Flying Flapjacks

cluttonfred · 7 February 2009

I am sure everyone is familiar with the 1940s V-173 and XF5U-1 projects. If not, the Vought Heritage Museum has some nice pages and pics here: http://www.voughtaircraft.com/heritage/products/html/v-173.html

I know of the similar Boeing design from the same era, the Model 390/391. Aerofiles.com has a little info and a pic on that one here (scroll down to the 390): http://aerofiles.com/_boe.html

I know of some pre-war and WWII-era design like those, but does anyone know of any similar low aspect ratio designs in the post-WWII era?

And no, I don't mean something like the Lockheed F-104, which certainly has low aspect ratio wings. I mean low-aspect ratio flying wings or something otherwise similar to the Vought and Boeing designs above.

Thanks and regards,

Matthew

AeroFranz · 7 February 2009

I was reading in "Radical wings and wind tunnels" that Zimmermann first got interested with low AR circular wings when he saw the Arup S-2 (supposedly designed by a podiatrist!)

Jemiba · 7 February 2009

Does the FMX-4 Facetmobile count ?
(picture from http://www.wainfan.com/facet.htm"

cluttonfred · 7 February 2009

Thanks for the Arup, which is one of the pre-war inspirations, and the Facetmobile, which certainly does count. I had in mind something high performance, however, whether jet or prop, military or civilian.

I am not so sure how useful the XF5U-1 would have been as a fighter for the U.S. Navy, but it would have made rugged ground attack aircraft to support the Marines.

Just call me Ray · 7 February 2009

I have a Sport Pilot magazine article about that plane (incidentally it's one of the few artifacts recovered from old Aurora Airpark in Colorado before they closed for good, I just happened to have been there a few days before its demolition). I'll dig it out and summarize in a bit.

hole in the ground · 8 February 2009

not post war designs but of a similar layout?

images from your one stop R. Payen shop http://home.att.net/~dannysoar2/Payen2.htm

Retrofit · 8 February 2009

The formula has also been tested by Alain Mirouze, in France, in the late 70's and 80's.
Without much success.
The "Pulsar" performed her first flight on November 11th, 1974.
The "Pulsar 2" just some hops in 1984.

cluttonfred · 8 February 2009

Thanks, I am a big French aviation fan so I know about the Payen and Fauvel designs, some of which are very low aspect ratio flying wings or near-flying wings, but the Mirouze designs are completely new to me. Anyone have any more on the Mirouze designs? In French is fine....

I am still looking for more, though, especially something high performance or military.

AeroFranz · 8 February 2009

Nice post, i had never seen the Mirouze designs. The pusher prop looks awfully close to the fuselage...was there a slot for it to go in? I can't tell from that picture.
Regarding the Flapjack, one curious bit of information that I read somewhere was that the planform of the V-173 was arrived at by drawing an ellipse and half a circle. The ellipse was the front part, and the half circle was the rear and had the same diameter as the major axis of the ellipse (see attachment).

saturncanuck · 8 February 2009

Mole said:
Thanks for the Arup, which is one of the pre-war inspirations, and the Facetmobile, which certainly does count. I had in mind something high performance, however, whether jet or prop, military or civilian.

I am not so sure how useful the XF5U-1 would have been as a fighter for the U.S. Navy, but it would have made rugged ground attack aircraft to support the Marines.

Here is some info on how it worked...

"The positioning of the propellers was paramount to the design, and, in effect, offered the V-173 its unique low-speed characteristics. Traditionally, a wing with such a low aspect ratio will suffer from very poor performance due to the induced drag created at the wingtips, as the higher pressure air below spills around the wingtip to the lower-pressure region above, causing wingtip vortices. With a conventional aircraft, these vortices carry a lot of energy with them, and, thus create drag. The design of the V-173 – and the location of the propellers – overcame the wingtip vortex dilemma, by using the propellers themselves to actively cancel the drag-causing tip vortices. The propellers were designed to rotate in the opposite direction to the wingtip vortices, thus retaining the higher-pressure air below the wing. Since this source of drag was eliminated, the aircraft could fly with a much smaller wing area, and this small wing would offer a high degree of manoeuverability. As well, the contra-rotation of the propellers virtually eliminated the aircraft’s natural torque, making the V-173 much more agile and easier to fly"

"Although criticised as being underpowered, the V-173’s low aspect ratio wing allowed it to take-off at only 29 mph, and in calm winds required a take-off run of only 200 ft. Landings were possible in considerably less distance. As well, the aircraft could successfully maintain controlled flight at a 45 degree angle-of-attack – three times that of aircraft with conventional wings – and the aircraft was found to lose speed rapidly when entering a tight turn. This was theorized to be an advantage during a dogfight situation"

Oh, the V-173 and XF5U-1 used the same concepts.

These excerpts taken from "Clipped Wings – The History of Aborted Aircraft Projects", AeroFile Publications, Markham, 2007.

Justo Miranda · 8 February 2009

Please see http://www.secretprojects.co.uk/forum/index.php/topic,6213.msg51204/topicseen.html#msg51204

hole in the ground · 8 February 2009

saturncanuck said:
"the aircraft was found to lose speed rapidly when entering a tight turn. This was theorized to be an advantage during a dogfight situation"

I guess this depends on how quickly the aircraft can accelerate out of the turn.
Might be a good defensive manoeuvre, tightly turning inside your opponent and have him overshoot you but you've then got to be able to keep up to turn on the offensive.

Retrofit · 10 February 2009

Mole said:
I am still looking for more, though, especially something high performance or military.

Several Avro-Canada's VTOL combat aircraft projects may respond to those criterias:

saturncanuck · 10 February 2009

Ya, the trouble is that the "AvroCar", aka, Project Y, didn't work.

Retrofit · 10 February 2009

AeroFranz said:
Nice post, i had never seen the Mirouze designs. The pusher prop looks awfully close to the fuselage...was there a slot for it to go in? I can't tell from that picture.

No slot. In fact, Mirouze's system was trying to force the airflow over the central section of the wing extrados, a little bit as on Custer's Channelwing experimental aircraft.

AeroFranz · 11 February 2009

Thanks for posting the pictures, now I see what you mean. The rear of the fuselage is concave and provides enough clearance. interesting.

cluttonfred · 12 February 2009

Philippe,

Thanks again for the Mirouze posts and info. Are you (or anyone else) aware of any reviews or flight tests done on either of these designs? How well did it work? I can imagine a high-bypass turbofan in the same position to really amplify the effect, if it works.

Thanks!

Cheers,

Matthew

robunos · 12 February 2009

Re: Italian all-wing aircraft

was reminded about this by the 'flying flapjacks' thread,

http://www.secretprojects.co.uk/forum/index.php/topic,6203.msg51102.html#msg51102

here, as promised, are the arups, from 'Aeroplane Monthly' july 1979, pp.340-45, article entitled,
'Those Amazing Arups'

cheers,
Robin.

Sundog · 14 February 2009

Re: Italian all-wing aircraft

Has anyone ever found drawings of the Arup aircraft? I've looked, but I don't recall finding good drawings of either the S-2 or S-4.

Retrofit · 14 February 2009

Re: Italian all-wing aircraft

Sundog said:
Has anyone ever found drawings of the Arup aircraft? I've looked, but I don't recall finding good drawings of either the S-2 or S-4.

I find this one in an old EAA publication,

Cheers,

robunos · 14 February 2009

Re: Italian all-wing aircraft

in an earlier post here:-

http://www.secretprojects.co.uk/forum/index.php/topic,5110.msg40631.html#msg40631

i wrote,

http://www.flightglobal.com/pdfarchive/view/1935/1935%20-%200956.html

the Hoffman monoplane, illustrated in the link above, looks very like the 'Arup' series of aircraft,

now, re-reading the 'Aeroplane Monthly' article, i find the attached paragraph. Further, the image 'Arup006.jpg' is attributed to one 'R.J.Hoffman'.
So, i think it's highly likely that the Hoffman who designed the Hoffman monoplane, is the same Hoffman who helped to design the Arups.

cheers,
Robin.

Justo Miranda · 14 February 2009

Re: Italian all-wing aircraft

S-2
Span 5,79 m.
lenght 5,23 m

robunos · 15 February 2009

Re: Italian all-wing aircraft

Indeed, Raoul Hoffman designed the Arup S1 and S2 before moving to Florida where he designed his "All Wing"
.
Ralph Grainchen was the designer of the Arup S3 and S4.

Excellent! that fills in some more of the story.

cheers,
Robin.

OM · 6 August 2010

...A few clips of the Flapjack in flight:

http://www.youtube.com/watch?v=JBGhMN2KEvw

http://www.youtube.com/watch?v=5Gj_eFnFzpw&feature=related

http://www.youtube.com/watch?v=N2yzoMt6etc&feature=related

...And a clip with some renderings, thrown in for...oh, frack, just consider it syrup for the pancake

http://www.youtube.com/watch?v=n1tFy9Rgx68

Antonio · 6 August 2010

What a great renders, I'd love to see it as jpg files!

OM · 6 August 2010

pometablava said:
What a great renders, I'd love to see it as jpg files!

...What I'd like is a decent-poly 3DS or LWO mesh of the Flapjack.

PlanesPictures · 6 August 2010

http://www.secretprojects.co.uk/forum/index.php/topic,1671.0.html
http://pmc.sk/gatial/angelfire/lastnews.html

walter · 6 August 2010

The only info I ever found on the (first) Mirouze Pulsar.
Two-seater with 90hp Continental C90 engine.
Wingspan 5,20 meter, length 4,70 meter.
If I remember well, the aircraft may have joined the RSA collection years ago, so possibly it still exists?

walter · 6 August 2010

....forgot to mention it had a largely so called Geodetic construction.

Antonio · 6 August 2010

Thanks Mr Gatial!

Stargazer · 6 August 2010

OM said:
...A few clips of the Flapjack in flight

Well, not quite, actually...

- First video is of the NACA Tank Model 133 test model (not a related design at all).
- Second video is of the XF5U-1 Skimmer, but in wind tunnel model form.
- Third video is of the only real Skimmer, but not in flight, since it never took off, only doing taxiing tests!
- Fourth video is of the Skimmer in flight, but only in artwork form!

pometablava said:
What a great renders, I'd love to see it as jpg files!

Not top quality, but that's the best I could get from the video:

OM · 6 August 2010

First video is of the NACA Tank Model 133 test model (not a related design at all).

...Fine. I'll leave it to you to let the guy who posted the clip know his description was wrong.

fluxflyer · 8 June 2011

Re: Italian all-wing aircraft

A former U.S. Air Force test pilot, Chuck Tucker had recently tested a low aspect flying wing
model he designed named Vortex. It was a scaled down prototype of 12 ft. span and 10 ft. chord
rectangle. The tricycle landing gear had mains, wingtip mounted, and nose, beneath firewall ,
squared off wingtips and a large center mounted vertical stabilizer, rudder. Chuck's Vortex
project may have been adopted and ompleted by model club members of Morgan Hill, California
after He passed away more than a year ago. There were a few photos of Vortex posted at

http://twitt.org , month unknown.

Stargazer · 26 March 2012

An item published in the French Science et Vie monthly magazine circa 1946-47:

Stargazer · 26 March 2012

And the XF5U-1 even got cover art treatment in this 1946 issue depicting it in olive drab camo, suggesting an Army rather than Navy use (or, most likely, how little documented the artist must have been!).

Abraham Gubler · 26 March 2012

Stargazer2006 said:
And the XF5U-1 even got cover art treatment in this 1946 issue depicting it in olive drab camo, suggesting an Army rather than Navy use (or, most likely, how little documented the artist must have been!).

Great picture. Shame it isn't landscape as it would have made a great wallpaper.

Jemiba · 27 March 2012

Is it just perspective distortion, or really a twin-seat cockpit ?

Stargazer · 27 March 2012

Looks like it... but asking the cover artists of the time for technical accuracy is like expecting gourmet food from a McDonald's!

Let's call it "artistic license"... :

Dass.Kapital · 1 April 2012

Hello.

so, my firts post and I have a question about the 'Flapjack'.

Why was it better/necessary for the propellers to be made/operate in the way that they did?

Much cheers to you and yours.

AeroFranz · 2 April 2012

short answer: supposedly the swirl imparted to the airflow by the props cancels out the tip vortex shed by the wingtips. This should lower the induced drag/give you a higher apparent aspect ratio.

In practice I have no hard evidence it worked. By hard evidence i mean an NACA paper or similar.

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