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In lugnet.space, Jesse Alan Long writes:
> I knew that an airplane wing will continue to fly, even if
> it was inverted but that is because, I believe, unless otherwise corrected,
> that the plane has a curved surface and as long as it has the curved
> surface, then no matter how you fly, you still receive lift from the air and
> a downward force but the lift is stronger than the downward force because
> more air goes down than it does going up on the airplane but it is not of
> such an unbalanced ratio that it can not fly down to Earth because that
> would violate the laws of gravity.
Well, it's more about the angle the wing is inclined to the airflow. Just
keep it tilted upward to the air flowing past you, keep your speed up, and
you should get some lift. Newton says you're deflecting air downwards.
Aerodynamics says a lot more but it's much harder to follow.
> I always thought that heat was able to boil liquids into gas but why does
> heat not present a role into outer space? Why would pressure matter in
> outer space?
The boiling point of a liquid depends on the pressure of the environment
it's in. Under high pressure, like in a pressure cooker, water boils at a
higher temperature (that's the point of the cooker). Under low pressure, it
boils at a much lower temperature. High on a mountain, in thin air, it
takes a lot longer than 3 1/2 minutes to boil an egg, because the water
boils below 100°. In space, with zero pressure, liquids boil instantly.
Inside a pressurised space capsule, water sticks together in floating
bubbles - but outside, the molecules would just disperse. [There are
rumours of water droplets on surfaces in a depressurised section of Mir
following an accident, but these have yet to be confirmed or explained].
I wouldn't try tis with other liquids in your space capsule - water
molecules have a little stickiness (which gives us surface tension - how
insects can stand on the surface of water). It's possible to break this
down by adding detergents - so soapy water would probably go everywhere.
> I always thought that you could make a plasma powered space
> craft in a similar manner as you would build a welding torch so please
> explain to me why the plasma engine would present a terrible idea for my
> space craft? I mean, I know that plasma, in a uncontrolled state, can
> present a great danger but what about a controlled plasma environment, if
> any such environment is possible on a space craft?
Well, conventional propulsion is all about reaction thrust. You blow some
mass backwards, and you get a reaction pushing your mass forward. Jets,
rockets and propellors all use this trick. The difference with rockets is
they don't take anything in from the atmosphere. Propellors and jet engines
use air as their propellant. A rocket, and the combustion chamber inside a
jet engine, both use a chemical reaction (burning) to generate gas at a high
temperature. This causes rapid expansion, and the only vent for this is
rearwards. In a jet engine, it also heats the air, and that expands and
blows backward too. A propellor just pushes air (or water) backwards.
My knowledge of plasma is limited, but I guess it would be an extreme
example of the super-heated expanded gas. I believe it can be guided by
electro-magnetic fields, so maybe you could accelerate it even more with
such fields.
> The final question I have to ask is could it be possible, either in a
> science fiction realm or a realistic realm for a Harrier type space craft to
> actually fly into outer space? I thank you for clearing the confusion in my
> mind, Jason.
Yes - if you had enough thrust you could go straight up - but you'd need to
keep the thrust on just to hover against the force of gravity. All our
spacecraft (Apollo, Shuttle, French and Russian satellite launchers) start
off going straight up, but soon tilt over into orbit. To get away from
Earth, they accelerate around and around, getting into higher and higher
orbits, until they're going fast enough to fly off ('escape velocity') -
though they still fly off in an arc, not in a straight line away from Earth.
It would take too much fuel for NASA to send a rocket straight up, but it
might be possible one day. Anti-gravity devices would help.
Jason J Railton
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Message has 1 Reply:
 | | Re: Couldn't resist
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| (...) You said in the last letter before this letter that some liquids (referring to the reaction to friction of certain particles in outer space) are viscious while some solids are very hard and smooth in reaction to friction in outer space. If (...) (23 years ago, 29-Jun-01, to lugnet.space, lugnet.off-topic.geek)
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Message is in Reply To:
| | Re: Couldn't resist
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| (...) I was only having some fun with the oil part of the letter, I knew that you probably did not use oil in outer space, I mean, after all, the general consensus in outer space would reflect that you would use environmentally friendly materials (...) (23 years ago, 28-Jun-01, to lugnet.space, lugnet.off-topic.geek)
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