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Composite rocket engines?

Posted by: lightningbob - Sat May 26, 2012 12:53 pm
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Composite rocket engines? 
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Post Composite rocket engines?   Posted on: Sat May 26, 2012 12:53 pm
...are there any? I was wondering if any have been experimented with. They may produce less thrust but with perhaps enough weight loss (of the entire craft not just the engines) they would be feasible. Perhaps they could produce as much thrust as there metal counter parts. Who knows?


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Post Re: Composite rocket engines?   Posted on: Sun May 27, 2012 3:22 pm
You have rockets which use graphite chambers and nozzles. A sort of carbon-carbon.

The problem with trying to use a conventional composite is in finding matrix material, the resin, that take the temperatures and erosion of not only the noisy part of the engine, but also the ancillaries like turbo-pumps etc. Its still cheaper, easier, and good-enough to use alloys.


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Post Re: Composite rocket engines?   Posted on: Tue May 29, 2012 5:56 pm
For low cost liquid engines meant to only last one firing, there have been a few engines with ablative liners and carbon fiber overwrap to hold the pressure. Garvey and Protoflight both fired such engines.


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Post Re: Composite rocket engines?   Posted on: Wed May 30, 2012 5:24 pm
Could a virtual nozzle be made? By either ionization or another means could two neutral fuel products combine and then be repelled by the surface of the rocket? I know this could be light if the ionization energy could be beamed in, from something not carried by the rocket. Also what about active cooling elements designed to be eventually replaced? Extracting work from lost heat and adding it back to thrust is like having more fuel....

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Post Re: Composite rocket engines?   Posted on: Fri Jun 01, 2012 12:42 pm
Sigma wrote:
Could a virtual nozzle be made? By either ionization or another means could two neutral fuel products combine and then be repelled by the surface of the rocket? I know this could be light if the ionization energy could be beamed in, from something not carried by the rocket. Also what about active cooling elements designed to be eventually replaced? Extracting work from lost heat and adding it back to thrust is like having more fuel....


Yes, this has been proposed. Do a web search on "magnetic nozzle".

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Post Re: Composite rocket engines?   Posted on: Fri Jun 01, 2012 12:49 pm
lightningbob wrote:
...are there any? I was wondering if any have been experimented with. They may produce less thrust but with perhaps enough weight loss (of the entire craft not just the engines) they would be feasible. Perhaps they could produce as much thrust as there metal counter parts. Who knows?


Not exactly composites but fits in with your idea of using lightweight materials other than metals to reduce the weight of engines:

Ceramic Materials for Reusable Liquid Fueled Rocket Engine Combustion Devices.
Quote:
Part of the Integrated High Payoff
Rocket Propulsion Technology (IHPRPT) program, the efforts of the directorate include:
1.Developing continuous fiber reinforced ceramic matrix
composites (CMCs) for actively cooled thrust chambers and
nozzles
2.Demonstrating the feasibility of a transpiration-cooled thrust
chamber
3. Evaluating ceramic matrix composites for radiation cooled
nozzles.
The goal is to develop and demonstrate these new technologies
so that they may be incorporated into future rocket
engines. Using lightweight ceramics has the potential to reduce
the weight of the combustion devices by up to 50%.

...
Table 1 lists the materials and type of construction of
numerous combustion devices, both historical and current. As
the table shows, the materials of choice (for all the engine manufacturers)
for combustion devices in large liquid fueled rocket
engines have historically been stainless steels, nickel-based
superalloys, and copper alloys. These materials are selected for
their high strength and high thermal conductivity in order
to cope with the stresses and extreme thermal environments
of rocket engines. Since these alloys also have high densities
(8-9 g/cm3), widespread reliance on them has traditionally
resulted in heavy engines.
Designers would like to reduce the weight of rocket
engines. A key performance criterion for engines is thrust-to-weight
ratio. Lighter engines and launch vehicles would allow
heavier payloads to be placed into orbit at a lower cost. One
path to lighter weight engines is replacement of conventional
high-density engine alloys with lightweight, high specific
strength ceramic composites. Two attractive candidates for
this application are carbon fiber reinforced silicon carbide
(C/SiC) and silicon carbide fiber reinforced silicon carbide
(SiC/SiC). These materials have low densities (2.0-2.4 g/cm3)
and high strengths that they maintain to relatively high temperatures
(2400-3000°F).
http://ammtiac.alionscience.com/pdf/AMPQ8_1ART06.pdf

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Blog: http://exoscientist.blogspot.com


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Post Re: Composite rocket engines?   Posted on: Sun Jun 03, 2012 1:43 pm
Cool I didn't know alot of this. I believe to get into orbit cheaply weight reduction is critical including the engines. I wonder the what the weight comparison of todays rockets of simular capacity is to rockets during the Apollo missions (sans fule of course).


Also I do like the first stage aircraft lifted idea. I knows it's not really a single stage operation but I like the 30% reduction in fuel by simply launching about ten miles up.


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Post Re: Composite rocket engines?   Posted on: Wed Jun 06, 2012 5:38 pm
I'd like to look into Vacuum Carbon, or Silicon deposition to make a diamond/silicate substrate. If you burn Silane, or Methane in a vacuum, the elements deposit at the base in molecular layers, which you can reinforce with your high temperature fibers. Graphite is fairly thermostable, but not at the tempratures typical of a chemical rocket's exhaust. So, the substrate would have to be thermaly resistive enough to insulate the fiber as well. Diamond would also have to be designed not to harmonically shatter from the vibration of the exhaust, so I'd go for Silicate.

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Post Re: Composite rocket engines?   Posted on: Sun Jun 17, 2012 5:14 pm
http://www.chm.bris.ac.uk/pt/diamond/thermionic.htm

Using a diamond thermionic layer a rocket nozzle could insulate the rocket by making electricity. A secondary layer that was piezoelectric could absorb turbulance.

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Post Re: Composite rocket engines?   Posted on: Fri Jul 06, 2012 3:17 pm
Assuming we're talking about the Nozzle, or ventury here (There's a lot more to a liquid fueled rocket, and most of those parts could also be made from various composites.) The properties you're looking for are thermal stability, tensile strength, and then light weight. It doesn't matter how light it is, if it burns up, or shatters when you fire it. This is why most modern rockets pump cryogenic fuel in spiral tubes around the reaction surface. It pre-heats the fuel, and cools the nozzle so it doesn't melt. This requires a thermally conductive material, like alluminum, usually an alloy.

I know "Thermionic" is your new buzzword, and peizoelectric sounds pretty cool too, but Diamond, and Quartz (the most readilly availible Peizoelectric crystal) are less than ideal for a few reasons. First of all, these venturi are large, like cut a door in the side and live in them sized. (For Surface-Orbit launchers) We don't have the technology to make precision crystals on that scale, it would require a pressure kiln big enough to rent out as low income housing, and measument/themal control orders of magnitude more precise, and responsive to prevent flaws. That, and they tend to shatter when overstressed, because while they have high surface hardness, they're also brittle, with next to no tensile strength. Thermal expansion is also an issue, as they go from room temperature to vaporize your bones hot in fractions of a second, not to mention having all the pressure, and concussive vibration of containing half a steady state explosion.

Now, these pretty much run off of heat and pressure. Simplifying a lot here, but the chemical reactions (Hydrating oxygen, and tribonding N2) creates heat, which expands the gasses, which create pressure pressing up on the nozzle, and down on the atmosphere to make the rocket go thataway. Drawing off heat, thermionically, or otherwize basically pulls energy out of the system, making it less efficient. The heat-exchanger from pumping fuel into the nozzle raises efficiency by recycling that heat directly back into the chamber, and nozzle. Whatever you would use that energy for, it'd serve you a lot better for the job at hand, namely getting you to orbit in the first place.

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Post Re: Composite rocket engines?   Posted on: Sat Jul 07, 2012 7:45 pm
The idea is to use the thermionics to produce electricity, from heat, to cool the components that need it, and then that electricity could power other performance boosting components, like the ion rocket engines that have been researched lately, if I can take something that needs cooling and use it to fix another problem with it......

Thermionic diamond substrate and Piezoelectric substrates could be grown on a surface of another material. A laminate weave of a thin layer of each as well as a tensile layer could absorb both excessive heat and turbulance, and then redirect it into exaust acceleration then I can have a rocket that is lighter, reusable and more powerfull,... and safer, you could also control the heat in the ignition chamber walls, making them much more durable.

Another thought is upon re-entry the system could cool the ship and produce power for landing.

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Post Re: Composite rocket engines?   Posted on: Thu Jul 26, 2012 9:17 am
I found this while looking through the lunar xprize teams. They seem to be using composite materials for their engine.

https://www.arcaspace.com/en/programs.htm

http://en.wikipedia.org/wiki/Executor_% ... _engine%29

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Post Re: Composite rocket engines?   Posted on: Thu Jul 26, 2012 11:14 am
Did ARCA ever actually get to space!? I forgot about them

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Post Re: Composite rocket engines?   Posted on: Sat Aug 04, 2012 10:19 am
Rob Goldsmith wrote:
Did ARCA ever actually get to space!? I forgot about them

By looking at their website they probably haven't but they are still in the competition so hopefully they will make it up there.

I like the looks of their rocket plane. :D

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