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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."
It is a cessna engine, it doesn't run on air but on money.
i thought once I was found, but it was only a dream.
"plane would fly pretty well, except it would be on fire the whole time"
I think Boeing has a plane that meets part of the criteria already.
It would be an X-Plane!
Any sufficiently unpopular but cohesive argument is indistinguishable from trolling.
This is covered in the simulations as well. Is there something in particular preventing you from reading it?
Mach 1 is the speed of sound - in that medium.
I want to delete my account but Slashdot doesn't allow it.
Although I am not the poster you asked this question of, I have to admit not ever reading xkcd, having more important things on my Kindle
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no taxation without representation!
Correct. Also, it's important to point out that the Mach number of a vehicle is a local measure of vehicle speed. As the speed of sound varies with temperature, and thus altitude, you'll find that two vehicles having the same trace ground speed but that are flying different altitudes will be at different Mach numbers. Acoustics and aerodynamics are fun.
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Not to mention when he says that Venus' upper atmosphere is "room temperature" - duh! rooms on Venus would have a very different temperature from Earth's rooms! What and idiot.
sic transit gloria mundi
You can't hand-waive away physics.
Sense of humor, on the other hand, is commonly waived.
FTFA: The motor is electric, and the fuel tanks are replaced with Li-Ion batteries. But I'll give you style points attempting to stifle scientific hypothetical inquiry and outside-of-the-box thinking with cynical non-imaginativism. Keep it up and you might win the scientific curmudgeon of the year award!
Icebike is proving what I have previously pointed out about him. It is not important to him that he knows what he is talking about. Knowing what you are talking about is hard.
"His name was James Damore."
They also didn't point out that if attempting to fly in the Sun's atmosphere, you may last longer if you do it at night. :P
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http://m.xkcd.org/ is a better version for mobile. The title below the comic has a clickable superscript (alt text) link that will display the alt text underneath.
It is explained that on one world, you burn then crash - as opposed to crash and burn - and why it would happen in that order. And, on another world, you would crash, but not burn, and why.
This little "what if" is a reasonable explanation of conditions on other worlds, as we understand them, and how they would affect flight in a particular type and model of aircraft.
If the story teller were addressing an international physics conference, he might sound a bit stupid with this presentation. As he is addressing an audience of nerds, with the intent of amusing and possibly educating them - he's done an excellent job.
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Wow-- I just noticed this-- I got linked!
(at the pdf report linked at the words "...The acid's no fun, but it turns out the area right above the clouds is a great environment for an airplane" in the Venus section)
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20030003716_2002108457.pdf
http://www.geoffreylandis.com