A couple of years ago, I had a thread going about a wingless "contraption" built by a friend, which I was a little skeptical about.
It flew quite well and I was a little surprised that it could almost go slow enough to be hovering.
Now he's done a much improved version, which flies super slow or fast and can do quite a few aerobatics.
Has anyone got any ideas on what makes this thing actually fly as well as it does? - I've included a few photos taken about 9 months ago, - haven't seen this guy around much lately, so I didn't get many details of the plane, just the photos.
I do know though that it doesn't "prop hang", ( not much power, - it has a 20 size motor I think).
The first photo is of his original effort.

Actually, it's not exactly wingless. It has a wing for lift, tail feathers for control. Obviously the wing loading is low enough to fly okay.

It certainly is an ungainly contraption. It bears an uncanny resemblance to the T-2 Buckeye from certain angles.

At model sizes, it's more power than aerodynamics that makes things fly, even that thing.
It has a wing so to speak, a tail more or less, and a motor... no reason why it shouldn't fly.

SHOE
From what I saw it wasn't ungainly, quite nimble in fact, - but it does look a little ungainly, the deep front fuselage I think is just to keep the prop off the ground so he doesn't have to use an undercarriage!
PAUL,
He did say something about it flying in a stalled condition (when flying slow I guess) and it was using a vortex to keep it in the air, rather than a lot of power, - guess I didn't fully understand what he was driving at!

You could fly a barn door if you set it up right!

flown an F-4 Phantom too have ya

with enough power anything can fly. it may not be the most relaxing and enjoyable flight of your life but stranger contraptions have flown.

kc

Well, the consensus seems to be "with loads of power you can fly anything" - trouble is I didn't see that in this case! - guess I'll never know.....

it has enough power to provide the airspeed to produce lift from the wings and tail surfaces it has, it's NOT wingless, it also gets considerable lift from the very big and flat fuselage bottom. it's not rocket science here, what part are you having a hard time with?? it's really no differen then any other plane.

kc

Not having a hard time at all, just mildly intrigued by the thing but now you're getting me more interested by the minute!
So how does the flat bottom produce lift when there's virtually no forward movement?

weight v/s lift and the AOA

kc

I'm still in the dark, - maybe I'm not the sharpest tool in the shed, or getting too old - but
there can't be much lift if there's hardly any forward movement, so any air movement comes from prop wash, which is always in the same plane as the flat bottom (so no deflection forces there).
I guess then the lift must be coming from the camber on the top surface of the "wing". - but the wing area is extremely small, as is the prop.
The AOA in the photo was when it was almost at a hover (virtually no forward movement).

He did say something about getting lift from vortexes (or is it vortices?) which I really didn't understand, so I was hoping someone coud shed some light on the subject

Forward movement is ground speed. Ground speed isn't a part of any lift equations because it's got nothing to do with the flight of the airplane. Lift comes from the velocity over or against the lifting surfaces, which you mention as prop wash. Prop wash isn't usually anywhere close to laminar. It's almost always helical (curling around, heading aft). So.... there can't be much lift if there's hardly any forward movement The sucker isn't falling, so it's obvious that forward movement has little or nothing to do with the problem.

Wing area can be small or not, if it's "enough" and that also depends on the wing loading. And the prop can be large or small so long as it's operating in it's rpm range efficiently. And the sucker isn't falling, so the wing area is proving to be perfectly adequate and the prop is proving beyond question to be more than sufficient to not only fly the airplane but to "helicopter" it as well.

As for getting lift from vortexes......... Vortexes are not producers of energy. They are produced by energy. The energy comes from somewhere else and has already done a lot of work, some of which most would assume was to generate the lift that is being described as not possible.

BTW, one detail that should be mentioned...............

We marvel at "normal looking" models doing 3D maneuvers. We see all that wing hanging in the air or flopping about. think about it.............

How much wing in a normal configuration is contributing (when it can) to the maneuvering? About as much wing as that ugly thing has. So what is the ugly thing losing by having such short wings? A lot of useless weight and useless wing.

Rather than being wingless, the pictures seem to show an aircraft with a low aspect ratio wing, not much lower, in fact, than a Lazy Bee. The ubiquitous flying lawnmowers, doghouses and sports cars all have lower ARs. The trailing edge looks very thick, too, but it does have a wing.
I'm guessing that it's pretty light and has plenty of power and all in all not a very efficient airplane.

Would it be cruel to say it's so ugly that the ground is simply repelled by it?

yeah you're still in the dark, Lift isn't caused by wind 'blowing' the surface up, it's caused by the air passing over the airfoil. in a sub-sonic airfoil (where you get good lift as opposed to the 'with enough power you can fly anything') and especially in a flat bottomed airfoil, the air passing over the wing by design of the wings airfoil is less dense across the top of the wing (it's passing across faster) and that produces Lift.

kc

And he said there was some forward movement and maybe that was into a bit of a breeze yet which would make it look like it's hovering.

A lot of food for thought here,
First let me say that there was hardly any breeze, and it performed the same in any direction.

I only said that his first effort was "wingless" for want of words to describe it, but it was just a term rather than a description.

I like the one about the ground repelling it! . - and yes, it's a bit ugly, but not as ugly as the first one!

I understand the ( Bernoulli ? ) principle of air speeding up etc. and I understand that it is actually the higher air pressure underneath, which is pushing it up, but a lot of people look on it as being sucked up by the vacuum which is technically incorrect of course.

Talking about wing loading, I guess the plane is quite light as it hasn't got a U/C, but with such a small wing area, surely the wing loading must be a little higher than the average plane, and the average plane needs quite a lot of airspeed over the surfaces ( as obtained by forward motion) to fly at all? let alone sit at hovering speeds, - I do realise that at a high angle of attack, the prop will contribute a little - ( miniscule amount maybe?).

Remember I don't really know much about this plane and the statements I make on it are just my thoughts on the subject, but I distinctly heard the guy who built it say on the day the photos were taken, that it was flying in a stalled condition ( when not moving forward), and that it was being kept aloft by vortices, and I guess the evidence seems to support that, - this guy always thinks outside the square in everything he does, so no doubt he's put in a lot of thought to this.

I do remember reading somewhere that some fullsize ultralight aircraft use a wing with a flat angled end to obtain more lift by forcing the vortex outward ( in effect increasing the span a little) and I see that this thing has airfoil ends like that, - don't know if this has any significance.

wow - that theory STILL exists?

Seriously
anytime there is a pressure difference - you can get lift - the classic airfoils are all simply compromises for particular tasks and in most cases structurally-- that old shape worked for a lightweight lifting surface .
perfectly flat plates make mighty fine lifting surfaces cept'n they are flimsy

Not everyone who comes up with eccentric stuff really knows the science behind it.

Dick, Paul,
Well, at least I've got replies, however blunt some of them may be!

Dick, I do know that you've tried most things in regard to flying machines, so I guess you've got more ideas about this "thing" than I have, and Paul I believe that you are more of a traditionalist in your way of thinking, but you both have probably got a lot to offer.

Yes, this guy ( not me, just in case you thought that) is definitely eccentric in his ways of looking at things, but he is intelligent and thinks a lot and his conclusions sometimes may look a little distorted to the average person, but a lot of his crazy ideas work, so who knows!

He's interested in a host of other things, - builds his own fullsize ( successful) boats, in fact
you name it and he'll have built something like it with his own twist to it!
Also he has a dislike of computers which is why you never actually hear from him.

You guys have been around a while and I respect your opinions and approaches (which very often would be diametrically opposed), but I guess that in this case you are in complete agreement! so who am I to argue?
I just thought there might have been some wisdom behind his theory.

Nothing wrong with trying stuff - as long as no one gets hurt
If it fails you have learned that something is wrong .
The Wright bothers came up with a machine which flew -- so did a few Frenchmen- and if you look for commondesign features -you won't find many --except
when the power overcomes the weight it moves and when the lift overcomes the drag - it can leave the earth
After that - there are many configurations which work just fine
th old classic airfoil we see over n over -is just one of many.

The thick trailing edge provides a large, strong area of low pressure behind the wing, and an enormous amount of drag. This low pressure causes at least two lateral vortices per wing trailing edge, one relatively small one rolling upward from the bottom, and another rolling downward from the top. The air coming from the top is moving faster, so the top vortex has more velocity, and since the density is assumed to be the same or very nearly so, it has more energy, and augments downwash somewhat. This, I believe is part of why the ugly thing can fly so slowly. All this happens on any airplane, but the effects here are multiplied because the trailing edge thickness is such a large percentage of chord. It is not efficient in terms of being able to fly fast with little horsepower, but it seems to be effective in this application, since the mission seems to be to fly very slowly. It isn't a new principle, but it is a clever and unusual application of a known principle. Effectively, it creates extra drag and converts some of that drag to lift, by adding energy to the downwash in a direction it was already inclined to go. It is not flying solely using the vortex, but rather using the lateral vortices to augment low-speed downwash and therefore lift. At high speeds, where the downwash angle is less, the thick trailing edge produces almost exclusively form drag.

Also, the low aspect ratio wing allows very high deck angles, which does angle the prop upward significantly, and splits the thrust into a horizontal and a relatively large vertical component. At the higher angles I see in the pictures, I calculate that somewhere around 5% (or more) of the thrust being generated is effectively vertical. This may not seem like much, but it has the effect of reducing the amount of lift force the wing is required to generate. And there is the prop slipstream over the center section/fuselage that helps increase lift.

It's a clever design and since it's purpose seems to be to fly exceptionally slowly; I would say by the OP's description, it has succeeded. I think it would be fun to talk to the designer about his ideas.

Incidentally, the low pressure above cannot be separated from the higher pressure below, when determining the cause of the lift force, since as Dick and others pointed out, it's the DIFFERENCE in pressure that imparts acceleration to the air, causing lift. It isn't the curvature alone of the airfoil that causes the lower pressure above, since we all know that curvature is not necessary to produce lift. The curvature does greatly increase the efficiency of the airfoil and must be considered with AOA and speed to determine lift produced.

And I could be completely wrong.

Thanks for all the replies you guys,

MESAE,
Your post more or less vindicates my friend's "eccentric" line of thought and makes some sense of the message he was trying to convey to me, so I'll (try) get in contact with him and see what he thinks of the replies so far ( he doesn't know about me putting this on the forum as yet but I know he won't mind).

I don't think he has flown it much lately because he has many and varied interests, this being only one of them, also this is only one of his arsenal of weird and wonderful flying "experiments".

When he flies, it often attracts a crowd of passers by, and he gets comments like " what is it? - aren't you going to put the wings on?, - that thing can't possibly fly but it does, - ooh aah "- or, haw haw what a load of crap ( this often from people who consider themselves expert fliers of course), but it doesn't faze him at all.

Thanks again everyone.

What's the big deal? I've hear that on the F14,F16 and F15's that more than 1/2 the lift comes from the fuselage and inter engine areas of the strakes and bodies as opposed to the actual wing panels.

All that I see is a clever design that uses a very thick wing section and very low aspect ratio and light weight.