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Sky Whale II... feasible?

Foolmewunz

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Foolmewunz
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I would've sworn we had a thread on Oscar Vinals idea from last year but can't find it. (it's referenced in the breathless omg article - the "Skywhale")

But now he's upping the ante to "trip to Mars" fantasy levels, I feel. Apparently we have 40% of the technology already! (Just that those missing 60 points include some pretty high hurdles.)

Zero emissions, hydrogen engines, noiseless.... What's not to love. But within 15 years? I'd be curious to hear some physicists and aeronautics folks' take on this.

http://edition.cnn.com/2015/04/21/travel/progress-eagle-future-plane/index.html


ETA: I realize it's a puff piece and not in a scientific journal but couldn't they have phoned, like I dunno, maybe one person to get some balance?
 
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Phycisist: This will happen 20 years after sustainable fusion power.

Currently, solar power produces barely enough energy to keep the solar panels aloft, let alone an airframe that size. Power produced would go up by only the square of the size, but weight would be cubed.

Heck, I suspicious we could even build 40% of this thing now. It's 50% longer than an airbus 380.
 
Let me rewrite the article very slightly.

Cartoonist and aviation enthusiast Oscar Vinals is slightly addicted to crafting cartoon planes.

Last year, he came up with the design for the AWWA Sky Whale, a cartoon aircraft that he said would revolutionize green air travel and carry an astonishing 755 passengers. Now, he's bested himself.

With his newest cartoon, the AWWA-QG Progress Eagle, he imagines the future of travel as a triple-decker aircraft with zero carbon emissions.

Rather than relying on traditional fossil fuels, the plane is drawn with six hydrogen engines to lift the plane off the ground. The aircraft is also drawn with a rear engine that would double as a wind turbine, and solar panels on the roof and wings.

"I drew cartoons where the Progress Eagle would be its capacity to generate its own energy," says Vinals. He adds that the flight would also be "noiseless."

"Quantum solar cells, nanowires to kinetic power, micro radio wave harvesters -- these technologies only exist in cartoons. But in cartoons, we could overcome our limits and build anything imaginable."
Click to expand...
 
GodMark2 said:
Phycisist: This will happen 20 years after sustainable fusion power.

Currently, solar power produces barely enough energy to keep the solar panels aloft, let alone an airframe that size. Power produced would go up by only the square of the size, but weight would be cubed.

Heck, I suspicious we could even build 40% of this thing now. It's 50% longer than an airbus 380.
Click to expand...

And sustainable fusion power is 10 years in the future, and has been for the last three decades or so. :D
 
GodMark2 said:
......Heck, I suspicious we could even build 40% of this thing now. It's 50% longer than an airbus 380.
Click to expand...

The designer forgot to mention that it is mostly filled with helium and is actually just a glorified dirigible.
 
Okay, I'll bite. Let's look at the solar-powered cruise thing.

The wingspan is ~100 meters, the aspect ratio looks to be ~8, so the total wing area is 1250 sq m. Let's assume the fuselage and tail have about the same area as the wing, so the total area available for solar cells is ~2500 sq m.

Also, let's assume that it's flying very, very high, so that only 5% of the sun's energy is lost in the atmosphere1, so the incident flux is 1.29 kW/sq m. Also, let's assume that we only fly when the sun's at least 60 deg above the horizon2, so our cosine loss is only ~13%. And let's assume our solar cells are 80% efficient.3 2500 x 1.29 x (1-0.05) x 0.866 x 0.8 gives us 2.24 MW to propel our totally-not-crazy airplane.4
Is that enough?

Well, a loaded-without-fuel A380F weighs 402,000 kg. The Sky Whale is much larger, but let's assume it has the same weight.5 A typical airliner has a lift/drag ratio of about 17, but this one has genuine cartoon aerodynamics so let's give it a L/D of 276. 402,000 x 9.8 / 27 gives us 146 kN of drag. To keep up with other airliners, we'll be cruising at about 800 km/hr = 222 meters/sec.

Thus the total power needed to maintain cruise is about 146,000 x 222 = 32.4 MW.

With 2.24 MW available, that means we need our engines to convert electricity to thrust with 1440% efficiency7.

I'm dubious.


1About 17,000 meters/55,000 feet, I think. This is higher than any current airliner but not crazy by itself.

2This will limit flight time based on direction, latitude and season. The best case is near the equator flying west, which will allow up to 5 hr/day of flying. At London's latitude it would be limited to ~2 hours on the best day (June 21) and wouldn't be able to fly at all for 46 weeks of the year (July 15 to May 28)

3Crazy. AFAIK the current world record is 44.4%

4That was sarcasm.

5A little crazy.

6Pretty crazy. That's the same aerodynamic efficiency as Rutan's Voyager.

7Absolute giant mutant batcrap crazy. You shouldn't need to be told this.
 
Oh my sweet Lord. Look, anybody who suggests (as the link does) that "The aircraft would also be fitted with a rear engine that would double as a wind turbine" is clearly having problems dealing with reality. The missing piece of technology is apparently a perpetual motion machine.
 
Not at all. We can reverse the engine and have it blow forward into large sails.
 
WhatRoughBeast said:
Oh my sweet Lord. Look, anybody who suggests (as the link does) that "The aircraft would also be fitted with a rear engine that would double as a wind turbine" is clearly having problems dealing with reality. The missing piece of technology is apparently a perpetual motion machine.
Click to expand...

I don't think this guy is that wrong. I think he's thinking to use that to recover energy during descent and landing.
 
Hydrogen is a good fuel. It has a lot of energy per kilogram. Only trouble is that the kilogram takes up a lot of space. Plus you need a good way to produce it in bulk.
 
dasmiller said:
I'm dubious.
Click to expand...

I'm dubious from an aerospace/airframe angle. Why on earth is the cockpit protruding? Why are the wings curved that extremely for this kind of load?

It makes the Beluga look downright sensible. (The Beluga actually is a kind of sensible, but you know what I mean.)
 
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