backtop

Print E-mail del.icio.us 37 comment(s) - last by GeeSussFreeK.. on Aug 3 at 11:12 AM

  (Source: Boeing)

  (Source: Boeing)
The X-48B finally takes flight

The X-48B blended-wind experimental aircraft has been profiled twice before on DailyTech. We first brought you news of the aircraft in May 2006 -- at the time the X-48B was scheduled to take to the air for the first time at the end of 2006.

As is the case with many complex research projects, that first flight was delayed. In March of this year, DailyTech noted that the Air Force, Boeing and NASA were getting close to flight trials for the X-48B. Again, months passed and nothing happened.

Today, we're happy to report that the 8.5 percent scale X-48B finally took to the air on July 20. The 500-pound, 21-foot remotely-piloted aircraft stayed aloft for 31 minutes and reached an altitude of 7,500 feet before touching down at Edwards Air Force Base.

"Friday's flight marked yet another aviation first achieved by a very hard-working Boeing, NASA and Cranfield team," said Dryden Blended Wing Body project manager Gary Cosentino. "The X-48B flew as well as we had predicted, and we look forward to many productive data flights this summer and fall."

The X-48B is powered by three turbojet engines. The engines have the ability to propel the aircraft at speeds up to 138 MPH and can push it to a maximum altitude 10,000 feet.

The research gathered from the X-48B program will be used to help develop next-generation blended-wing military and commercial aircraft that are more fuel efficient, offer increased cargo/passenger space and are quieter than their traditional counterparts.

Comments     Threshold


This article is over a month old, voting and posting comments is disabled
138MPH?!?!
By Cobra Commander on 7/27/2007 1:51:52 PM , Rating: 1
Sounds awfully slow...????




RE: 138MPH?!?!
By Brandon Hill (blog) on 7/27/2007 2:10:13 PM , Rating: 3
It's a scale model remote control research plane, not a full-size craft.


RE: 138MPH?!?!
By jay401 on 7/27/2007 2:47:47 PM , Rating: 5
maybe that's 8.5% of the full-size speed too ^^


RE: 138MPH?!?!
By helios220 on 7/27/2007 2:50:46 PM , Rating: 4
Obviously the engines on the 8.5% scale model are not the engines that will be on the full scale production aircraft.

The point of scale tests of this nature are to test the aerodynamic tendencies of the blended wing shape, not to replicate the exact performance of a final product. The 138 MPH speed is no real indication of the speed of a full size platform with full sized engines.

What you also may be missing in the article is the 500 pound weight of the scale model. A single contemporary GE90-94B engine weighs 16,644 pounds. I’d be interested to know the weight and thrust of the scale model engines, but regardless 138 MPH is not too shabby for such light weight engines.


RE: 138MPH?!?!
By killerroach on 7/27/2007 3:07:15 PM , Rating: 2
Well, 8.5% scale would mean each dimension is 8.5% of the original, meaning the volume (and presumably mass) would be .0614% of the original. By those figures, you'd end up with your finished bird being somewhere in the neighborhood of 400 tons, more than enough to support your modern aircraft engines.


RE: 138MPH?!?!
By bubbacub616 on 7/27/2007 3:52:14 PM , Rating: 2
"presumably mass" is a pretty big assumption. i doubt that mass will scale linearly with size.

to compare, a 747 is around 130 tons. given that one of the proposed benefits of BWB design is a lighter aircraft i therefore find myself disputing your assumptions.


RE: 138MPH?!?!
By Anonymous Freak on 7/27/2007 5:11:29 PM , Rating: 2
The benefit is lighter design compared to equivalent capacity. BWB is a *LOT* bigger than a 747. 400 tons may not be out of the question for an aircraft the same length and wingspan as a 747, since it will have many TIMES the usable interior volume.


RE: 138MPH?!?!
By bubbacub616 on 7/27/2007 3:52:35 PM , Rating: 2
"presumably mass" is a pretty big assumption. i doubt that mass will scale linearly with size.

to compare, a 747 is around 130 tons. given that one of the proposed benefits of BWB design is a lighter aircraft i therefore find myself disputing your assumptions.


RE: 138MPH?!?!
By Danthrax on 7/27/2007 5:26:54 PM , Rating: 4
quote:
i doubt that mass will scale linearly with size.


The mass will scale linearly with volume, so killerroach is right, it will be 0.0614% of the mass, if everything is scaled accurately. Of course, models are somewhat simplified, so the model will be somewhat heavier than a perfect scaled replica would be.

quote:
a 747 is around 130 tons


The max takoff weight of a 747 is 900,000 pounds, which is over 400 tons. So this BWB model is right where we'd expect it to be.

As to 138MPH, the Reynolds Number for the scale model will be very different than for the full sized aircraft. In effect, the model will experience much more viscous air, so 138MPH is quite reasonable.


RE: 138MPH?!?!
By Keeir on 7/27/2007 6:51:02 PM , Rating: 2
1. Scale models for aerodynamic purposes are rarely fully scale models due to the desire to have flight condition full sized Reynolds numbers with the much smaller devices.

2. Due to the smaller size, many structures that would be peiced in a final aircraft will be monolithic/extra large

3. Certain materials are very difficult to form properly into small models, but can be formed correctly at larger sizes for additional wieght savings as well

At least I hope so, because at a structures wieght of 814 kips for BLB (in comparision, the empty wieght of the 747-8I/F is 410 kips) there won't be alot of room left over for cargo once the fuel has been loaded. The 747-8 series has a maximum cargo wieght of around 140 kips and a Maximum Take Off Wieght of 970 kips. That says to me, to fly the plane requires 420 kips of fuel.


RE: 138MPH?!?!
By HotFoot on 7/30/2007 3:01:23 AM , Rating: 2
I'm wondering what this group is trying to prove by flying this scale model. Surely it must be stability/controllability of an unconventional design. However, the similarity criteria are so far from matching that it will limit the usefulness of the results. Really, with a scale model, it's hopeless to match any of the similarity criteria, ie:

1) Mach number: as has been pointed out, there's not much hope of getting to 0.8-0.9 M range with this model or these engines (the criteria is missed by a factor of over 4.25). No matching Mach number means no matching pressure distribution over the wings (though the model design can be fudged to compensate at least somewhat). That totally changes the aerodynamic response of the flight control surfaces, to mention one thing.

2) Reynolds number: proportional to length scale * velocity scale. In this case, the Reynolds number is un-matched by a factor of around 50. I'm sure the boundary layer is tripped using some roughness strip-esque technique, but even so, how useful will the collected data be?

The model can be completely flyable, but how much will that mean in terms of a full-scale, full-speed aircraft?


RE: 138MPH?!?!
By bubbacub616 on 7/27/2007 6:56:05 PM , Rating: 2
"The mass will scale linearly with volume, so killerroach is right, it will be 0.0614% of the mass, if everything is scaled accurately. Of course, models are somewhat simplified, so the model will be somewhat heavier than a perfect scaled replica would be."

thank you for making my point

a planes weight is generally taken as being the unladen load. which is 130 tonnes for a 747 (you are correct in stating that the max load is 400). This is all a moot point since this is an experimental radio controlled model that we are using to extrapolate data. We need to see full size prototypes flying before the internet reading public can make conclusions about the viability and load caring capacity of BWB designs.


RE: 138MPH?!?!
By Triring on 7/29/2007 10:57:48 PM , Rating: 3
What in the hell are you talking about???

Mass and volume only scale linearly if it is made with the same material in the exact weight ratio. Since we do not know what this model was made out of it is meaningless.

It could be made out of paper and plywood for all we know, and the electrical wiring will be much more complex larger size means heavier standard landing gears and so on and so forthe.


RE: 138MPH?!?!
By Jammrock on 7/27/2007 10:08:44 PM , Rating: 2
I believe the plane's end goal is upper atmosphere hypersonic flight. The theory is that if you fly above the area into the lower mesosphere (about 50 km or 30 miles) you can fly at MACH 5+, i.e. hypersonic. To save on fuel the plane would little skip, like a stone on a pond kind of skip, off the stratosphere so the only time the plane would require heavy fuel burn would be to accelerate back up after the "bounce," and then slow burn while you drift up and then down.

All theoretical, of course, but that's the rough plan, and the X43 and X48 are supposed to the very early predecssor for this kind of travel. The hope is along the lines of NYC to Tokyo in under 5 hours. Not too shabby.


RE: 138MPH?!?!
By JeffDM on 7/30/2007 1:10:14 AM , Rating: 2
I don't think this blended-wing model was intended to go hypersonic. The sweep on the picture shown doesn't have enough of a backwards sweep to sustain supersonic travel. The X-43 you mention has a much more rakish wing sweep.

The idea of BWB isn't for supersonic or hypersonic, the idea of blended wing is to carry a LOT more passengers and cargo without being a lot more expensive, meaning less cost per passenger/per package/etc.


RE: 138MPH?!?!
By roadhog74 on 7/30/2007 3:50:52 AM , Rating: 2
The most critical times for an aircraft is take off and
landing. At these times you would expect the full sized
edition to be traveling about this speed.

So I would expect that they would be able to gain quite
a lot of data that is significantly more important than
how it behaves at MACH 0.9.


Wait- did I miss something?
By Comdrpopnfresh on 7/27/2007 1:22:06 PM , Rating: 2
8.5% model? How big is the real thing supposed to be?

Also, 136 mph doesn't sound right. You'd think turbo-jets could get the thing going...




RE: Wait- did I miss something?
By h0kiez on 7/27/2007 1:41:36 PM , Rating: 4
Uhhh....

21' / .085 = 247'?

I'm not a mathemetician, but this one doesn't seem that complicated. Oh yeah...I'm guessing the full scale one will be faster too.


RE: Wait- did I miss something?
By spluurfg on 7/27/2007 2:00:49 PM , Rating: 2
247 feet would be just longer than a 747. I'm not totally sure if 8.5% is scaled just from the length... it might be by volume, so the resulting aircraft wouldn't be quite so large... don't forget that if you, say, double each dimension of a rectangular object, its area increases by a factor of four and its volume by a factor of eight. Granted planes aren't rectangular...

Anyway, 130ish mph is pretty slow, but don't forget it's just a small model... also, since the whole thing looks pretty much like a flying wing, the idea may be to get more lift at a given speed than a conventional fuselage+wing approach, allowing you to fly at slower speeds economically (as speed increases linearly, the force of drag increases exponentially).


RE: Wait- did I miss something?
By masher2 (blog) on 7/27/2007 2:33:07 PM , Rating: 3
> "Granted planes aren't rectangular..."

The cube-volume relationship holds for any object geometry, not just rectangles. So I think we can assume the full-size vehicle would have (1/0.85)^3 = 1600 times the volume of this scale model.

> "I'm not totally sure if 8.5% is scaled just from the length..."

That's the typical usage of the term "scale model". I don't think 247 feet is out of the question for the full-size craft. Remember that a blended-wing variants contain significantly less passenger space, when compared to traditional craft of roughly the same size.


RE: Wait- did I miss something?
By skroh on 7/27/2007 5:00:00 PM , Rating: 3
quote:
That's the typical usage of the term "scale model". I don't think 247 feet is out of the question for the full-size craft. Remember that a blended-wing variants contain significantly less passenger space, when compared to traditional craft of roughly the same size.


I thought the design was going to have significantly MORE passenger space, because the cabin extends laterally into the wing area?


RE: Wait- did I miss something?
By RubberJohnny on 7/29/2007 11:18:00 PM , Rating: 2
quote:
Remember that a blended-wing variants contain significantly less passenger space , when compared to traditional craft of roughly the same size

Is this correct? according to the article:

quote:
The research gathered from the X-48B program will be used to help develop next-generation blended-wing military and commercial aircraft that are more fuel efficient, offer increased cargo/passenger space ...


RE: Wait- did I miss something?
By Hawkido on 7/30/2007 2:13:06 PM , Rating: 2
I believe he got his words jumbled... I believe he meant "A traditional wing plane has less passanger space than a BW plane."


RE: Wait- did I miss something?
By drinkmorejava on 7/27/2007 3:44:16 PM , Rating: 2
The 247' sounds appropriate. One of the goals of a blended wing aircraft is to reduce the affect that wingtip vortices have on aircraft lift. In a conventional aircraft, you would do this by having a high aspect ratio (wing length to width), but as you can see, blended wing aircraft don't really have a direct comparison, instead, the whole body acts like a single wing to achieve the AR.

There has been a great deal of work into the economics of them, and so far some of the factors holding them back have been the large wingspan and the possible reactions of passengers having to sit in very long row layouts.


RE: Wait- did I miss something?
By Alphafox78 on 7/27/2007 5:22:42 PM , Rating: 2
Just give me some DirecTV on the back of the headrests and Ill be fine. How I miss thee, Delta Song...


Does it come with a . . .
By JohnnyCNote on 7/27/2007 3:25:01 PM , Rating: 3
. . . breathalyzer?




RE: Does it come with a . . .
By Ryanman on 7/30/2007 12:39:32 AM , Rating: 1
joke man. Insinuating that whoever wrote the article was drunk.


"The X-48B blended-wind experimental aircraft"
By NedKelly on 7/27/2007 8:30:46 PM , Rating: 2
Did anyone else notice this?

Is it blended-win d or blended-win g ?




By JohnnyCNote on 7/27/2007 9:13:39 PM , Rating: 2
quote:
Is it blended-win d or blended-win g ?


That was before they installed the breathalyzer . . .


8.5%???
By x86biosgeek on 7/29/2007 10:11:57 PM , Rating: 4
8.5 percent? 8.5 percent? what is this, an airplane for ANTS!!!! it needs to be, uhhh, at least 3 times this big
- Derek Zoolander




Speed stats and stuff.....
By GeeSussFreeK on 8/3/2007 11:05:52 AM , Rating: 2
"Preliminary analyses indicate that the BWB
would outperform all conventional aircraft. It is conceived
to carry 800 passengers over 7000 miles at a
cruise speed of approximately 560 mph. This is almost
twice the passenger capacity of the Boeing 747-
400."

From the PDF of NASA from the post above for those who are to lazy (or scared) to open the PDF.




By GeeSussFreeK on 8/3/2007 11:12:25 AM , Rating: 2
BTW, LOTS of other good stuff in that PDF, including maximum weight, pressure on flight control issues, and other interesting things. Its a good read, and has most of the answers to the questions people posted here...mod that guy up to the stars!


Why do they even need a prototype?
By timmiser on 7/31/2007 5:47:49 PM , Rating: 3
Seems to me that all of this aerodynamic scale model nonsense could have just as easily and inexpensively been done by computer simulation. For example, the Boeing 787 was designed solely on computer and no models or prototypes were necessary to come up with the revolutionary design in efficiency.

Also, there is still a major problem with these types of winged aircraft in that they haven't figured out how to keep the passengers from getting sick from the extreme up and down movement you would experience from sitting far outside of the aircraft's axis. No matter how efficient it is, if the customers are puking, your days in the airline industry are numbered!




By Amiga500 on 7/30/2007 5:03:59 AM , Rating: 2
Evaluation of the control surfaces at takeoff and landing.

With the 'elevators' not having much moment arm, at higher angles of attack, and with any LE/TE high lift devices deployed moving the aerocentre around, longitudinal control authority may be questionable.

Thus, I expect this model to run through that section of the flight envelope.

As for the scaled weight/volume discussion ongoing here - yes, they would ballast the thing right to give a representative wing loading.

But for engine out simulations (if they do them), they will be taking care to keep thrust:weight ratio in check as well.




How many sardines will it fit?
By OxBow on 7/30/2007 11:19:55 AM , Rating: 2
So, if they stack the travellers in like cord wood, how many customers will this thing be able to haul?




For people like me ..
By badmoodguy on 7/30/2007 2:42:55 PM , Rating: 2
that had no idea what this was about. You can see a schematic and info here: http://oea.larc.nasa.gov/PAIS/pdf/FS-1997-07-24-La...




Blended Wing?
By Vertigo101 on 8/2/2007 10:03:51 AM , Rating: 2
I saw this article title and thought that the Blendtec guys had gotten ahold of a plane.

Suffice it to say that this article doesn't come anywhere close to its potential. ;)

http://www.willitblend.com/




"If you look at the last five years, if you look at what major innovations have occurred in computing technology, every single one of them came from AMD. Not a single innovation came from Intel." -- AMD CEO Hector Ruiz in 2007

DailyTech Poll
Which web browser do you use on your primary personal machine? 






44 Comments









botimage
Copyright 2009 DailyTech LLC. - RSS Feed | Advertise | About Us | Ethics | FAQ | Terms, Conditions & Privacy Information | Kristopher Kubicki