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Author Topic: Flying Flapjacks  (Read 32536 times)

Offline cluttonfred

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Flying Flapjacks
« on: February 07, 2009, 11:53:49 am »
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
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Offline AeroFranz

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Re: Flying Flapjacks
« Reply #1 on: February 07, 2009, 12:57:24 pm »
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!)
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Offline Jemiba

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Re: Flying Flapjacks
« Reply #2 on: February 07, 2009, 12:59:10 pm »
Does the FMX-4 Facetmobile count ?
(picture from http://www.wainfan.com/facet.htm"
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Offline cluttonfred

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Re: Flying Flapjacks
« Reply #3 on: February 07, 2009, 02:55:32 pm »
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.
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Offline Just call me Ray

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Re: Flying Flapjacks
« Reply #4 on: February 07, 2009, 06:57:23 pm »
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.
It's a crappy self-made pic of a Lockheed Unmanned Combat Armed Rotorcraft (UCAR), BTW
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Offline hole in the ground

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Re: Flying Flapjacks
« Reply #5 on: February 08, 2009, 03:05:46 am »
not post war designs but of a similar layout?



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

Offline Retrofit

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Re: Flying Flapjacks
« Reply #6 on: February 08, 2009, 05:19:13 am »
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.
« Last Edit: February 08, 2009, 05:35:06 am by Retrofit »

Offline cluttonfred

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Re: Flying Flapjacks
« Reply #7 on: February 08, 2009, 05:40:13 am »
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.
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Offline AeroFranz

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Re: Flying Flapjacks
« Reply #8 on: February 08, 2009, 09:15:04 am »
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).


All modern aircraft have four dimensions: span, length, height and politics.   TSR.2 got the first three right - Sir Sydney Camm

Offline SaturnCanuck

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Re: Flying Flapjacks
« Reply #9 on: February 08, 2009, 12:50:34 pm »
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.
Saturncanuck

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Offline Justo Miranda

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Offline hole in the ground

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Re: Flying Flapjacks
« Reply #11 on: February 08, 2009, 02:27:12 pm »
"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.

Offline Retrofit

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Re: Flying Flapjacks
« Reply #12 on: February 09, 2009, 09:41:12 pm »
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:


Offline SaturnCanuck

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Re: Flying Flapjacks
« Reply #13 on: February 10, 2009, 07:07:08 am »
Ya, the trouble is that the "AvroCar", aka, Project Y, didn't work.
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Offline Retrofit

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Re: Flying Flapjacks
« Reply #14 on: February 10, 2009, 11:58:24 am »
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.

« Last Edit: February 10, 2009, 12:02:31 pm by Retrofit »