Slashdot Mirror
Boeing Blended Wing Body Aircraft
pcolley writes "I love it when Science Fiction becomes reality. Boeing is nearly finished designing their super efficient Blended Wing Body (BWB) airplane. It looks like the BatJet." Boeing is considering both civilian and military roles.
I just hope that they have worked out the stability problems. The "all-wing" design has been notorious for being unstable except with computer help and "fly by wire" controls. If they have trumped these problems, go ahead; besides, I have no need to see outside the craft (one of the downsides mentioned. The passengers would be seated in wide rows only a few deep- think of the current tube and turn it 90 degrees, so only a few people would have window seats). But they are considering placing LCDs in front of all the seats with the option of seeing outside the plane. Now if they gave me ultra zoom over the midwest so I could see that farmer's daughter......
Vote monkeys into Congress. They are cheaper and more trustworthy.
It's difficult to imagine anybody flying in this thing. For one thing, the passengers are intended to be kept in compartments close to the center of the aircraft, so no window seats. The very wide body means much greater displacement when the aircraft banks so even a slight bank would feel like a roller coaster ride for those on the extremities. One of the most important design challenges is emergency evacuation. And -- would the average person fly in a radically new, untested airframe?
Toronto-area transit rider? Rate your ride.
I'm inclined to act on behalf of Jack Northrop, who was flying blended wing bodies in the 40's. I'm calling BULLSHIT! The N-1M is still a popular flying wing aircraft with private pilots today. The N-9M is equally popular with model aircraft enthusiasts (I personally spent two years of my youth finding a rare Tamiya kit of one of these). Then theres the B-35 which just barely missed WWII, but was featured in the original Orsen Wells "War of the Worlds" movie. Then there was the YB-49, a jet powered blended wing bomber. And lets not forget the MX324, Americas first rocket powered military aircraft (the designation "MX" is for "Missile, Experimental", which probably didn't comfort the pilot too much). Of course, the Nazi's had everyone beat with their ME-262 Komet - a rocket powered blended wing fighter-interceptor.
Boeing can no more claim this is "revolutionary" than I can claim that my G3 PowerPC powered linux server at work is revolutionary.
http://www.wpafb.af.mil/museum/fta/fta198.htm"
And -- would the average person fly in a radically new, untested airframe?
Boeing has a solid method of both ensuring an plane's good design and ensuring the public that their plane is airworthy.
The send the design engineers out with pretty much all the first flights. As a budding mechanical engineer, that's damn good motivation for me to make sure my plane is designed well.
Alcohol, Tobacco and Firearms should be the name of a store, not a government agency.
There've been delta-wing type aircraft since the 50's. Always touting the "lift of the entire aircraft". What exactly is the issue that 1) they have never caught on with the airlines or public and 2) Boeing thinks it's solved? What am I missing?
Calling this airplane a "delta-wing" is a misnomer. The Saab Gripen fighter and the Concorde are delta-wing aircraft, the BWB is not. The blended wing body is best described as *suprise* a "Blended-Wing Body." It is not just a flying wing, and is not a delta wing.
The "revolution" is in the application of this technology to a practical and profitable passenger aircraft. The idea that blended wing aircraft have not caught on with the airlines or the public is ridiculous. The airlines are in fact eager to purchase airplanes that are more profitable, and the public is eager to save money.
I notice several posters questioning why, if this thing's so great, we haven't seen it before. While this would seem a rather odd question on a TECHNOLOGY based forum such as Slashdot, I've tried to offer a bit of an explanation.
Prior to now the BWB was not an option for several reasons, perhaps the greatest being the design of a pressure vessel (remember airliners are pressurized). Typical tube and wing style airliners solve the problem of the pressure vessel by taking pressure load in hoop tension. While this is, from a structural perspective, the preferred way to carry the pressure load, it is not feasible to do so in a BWB aircraft, as the vessel is shaped more like a pancake. This brings is to our first point, modern composites permit a pancaked pressure vessel that will tolerate the load at an acceptable weight. The materials available prior to now (aluminum) were simply not workable in the design of such a pressure vessel without an enormous weight cost-thus vitiating the efficiency increase of the design and sending costs prohibitively high.
In addition to the materials issues, another factor that made Blended Wing aircraft heretofore infeasible was the fly-by-wire systems needed to solve the stability issues associated with the design. Although Northrop's early flying wings flew without benefit of computers, they did exhibit some nasty characteristics and were very sensitive to center of gravity changes, issues that aren't acceptable in a commercial airliner.
That said, the fly-by-wire systems of today eliminate the stability issues that plagued early designs. For those of you who believe computer controlled and stabilized aircraft are not feasible for service in commercial applications due to safety considerations, look no further than the Airbus A-320 & A-319. Both of these aircraft use full authority fly-by-wire. All control actuators are electro-hydraulic, when the aircraft is in autopilot, the stick does not move when control inputs are made by the autopilot, and the throttles sit fixed in a "cruise" detent-regardless of actual throttle position as seen from the perspective of the engine's fuel distribution unit. Further, the aircraft has full trim authority, constantly trimming to 0 G, with no provision for pilot override. What all of this adds up to is that there is no physical link between the pilot and the control surfaces of the aircraft. When the pilot makes an input, the computer decides if, and how much, a given surface will deflect. Complex as it sounds, it works, and works well, and given the degree of redundancy required of flight-critical systems (10^-9 I believe) for certification, the likelihood of full failure is less than today's direct-hydraulic systems
With these problems solved, the design makes infinitely more sense than the tube and wing designs of old. It is much more fuel efficient, and given the overwing engine mounting, much quieter, as aircraft with engines slung under the wings reflect noise off the wings and back at the ground, whereas overwing mounted engines reflect the noise up. Overwing mounted engines are also less susceptible to ingesting debris, and bird strike on rotation.
In short, the BWB is a better way to design an airplane, and this note only scratches the surface as to the reasons why. We haven't seen them before because they weren't feasible before, but now that they are, let's hope Boeing pulls up their socks and builds one
Boeing, fielding a flying-wing-type design?? Sheesh... Boeing is the reason these sorts of planes weren't commonplace 50 years ago!!
Listen, children, to today's aerospace history lesson....
Waaaay back in the late 1940's, Boeing was the darling of the newly formed US Air Force, on the strength of their sturdy, functional WWII bomber designs (B-17, B-29).
However, they were not the only manufacturer capable of designing high-capacity long-distance aircraft.
One of the sucesses of the WWI aircraft industry was a startup called Northrop Aircraft. Led by the brilliant and iconoclastic designer John Northrop, they had started with nothing but ideas, but by the end of the war had already provided one remarkable aircraft to the war effort, the US' first dedicated radar-equipped night fighter, the P61 Black Widow, which decimated Japanese airpower in the latter stages of the war.
John Northrop was well versed in our enemies' aircraft design efforts. He was particularlry intrigued by the work of Germany's Horten brothers, who did pioneering work on "flying wing" aircraft. Much like Boeing's "blended body/wing" designs, there was no separate fuselage; the entire aircraft contributed to lift, and hence were astonistingly efficient.
(Aside: the Hortens also experimented with the use of evading technologies. Their early wings were built of plywood, but their shape, with no corners, no edges, no right-angle "reflector" areas between tail fins or between fuselage and wing, made them unusually hard to detect on the primitive radars of their day. The Hortens added conductive layers of charcoal to the plywood layup, reducing the already low signature dramatically, creating the world's first "stealth" aircraft.)
In 1940, after the defeat at Dunkirk, the US Army Air Corps was convinced that Britain would soon be overrrun by Germany, and realized that it had no way to strike at European targets from North America. They were desperate to develop a bomber that could reach the Germans if England fell. So they put out an open competition for a transcontinental bomber.
Boeing had already designed a pressurized, high-altitude bomber, the B-29, which later in the war would help decimate Japan, both with conventional ordnance as well as the the first atomic bombs. They offered up an improved version of the B-29 to the competition. (yawn)
Another established airframer, Consolidated Vultee Aircraft (later Convair), borrowed heavily from Boeing's B-29, but proposed a much larger, eight(!)-engine monstrosity, the YB-36, IMHO one of the most homely aircraft ever laid out on paper.
Northrop, on the other hand, shot for the moon. They proposed a radical flying wing design, far larger and more sophisticated than the Horten designs. For the sort of long ranges missions the USAAC was proposing, the efficiency of the flying wing gave it a distinct edge. With a weight similar to the B-29, it had the range of the far larger Convair design, with the same bomb capacity. Northrop had already built experimental flying wings; they folded their accumulated experiment into an amazing prototype, the four-engine YB-35.
Suffice it to say, the USAAC wasn't all that open-minded to such a radical design. Boeing's design was a non-starter. Plus, at the time the congressional delegation from California had leadership positions in key appropriations committees... so the huge, ugly, inefficient B-36 got the nod for full production.
But that wasn't the last of Jack Northrop, or his flying wings.
Almost before the ink had dried on Japan's surrender on the deck of the USS Missouri, tensions with the USSR had escalated to the point where the US military had to consider yet another intercontinental war scenario, but this time the ranges were even longer, up over the North Pole. Hence, another design competition.
Convair's B-36 proved to be a disappointment; even retrofitted with newer turboprop engines, it didn't have the sort of speed and range the new US Air Force needed.
Boeing went back to the well yet again, with a technologically modest design; huge, conventional winged airframe, with four pairs of new turbojet engines to get it off the ground.
Northrop went back to their YB-35, refined the design with the results of the extensive testing they'd done on flying wings since the YB-35, scaled it up for enough volume to carry the bombload and fuel required (and then some!), and replaced the prop engines with turbojets, to create the YB-49.
By all accounts, technologically the YB-49 cleaned up. Northrop was so enthused by their success, they set about designing commercial passenger and cargo versions.
But once again, politics won out.
The details are a but hazy, but Boeing lobbied all the right people very heavily, and in a decision that surprised the entire industry, their design was chosen to become the first nuclear-era strategic bomber: the B-52. Northrop was howling mad, and were quite public with their displeasure.
Just to make the whole affiar that much more scandelous, the Department of Defense sued Northrop, claiming that since the YB-49 was designed for them, they owned the design. They won, and the blueprints vanished from history, precluding the commercial version from ever seeing the light of day. The prototypes and test aircraft were ordered cut up for scrap, to prevent Jack Northrop from embarassing the Air Force with a better plane.
Dont' get me wrong, the B-52 has proved to be an amazing aircraft; whiel far from efficient, it's sturdy enough to allow almost endless modifications, and that has allowed it to survive as a front-line weapons platform even today, 50 years after it's first flight.
But stop and think for a moment where we might be today if the better plane had won, validating the general design. If Northrop's commercial models had been allowed to compete with the more conventional early Boeing and Lockheed airliners.
Yeah, the Blended Wing/Body looks radical in the current context. But it shouldn't.
Learn from the mistakes of others. You won't live long enough to make them all yourself.