nec209 Posted March 30, 2009 Share Posted March 30, 2009 They say this problem was fixed and it will not work.They say this was the problem in the old days and now it is fixed. +++++++++++++ Can a rocket engines be inprove by doing the following things? Can we get a rocket engines more powerful and fuel efficient by re-designing the combustion chamber ,inproving the thrust chamber ,amout of fuel burn or the layout of the thrust chamber where the oxydizer are mixed and burned? And cutting back on moving parts and heat ?I just thought inproving the combustion chamber or new layout of the combustion chamber or a new state of the art combustion chamber . Or cutting back on moving parts or heat.Or the amout of fule burn. It will be intresting to see what NASA is doing. +++++++++++++++++ Thay say NASA has done the above and there is no way for those things above will work. Anyways I'm lost has I know nothing about rocket engines .Will this work or not? Link to comment Share on other sites More sharing options...
CaptainPanic Posted March 31, 2009 Share Posted March 31, 2009 They say this problem was fixed and it will not work.They say this was the problem in the old days and now it is fixed. +++++++++++++ Can a rocket engines be inprove by doing the following things? Can we get a rocket engines more powerful and fuel efficient by re-designing the combustion chamber ,inproving the thrust chamber ,amout of fuel burn or the layout of the thrust chamber where the oxydizer are mixed and burned? The modern rocket engines are pretty optimized already, but there is always room for improvement. However, the improvement might come at a price: extra weight / cost. And cutting back on moving parts and heat ?I just thought inproving the combustion chamber or new layout of the combustion chamber or a new state of the art combustion chamber . Just curious - what is moving in the rocket apart from a number of pumps? Or cutting back on moving parts or heat.Or the amout of fule burn. Heat is necessary, because it provides thrust. Fuel that is burnt is also proportional to thrust (linearly). It will be intresting to see what NASA is doing.+++++++++++++++++ Thay say NASA has done the above and there is no way for those things above will work. Anyways I'm lost has I know nothing about rocket engines .Will this work or not? All I can say is: study, study, study. Read the wikipedia pages about rocket propulsion, and try to understand it. Make sure to click around too, and read more than just the page I just sent you. You have started to ask about a topic, but please realize that the answer is complicated. Be ready to invest quite a lot of time here... Rocket engineering is not something you will learn in 1 weekend. Link to comment Share on other sites More sharing options...
Moontanman Posted March 31, 2009 Share Posted March 31, 2009 While I'm not a rocket scientist is do know one:D I do agree that improvements will always be possible but at some point you come up against the idea of diminishing returns. The real problem with rocket engines isn't the design of the engine it's the fuel. The theoretical limit of current rocket fuels is an ISP of about 450 Specific Impulse is often abbreviated as ISP. Isp is a little more complicated, but it is very important. ISP is sort of like the fuel efficiency of a rocket. It is easiest to explain with an example. The two giant rockets we use to launch the Space Shuttle have an ISP of about 250 at takeoff. What this means is that for every pound of fuel they fire out the back in a second, 250 pounds of thrust is generated. Simple! Another way of looking at it is if you have an ISP of 250, you can make one pound of thrust for 250 seconds. High ISP is very important for efficient rockets. ISP is very like fuel economy for a car. If one car has a very old motor that makes 100 horsepower but gets 5 miles per gallon, and a second car has a new motor that makes the same 100 horsepower but gets 50 miles per gallon, which one would you rather have? http://www.nuclearspace.com/Liberty_ship_pg6.aspx The best chemical fuels in use today are liquid hydrogen and liquid oxygen, the stuff burned by the three Main Engines on the Space Shuttle (SSME's). The SSME's produce a maximum of about 450 Isp. http://www.nuclearspace.com/Liberty_ship_pg7.aspx Ok, now the main engines of the space shuttle have an ISP of about 450. That is pretty close to the limit of chemical fuels, you can get a tiny bit better by using something like liquid Florine but besides being a very dangerous chemical the exhaust is not very nice either. Liquid Hydrogen and oxygen only produce water vapor. So not matter how good you make a chemical rocket engine it has a limit as to how much energy you can get out of the fuel, IE an ISP of about 450. Link to comment Share on other sites More sharing options...
Mr Skeptic Posted March 31, 2009 Share Posted March 31, 2009 Three things you want to do with the rocket engine are: 1) Have the exhaust be as hot as possible, since hotter exhaust means more momentum per unit mass. 2) Have the exhaust be composed of lighter molecules with little degree of freedom, since they move faster at a given temperature. 3) Have the exhaust move in one direction as much as possible -- otherwise some of the momentum cancels out. For #2, it is completely a question of fuel, and for #1 mostly a question of fuel. However, if you have the fuel running along the inside of the engine you can cool the engine and preheat your fuel, increasing the efficiency a little. For #3 you have the shape of the nozzle. A longer nozzle means you can direct the exhaust just a little more, and eventually it is not worth it to extend the nozzle, and there is little you could do to improve what we have. IMO we need to stop relying on chemical rockets. Nuclear powered rockets can do far better, because they can use nuclear processes to heat hydrogen or helium far hotter than any chemical process could, and you can't beat hydrogen (except for ionized hydrogen) since it is very light and has few degrees of freedom. A nuclear powered rocket could easily do far better than the best a chemical rocket could do in theory. Link to comment Share on other sites More sharing options...
Moontanman Posted March 31, 2009 Share Posted March 31, 2009 Agreed, a nuclear rocket with a solid core can easily give an ISP of 900 twice that of the best chemical rockets. No amount of tweaking the design of rocket nozzles will ever give us an ISP even close to that. A gaseous core nuclear reactor can give us an ISP of 5000 more than 10 times as much as the best chemical rockets. Yes I think nuclear will be the way to go once we get the superstitious fear of nuclear out of our social mind set. see this link http://www.nuclearspace.com/Liberty_ship_menupg.aspx Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now