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Futuristic biplane design eliminates sonic boom

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March 19, 2012

The Tohoku University design would change shape during flight to adapt to supersonic speed...

The Tohoku University design would change shape during flight to adapt to supersonic speeds (Image: Tohoku University)

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A throwback to early 20th Century aviation may hold the key to eliminating the sonic boom - at least according to researchers at MIT and Stanford University. Strongly reminiscent of biplanes still in use today, the researcher's concept supersonic aircraft introduces a second wing which it is claimed cancels the shockwaves generated by objects near or beyond the sound barrier.

In fact the idea is not a new one. The idea of a biplane to negate the sonic boom was proposed in the 1930s by aviation pioneer Adolf Busemann, also responsible for the idea of swept-wing aircraft.

Aircraft traveling at supersonic speeds cause shockwaves in the air around them. A first boom is caused by the rapid compression of air at the front of the plane, literally pushed together by the aircraft. A second is caused by the negative pressure left in the plane's wake - or rather, the rapid return to normal pressure that follows soon after. Though the two booms separate phenomena, they occur so close together that they they are usually perceived as a single sound. An aircraft in supersonic flight creates a continual boom as it goes.

And that's a problem. Sonic booms might be all part of the drama at an air show, but if you were to live under a supersonic flightpath in regular use, the novelty would likely quickly wear off. There are also the concerns of the effect of supersonic flight upon wildlife which might include shock or injury in the short-term, and wholesale habitat abandonment over time. It's no surprise, then, that a return of commercial supersonic flight is considered a doomed enterprise in certain quarters.

The flow features of the Busemann Biplane. Red lines indicate the positive shock waves, bl...

Adolf Busemann's design, known as Busemann's Biplane, features two wings with a triangular length-wise cross section. The points of the wings point towards each other so that the outer face of the wings is completely flat, parallel to the air passing over and under. The wings must be sufficiently far apart that the passage of air between isn't stifled. With this design, the first positive shock wave is created and reflected between the wings, filling the space created in the plane's wake, canceling the negative shockwaves and negating the sonic boom.

What's the catch? At sub-supersonic speeds, a Busemann Biplane doesn't produce sufficient lift under acceleration, undergoing considerable drag. The design is said to work perfectly at supersonic speeds - it's getting to them that is the trouble. So though there may be no sonic boom, there's no flight either.

But the joint MIT/Stanford research at least appears to confirm that Busemann's noise-canceling concept was sound. The study, which used computer simulation, demonstrated that the biplane concept exhibited "significantly less drag." Additional research at Tohoku University in Japan claims Busemann's concept is effective in reducing the intensity of shock waves at ground level by 85 percent.

Better yet, the MIT/Stanford team think they might have cracked the problem of lift at sub-supersonic speeds. Through an iterative processes, modeling differing design variations, the team has discovered that smoothing the wing's inner surface eases the passage of air between the wings. By additionally "bumping out" the outer edges of the two wings, the team has come up with a design it claims will fly below the speed of sound, and with half the drag of Concorde.

"If you think about it, when you take off, not only do you have to carry the passengers, but also the fuel, and if you can reduce the fuel burn, you can reduce how much fuel you need to carry, which in turn reduces the size of the structure you need to carry the fuel," said Qiqi Wang, assistant professor of aeronautics and astronautics at MIT. "It's kind of a chain reaction."

The MIT/Stanford team is now pursuing a 3D model to address other practicalities in flight, with the hopes of approaching a static, optimized design. In contrast, the Japanese concept, identified by Wang, would change shape during flight to adapt to supersonic speeds.

Sources: MIT, Tohoku University, via Live Science

About the Author
James Holloway James lives in East London where he punctuates endless tea drinking with freelance writing and meteorological angst. Unlocking Every Extend Extra Extreme’s “Master of Extreme” achievement was the fourth proudest moment of his life.   All articles by James Holloway
24 Comments

Given that military training areas are de facto wild life sanctuaries I think that sonic booms have no lasting effect on wildlife.

Slowburn
19th March, 2012 @ 07:44 am PDT

You will still have termination shocks. In order to avoid a shock off the top of the top wing or the bottom of the bottom wing, the wings will have to tilt inwards so there is expanding flow around the outside (avoiding the shock). However the consequence of that design is that you will have 2 trailing shocks off the back of the vehicle as the flow re-compresses. If the plates are perfectly flat with respect to the flow streamlines, you will still have a shock as the boundary layer on the wing will trip the flow.

Also as shown in the flow configuration it has zero lift: the interior gemetry is identical top and bottom so the integration of pressures over both surfaces has a net of zero. There needs to be different shock angles to generate positive pressure.

Also neglects shock impingement aeroheating.

Philip Hahn
19th March, 2012 @ 08:36 am PDT

Forget about SSTs already. Boeing tried to interest the airlines in a faster (though not supersonic) airplane, the Sonic Cruiser. The airlines instead wanted to save on fuel costs and we got the 787 instead. I don't blame them. Until you can combine SST speed with subsonic fuel consumption... nothing will ever get built.

iamwho2k
19th March, 2012 @ 12:41 pm PDT

I know what supersonic is, and what subsonic is, but what is sub-supersonic? Is that the same as super-subsonic?

Christine Karman
19th March, 2012 @ 02:15 pm PDT

I don't believe that design will do MACH 1.

b@man
19th March, 2012 @ 02:46 pm PDT

It should be clear to most that the diagram is only to explain the concept. The angles are clearly exaggerated and no representation of the final product.. I completely disagree with B@Man, this shape could easily get to mach speeds in thinner air. It can get to thinner air because of the increased lift of an all wing design and the extra wing..

Michael Mantion
19th March, 2012 @ 05:26 pm PDT

When the article says that they can create lift with the Busemann wing, they mean 'some' lift. Not nearly enough to support an airliner in flight.

Adding any kind of structure to the Busemann wing will also create a shockwave and hence a boom. This includes engine pods, passenger compartments and control surfaces.

You could run a fleet of SSTs that were restricted to flying over water, and also in arctic airpaces in sparsely-inhabited Siberia and Canada. All this research is in a desperate attempt to speed travel across the USA, which is currently the biggest market. In 30 years (the earliest an airliner like this could fly) the market will have moved East where Supersonic travel can take place over water.

mommus
20th March, 2012 @ 03:23 am PDT

The claims made about wildlife are unproven and speculative.

A supersonic aircraft could be flown to an airfield away from heavily populated areas and then passengers could be transported by high-speed rail to the major cities and towns.

It would be nice if they end up building a unmanned demonstrator.

Oztechi
20th March, 2012 @ 03:24 am PDT

Clearly the ugliest aircraft concept in the last years.

I would ran away if I see this!

How will it start or land? How will passengers enter the fuse?

The high complexity is a clear showstopper.

It's such a nonsense. It is heavy as hell, it has a drag as hell, it is inagile as hell, it is ridiculous!

There is a reason why we don't see biplanes or should i say "boxwings" in the air. Too complex, too heavy, too ... useless!

Suvilo
20th March, 2012 @ 03:26 am PDT

looks less like an airplane and more like a Romulan Warbird to me.

toolman65
20th March, 2012 @ 04:46 am PDT

The busemann's biplane concept only addresses the cancelling affect of shockwaves between two planes, what about the top and bottom of those planes? It's more applicable to variable geometry air intakes than anything else.

The biplane concept depicted looks like it would have massive parasite drag (due to surface area) and wave drag (due to large changes in cross sectional area), so it would produce an enormous mach cone and a huge sonic boom if it could reach those speeds.

The seers-haack body is the best shape to reduce the size of a mach cone, a seer-haack body with small stubby wings is about the smallest mach footprint you can get, the Aerion SSBJ has an ugly rough interpretation of this.

As for sonic boom impact, the impact on peoples lives and wildlife would actually be minimal, properly managed supersonic travel corridors would not have any adverse affect on the population or wildlife. In fact, the 1964 Operation Bongo II sonic boom tests in Oklahoma City showed that the vast majority of citizens being boomed DAILY were unperturbed, but a general resistance to the concept of being 'boomed' arose mainly due to the manner of how the FAA conducted the Bongo II so poorly, and failed to compensate victims of damage (mainly cracked glass) resulting from the direct-city overflights. BUT what it showed was that generally, most structure and glass was resiliant to sonic booms, and that citizens could live would it.

The political backlash against the nonchalant manner in which the FAA conducted Bongo II led to the cancellation of the Boeing and Lockheed SSTs, in spite of the favorable results!!

PeetEngineer
20th March, 2012 @ 07:53 am PDT

Yes the diagram showed no lift, but that is because they did not want to confuse the issue, which was just noise cancelling. With trailing surfaces, you can change the lift capacity of both wings at super and subsonic speeds.

Sure 2 wings means 2 trailing shock waves, but trailing compression noise from the 2 wings will cancel each other out.

Rigby5
20th March, 2012 @ 09:43 am PDT

Looks like a good candidate for variable geometry wings. But instead of changing the leading edge, change the chord shape of the wing itself.

Larry Hooten
20th March, 2012 @ 11:34 am PDT

Growing up in Savannah, Ga. Sonic boom's were a daily occurrence. My wife's brother while stationed in Jacksonville would boom Savannah every chance he got as a Hello to his mom. It never seemed to be a big issue until the cry babies convinced big industry a buck was to be made solving this "Problem". If there's a $ to be made a problem can be ceated out of thin air, hence this abdominal solution.

Aeronautical Moron,

Zapp

Zappenfusen
20th March, 2012 @ 11:55 am PDT

Damn, toolman65 that's exactly what i was thinking! Romulan Warbirds!!!

Jay Lloyd
20th March, 2012 @ 12:02 pm PDT

Good one there, Christine!! It should have read "high subsonic speed". Back when Grumman was experimenting with their forward swept wing and canard design in the early 80s, they had a problem with the wing "torquing upwards" when at high subsonic speeds. My idea back then was to build it as a bi-plane, and use carbon fiber composites and a skin of titanium. My name for it was the Tandem Saber, as the wings would have a curve to them. Not a real radical amount of curve, just a gentle paraboloid.

Randy

Expanded Viewpoint
20th March, 2012 @ 01:46 pm PDT

lol why worry about the sonic booms, when we first have to find an adequate fuel to replace our diminishing fossil fuel stocks or we simply wont have to worry about sonic booms at all!

Lets fix the impending problems first - like powering our civilization, then worry about noise later.

cm
20th March, 2012 @ 04:23 pm PDT

But sonic booms are so awesome!

Craig Smale
20th March, 2012 @ 10:16 pm PDT

The other things that make too much noise from super-sonicness are prop blades.

christopher
21st March, 2012 @ 06:25 am PDT

I don't see what all the debate is about. This is obviously a ripoff of the TNG Romulan Warbird. The Romulans have been using this same bi-wing configuration for decades now and they have the proven track record of success against most of Star Fleets finest vessels...oops.

owndao
21st March, 2012 @ 05:30 pm PDT

What happened to that guy that made a joined wing toy plane and it was selling really well because it glided forever? I can't find him by google and I can't remember the name of his design.

Aaron Baker
24th March, 2012 @ 10:20 am PDT

Looks like a flick from Ultraman....

Jude Imran
1st June, 2012 @ 06:07 am PDT

I quite like the futuristic biplane design and hope it will enter commercial service in the not too distant future. With the aid of modern computer technology I don't think it should decades to develop. People may talk about making the future now. If it looks futuristic now, won't it always? What about Vauxhall's SRV back in 1970? I have a likewise opinion regarding the bi-directional aircraft. Even if such aircraft do get to enter commericial service, how successful will they be? After all, 40 years ago Concorde probably intended to make hundreds of them. However, probably no more than 20 were made altogether and probably as many as six of them didn't even get to enter commercial service.

I am very much in favour of flying cars and would even like them and flying saucers to displace the conventional aeroplanes and helicopters altogether, except perhaps for special occasions. Now that the Maverick has been referred to as the flying car that does, how about other manufacturers following suit with such technology? After all, I don't suppose the Ford Motor Company was the only motor company back in 1903. Furthermore, on the 9th of August I dreamt that a lorry could be transformed into a passenger aircraft using the hidden wings it had. At the time I was convinced the technology had already arrived. I was therefore later disappointed to learn that it was just a dream. This is not to mention the dream I had, probably back in September 2010, when I saw what appeared to be hexagon-shaped aircraft fly past, followed by what appeared to be aircraft of the German Luftwaffe of 70 years earlier. I was similarly disappointed to learn that that was just a dream.

Furthermore, I believe there is the website www.lightcrafttechnologies.com. I am hopeful that they will be able to get flying saucers going in the not too distant future. I even hope that some of them will be used as airliners.

Jeremy Keller
21st October, 2012 @ 03:09 pm PDT

Wow,so this design according to the drawings is an X-Wing Fighter.

Anthony Osborne
30th June, 2014 @ 04:57 pm PDT
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