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Improving Rocket Engines

Posted by: Andy Hill - Tue Feb 08, 2005 10:07 am
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Improving Rocket Engines 
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Post    Posted on: Wed Feb 09, 2005 2:33 pm
Ekkehard Augustin wrote:
NASA is thinking about use of nuclear based propulsion outside the atmosphere - not inside

Quite right. Even the NERVA studies were for an upper stage, not an engine to be fired starting on the ground. And there are serious proposals to resume research into such engines, and other types too, for use exclusively in space.
But that will not help us get off the ground and into orbit, which is about 90% of the problem. For better or worse, the way we are going to get to orbit is low cost chemical engines, some of which may be air breathing (X43). And these will be developed by the new generation of aerospace engineers, including some of the members of this forum.


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Post    Posted on: Wed Feb 09, 2005 2:51 pm
That's the reason why I referred to the study about using lasers to improve the efficiency of hydrogen.

As far as I remember the contents of that study the ground-based lasers are proposed for use on the way from ground into orbit.

The study assumes a battery of laser on ground only - the lasers in space wouldn't be used on the way from ground to orbit.

But the study doesn't consider floating ports like those proposed by adiffer etc. But JP Aerospace is working on such ports. They are constructing and building the Dark Sky Station. My understanding of adiffer's posts is that heavy cargos can be lifted to Dark Sky station - which means that it should be possible too to install lasers there. The power, the electricity could be provided by other technologies currently under development and discussed in other threads here.

So at least one battery of lasers could be installed at Dark Sky Station. It could take over the heating of the hydrogen at a certain altitude. And during the last part of a vehicle's way to orbit it could be done by a space-based laser battery.

The study is very interesting - an improvement of conventional rocket propulsion by adding another technology that already exists.



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Post    Posted on: Thu Mar 03, 2005 4:06 pm
According to this article the Russians want to work with the US on Nuclear engines that could result in a manned mission to Mars as early as 2017. Cant see the US going for it as they're a little twitchy about anything concerned with Nuclear technology.

http://www.mosnews.com/news/2005/03/02/russiamars.shtml

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Post    Posted on: Thu Mar 03, 2005 5:32 pm
Have you seen the Timberwind?
http://www.friends-partners.ru/partners ... mind75.htm
There is lots of good information about it here too:
http://www.fas.org/nuke/space/index.html
(This site seems to be against nuclear rockets in general, calling them a solution in search of a problem, but the information is very detailed.)


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Post    Posted on: Fri Mar 04, 2005 11:41 am
That the russian are interested in development of nuclera drives together with the US seems to mean new and very good chances from my point of view.

1. NASA has said that they want to use nuclear engines for manned missions to Mars in the past.

2. The major obstacle for the use of nuclear engines in space are political ones: UN treties and agreements which have to be removed.

3. ESA too wnats nuclear engines.

So the Russians and the British at least may be willing to modify or to remove Un treaties and agreements to allow for nuclear engines. I think the US too will agree. China ís looking to future manned missions to the moon - but to the Mars too. France will be no problem I suppose.

All this may be a significant step to Pulsed Fusion Engines too which are the most crafty and realistic drives ever concepted, studied and initial testind and experimental results and data are available for.



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Post    Posted on: Sat Oct 15, 2005 9:28 am
Sorry for resurrecting this old thread but I thought this article was interesting and was related to the original topic.

US researchers have been trying to change the flow through the preburner to increase turbo-pump efficiency and reduce its temperature (sounds a bit like the Russian RD-180 concept to me :?: ). What I cant understand is that they talk about the work producing better rocket engines in a few decades, why so long the Russians achieved the RD-180 in under a decade?

http://science.nasa.gov/headlines/y2005 ... rocket.htm

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Post    Posted on: Sat Oct 15, 2005 10:32 am
Hello, Andy Hill,

is the reduction of temperature by several hundred degrees a step that can assist or improve reusability? Only the turbopump is concerned as far as I understand it - but it seems to me as if no reusability is possible without turbopumps working at sufficiently low temperatures.

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By the way - there is no problem in using and continuing old, older, very old or oldest threads - that keeps the number of threads low which keeps oversight of the section. It also keeps the threads on topic to some degree - and - very essential - it helps to focus attention on progresses, changes and the like.



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Post    Posted on: Sat Oct 15, 2005 11:40 am
Ekkehard Augustin wrote:
is the reduction of temperature by several hundred degrees a step that can assist or improve reusability? Only the turbopump is concerned as far as I understand it - but it seems to me as if no reusability is possible without turbopumps working at sufficiently low temperatures.


Although I cant say for definite that this will increase an engine's reusability, I would think that it almost has to. From what I've read turbopumps work at very near their limit and as such must wear out pretty quick, any reduction in the temperature should mean that less stress is placed on them.

Also the flow through the turbopump is sent on to the combustion chamber to be expelled out of the nozzel which should increase thrust, in most engines (excluding RD-180 type closed loop designs) the exhaust from turbopumps is normally just vented.

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Post    Posted on: Sat Oct 15, 2005 12:12 pm
Do I undertsnad correct that increased thrust may assist reusability?

By the way - what about the nozzles? are they those parts which to make reusbale is one of the hardest challenges? If yes - what about using materials for reusable heat shields for them?



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Post    Posted on: Thu Oct 20, 2005 5:31 pm
Some developments:

NASA Advanced concepts
http://www.bautforum.com/showthread.php?t=33782
http://www.spaceflightnow.com/news/n0510/15advanced/

Here is a nice link that shows how our Apollo-era tech-savvy is falling apart:
http://www.nap.edu/books/0309100399/html


Hypersonics
http://www.spacewar.com/news/rocketscience-05zzm.html

Powerhead engines
http://www.space.com/businesstechnology ... 9_ipd.html
http://www.spacedaily.com/news/rocketscience-05zzl.html


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Post    Posted on: Sat Oct 22, 2005 4:33 pm
Ekkehard Augustin wrote:
Do I undertsnad correct that increased thrust may assist reusability?)


Not directly but if you have an engine with increased thrust for the same mass it means that you could operate it at less than full throttle for longer periods which should reduce the wear and tear on the engine making it last longer. The shuttle's SSMEs operate at something like 110% full throttle (effectively exceeding their normal thrust level) for portions of its ascent which must result in excessive wear, if you only needed to run them at 90% then they might not need such a overhaul after each flight.

Ekkehard Augustin wrote:
By the way - what about the nozzles? are they those parts which to make reusbale is one of the hardest challenges? If yes - what about using materials for reusable heat shields for them?


My understanding (please feel free to correct me anyone if you have a better understanding or I am completely wrong) of what a nozzle does is that it is used to direct thrust in a particular direction and helps the exhaust gases expand in a predictable more efficient manner, essentially matching the high pressure exhaust to the low pressure air. Its dimensions and shape are one of the things that determine the rocket motor Isp. Normally nozzles are a compromise and are tuned for a specific pressure differential (equating to specific altitude range) hence Isp is normally quoted in a vacuum or sea level. As far as I can tell none of this has an effect on their reusability and with regard to heat shields, I think I am right that the Delta IV already has such a coating on its nozzles.

I hope that this answers your questions Ekkehard, if you need any further information you'll need to speak with someone with more detailed knowledge than me. :)

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Post    Posted on: Sun Oct 23, 2005 4:56 pm
From what I know, Andy, you hit it right on the nose. One thing: rocket nozzles don't have coatings to allow reuseability, but to keep them from turning to slag whilst the engine itself is firing. Reuseability during a stern-first reentry, from what I can see, would be a bit of an issue, possibly necessitating the disposal of the nozzle, and then covering the hole over with a piece of heatshield. Of course, having a nozzle that is designed to drop off during the flight can lead to its own problems...

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Post    Posted on: Wed Oct 26, 2005 5:07 pm
Its more trouble than what it's worth. The interorbital systems keeps tankage in orbit for living space to grow over time, and you get a simple capsule back.


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