X-48B Blended Wing Body makes its first flight

I had no idea that this had progressed this far already:

x-48b blended wing body

NASA: X-48B Blended Wing Body Research Aircraft Makes First Flight

Boeing’s Phantom Works designed the X-48B flight test vehicles in cooperation with NASA and the U.S. Air Force Research Laboratory at Wright Patterson Air Force Base, Ohio, to gather detailed information about the stability and flight-control characteristics of the blended wing body design, especially during takeoffs and landings.

The Boeing blended wing body design resembles a flying wing, but differs in that the wing blends smoothly into a wide, flat, tailless fuselage. This fuselage blending provides additional lift with less drag compared to a circular fuselage, translating to reduced fuel use at cruise conditions. Since the engines mount high on the back of the aircraft, there is less noise inside and on the ground when it is in flight.

Three turbojet engines enable the composite-skinned, 8.5 percent scale vehicle to fly up to 10,000 feet and 120 knots in its low-speed configuration. The aircraft is flown remotely from a ground control station in which the pilot uses conventional aircraft controls and instrumentation while looking at a monitor fed by a forward-looking camera on the aircraft.

Up to 25 flights are planned to gather data in these low-speed flight regimes. Then the X-48B may be used to test the aircraft’s low-noise and handling characteristics at transonic speeds.

Blended wing body aircraft offer the potential for greater internal capacity, increased efficiency, and general coolness. Some had thought that the next mid-air refuelling tanker aircraft should have been a blended wing body.

More, including another picture, below…

From Air Force Times, which includes

“The blended-wing body concept holds tremendous promise for the future of military aviation as a multipurpose military platform in 15 to 20 years,” said Darryl Davis, Boeing’s general manager of advanced precision engagement and mobility systems. “Its unique design attributes will result in less fuel burn and a greatly reduced noise footprint, which are important capabilities to offer our Air Force and mobility customers.”

Two X-48Bs were built. The first one was used for wind tunnel and static testing and will serve as a back-up to Ship 2.

Comments

  1. This was a better design aerodynamically. Too bad they don’t seem to be pursuing it. It could use a few tweaks. The canard is up too high as was the XB-70s. I know I’ve posted this before, but for those who missed it last time go take a look at this video. Right at the end you can see the vortex from the canards (those things that look like smoke) are too far above the wing to develop much lift. Big mistake. Otherwise it was really good.

  2. Sometimes the Vorticies aren’t placed for lift. In the case of an SST like that, they would want minimal vortex generation away from the wings to reduce drag. Thats one of the reasons that they put the little vortex generators at the ends of wingtips, to help reduce wingtip vortex generated drag (not sure exactly how it works). I do know that the F/A-18 had issues with the flared sections above the intakes (chines?) which were supposed to produce vorticies to increase lift at high angles of attack, weakening the vertical stabilizers to the point they actually had to put L braces on the early models to keep them (and the attached rudders) from cracking and falling off the plane. Yah, the SST concept is neat, but the blended wing concept is more of a high efficiency, large volume transport than a high speed (high fuel consumption) low volume transport. Different concepts for different jobs.

  3. Personally I think this blended wing concept has a lot going for it. The most important aspects is its slow speed efficiency and massive internal volume. It would make a great P-3 replacement. If scaled up a tad, it could be made into a true multi-role craft. Cruise missile carrier, fuel truck and bomb truck. That said, the Sonic Cruiser was a beautiful bird, it just showed up at the wrong time. If it showed up say in 1990 when fuel costs were not such a big issue, I think it would of made it into production. Right now, fuel costs are all the rage, and Sonic Cruisers speed advantage was just is not big enough to overcome the Dreamliners operating cost advantages. If we could get serious about find out how to mitigating sonic booms – I could see a sweet spot for Mach 1 to Mach 1.5 passenger supercruiser. As for canards? I have no clue why any plane is dead on arrival if it has canards. There is no logical reason, so it has to be cultural.

  4. The cultural part is really ironic because the Wright brothers airplane had a canard. It was the French who developed the rear stabilizer design. Now the French build canard fighters and our designs are dead on arrival if they have one. The blended wing body designs carry a substantial drag penalty due to the build up of boundary layer air. You don’t get nearly the lift you think you would out of the air that flows over the center section because it is feet deep in boundary layer air. Boeing’s early designs of the blended wing body airplane were interesting because they had the intakes down in the boundary layer sucking it away. Their latest models have them stuck way up in the air where they do nothing to the boundary layer. They are forced to do that because even though they’d gain efficency by sucking up boundary layer air, the drive core section of the engine itself loses performance in that layer because of the ram air pressure loss. Now if they could separate the drive section and the fan section, oh, let’s say like the way LM does with the lift fan of the F-35 VTOL, then they could have the best of both worlds.

  5. Oh, one more thing with regard to the sonic cruiser. There is a sweet spot in the Mach 1 to 1.5 range where you get all the benefits of going supersonic while paying very little in entropy losses. The problem with that region is the shock waves tend to be very unstable and jump around a lot with the slightest air temperature variations. As you recall from your compressible flow books, this can cause the center of lift to jump as well between 25 and 50% of the chord (fuselage) length. Even so, it would be a very efficient design at conventional speeds too. It just wouldn’t be as big a leap as they’d get in the low supersonic realm.

  6. I should read before I hit post. The center of lift jumping around would cause the ride to be horrible for passengers. That’s the down side.

  7. My take on the blended wing design, at this stage of development I think they are just trying to validate their numbers. In 2004 they pretty much proved that the inlets can be used to address the boundary layer problem enough to make it worthwhile, but you hit the nail on the head with the engine problem. That issue is being addressed with active flow control. As far as I know, the AFC is not ready for primetime, but the work to date is promising. That would explain why the current model parks the engines topside. If they can validate their wind tunnel results and get the air force interested enough, Boeing may get a fully funded R&D project going.

  8. Flow control helps the lift, but ingesting boundary layer air in the fan portion of the motor increases the propulsion efficiency, where as flow control usually costs propulsion efficiency. What I would envision working well would be what is now a drive core that would be mounted on the top side of the fan. It would drive the fan via a shaft similar to the shaft they have now to drive the generators and hydraulic pumps, but heavier, of course. That way the fan sits down in the boundary layer and the core is in clean air where it gets plenty of ram air pressure. There are other ways to do the same thing. This would be a good application for those prop fans they did research on years ago. You could feed the core with an S duct like a 727 uses for the center engine.

  9. Funny you should mention an S shaped duct. http://www.ueet.nasa.gov/toi/viewtoi.php?id=79 ‘In support of the Ultra Efficient Engine Technology (UEET) program, a demonstration of Active Flow Control for a boundary-layer-ingesting S-inlet has been completed in the Basic Aerodynamics Research Tunnel after seven weeks of testing.The model is an inlet shape representative of the class of inlets that might be used on a Blended Wing Body configuration. ‘