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Author
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Topic: Command Module Potential Energy
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trajan
Member Posts: 111
From: Chester, Cheshire, UK
Registered: May 2004
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posted 11-08-2005 11:49 AM
   
I remember once reading an impressive statistic that, on re-entry, Apollo Command Modules generated enough energy to light a city for x number of minutes. Does anybody recall the size of the city or the number of minutes? (Cos otherwise, it's not a very good fact!! :-) ) |
nasamad
Member Posts: 2141
From: Essex, UK
Registered: Jul 2001
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posted 11-08-2005 12:29 PM
Taken from the Command Module News Reference:
When the Apollo spacecraft re-enters the atmosphere it will generate energy equivalent to approximately 86,000 kilowatt hours of electricity - enough to light the city of Los Angeles for about 104 seconds; or the energy generated would lift all the people in the USA 10-3/4 inches off the ground.Adam |
trajan
Member Posts: 111
From: Chester, Cheshire, UK
Registered: May 2004
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posted 11-08-2005 01:07 PM
Wow, 2 facts for the price of one!Thanks, Adam |
mjanovec
Member Posts: 3811
From: Midwest, USA
Registered: Jul 2005
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posted 11-08-2005 01:41 PM
quote:
Originally posted by nasamad:
Taken from the Command Module News Reference:
When the Apollo spacecraft re-enters the atmosphere it will generate energy equivalent to approximately 86,000 kilowatt hours of electricity - enough to light the city of Los Angeles for about 104 seconds; or the energy generated would lift all the people in the USA 10-3/4 inches off the ground.Adam
I wonder how that would compare to the amount of energy expended during the launch of the Saturn V. I would have to assume the energy expended on launch (including TLI) would be much greater. |
spacecraft films
Member Posts: 802
From: Columbus, OH USA
Registered: Jun 2002
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posted 11-08-2005 03:09 PM
Of course this would have been lighting up Los Angeles in the 1960s, and lifting all the people in the U.S. in the 1960s... back when there were about 200 million or so...Now it's closer to 300 million, and I suspect L.A. uses a bit more power now than then. Mark |
nasamad
Member Posts: 2141
From: Essex, UK
Registered: Jul 2001
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posted 11-08-2005 03:12 PM
A few more from the same source as above, some info on the Saturn V;
During its 3.5 second firing, the Apollo Spacecraft's solid-fuel launch escape rocket generates the horsepower equivalent of 4,300 automobiles.
The engines of the Saturn V launch vehicle that will propel the Apollo spacecraft to the moon have combined horsepower equivalent to 543 jet fighters. The power of one Saturn V is enough to place in earth orbit all U.S. manned spacecraft previously launched. The F-1's fuel pumps push fuel with the force of 30 diesel locomotives. The five F-1 engines equal 160,000,000 horsepower, about double the amount of potential hydroelectric power that would be available at any given moment if all the moving waters of North America were channelled through turbines.
Adam
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STEVE SMITH
unregistered
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posted 11-08-2005 05:07 PM
Forgive the engineer in me, but the topic header should be "Kinetic Energy", not "Potential Energy". Potential Energy is energy stored at rest such as water stored behind a dam ready to overflow. If a one pound weight was held 10 feet above a level, it's potential energy relative to the level would be 10 foot pounds.Kinetic Energy is for a moving object such as the Apollo CM and is a fuction of the mass and velocity squared, that is KE=1/2MV2(forgive me, I can't make an exponent "2"). For instance, if an object is 4 times the mass of another, but the lighter object is going twice as fast, their Kinetic Energy is equal. Thank for your attention students (and aren't we all). |
trajan
Member Posts: 111
From: Chester, Cheshire, UK
Registered: May 2004
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posted 11-09-2005 09:23 AM
I did ponder before submitting the question whether it was potential or kinetic energy. I assumed that the command module had built up potential energy in the form of speed but that this was then converted to kinetic energy as it hit the atmosphere. But it sounds from your comment, Steve, that it was kinetic energy all alonmg, whether in the form of speed or heat. Is that the correct interpretation? (I ask as a biology graduate!)Jason |
mzieg
Member Posts: 72
From: Seneca, PA USA
Registered: Nov 1999
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posted 11-09-2005 06:04 PM
quote:
But it sounds from your comment, Steve, that it was kinetic energy all alonmg, whether in the form of speed or heat. Is that the correct interpretation?
Not quite - it's all energy, but it changes forms a couple of times. As the spacecraft approaches the Earth graviational sphere, it has a little kinetic energy from its velocity leaving the Moon, but its got a LOT of potential energy since it has a long "fall" back toward Earth, just like any object being dropped. As the spacecraft approaches Earth it gradually trades its potential energy for more kinetic energy in the form of increased velocity, which it converts into heat and shock waves as it slams into the atmosphere. It's the same conversion of energy that occurs when you slam on the brakes to stop your car - the car slows down and converts the kinetic energy into heat (hot brakes). Mark (another engineer) |
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