Futuristic Biplane Design Eliminates Sonic Boom

Zothecula writes "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."

Comments

Re:The problem.

[Icyfire0573]

I read the article, so I know that they fixed that by taking the old design which had no lift, ran it through a ton of simulations and found a design which has the lift necessary to fix this. It's not like people never discover new things.

Re:The problem.

[oldwindways]

Actually its even older than that, according to the article:
"Wang credits German engineer Adolf Busemann for the original concept. In the 1950s, Busemann came up with a biplane design that essentially eliminates shock waves at supersonic speeds."

The real breakthrough is in minor modifications to the wing design that cut down drastically in drag, reducing necessary fuel burn. While it may not be a field-able concept yet, they are gradually breaking down the barriers to a more efficient supersonic transport design.

Re:The problem.

[Intropy]

The article discusses that. The news here is that the researchers think they have a modification of the design that does generate significant lift at subsonic speeds.

Re:The problem.

[sexconker]

Even a flat piece of plywood will get lift if you angle up (from horizontal) and move it forward with the higher edge being the leading edge.
Lift is generated by air being redirected.

You can have contoured wings, flat angled wings, or wings that change attack angle or have adjustable flaps on the back that redirect the spilling air.

Re:The problem.

[taktoa]

False. For example, when I was building a supersonic rocket, I thought of using a Busemann biplane to decrease drag drastically in the supersonic regime. However, the stabilizing function of fins on a rocket is a result of the lift they produce at nonzero angles of attack. As a result, the rocket would have no stability, and would consequently fail to launch (alternatively, I could have used gyroscopic stabilization, but putting anything in the path of the exhaust tends to be highly dangerous, so I went with a super-light rocket).

No sonic boom?

[93 Escort Wagon]

Where's the fun in that? Seriously, when I was a kid living near an air force base, I thought the sonic booms were the coolest thing ever.

Re:No sonic boom?

[MozeeToby]

They're really not supposed to do it according to the rules, but yeah, I had the same thing growing up. Every so often the whole house would shake, and we didn't even live all that close to an airforce base (just in the middle of nowhere so I imagine they liked to do training there). I imagine some people got dressed down pretty thoroughly whenever it happened. But the only thing cooler was the mock dogfights (only ever saw those twice the whole time I was growing up though).

Re:No sonic boom?

[X0563511]

From my limited understanding of things, that shock front on the leading edges causes a rather large amount of heat to be dealt with. I'd imagine getting rid of that lets you save cost/weight/designer-hairpulling when working with the principle.

Eg, I seem to recall the SR-71's leading edges were actually designed to handle deforming at said high-temperatures. You have to admit that getting rid of that complexity would be a good thing.

Re:No sonic boom?

[Anonymous Coward]

Only the air force is allowed to make those sonic booms over land. A no sonic boom aircraft would make it possible for a commercial airliner to fly supersonically overland. The Concord was only allowed to fly supersonically over the ocean, limiting it's usefulness. A silent supersonic airplane with a high enough fuel efficiency would mean intercontinental flights in much shorter time. NY to LA would take 0h (after time zones) and LA to NY would take 6h instead of 9.

Re:No sonic boom?

[Eponymous Hero]

i grew up on air force bases. i could be wrong, but as frequently as the sonic booms occurred, i'd bet nobody got dressed down for that. if they gave a shit about sound pollution, they wouldn't put housing next to tarmacs where they keep their C-5s. i can't count how many times i feel asleep (or woke up) to their engines.

Re:No sonic boom?

[jamstar7]

One of the problems with the Concorde was, they weren't allowed to fly at supersonic speeds across the US because of the booms. So, supersonic London to LA was flat out of the question. From what I understand, a lot of other countries followed suit, outlawing supersonic flights in their airspaces. Without the speed advantage, the Concorde was a low passenger fuel hog that turned into a hanger queen and eventually got grounded and decommissioned. Fix the sonic boom problem, get fuel economy as a bonus, and we just might see the Concorde II in our lifetimes. LA to Melbourne in under 14 hours? COOL!!!

Re:No sonic boom?

[todd_is_not]

I grew up right outside (literally the last house to the south gate) of Edwards AFB in the late 80s-early 90s. I miss all the cool aircraft that flew right past our house.

I watched everything from the B-1, when it was still in flight test, to the maiden voyage of the B-2 from my front yard. Also watched the Space Shuttle a couple of times, when it had to come in on a non-standard approach.

Living in the middle of the desert, sonic booms were about the last thing we complained about

Re:No sonic boom?

[Baloroth]

And of course the shock-wave itself causes some major control issues as you pass through the barrier itself, at least as I understand it, as well as creating a huge amount of drag. That is a large reason they had so much trouble breaking the barrier in the first place: the planes would lose control as they passed through it and crash. How much eliminating the "boom" itself will help with these problems, I don't know.

Re:No sonic boom?

[element-o.p.]

And of course the shock-wave itself causes some major control issues as you pass through the barrier itself, at least as I understand it, as well as creating a huge amount of drag. That is a large reason they had so much trouble breaking the barrier in the first place: the planes would lose control as they passed through it and crash.

Yep. There were two big problems with control. The first was that as you move from subsonic to supersonic, the center of lift would move. The aircraft was balanced for controllability at subsonic flows, but when you passed from subsonic to supersonic, the aircraft became unstable and would either crash or break up. The second problem was that the control systems were easily manipulated by the pilot at subsonic speeds, but the shock wave created at the control surface hinge was too great for a human to overcome -- pilots literally weren't strong enough to push the control surfaces against the shock wave until engineers developed all-flying tail surfaces (stabilators rather than elevators). Overcoming drag was basically just a problem of developing a powerful enough engine.

Re:No sonic boom?

[AmiMoJo]

Actually the banning of sonic booms was more political than based on reality. Boeing had pretty much given up on their supersonic passenger aircraft and the French/British design looked set to rule the long distance market.

Concord was still an impressive aircraft, cutting flight times to the US down to five hours. Unfortunately it cost a lot to design, build and run, but had it not been effectively banned from many parts of the world those costs would certainly have come down with volume and improvements to the technology. Instead the supersonic passenger jet market was killed before it really started.

We have been promised radically new aircraft designs for decades but they never seem to come. In many ways Concord was the last big step forwards, everything after that was just a refinement of existing technology.

Re:No sonic boom?

[WindBourne]

Well, first off, nothing stopped LA->melbourne. In fact, other than a few routes overland (i.e. LA->NYC), there are very few routes passing over land that required supersonic speeds for major savings.

Re:No sonic boom?

[sjames]

They don't care about the noise pollution, they care about the broken windows and things rattled off of shelves.

Re:No sonic boom?

[rtb61]

Wohoo, you'll spend more time being stripped, radiate and sexually probed by the TSA then you will on international flights, hmm, perhaps not so cool after all. So cheap fast flights to the US at a time when it is no longer desirable to do so.

Re:No sonic boom?

[Eponymous Hero]

i don't think they care about that either. the planes would have to fly pretty low to the ground while breaking the sound barrier to break glass or shake things off shelves. it does happen, but not that frequently if you're one who lives around these planes. living around air force bases, you'd be used to the sounds of sonic booms, but most of them occur too high up to do any physical damage. it just sounds like thunderclaps all day without the storm.

but we do agree, they don't care about noise pollution.

Re:No sonic boom?

[isorox]

Well, first off, nothing stopped LA->melbourne. In fact, other than a few routes overland (i.e. LA->NYC), there are very few routes passing over land that required supersonic speeds for major savings.

Europe to anywhere in the east. If it was really about flying over populated areas, and not just a political move, then London/Paris to Japan would have worked (Siberia being fairly empty).

Concorde's range was limited too, about 4,500 miles. LAX-MEL is 8,000 miles, that's longer than most flights.

LHR-DXB would have worked distance wise, but is entirely land based. LHR-JFK obviously worked technically, just not commercially. DXB to SIN/HKG/PVG would work, without the ban over land, but is the market there?

Re:No sonic boom?

[riverat1]

LA to Melbourne if under 14 hours would be cool but you could do it even faster with a sub-orbital ballistic flight, probably under 3 hours. Normal low Earth orbits are about 90 minutes for a full orbit.

Re:No sonic boom?

[chrismcb]

LA to Melbourne in under 14 hours? COOL!!!

You talk about not being able to fly supersonicly over land... And then you give one of the few routes that doesn't require flying over land?

Re:No sonic boom?

[jamstar7]

At those speeds, you'd spend more time getting through security & customs than you would in flying out.

Re:No sonic boom?

[jamstar7]

LA to Melbourne in under 14 hours? COOL!!!

You talk about not being able to fly supersonicly over land... And then you give one of the few routes that doesn't require flying over land?

As has been pointed out, Concorde had a 4800 mile range. LA to Melbourne is quite a bit further than 4800 miles. However, the 'Concorde II' might have been designed with longer range, perhaps enough to make the flight nonstop.

Re:No sonic boom?

[Anonymous Coward]

As a general rune, Air Force and Navy regs prohibit supersonic flight over land outside designated airspace. Of course if you are living near an Air Force or Navy fighter base, it is likely that there is a nearby chunk of Special Use Airspace that is approved for supersonic flight. If you lived "in the middle of nowhere" it is likely that you were living under SUA and supersonic flight was approved, usually above 10,000'.

Re:No sonic boom?

[wreakyhavoc]

I remember seeing an aircraft of some sort in the daytime with a trail of fire coming out of the back of it. It was too far up to see if or what kind of wings it had. Didn't seem to be a rocket. Moved slow like a passenger jet. Never did figure out what it might have been. Was on the Northwest coast of USA.

Re:No sonic boom?

[Arrepiadd]

I seem to recall the SR-71's leading edges were actually designed to handle deforming at said high-temperatures.

It was not only the leading edges that were designed that way, the entire plane was designed taking into account that it would expand. Here's an interesting citation from the Wikipedia page for the SR-71:
"To allow for thermal expansion at the high operational temperatures, the fuselage panels were manufactured to fit only loosely on the ground. Proper alignment was only achieved when the airframe heated due to air resistance at high speeds, causing the airframe to expand several inches. Because of this, and the lack of a fuel sealing system that could handle the thermal expansion of the airframe at extreme temperatures, the aircraft would leak JP-7 jet fuel onto the runway. The aircraft would quickly make a short sprint after takeoff to warm up the airframe before being refueled in the air, prior to departing on a mission."

Re:No sonic boom?

[todd_is_not]

No. That house was over around 50th or 60th East, north of Ave. E. We went and checked it out after the feds got done with it.

We lived off of 120th East. If you drove into the base, our house was the last one. It was on the west side of the road, about 1/4-mile back.

Re:No sonic boom?

[WindBourne]

That was only a recent item. Just 10 years ago, I would have said that NYC/LA or NYC/europe were far more useful routes.

Re:No sonic boom?

[Sardaukar86]

I remember seeing an aircraft of some sort in the daytime with a trail of fire coming out of the back of it. It was too far up to see if or what kind of wings it had. Didn't seem to be a rocket. Moved slow like a passenger jet. Never did figure out what it might have been. Was on the Northwest coast of USA.

As an ignorant layperson replying far too late to your post, my limited experience knows this phenomenon as 'Torching' - the wiki article on Fuel Dumping has a nice picture at the bottom that seems to fit your description and mine (although I've only ever seen this done in the air at shows rather than at takeoff as per the Wiki pic)

Romulans?

[gstoddart]

Is it me, or does that look like a Romulan War Bird? :-P

Re:Romulans?

[nschubach]

They are designed that way to reduce warp booms.

Re:Romulans?

[Guppy06]

They don't want the Federation to hear them coming.

Re:Romulans?

[jamstar7]

Who knew Warbirds had to do sonic boom-less flight?

Of course, considering they're supposed to be heavy on the stealth, it shoulda been obvious...

Re:Romulans?

[tiago.bonetti]

Paint it green and travel the galaxies...

Re:The problem.

[taktoa]

No shit, but the fundamental problem with the old Busemann biplane is the the lift from each wing would cancel out.

They failed to mention the crash on takeoff...

[JoeMerchant]

They didn't mention the fatal crash on takeoff as one of the contributing factors grounding the Concorde, but they did say:

and there may be a boom in the field in the coming years.

Re:The problem.

[sexconker]

Except it wouldn't.

Tom Swift

[RoccamOccam]

Pshaw. Tom Swift, Jr. solved this years ago: http://en.wikipedia.org/wiki/Tom_Swift_and_His_Sonic_Boom_Trap

Solving the worng problem

[TrumpetPower!]

Sure, sonic booms are (more than just) annoying, but that's not why we're highly unlikely to ever see supersonic commercial flight again.

The problem is that supersonic flight requires too damned much fuel for too little gain. Airlines are struggling to make a profit with today's already-fast airliners as fuel costs skyrocket. Cutting a six-hour flight (with a hour of "secure" groping before takeoff and another hour each to get to and from the airport) to a four-hour flight (with the same groping and pre- and post-travel times) just isn't that big of a deal. And it's especially not worth more than double the expense.

Figure out a way to move just as many people at a time with existing infrastructure with half the fuel, even if it means adding 50% to the travel time, and then the airline industry might get excited.

But this thing just ain't gonna take off.

Sorry.

b&

Re:Solving the worng problem

[Anonymous Coward]

with a hour of "secure" groping before takeoff and another hour each to get to and from the airport

Not at the pass classification they would be flying. You pay enough for your tickets or you fly enough and they cut down the lines.

Re:Solving the worng problem

[T Murphy]

The problem is that supersonic flight requires too damned much fuel for too little gain

Of course, at altitude the speed of sound is slower, further aggravating the problem of trying not to inch too close to the sound barrier. Although faster subsonic flight could be achieved simply by flying in lower, denser air, obviously the best solution is to take advantage of the speed of sound being many times faster through water and make submersible airplanes. By flying planes through the water, we could save time even going only half the speed of sound, which clearly means we would save fuel too. It also has the added benefit of eliminating air pollution.

It goes without saying, but after getting this technology to market, we will have to develop planes that fly through the ground, taking advantage of the much higher speed of sound in solids.

Re:Solving the worng problem

[SleazyRidr]

Sure, shaving 2 hours of a six hour flight time isn't that big of a deal, but there are places outside the US, and sometimes people like to fly there. Cutting 6 hours off the flight from LA to Sydney would make my life significantly more enjoyable when my mother tells me that I have to come visit her lest I be disowned.

Re:Solving the worng problem

[Chuckstar]

Concorde flight time from JFK to Heathrow was closer to 3 hours. And among a very wealthy (or expense accounted) class it was very popular (just not quite popular enough).

But remember that the biggest impediment to the success of Concorde might have really been that it only made sense to fly JFK Heathrow and JFK de Gaulle. Because of this, few planes were built, eliminating any economies of scale of building or even maintaining them. Also eliminating the possibility of follow-on models -- as it is often the subsequent models where the manufacturer finally gets it "right".

The reason this is announcement is a big deal, therefore, is that it potentially fixes Concorde's achilles heel -- that it was only allowed to go full speed over water, and didn't have the range to go over water any further than NY to Europe. This plane could fly over land, and have a longer range -- opening the possibility of many more city-pairs, many more sales, therefore economies of scale.

Having said that, barring a magic bullet like "engineers figure out sure-fire way to make a Mach-2 passenger jet at only 50% higher cost per passenger mile with limited up-front development risk", you are correct that no one is going to spec billions to see if they can make the thing work. Concorde was cool, but a financial boondoggle for Britain and France. Boeing thought about making a (relatively) efficient Mach-0.95 jet, but at the cost of a dramatic departure from traditional airliner design. They decided the risk was too great and went with the more traditionally-shaped 787.

We're stuck at Mach-0.85 until another government decides to underwrite the development costs. There's just too much risk for a private corporation to take on. They could spend billions and have it just not work.

The one possibility for this tech, however, is for a really high-end private jet. A guy like Burt Rutan might be able to put together a skunk-works-style prototype of the thing, and then sell copies at a few hundred million a piece. At that price, could probably sell a half-dozen around the world.

(Note: current passenger jets can reach top speeds above Mach-0.9, but typical cruising speed is right around Mach-0.85.)

Re:Solving the worng problem

[Anonymous Coward]

It depends at what speed you are flying at. Drag generally decreases once you go past mach 1. Once you get out to mach 3.3 or so, your drag is about the same as flying at high subsonic. This means that your fuel use would be about the same for modern airliners, but you could go from NY to London in about 3 hours.

There are studies for straight wing high AR transports. These would be slower than a modern airliner but could be more efficient, requriing small engines and not using as much fuel per passenger mile.

Hybrid airship is the way to go if you want little or no fuel cost. It might take a week to cross the atlantic, but a solar powered airship would elminate fuel costs entirely.

Re:Solving the worng problem

[Sez Zero]

Sure, sonic booms are (more than just) annoying, but that's not why we're highly unlikely to ever see supersonic commercial flight again.

The problem is that supersonic flight requires too damned much fuel for too little gain.

That's the whole point of the research, to find out how to fly faster, with less fuel. From the fine article (the MIT release):

They found that smoothing out the inner surface of each wing slightly created a wider channel through which air could flow. The researchers also found that by bumping out the top edge of the higher wing, and the bottom edge of the lower wing, the conceptual plane was able to fly at supersonic speeds, with half the drag of conventional supersonic jets such as the Concorde. Wang says this kind of performance could potentially cut the amount of fuel required to fly the plane by more than half.

Cutting fuel requirements by half and cutting drag by half, that's pretty good. Really, the headline is wrong-- they weren't out to remove sonic booms, but how to use and modify an old biplane design that reduces sonic booms to make a more fuel efficient supersonic design.

Re:Solving the worng problem

[peragrin]

if your going to fly through the ground you might as well,
Dig a tunnel,
setup a maglev train with self contained atmosphere,
Seal the tunnel and vacuum all the air out of it,
travel at ridiculously high speeds without air friction slowing you down

Re:Solving the worng problem

[AmiMoJo]

That's why high speed rail is a better option for most short and medium haul flights. No security, just get on at a station right in the middle of town and relax in comfort, space and quiet. Luxuries like in-seat power and in-flight wifi are standard, plus you can use your phone and other electronics as much as you like. No luggage limits either.

Current 320kph speeds are not bad, but mag-lev will hit 550kph easily. I just wish the Japanese would hurry up and build their long distance mag-lev track because, well, there always has to be a first.

Re:Solving the worng problem

[isorox]

Sure, sonic booms are (more than just) annoying, but that's not why we're highly unlikely to ever see supersonic commercial flight again.

The problem is that supersonic flight requires too damned much fuel for too little gain. Airlines are struggling to make a profit with today's already-fast airliners as fuel costs skyrocket. Cutting a six-hour flight (with a hour of "secure" groping before takeoff and another hour each to get to and from the airport) to a four-hour flight (with the same groping and pre- and post-travel times) just isn't that big of a deal.

Heathrow to Singapore is currently 14 hours. Increase the range, double the speed, and you're saving a lot of money.

Concorde was never for you and me. It's for people that don't blink about prices. A walk on return fare from LHR-JFK is about $15k. People pay that without blinking.

Concorde might work if
1) Range + boom meant you could fly longer, like NYC-SIN/DXB, LHR-DXB, maybe even IAH-DXB. 6 hours New york to dubai rather than 13? Currently Emirates share $20k for that trip. Would people pay $50k to save 7 hours? An extra $5k an hour.
2) Internals were remodelled with decent seats (Something like Emirates F suites, or even just a plain old BA club world seat) to make a 6 hour flight comfortable

Re:Solving the worng problem

[bill_mcgonigle]

We're stuck at Mach-0.85 until another government decides to underwrite the development costs

Go tell DARPA it would make a super-stealthy spy plane. Come back in 2030 for your NY to New Delhi 6-hour flight.

Re:Solving the worng problem

[damburger]

It wasn't that it only "made sense" to to flights to JFK - it is that the US attempt at a supersonic passenger jet was an utter failure, and when UK/France got theirs built first you guys basically through a hissy fit, banned some of the most profitable routes (across the US and back in 1 working day) on the shallow pretext of sonic booms

(hint: The US isn't exactly densely populated. The problem was manageable even over land)

Re:Solving the worng problem

[91degrees]

The US wasn't the only potential buyer. Concorde had over 100 pre-orders, including those from Germany, Japan, Australia, Canada and the middle east.

The problem may have been manageable from a technical point of view but public perception was a problem.

Re:Solving the worng problem

[damburger]

...and all those orders were scuppered by various countries who basically didn't like the fact we had something they didn't. Grumbling from a few members of the public was just a pretext. The corralling of Concorde into transatlantic trips was a purely political decision from all parties, to stick it to France and the UK.

Would be nice if they get it working

[ArcadeNut]

The major thing holding back the Concord from operating domestically was the noise factor. If they could eliminate or reduce that noise level, then we could see super sonic flight from coast to coast... Probably won't happen, but one could dream....

Re:Would be nice if they get it working

[UnknowingFool]

Fuel efficieny is another problem. The Concorde could use as much fuel as a 747 but the 747 could carry 3 times as many passengers. Air France and British Airways simply charged more for Concorde tickets but not all airlines can do this.

Re:Would be nice if they get it working

[peragrin]

part of that though was afterburners. newer jet engines are supersonic capable without afterburners.

See F-22 raptor.

The concord used afterburners to get up to speed and then could use it's regular engines to maintain it.

The F-22 dones't need afterburners to get to mach 2.

Re:Would be nice if they get it working

[Richard_at_work]

The fuel efficiency of the F119s on the F-22 isn't all that better than the Olympus's on Concorde, and Concorde could push all the way to Mach 2 without reheat but it's more fuel efficient to use reheat than not (using reheat means Concorde spends less time in the transsonic region of high drag). What the F-22 has in its favour is its thrust to weight ratio, which is a lot better than Concordes...

Remember, civil operators have an entirely different set of criteria to military operators, and military operators are more than willing to sacrifice some elements of efficiency to achieve better survivability. For civil operators, efficiency means more revenue and profit.

Re:Would be nice if they get it working

[UnknowingFool]

The size of the plane is another factor. The Concorde could only hold 100 passengers which is pretty small. While engines have advanced, structural engineering has as well. I don't know if it has advanced enough to where they make a much larger plane that could go supersonic without costing too much for it to be competitive. Boeing's 787 is using advanced materials to lower fuel costs but project overruns has started to become evident. And the 787 does not have to factor in supersonic considerations.

Re:Would be nice if they get it working

[rdebath]

I've worked under the flight path of Concord taking off from Heathrow.

You are not wrong, the engines are very very very loud.
The office was specially soundproofed. From the right rooms you could see the planes landing; they are heading straight for you looking like they're rather likely to land in the car park.
The Smokers (who weren't allowed to smoke in the office) made real sure that they were never outside when the Concord went over.

It sets of car alarms.

On a good day shakes your eyeballs, the whole world goes wobbly.

Re:The problem.

[Anonymous Coward]

Why don't you guys figure this out, OOB, and get back to us.

What?

[dezent]

Not very much to discuss here is it? Old blade with some text on it.

Re:What?

[dezent]

Not very much to discuss here is it? Old blade with some text on it.

I was commenting on the wow server, why is my comment here?

Re:What?

[Digital Vomit]

It is not for us to ask why the Slashdot Servers do what they do, peace be upon them.

Re:Would would want . . .

[X0563511]

... only if:

1. When you have an orgasm, everyone within a few miles felt it, but you didn't
2. Instead, you only got a light shudder

Re:The problem.

[Chuckstar]

The MIT team is not using an adaptive wing. As described by Icyfire0573 above "...they fixed that by taking the old design which had no lift, ran it through a ton of simulations and found a design which has the lift necessary to fix this."

There is a team in Japan that is using an adaptive wing. Depending on exactly how the Japanese team's wing adapts, that could be an impediment to use in a commercial airliner. Thinking about current airliner designs, the wing surface shape is modified by flaps and slats, but the core load bearing structures of the wings (spars and the connection points to the airframe) remain fixed. I would be wary of a swing-wing design for commercial air, for instance, but something similar to flaps/slats would theoretically be no more of a safety risk than today's (incredibly safe) designs.

In addition to safety, there is also the simple fact that fewer moving parts would be cheaper to build and maintain.

Sub-supersonic speeds?

[damburger]

At sub-supersonic speeds, a Busemann Biplane doesn't produce sufficient lift under acceleration, undergoing considerable drag.

Well, that is all well and good - but what happens at super-subsupersonic speeds?

Re:The problem.

[HornWumpus]

E and F engine rocket kits are supersonic. Not much more then an Estes.

I'm pretty sure some of the 3 stage Estes rockets can go supersonic on 2 Ds and a C. They lose their fins when they do though. I never did find anything but one of the fins.

Re:The problem.

[pittance]

The Busemann biplane came up when we did supersonic aero in University back in '98 or '99 and it was always stated to be an impractical wing design because, at the supersonic zero boom/zero wave drag condition, it couldn't produce lift; this doesn't stop it being useful for other things like shells etc. where you don't mind zero supersonic lift if you can get low drag

The diagrams in the article seem to look like that condition in supersonic flow where the "inner" surfaces interfere favourably with each other to cancel wave drag and have the upper and lower surfaces with no incidence to the flow so they produce no shock waves.

Supersonically it should still produce lift quite happily if you angle it so there is incidence to the flow but I think that it should then produce wave drag and booms... For example I can't see from the article how, in a lifting condition, the shock wave from the compression of the supersonic flow on the undersurface (which produces the compression & higher pressure that helps lift the wing) could be cancelled out without having another wing underneath that; then you have the same problem with the undersurface of that wing & then you're in a "it's wings all the way down" problem.

Conventional 'low boom' solutions (like the Gulfstream/NASA "quiet spike") all tend to shape the nose of the aircraft to reduce the suddenness of the pressure increase across the shock wave but they aren't able to eliminate it...

It could be that they've found a case where they can get low wave drag/boom while still producing some lift and also getting decent subsonic lift/drag - that would be really interesting...

How is the pilot supposed to see the runway?

[s_p_oneil]

How is the pilot supposed to see the runway in that? One of the problems with the Concorde was that the pilot couldn't see the runway, which they addressed by causing the nose-cone to pivot downward during take-off and landing (which caused its own problems). This design looks even worse from that perspective.

Re:How is the pilot supposed to see the runway?

[grumbel]

Given that it will take quite a few years or decades before such planes go into production, it will probably all be done by autopilot by then.

Re:The problem.

[element-o.p.]

What's wrong with a swing-wing? The USAF has used them since at least the 1960s and still uses swing-wing aircraft today. The B-1 even is similar in size to an airliner: Rockwell B-1, Boeing 737 (smaller) and Boeing 747 (bigger). It would seem to me that if a similar sized aircraft, travelling faster, at comparable weights, is sufficiently strong for military use, it should be plenty strong for commercial air travel. I imagine that it would be quite a bit more expensive to maintain than a fixed-wing airliner, however.

Ugly

[DaMattster]

It is kinda cool that they found a way to eliminate the sonic boom, however the concept is ugly. Plus, I don't think there is much interest in super sonic aircraft as they tend to be very thirsty and oil is not inexpensive.

Re:The problem.

[element-o.p.]

With a zero degree angle of attack your aircraft with any amount of thrust will fall...

Are you sure about that? I think you confused "angle of attack" with "coefficient of lift."

There are airfoil designs (basically, any asymmetric airfoil) that will produce lift at an AoA of zero degrees. If lift is non-zero, then the only question is how fast does an aircraft need to be going to generate enough lift to overcome weight at a zero-degree angle of attack?

Also, just to be pedantic, the balancing act is between lift, weight, thrust and drag. Lift is related to AoA so I'll concede that you basically covered that force, but you completely neglected to mention drag above.

Re:The problem.

[mhajicek]

Looks to me like it might be a good profile for a ramjet. If so you could have your whole wingspan produce thrust. Am I wrong?

Re:WW1 biplanes...

[element-o.p.]

Only if by "near the speed of sound", you really mean "a little over 100 mph."

Re:The problem.

[WindBourne]

you need to finish reading the whole thing. The stanford/MIT version is what is being talked about. The japenese version simply was a reconfirmation of work done earlier that backed the dual wing. Nothing more. The stanford/MIT modification gave it lift via static configuration, while the japanese version would have to change wing shape dynamically ( read expensive).

Re:The problem.

[WindBourne]

The B-1 is from carter's time. IOW, it is an OLD bomber. Not as old as B-52, but old in design nevertheless.

Re:The problem.

[ericloewe]

Cost, weight and lost cargo/fuel space. The three demons of commercial flight.

Re:The problem.

[element-o.p.]

Sure, but it's still in service today, which is all I said above.

Re:The problem.

[element-o.p.]

I agree that all of those are valid reasons for manufacturers not to build a swing-wing airliner. However, and perhaps I was reading to much into the post, it sounded to me like Chuckstar didn't trust a swing-wing design, not that he thought it would be too costly and inefficient to use in commercial air service:

I would be wary of a swing-wing design for commercial air, for instance, but something similar to flaps/slats would theoretically be no more of a safety risk than today's (incredibly safe) designs.[emphasis mine]

My point is that if an F-111 or B-1B can survive combat, they certainly can survive commercial service.

Re:The problem.

[funwithBSD]

This is not a breakthrough, it is just a canard.

but

[Hsien-Ko]

they didn't eliminate flash kick

Re:WW1 biplanes...

[Samantha Wright]

Of course that's the speed of sound. It's the speed at which the wind resistance makes sound.

I hear it's a big wooshing noise...

Re:The problem.

[bill_mcgonigle]

I'm pretty sure some of the 3 stage Estes rockets can go supersonic on 2 Ds and a C. They lose their fins when they do though. I never did find anything but one of the fins.

I got bored with model rocketry after my first three rockets were one-shot flights, never to be found again. I wonder if this explains why. How soon do they go supersonic? I was able to at least see that mine went straight up until my eye couldn't resolve them anymore. If they went supersonic, they'd start to tumble, right?

I never saw a parachute, but didn't hear any explosions either.

Re:The problem.

[Whippen]

It's not a canard at all, completely different principles. A canard is designed so that the forward wing will always stall before the main wing, ensuring that the entire aircraft has significant positive stability. Combined with the benefits of a pusher propolsution, you get a stable yet maneuverable aircraft.

Designing a bi-plane to reduce the sonic boom is resolving a completely different problem, using completely different designs.

Re:The problem.

[QuantumLeaper]

Estes rockets were fun, I remember when I lost a fin on one of mine, it hit a boat behind a house, I really thought it was going fly right into the house. I do agree, I never tried it but a friend of mine would use a couple of Ds, and always lose the rocket.

Re:The problem.

[Ihmhi]

It is kind of... weird that we can't seem to scale up the speed of fighter jets and the like. But we'll solve it soon enough. The Concorde was an interesting experiment, but this might actually be usable.

I just hope the layperson would be able to use it in 20 years and that the airports still won't be a wasteful black hole of time-seeping despair. A 5 hour security checkpoint kinda deflates the fun and novelty of popping over to Britain for dinner with a friend and then back home to sleep.

Re:The problem.

[WindBourne]

Sure. But so is the B-52 as well as KC-135 (military version of B-707). Think that those are good models to follow?

Projectiles?

[Mike Buddha]

I wonder if there's any way to make a projectile with similar characteristics?

Re:Projectiles?

[Spy Handler]

you mean put biplane wings on a bullet?

Sounds practical...

Re:The problem.

[Anonymous Coward]

I wonder what happens if the cancellation effect gets out of sync. Maybe a wing loses a bit of material or hits an air pocket that the other wing doesn't experience.

In my head I see this plane zooming along supersonic, hitting some turbulence, shaking a bit, then BOOM! the whole thing explodes into bits of carbon-fiber and aluminum confetti.

Re:The problem.

[funwithBSD]

Try some lateral thinking.

Re:The problem.

[mosb1000]

The military isn't investigating new swing wing designs, even though they have obvious benefits for carrier launch planes and supersonic planes, simply because they cost too much to keep in the air. It's unlikely you'll ever see a commercial one for the same reason. It's too expensive to have moving portions of the wing supporting the weight of the aircraft.

Re:WW1 biplanes...

[element-o.p.]

Okay, the first half of your post was funny...but is this reading-comprehension-fail-day on /.? No, there was no whooshing noise over my head. I understood the joke that the "sonic boom" was the sound of the airplane crashing ("Boom!" ha ha). My point was that WWI biplanes don't approach anything even vaguely resembling the speed of sound. WWI biplanes come apart in the air at speeds that I have achieved in the low-end Cessnas* in which I learned to fly -- which is a far, far cry from the speed of sound.

*Granted, not in level flight, and I was approaching red-line speed, but flying short-final at near Vne was a lot better than getting run over by the 747 that was breathing down my neck.

Re:WW1 biplanes...

[Samantha Wright]

Yeah... it was weak. I'm sorry, I was in the middle of battling three deadlines. (Two of them are now winning.) It seemed like a witty thing to throw in there at the time. The true Tao of Slashdot, though, is that you can always make a "Woosh!" comment, and claim there is some inner secret in the previous statement that no one else will ever understand. Sort of like a socially inept version of no soap radio.

Re:WW1 biplanes...

[element-o.p.]

LOL. Good luck with the deadlines!

By the way...sorry to be grouchy earlier

Re:The problem.

[Magada]

You are thinking of scramjets. The flow is supersonic here.

New character...

[lothar4ever]

Now Guile will probably lose all his fights :(

Re:The problem.

[VisceralLogic]

Now I might well be wrong here, but doesn't the leading edge of the aysmmetric airfoil have to be higher than the trailing edge to create lift once power is applied?

Nope, camber can be used to generate lift.

Re:The problem.

[HornWumpus]

You missed out. I recall one rocket that I got over 50 flights on. Then we discovered the reloading department at the local gun shop (truth is, Dad clued me in when he caught me getting ready to cook some nitroglycerin.)

I only ever launched one 3 stage D engine rocket. Never saw the top stage light. Only found a fin. Barely found the second stage.

Re:The problem.

[bill_mcgonigle]

.I only ever launched one 3 stage D engine rocket. Never saw the top stage light. Only found a fin. Barely found the second stage.

Oh, I forgot to write that this was my problem. They all had multiple D engines in them. If I had stuck with the smaller ones (or perhaps lived on the Great Plains) it would have been much more rewarding!

Re:The problem.

[element-o.p.]

I repeat:

I agree that all of those are valid reasons for manufacturers not to build a swing-wing airliner. However, and perhaps I was reading to much into the post, it sounded to me like Chuckstar didn't trust a swing-wing design, not that he thought it would be too costly and inefficient to use in commercial air service:

I would be wary of a swing-wing design for commercial air, for instance, but something similar to flaps/slats would theoretically be no more of a safety risk than today's (incredibly safe) designs.[emphasis -- and additional emphasis -- mine]

My point is that if an F-111 or B-1B can survive combat, they certainly can survive commercial service.

I did not say that it was economical, efficient, or even a good idea to build a swing-wing airliner. I said that concerns about structural integrity was not a reason to avoid swing-wing aircraft.