Translation talk:Ufo scout txt/en
I have some problems with this paragraph.
The alien propulsion system is a type of rocket engine unlike any ever built on Earth. It uses direct matter-antimatter annihilation to generate thrust by injecting protons and antiprotons into the reaction chamber, and then channeling this explosive force out the back of the engine. This gives a UFO extreme power and needs no air or other gases to fuel the reaction, allowing it to burn in hard vacuum. There is a highly-advanced cooling system continuously pumping liquid nitrogen through the engine housing in order to keep it cool and reduce the infrared signature. Engine heat is also used to supply the craft's electricity.
In antimatter annihilations you get antiparallel gamma rays. Momentum is conserved, the vector sum of the gamma rays momentum is the same as the vector sum matter/antimatter which annihilated. So you will not get any thrust by annihilating antimatter.
Antimatter is a good choice of fuel. It is the most energy dense fuel possible.
Any type of rocket needs reaction mass. Newton's third law. in order to generate momentum in one direction, you have to throw something with momentum out of the back.
You could have the UFO collecting gas in atmosphere to use as reaction mass. They could store some for use in space. once in space there is diffuse hydrogen that can be scooped up. if your UFO is going fast enough it can scoop hydrogen at quite a rate.
How about having an antimatter generator powering an advanced synchrotron which accelerates ionised reaction mass to generate thrust?
For any generator you need a temperature difference, not just a high temperature. (max efficiency is 1-cold/hot, where temps are in Kelvin).
So, cooling is a problem too. high altitude planes, for example, have trouble dissipating heat because the rarefied air does not conduct heat well. Space craft can only lose heat by radiating infra-red (or shorter wavelengths if they are very hot). I fear that if the craft is going to produce a lot of heat in space, it will need some new laws of thermodynamics invented: eg quantum thermal suppression or entropy absorption.
I hope you find these comments useful. I am happy to help with this stuff. My day job: radiotherapy physicist.
--Blondandy 15:29, 5 June 2007 (CEST)
Your idea seems too complicated to me. Certainly there must be some way of making a realistic direct or near-direct matter-antimatter rocket. --Winter 15:03, 23 June 2007 (CEST)
I think that this  is more plausible than this  I still plan to do some work to see. i confess it is less clear cut than i thought. i was thinking about positrons, not antiprotons. i am not convinced the magnetic funnelling described in that article is very useful. (apart from protecting you craft from radiation - i do not think it would help thrust much). i will put some more work into this when i have time.
--Blondandy 22:33, 26 June 2007 (CEST)