Nemeth Umbrellaplane ("Roundwing") and other projects

Nice pics! I have a better version of last one here, as well as a pic of the Alliance A-1 Argo, which I think was an earlier version than the one you posted here (look at the tail fin):

Ah, an extreme-aspect parasol wing...


Did they get it right ??

Another view of the Nemeth Roundwing:

Hi,

here is a strange airplane Model with levitator,designed by Mr. Nemeth
in 1935,I can't understand its work well ?,page 300,I think he was the same designer here;

Steven P. Nemeth's aviation career is not very well known. Besides a couple of cyclogyro projects in the 1920s and his obvious Roundwing of 1934 (also known as the Umbrellaplane), Nemeth also set up the Nemeth Helicopter Corp. after World War 2 and developed a two-place anti-torque helicopter with ramjets at the tips of the single rotor's two blades. Apparently the machine was finished and was tested in 1947. Unfortunately, I have never been able to find a photo of it. Could anyone help?

Great Info my dear Skyblazer,thanks.

Topics merged.

hesham said:

Hi,

here is a strange airplane Model with levitator,designed by Mr. Nemeth in 1935,I can't understand
its work well ?,page 300,I think he was the same designer here;

https://books.google.com.eg/books?id=Ji_ty9AEz58C&printsec=frontcover&hl=ar&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false

Click to expand...

It looks as if it is basically a tandem-wing ornithopter. The longitudinal frame is driven to oscillate like a see-saw. Each wing therefore moves alternately up and down, just like a flapping bird except the wings are out of sync. With careful cycling of their angles of attack, the wings can each contribute fairly constant lift but take it in turns to provide the thrust on the downstroke, giving the pilot a reasonably smooth ride.

It's clever and it's a lovely idea. I want one that's painted up like a Chinese dragon and designed to be ridden from a saddle!

There is an added subtlety in nature, in that many if not all birds also move their wings a little forward and backward out of phase with the flapping so they move more in a figure-eight than simply up-and-down, It improves STOL performance and, I think, makes the thing more efficient while allowing the body to remain steadier. It is not clear from the limited information given whether Nemeth slides his wings fore and aft to mimic that.

And I think there is one potential drawback. The power source for the see-saw must react against the fuselage or some other massive body and make it rock in the other direction. Compensation cannot be integrated with the lift distribution on the see-saw or you would have perpetual motion. So it would still be a rocking ride. A bit like riding a dragon, I suppose

Proof that Nemeth always had extremely unconventional ideas for flight, this 1929 "paddle-wing" system for one of his failed Cyclogyro projects:

Hi Stargazer, only four years late but here's a pic of the Nemeth Helicopter, taken from https://sites.google.com/site/stingrayslistofrotorcraft/nemeth-helicopter. This is also on this site at https://www.secretprojects.co.uk/threads/nemeth-ramjet-helicopter-design.606/ along with a second image of an earlier iteration of the design I would surmise.

Some additional info

From, Special Types of Rotary Wing Aircraft,

here is explanation for his activities,included his Odd Project,
which was displayed on reply # 5.

A common misconception is that these were draggy because of the very-low aspect-ratio and its STOL performance, but this is not demonstrated in very many planes of the type.

This plane follows the Arup S-2 which demonstrated the type and that it does not inherently always carry around the burden of the huge wing-tip vortices they're intended to produce at very low speeds, very high A. The "parachute lift" effect and attendant excessive drag is elective and temporary, and well known and documented.
Aspect ratio = span^2/area. if under 3, in order to fly slowly at high A, the vortices wrap around the wing capturing a "bubble" of low pressure above it (while A is compressing air under it, and increasing effective camber). At the same time, the vortices are trapping the flow from the front of the wing, keeping it from separating and providing strong smooth flow to the controls. They don't stall, as in departing uncontrollably from flight because of loss of lift and controls. At stupid slow speed and high nose-up, they'll be going nowhere but down, but they're still flying.
Zimmerman found that near the aspect ratio that the Arup was built for, the effect is maximized, and that's what he chose the shape of the V-173 for, as the starting point for his interest in a VTOL tail-sitter.

The Nemeth with less power than the original could keep up with it, was faster with the original power.
The Arup S-2 was 780 lbs, flew 85 kts on 37hp engine, with 18 kts landing speed. With steep climb, super-STOL, stall proof. The S-4 was ~1150lbs, 70 hp, 100 kts.
Wainfan demonstrated cross-country to Ohskosh in the Facetmobile; 100 kts on 40 hp with 340lb useful load. It could stay in flight at <16kts (his pitot tube couldn't read any slower).
I've seen a few equations and heard several explanations why very-low aspect-ratio is poor or inefficient: If this alleged inefficiency isn't manifested in power vs speed or fuel vs range, then what is it?
See also the Farman 1020 of the same time. Like the Nemeth "parachute plane", built on the fuselage of a known successful plane, faster than original, STOL, stall-proof.

Zimmerman wrote about the parachute lift effect for NACA and UAC, and Wainfan wrote about it for NASA, who was looking for a re-entry vehicle and at the novel, simplified construction.

John Frazer said:

A common misconception is that these were draggy because of the very-low aspect-ratio and its STOL performance, but this is not demonstrated in very many planes of the type. ....
Aspect ratio = span^2/area. if under 3, in order to fly slowly at high A, the vortices wrap around the wing capturing a "bubble" of low pressure above it (while A is compressing air under it, and increasing effective camber). At the same time, the vortices are trapping the flow from the front of the wing, keeping it from separating and providing strong smooth flow to the controls. They don't stall, as in departing uncontrollably from flight because of loss of lift and controls. At stupid slow speed and high nose-up, they'll be going nowhere but down, but they're still flying. ....
Wainfan demonstrated cross-country to Ohskosh in the Facetmobile; 100 kts on 40 hp with 340lb useful load. It could stay in flight at <16kts (his pitot tube couldn't read any slower).
I've seen a few equations and heard several explanations why very-low aspect-ratio is poor or inefficient: If this alleged inefficiency isn't manifested in power vs speed or fuel vs range, then what is it? ....

Click to expand...

Conventional CFD fail to consider the complex airflow in wing tip vortices.
Barnaby Wainfain discovered that wing tip vortices (AR less than 2) tend to try to cross the centerline, and when they collide, they cancel out each other making the downstream airflow far less turbulent aka. a flatter lift-to-drag ratio. That is one of the reasons that low AR airplanes do not work well with rudders at mid-span.
Another advantage is that the long chord (17 feet on Facetmobile) yields much higher Reynolds numbers, which in turn lift better and produce less drag than short chords. As an aside, few amateurs can build a precise wing airfoil with a chord of less than 4 feet (130cm).
Bart VerHees enjoys similar economies of scale with his Verhees Deltas.
Wainfain had lectured on the subject at several EAA Airventure Airshows (typically at Oshkosh, Wisconsin during late July).
Wainfain is currently in the later stages of building the prototype FMX-7 Facetmobile in Independence, Oregon. As of August 2023, most of the airframe is complete and he is mating the outer wing panels with the center fuselage.

Vortex lift is not unique to low AR planforms as swept-wings demonstrate similar vortex lift at high angles of attack. Leading edge sweep angle is the key.
Withold Kasper demonstrated similar high angle-of-attack, low-speed, vortex lift with his swept-wing, BKB tail-less sailplane. Later versions even had a panel hinged at the leading edge to encourage vortices to develop immediately aft of the leading edge.
Vortex lift is mainly a function of leading edge configuration. Delta-winged fighters can be more efficient at shallow angles of attack, but develop massive amounts of drag at high angles of attack. In the extreme, you get a sharply-swept delta like the Concorde SST airliner than developed such massive amounts of drag at low-airspeeds and high angles-of-attack that it could not "power" itself out of too slow an approach. Hence Concorde pilots spent plenty of time training to "fly by the numbers." An undesirable side effect was the massive amounts of thrust needed at low-airspeeds which prompted too many complaints about noise pollution from neighbors.