Biplane Jet Fighter

[GPMG]

Ok, this is going to be ridiculed I know but, I have been trying to think of a good reason why a modern jet fighter would not benefit from some kind of biplane configuration.

Modern emphasis seems to be on manoeuvrability as opposed to outright speed yet surely with modern aerodynamics and wing sections, an extra wing would not cause too many problems with drag.

You would have extra fuel load, enhanced payload capability, greater lift etc.

If not a fighter then perhaps a good design for CAS as the increased fuel and ordinance would increase loiter time and firepower.




< Retreats and awaits comments along the lines of 'Stupid Boy'.

[TowerDog]

If 2 is better than 1, surely 4 is even better..Much more fuel and loiter time..
Where has Boeing and Locheed been all this time?

[stiknruda]

Drag - airframe (all those extra bracing bits and interplane struts)
Drag - induced (twice as many wingtips)
Compression - interaction of airflow between the planes
Visibility - piss poor fwd vis as someone has left a wing in the way, poor rearwards as the pilot tends to sit low to overcome the fwd vis issues!

Biplanes, huh - I love 'em

I've flown the SEPECAT Jag, the Extra 300 and they were fun but I wouldn't swap my bipe for either!

Stik

[TEEEJ]

I believe the only biplane jet was the Polish PZL-Mielec M-15 Belphegor. Only a Mother could love it!

PZL M-15 Belphegor - Wikipedia, the free encyclopedia

Airliners.net | Airplanes - Aviation - Aircraft- Aircraft Photos & News

TJ

[Icare9]

OK then how about a "hollow oval" wing (in front view)? The bottom surface curves up to meet the top wing and still only one set of wing tips?
Twice the number of flaps, etc, space in lower wing for undercarriage and weapons bays, plenty of room for fuel in the top wing. Could still fit winglets and other fancy paraphenalia, swept or straight....
Any designers out there, it's MY patent!!

[GPMG]

Stiknruda,
fair points, thank you.

I don't think it would need interplane struts or bracing
Drag, regarding wingtips, yes thats a problem
Compression likewise
But visibility would depend on config, if it was like a modern jet then the pilot is way out in front of the wing anyway.

[Gainesy]

Icare, nope, Bert Rutan (he of the upsidedown drawing board) already did it.

[TURIN]

Ok If we're getting silly...

How about upper wing swept forward, lower swept back, crescent shaped wings (plan view) and joined at the tips...

....with winglet/endplates that extend to the ground with outrigger wheels on their ends. Both ends, then you can land upside down.

[TURIN]

Apparently not such a silly idea!

Lockheed/Martin Future Tanker Project

[Daz1985]

I thought the whole point of a biplane was due to early aviation materials not having the structural rigidity to use in a monoplane configuration, so two were used, one to support the other, the aerodynamics of which still only gave the lift equivalent of 1 wing?

[cockney steve]

Custer Channel-wing......why reinvent the wheel?

[ORAC]

Biplanes went out when it was found you could get the same gains by making a single wing thicker which lead to a simpler design with room for the undercarriage, fuel and weapons etc.

There is a case for tandem wings, of various designs such as the LM design, for larger aircraft; but they tend to make the platform more stable, which isn't design feature you want in a fighter.

The compromise in the fighter world is the canard combined with relaxed stability, which is what you have in the Typhoon.

[XV277]

I'd imagine there would be some structural issues with a fast jet biplane

[NutLoose]

They did do a Biplane Hurricane fighter that had a jettisonable top wing. it carried extra fuel and reduced takeoff runs, but was dropped ( excuse the pun) after the requirement was no longer there.

see

The Hawker Hurricane

[CirrusF]

Well as already pointed out, it is not practical.

BUT there has been research into supersonic biplane configurations, because it is possible to take advantage of compressible flow in such a configuration to produce a very low-drag lifting device. I'm afraid my uni days are too long ago to remember the exact details, but basically the idea was to arrange the separation of the biplanes so that at a given mach number the reflected internal shock waves cancelled out the external shock waves.

[ORAC]

CirrusF, are you talking about the "wave rider" effect?

It was used to great effect in the XB-70, but that used a single wing with downward folding wing tips which captured and compressed the wave to allow the aircraft to 'surf" on it's own wave.

[petit plateau]

The idea of a supersonic biplane is quite old, certainly back to von Karman, and not necessarily silly.

I've seen a picture of a von Karman design where the lower wing sweeps back and the upper wing sweeps forward and the tips angle to join which also gave improved structural strength (rather important on forward swept wings). I can't find a link to a picture unfortunately. At the time we were wondering about using the shock wave interaction to get a reduced acoustic signature for an SSBJ design. The original von Karman intent was to improve L/D. The best link I can find is :

1958 | 1- - 0474 | Flight Archive

Regards,

[Beancountercymru]

It's been done

I saw this plane at the CAF show in 2002

Jet Biplane

Its a Jet Waco with a T85 and Pratt and Witney Radial

[CirrusF]

CirrusF, are you talking about the "wave rider" effect?

No - I remember it from a lecture by Len Squires who was on the Concorde design team - it was a fairly simple mathematical model of a supersonic biplane. I have tried googling without success - I'll see if I can find it my notes.

[mr fish]

Saab Viggen!!!