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Burner117

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May 22, 2014
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Jackson, CA, USA
Hi all,
So ive seen aircraft that were human powered before, the only problem I see with them is that they're enormous. My brother and I have been working on plans for a human-powered WIG Effect vehicle built off of a recumbent bicycle. We've run into a snag while designing the wings of the vehicle since there is so little data on ground effect planes. We've decided on the lippisch reverse delta wing for the overall shape of the wing but we have no idea what its dimensions and geometry should be because we haven't found a way to accurately calculate the lift of the wing while in ground effect. So I decided to consult the interwebs to see if any of you knew a simple way to figure it out.

Thanks- Burner117
 

BBerson

Light Plane Philosopher
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Dec 16, 2007
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Port Townsend WA
I don't how to calculate ground effect, but I remember that Taras Kiceniuk built a human powered ground effect craft in the 70’s for the Kremer competition.
 

bifft

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Apr 17, 2011
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Utah
I don't how to calculate ground effect, but I remember that Taras Kiceniuk built a human powered ground effect craft in the 70’s for the Kremer competition.
Don't pretty much all human powered aircraft fly in ground effect? What with the huge spans required to get efficiency down to where a human can power it, and the fact they don't have enough power to climb hardly at all, they all seem to fly around 1/4 span or lower.
 

BBerson

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His was designed to fly about 6" high. With a short burst to clear the height rule once.
 

Norman

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Nov 28, 2003
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Grand Junction, Colorado
Don't pretty much all human powered aircraft fly in ground effect? What with the huge spans required to get efficiency down to where a human can power it, and the fact they don't have enough power to climb hardly at all, they all seem to fly around 1/4 span or lower.
There are two distinct but related phenomena called "ground effect".

First is span dominated ground effect (SDGE). It is simply a reduction of induced drag that the plane starts to feel 1/2 span above the ground.


Second is chord dominated ground effect (CDGE) which gives a lift boost and is typically considered to start about 1.3 times MAC above the ground.

Some WIGs are designed to fly higher than CDGE but most have wings that don't generate enough lift when they leave CDGE. I can't answer the question but it seems to me that if the wing were just a little too small to fly at the speed that you can pedal, without the help of CDGE, then you would have a self limiting system ie loads of lift below a limiting height and insufficient lift above the limiting high
 

Norman

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WIGs aren't really my thing. I just had to learn a bit about ground effect because it has a bigger affect on the landing behavior of the type of airplane I'm interested in than most others. The Lippisch reversed delta with a huge stabilizer looks pretty good.

[video=youtube_share;NvxzGERqDXI]http://youtu.be/NvxzGERqDXI[/video]
[video=youtube_share;i9sHtVzdW8Q]http://youtu.be/i9sHtVzdW8Q[/video]
 

Norman

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A WIG uses less power than an airplane of the same weight and speed so if MacCready could do it out of chord dominated ground effect it should be easier to do it in CDGE. The wings are smaller and low aspect ratio so can be lighter. I've heard that CDGE can double the lift but don't know that that was accurate but, as I said, If the wing is just a bit too small to fly above CDGE it will reach a critical altitude and stay there so if it's bigger than you need to get off the surface at all is just inconvenient. Of course at the speed you can reach the wing is going to be huge so 2X the wing area could be a big deal.
 

JamesG

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Feb 10, 2011
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Columbus, GA and Albuquerque, NM
What about a WIG that keeps its propulsion prop (screw?) in contact with the water to maximize the torque transfer? Yeah I know that makes it still a hydrofoil, but if the benefits outweigh the drag??
 

jedi

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Aug 8, 2009
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Sahuarita Arizona, Renton Washington, USA
I would think there is some kind of scale effect to consider, Perhaps hull speed versus flying speed (Sqrt Length versus area squared) if waterborne. Don't know of any similar limitations if launched over a hard surface. Is WIG lift still a direct function of Area and Velocity squared or is their a span/cord function in addition to the height ratio?
 

Starman

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High in the Andes Mountains
What about a WIG that keeps its propulsion prop (screw?) in contact with the water to maximize the torque transfer? Yeah I know that makes it still a hydrofoil, but if the benefits outweigh the drag??
I posted that idea here a couple of years ago, think it's good, you get more 'traction' and the prop shaft angle will help lift the vehicle out of the water if it's balanced. Something like on those longboats in Southeast Asia where they have an engine balanced/pivoting on a post on the stern and an 8-12 foot prop shaft angling down to the water, a steering handle at the front of the engine.

It would also make sure you couldn't fly out of ground effect so it would only need a boat license, then you could put a longer wing on it to get really good gas mileage.
 
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