From Bruce Sterling’s SF story The Gernsback Continuum:
Obviously, he’s referring to this. Tech specs here. But is it true the thing never could have flown? I mean, this contrivance of Norman Bel Geddes doesn’t appear to be much bigger than the Airbus A380.
Sure, right before it crashed.
Seriously, it’s my understanding that flying-wing designs are inherently unstable. They are possible today only because computers can handle the background task of keeping the aircraft becoming uncontrollable. Obviously, this sort of technology wasn’t available at the time. Today, the proposed aircraft could probably be built.
Looking at the “tech specs here” link you provided I see the weight figure is way too low for modern aero rules of thumb for size/weight ratio. In other words, if it was as big as they say, it’d weigh 5-10x more than they say.
The power provided is also about half of what would be required for the stated weight, much less the actual 10x larger weight.
In short, a nice picture & a bunch of pure fantasy numbers.
If you tried built it to size & held to the published weight limits, you couldn’t even assemble it; the wings would break off under their own weight, and the upper decks would crush the structure of the lower decks. If by magic that didn’t happen & it held together, the engines wouldn’t develop enough power to get it moving, much less flying.
I saw an interview with a pilot of one of the original flying wings that Northrup developed and the way he described it was that you had to completely relearn how you controlled the plane. You were strictly limited in the types of manovers you could do and if you tried to fly the plane the way you flew any other plane, you’d wind up crashing. Computer controls make it possible to fly the plane normally.
One thing which would make giant flying wing passenger planes difficult is pressurizing the plane. Tubular objects are easier to pressurize (no corners which are weak spots) than just about anything else (save a sphere).
I’ve been thinking a while about posting a question as to whether flying-wing passenger jets would be more efficient than the flying tubes we have now, pointing out that we have the technology to control them.
I completely forgot about pressurising them, remembering instead the old '50s-vintage image of passengers sitting in front of big greenhouse windows. Is the problem insurmountable? Maybe a composite pressure vessel would be able to withstand fatigue better than a metal one?
Given the stated speed of that thing , is pressurization really nessescary. Unless you want to add either anti gravity units or hydrogen or helium gas cells , I am wondering why you need to get above 14k altitude.
Declan
I wasn’t referring to the aircraft in the OP, but to a modern flying-wing design. Or maybe a blended-wing.
In order to achieve adequate efficiency, it would have to fly high.
Oh ,neuron misfire there.
Sounds like what they would need is what the military is using for NBC protection, which is pretty much overpressure
Declan
Why? (I know very little about aerodynamics.)
High altitude means less-dense air. That, in turns, means lower aerodynamic drag which is the primary enemy of flight efficiency.
What about ground effect, wouldn’t that help it stay aloft? The thing vaguely reminds me of pictures I’ve seen of an Ekranoplan or Boeing Pelican. The Geddes craft was supposed to be a seaplane, after all.
Ground effect is minor when more than 1 wingspan from the ground, and is significant only when closer to the ground than half a wingspan. The link giving specifications said this plane was desinged to fly at an altitude of thousands of feet (max was said to be 10,000).
But the big issue would have been supplying enough power for a takeoff from the water (quite a bit more drag than if launching from a runway).
Safety would be an issue, too. Certain computerized aspects of modern airliners can be on the fritz and the pilots still land, but would that be the case with these machines?
Sure, provided of course, you didn’t want to get more than a couple feet up in the air.
But the big benefits modern aircraft get from flying high (over 30,000’) are the huge increase in jet engine efficiency due to colder air aloft, and the fact that this gets them above about 97% of weather problems.
Speaking of ground effect, Ekranoplan.
But if you put it on a treadmill…???
:: d&r ::
Don’t tell any hang glider pilots this. The Horton Brothers of Germany did a lot of successful work with flying wings prior to and early in WW2. The design, as shown, pretty much has what it takes for a stable flying wing. The wing tips need to be behind the CG, as they provide the nose-up pitch moment supplied by the horizontal stabilizer in conventional designs. There is more than this, of course, such as providing washout (twist) in the wings, and choosing airfoil(s) with regard to pitching moments.
Power and strength-of-materials issues mentioned upthread would have kept it from flying of course, but flying wings can, and have long been made inherantly stable without resorting to electronic stability augmentation.
I mentioned Ekranoplan and the Boeing Pelican as well. The Pelican in particular is supposed to fly up to 20,000 feet at shorter ranges. I guess I wasn’t clear enough… if those beasts can work as ground effect airplanes, perhaps the Geddes craft could as well.
Regular airliners are leaky as hell as well. They aren’t sealed containers. For passenger comfort, they maintain only an atmosphere of 8000 feet. Ideas for new jetliners call for pressurization to 6000 feet and that is considered a huge improvement. You don’t need to perfectly seal any plane to make it viable for passenger transport.
Jet airliners hate low altitudes. They burn too much fuel and need to get very high before the fuel burn is economically viable. You can’t have a commercial airliner that spends most of its time at low altitude without an enormous penalty in fuel burn.