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  #11  
Old 04-06-2012, 02:53 PM
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Originally Posted by omegaman View Post
Watched the IRON SKY trailer a while ago and it showed a scene where some Nazis where firing a rocket launcher on the Moon's surface which of course has no atmosphere…

So… if in reality one re-enacted this event.

a) Would the fired rocket (depending on the nature of the propulsion system) leave a trail of smoke?
No. The exhaust immediately attenuates as can be seen when the shuttle engines are flying through the high atmosphere.

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b) If so, what would happen to the smoke? (obviously it cannot dissipate - no atmosphere)
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c) How long would it remain visible after the event?
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d) Would the person firing the rocket launcher be pushed in the opposite direction?
absolutely. The exhaust has mass and that mass is impacting both the rocket and the stationary launching the rocket.
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Old 04-06-2012, 03:37 PM
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No. The exhaust immediately attenuates as can be seen when the shuttle engines are flying through the high atmosphere.







absolutely. The exhaust has mass and that mass is impacting both the rocket and the stationary launching the rocket.
Thanks. Saquist.
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  #13  
Old 04-06-2012, 03:50 PM
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The flip side is, the Iron Sky trailer looks damn fun! And I think we can discount scientific accuracy as being a key component!
The only people who won't enjoy this film are pro-republicans XD
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  #14  
Old 04-06-2012, 07:20 PM
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The Space Shuttle Main Engines (SSMEs) burned Liquid Hydrogen with Liquid Oxygen as oxidizer. The exhaust was superheated steam, more or less, and the flames were quite faint as seen here:



Most of the exhaust plumes were from the SRBs burning solid fuels.

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  #15  
Old 04-06-2012, 10:55 PM
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http://youtu.be/vPQvTgD2quQ

Notice at launch that the SRB's have a rather narrow exhaust but as the get further up they becomes huge umbrellas because there is less air pressure.

The Shuttle Main Engines start off like little blue cones with a faith trail. As they get further up and the SRB's seperate the tril disappears....

Some believe that In Star Trek the Impulse engines of Starships are chemical Rockets using fusion Thrust. I've pointed out before that if that were true then we could see some sort of trail. The counter argument is that in space there would be no trails for rockets but that's not a certainty. As you can see the SRB's maintained a trail BUT this is not exactly at altitude that we could actually call "The vacuum of space." It's only 42 miles and ET SEP occurs at 80 miles on a parabolic course so they don't get there as fast as if they were going straight up. But the counter-counter argument considers the substance of Hydrogen into Helium which is still a transparent gas. Of course I offered a 3rd counter argument by reasoning of highly efficient directional nozzle's like the Aero Spike Engine that a trail would be visible. Curiously only Excelsior has impulse engines that could be considered Aerospike like...



OXYGEN/HYDROGEN AEROSPIKE
http://youtu.be/alTWVz1DrSA

But for just a Rocket or Missle my opinion is that you would see something but it wouldn't look like a thick trail of smoke (because of solid propellent) and it would still attenuate quickly.
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Old 04-07-2012, 11:10 AM
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Also, when a rocket lands on the moon it sends moondust flying horizontally in every direction. When it takes off later, the lower part is left sitting there, and only the upper part rockets skyward. Since it's higher, and the moondust below is depleted, there is no blast of moondust on takeoff. The NASA guys and gals didn't think sandblasting if a rocket landed near equipment already at the site would be a problem when someone first suggested it, but testing showed that it could destroy things. Moondust has highly jagged surfaces, having spent no time being worn smooth by water. That’s also why it sticks to everything.
One of the moon buggies couldn’t be used because of a broken fender, since the fenders are necessary to keep the moondust shooting back to the ground rather than kicking up a roostertail (plume). An astronaut repaired the fender with laminated maps and duct tape.

Moondust and duct tape

Another weird thing is that astronauts after walking on the moon have bruises all over their hands, because of the gloves.
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Old 04-07-2012, 01:12 PM
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  • Our culture has advanced beyond all that you can possibly comprehend with 100% of your brain."
  • "The moon has 1/3 less gravity than that of your earth. I don't know if you can understand that, but our vertical leap is beyond all measure."




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Old 04-07-2012, 02:10 PM
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What an angry looking little alien.
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  #19  
Old 04-07-2012, 10:39 PM
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Quote:
Originally Posted by LCARS 24 View Post
Also, when a rocket lands on the moon it sends moondust flying horizontally in every direction. When it takes off later, the lower part is left sitting there, and only the upper part rockets skyward. Since it's higher, and the moondust below is depleted, there is no blast of moondust on takeoff. The NASA guys and gals didn't think sandblasting if a rocket landed near equipment already at the site would be a problem when someone first suggested it, but testing showed that it could destroy things. Moondust has highly jagged surfaces, having spent no time being worn smooth by water. That’s also why it sticks to everything.
One of the moon buggies couldn’t be used because of a broken fender, since the fenders are necessary to keep the moondust shooting back to the ground rather than kicking up a roostertail (plume). An astronaut repaired the fender with laminated maps and duct tape.

Moondust and duct tape

Another weird thing is that astronauts after walking on the moon have bruises all over their hands, because of the gloves.
didn't know about the glove thing...
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Old 04-09-2012, 01:48 PM
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Quote:
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What an angry looking little alien.
They are the mooninites, and we will never be able to comprehend their advanced moon culture. We are hindered by our primitive Earth gravity.
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