Helicopters: they're completely sensible and simple. |
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Aerodynamic pipes = jets, yes? Why not use the jets to create lift directly, like a Harrier does? |
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It's OK, bris. I'm only tugging at your toes a little. I find helicopters funny, but I like them. |
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Since there seems to be some doubt as to whether this craft would fly, here's my reasoning: You can fly a craft by blowing air downwards. By extension you can fly a craft by blowing air backwards and deflecting it downwards by using an angled plate. Making the defelction plate an aerofoil, allowing some of the air over the top and playing with the angle of attack seems to follow. I think that this would work but doubt that it would make an improvement over other forms of flight. |
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The reason I brought a helicopter in as an example is to show that the airflow over the wings does not have to stem from the movement of the aircraft. |
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I think you could simulate the original idea by attaching a model-airplane wing to the front of a common house-fan. You’d have to take some care in selecting a suitable wing (small & light with high lift properties) and a fairly strong fan. If the fan produces a sufficient flow of laminar air, the wing should fly. |
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The larger problem will be in scaling this into a useable aircraft – it’s a lot easier to propel a traditional lifting wing through static air than it is to try to create a laminar flow of air over a stationary wing. By the time you find an engine and wing combination that are able to create useable lift, I think you’d find that the vectored thrust (think Harrier) approach is easier and equally effective. |
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And the vacuum option is really unworkable, unless you find a way to make sure that the only air sucked into the vacuum starts out in front of the wing. |
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<Aside>Helicopters are cool. Improbable, perhaps, but cool. </Aside> |
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Not so long ago, newsweek had a writeup about a new type of aircraft with horizontal winged fan over wing.
It flies!! |
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Now to the fan argument: just blowing air in front of the wing is one thing. Sending the air out in a stream NEAR the wing, and deciding which side gets more pressure is much more feasable. |
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Why not Harrier: Because Harrier is trying to reach ground effect or hovercraft effect, and I am trying to reach wing airlift effect, which is much stronger and needs less energy (because of existing air when machine IS moving forward). |
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[Bris and Ceder]: about the fan in the sailboat, interesting but my kids (oldest daughter) did just that, with a small battery powered fan, and it went forward. Then the fan tilted a bit downwards and the boat went flying backwards.
Now I know the physics in this case should be against this happening: the law of force and returned force (whatever the true English name of this law is), here in the Muddle East we are into that law a lot...
But in the case of my wingcraft, you don't have this problem: you aren't "pushing" the plane one way, and being pushed by the air the other way: you are pushing the air backwards, so you get a forward thrust, AND the wings are being used to create the lift, by having less air pressure above.
Now please show me the flaw in my logic. Thanks.
Oh yes, and please allow me a days time to reply. I work during the day, and don't get the chance to answer. |
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But, but, I didn't comment on the sailboat . . . . |
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You mean you think the sailboat thing is going to work..? [reaches for bz's other foot] |
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[pashute]: There is still a problem here. This idea claims that if you were to take air jets attached to the leading edges of the wings and blow wind over and under the at the same proportion as during normal flight, the plane would fly, even it had no ground motion. |
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The problem is that although you are pressing on the wings with the force of the air, the opposite force is also being applied to the structure supporting the jets. Net effect: zero. |
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I know nothing about sailing other than the boats float, at times. |
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//pipes AHEAD of wing, blowing air above//
That's baked. "Upper surface blowing", see Japanese ASKA and Boeing YC-14.
//and under wings//
That's baked. "Under surface blowing", similar to "externally blown flaps"; see McDonnell Douglass YC-15. |
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//vacuum in back// a couple of flaws: for one, you can't restrict the direction the ambient air is coming from to fill your low pressure area; and the absolute max pressure differential cannot be above 1 atmosphere. |
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//can elevate horizontally// well, not really; you end up moving forward because not all the thrust can be converted to downward using the Coanda effect. You could create a vectored thrust, but as noted, that's the Harrier and is a different idea. So you don't get a VTOL, but do get a pretty good STOL. |
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For aerodynamic simplicity I would skip the pipes and simply have a propellor; there will be a significant amount of turbulence exiting the pipes and flowing over the wing as the pressures redistribute. |
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If you move a sufficient amount of air on a wing using a prop, you *will* generate bernouli lift, but the lift generated from simple deflection would cancel itself out with the reactive force at the prop. |
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Baked and WKTE: you just described how most STOL aircraft work. |
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