I came across this picture of an early Mitchell wing. From what I can ascertain, it was developed from this pilot in wing version, to the pilot hanging underneath as was seen in the later versions.

Given the advantages of the PIW designs, I can only wonder why this idea has been so routinely abandon by almost all manufacturers?

Historically, Lilienthal's wings started this way, the Hortons FL wings were apparently successful, the Klingberg wing had no problems in this regard and this early Mitchel wing appears to have flown well enough. The recent caged Atos has also proven it can be done successfully so why has it been so thououghly eschewed?

It has been proposed that the hole in the wing causes problems with adverse pressure flow but I think this has been disproved and is easily resolved with sealing. I notice the PIW Mitchell wing design has more dihedral then the later pendular pilot version but the Atos cage has no more diherdral than the regular version so loss of pendular stability can't be too dramatic.

Possibly wing clearance on launch is an issue but in the attached pic it appears to be adequate (though I note the 3 launch assistants) and the Klingburg test pilot reported no problems to me in that regard. It may be that the wing now becomes reliant on elevons for pitch and roll - but so is the Swift and Millenium.

I's appreciate any info on the problems with PIW designs anybody can offer I'd like to try and build a design I have but don't want to go over old ground with an idea that has inherent problems.

I think it's quite simply put… pain in the a$$

or more elaborately, the advantages of the design do not justify the difficulty of it's implementation.
Jim

Brett,
See image and question.
I am trying to see the parts as a foot-rest or foot-grab, but I cannot quite stabilize my ankles or feet in the structure (vicariously).

I'll chime in here, although I'm not an engineer, so my opinion may not be worth a lot.
First, I'd say that structural issues may have something to do with it. I guess a structure using the highly stressed D tube like the Atos could be made to work. You could hang between two root ribs, using a "bikini" type harness with knobs on each side located at or near your bodys' cg that would clip into fixtures mounted on the root ribs. These fixtures could take the form of curved tracks if you want to use weight-shift for pitch trim or control. Twisting your body could cause one wing to rotate about the pitch axis relative to the other one, giving "wingeron" type roll control.

We all know that having the wing close to the ground during launch and landing will make these phases of the flight more critical in regards to allowable bank angle. Wind gradient makes bank angle unforgiving enough with pilot-under-wing (puw?)designs currently in favour. There can be considerable difference in wind velocity between say 2 feet and 8 feet, which on a 10 or 11 meter span would require only a very small bank angle to achieve at the tips. Now I guess if the ailerons/elevons/spoilers are effective enough you could handle it. One reason I envy the PG's is having the wing way up there out of the gradient.

I'm not so sure there's gonna be all that much advantage in drag reduction anyway. A well streamlined harness and control frame can come very close in this area,IMO. Remember that with PIW the root section of the wing will be thick, and if it's faired into the rest of the wing smoothly you could easily double or even triple total frontal area over that of PUW design.

In short, unless there's a "crashworthiness" advantage in it, then the best excuse for building one would be simply that you want to do it for some personal reason, like romance or asthetic value.

I'd love to see you build and fly one. It's been done before so you know it can work. It doesn't have to be better than what we now do to justify it. Like the mountaineer said, "Because it's there…"

steve

This is what Don told me:

Dr. Howard Long’s Mitchell Wing in the seated or supine position limited Howard’s forward and downward visibility. Howard was always ducking his head below the wing to see where he was going. So Don decided to place the pilot below the wing so the pilot could see. It was just so the pilot could see.

Generally speaking the spanwise flow on a swept tapered wing is slightly inward on the upper surface and diverges from the center outward below the wing, so by placing a pylon below the wing the divergent hole is being filled.

As for dealing with convergence on the upper surface, Irv Culver created a twist distribution where most of the twist was in the first 30 percent of the center section, creating a hole for the upper surface air to converge. Don called it the Culver Twist. This twist distribution was what Don was working on in the Stealth wings

Oz Report Culver Twist

http://www.a-i-r.de/ger/air_04.php?kat=115&par=4000&gp=4

(quoting entire message by Davis, right above)

Detail for above post.

Dayhead:

In short, unless there's a "crashworthiness" advantage in it, then the best excuse for building one would be simply that you want to do it for some personal reason, like romance or asthetic value.
steve

Steve,
In an esoteric event that I posted (then took off and posted at HangGlide) on "Flatland Long Glide", there occurs another reason to get pilot in wing (PIW): Run fast and with smooth hold of wing at lowest drag AOA in order to get as much running speed as one might in zero-wind condition (condition for the event in its most primitive form). Then before passing the takeoff marker line (like in track and field long jump), smoothly (if one is strong and prepared) move body up into wing (PIW) or into it as far as the chosen wing profile permits (or slap just under wing) and control AOA for best glide in ground effect. The first part of wing or pilot body determines the achieved long glide. So, hiding the pilot's body might be the best thing to do in this FLG event.
This event was also intimated in the first issue of Low & Slow in a list of things to do. Without microlift or other HPA and with a limited span, how far might one long glide in no-wind conditions in a long-jump type scenario. Wing-assisted long jump, if you will.
Joe