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Flying a Cessna On Other Worlds: xkcd Gets Noticed By a Physics Professor
djl4570 writes "xkcd's 'What If' series consists of humorous takes on highly implausible but oddly interesting hypothetical physics questions, like how to cook a steak with heat from atmospheric re-entry. The most recent entry dealt with flying a Cessna on other planets and moons in the solar system. Mars: 'The tricky thing is that with so little atmosphere, to get any lift, you have to go fast. You need to approach Mach 1 just to get off the ground, and once you get moving, you have so much inertia that it’s hard to change course—if you turn, your plane rotates, but keeps moving in the original direction.' Venus: 'Unfortunately, X-Plane is not capable of simulating the hellish environment near the surface of Venus. But physics calculations give us an idea of what flight there would be like. The upshot is: Your plane would fly pretty well, except it would be on fire the whole time, and then it would stop flying, and then stop being a plane.' There are also a bunch of illustrations for flightpaths on various moons (crashpaths might be more apt), which drew the attention of physics professor Rhett Allain, who explained the math in further detail and provided more accurate paths."
Very first tile in illustration: rip out engine, install batteries and electric motor.
RTFA
And get propulsion from a prop in an atmosphere of .6 that on earth?
Use your common sense son.
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You can't hand-waive away physics.
What exactly do you hope to gain by propping up this stupid article?
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How fast do you think you can spin that prop? Because with 0.6 of the earth's air density at the ground on mars, no matter how fast you spin it, you will not achieve any usable propulsion.
"Scientific hypothetical inquiry" does not dismiss physics. Childish daydreams of youth, maybe, but not science. You might just as well think outside the box about how many fairies can dance on the head of a pin.
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He makes no sensible assertion of "taking the atmosphere into account". It it totally not believable in ANY context.
But I suppose if you grew up watching Star Trek you might be forgiven if your science education suffered as a result.
You can't achieve propulsion with a prop at a pressure altitude of 35KM AGL.
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