Now look at the center section on this Horten 229 drawing
Now look at a BWB with "C-Wings"
BTTT
Posted on 07/27/2007 8:17:19 PM PDT by radar101
Um, you have actually seen a Northrop B-2, haven’t’ you?
ping
B2s have thrust through cg. They also don’t carry passengers and are piloted by the elitest of the elite who get paid to risk their lives.
Being able to see outside is somehow very helpful for passengers not controlling the aircraft. Lacking vertical control surfaces other than winglets makes me think it could have yaw difficulties when its equilibrium is upset, as would happen in turbulence. Combine those two and you have a bunch of sick passengers.
But you're right, by the time this design hits the mainstream, I'm sure the control and physiological issues will have been worked out. Flying wings and blended wing designs are very efficient, so it's possible they'll make it into commercial service someday.
I'm guessing that it can use other control surfaces, such as increasing the drag on one wing a little more than on the other, to keep the nose pointed in the forward direction.
But, yes, all things equal, something is going to have to work overtime to keep this baby flying steady.
The wind tunnel tests seem to be promising. From New Scientist
A futuristic "blended wing" plane developed by NASA has passed crucial wind-tunnel tests. These reveal that engineers may have overcome some of the controllability challenges associated with the revolutionary aircraft design.Designs for blended wing planes are a dramatic leap from that of today's passenger jets – instead having a tube-like fuselage. They look more like paper aeroplanes with engines mounted on top and at the rear.
The unusual shape is much more aerodynamic than a normal plane, which means it could use 20% less fuel. And it should also be much quieter for people on the ground because the engines sit on top of its wings instead of hanging below.
But the extremely sleek design means doing away with a tail – a crucial control element – so engineers have had to come up with other ways to make the aircraft pitch, yaw and roll. For a blended wing plane, this means relying on curved flaps along the edge of each wing and rudders on each wingtip.
Lift drop
NASA engineers have struggled to find the perfect configuration for the design but the latest tests suggest they are getting closer. They took a 5% scale model of their latest blended wing design to a wind tunnel at Langley Research Center in Hampton, Virginia, US, for a free-flying test.
"We were kind of concerned early on that it was going to be difficult to fly,” says Dan Vicroy, head of the project at NASA. "The bottom line from the test: this particular configuration flew great."
The engineers were particularly keen to see what would happen when the aircraft approached maximum lift and then lift suddenly dropped, as can happen when an aircraft hits turbulence. Unlike previous designs, the aircraft did not start to roll or pitch backwards.
During wind tunnel tests, a model is normally mounted while wind flows around it, allowing engineers to measure forces on the static design. This time, however, three "pilots" remotely controlled the scale model's movement during the test. It was the first time anyone has tried such a test of a blended wing design....
Well lookie there. I guess my instincts were pretty good. I took one look at that thing and thought “pitch like a mother”. Hence my 3x5 card analogy. And the roll problem is a result of not having any wing dihedral. The thing is gonna handle like a dictionary layed horizontal balanced on a beach ball sitting on a trampoline. One little jostle and WHOOPS.
Those winglets should provide a good deal of yaw stability, especially with computer stability control.
But clearly based on the X-48.
The thrust line of the B-2 isn't over the top of the wing, as in this design, ,but pretty much straight down the vertical center of the aircraft. However I don't think the position of the engines on the scaled down X-48B is what any eventual operational aircraft, military or civilian, would have. But if it was, a little thrust vectoring would go a long way.
....They also don’t carry passengers and are piloted by the elitest of the elite who get paid to risk their lives.
Actually, I bet most of the piloting is done by the flight computer...:^)
It has to be, since it is dynamically unstable...
http://www.vectorsite.net/avb2.html
Flying wing much bigger payload..
Wish I knew how to post pics. Go to:
http://www.strange-mecha.com/aircraft/FW/Northrop.htm
Northrup was actually flying the flying wing concept circa 1947-48 with plans for both military bombers and airliner versions.
ping (step towards a BWB Boeing 797?)
Now look at the center section on this Horten 229 drawing
Now look at a BWB with "C-Wings"
BTTT
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