Author Topic: Choice of fuel for a launch vehicle  (Read 4803 times)

Offline PMN1

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Choice of fuel for a launch vehicle
« on: 11/15/2005 06:28 pm »
What determines the choice of fuel for a launch vehicle?

Offline Boris the Space Dog

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RE: Choice of fuel for a launch vehicle
« Reply #1 on: 11/15/2005 06:51 pm »
Depending on launch vehicle's missions. Also depending on available exisiting components for cost and schedule reasons.
Barking where no dog has barked before.

Offline PMN1

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RE: Choice of fuel for a launch vehicle
« Reply #2 on: 11/19/2005 03:26 pm »
There is an article by Stephen S Pietrobon (Small World Communications) in the May/June 1999 Journal of the British Interplanetary Society about replacing the SRB’s with LRB’s

‘The use of high-density hydrogen peroxide/kerosene liquid rocket boosters for the Space Shuttle is investigated as a replacement for the existing SRB’s. It is shown that H2O2/Kerosine outperforms solids, LOX/Kerosene and LOX/LH2 as a general booster propellant due to its high density and moderate exhaust speed. With the same propellant mass and size as that of the current SRB’s, computer simulations indicate payload mass can be increased by a third from 24,950kg to 33,140kg for a 28.45°, 203.7km circular orbit.'


Offline AndyMc

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RE: Choice of fuel for a launch vehicle
« Reply #3 on: 11/19/2005 04:55 pm »
Hi,

Just googled, and found the article you mention is availabe as a pdf: http://www.sworld.com.au/steven/pub/lrb.pdf

His site may also have some more things of interest: http://www.sworld.com.au/steven/


Offline Colby

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RE: Choice of fuel for a launch vehicle
« Reply #4 on: 11/19/2005 05:07 pm »
As stated by kraisee in a previous post, the EPA does not like the unburned perchlorate that the SRBs give off. The fact that a hydrogen peroxide/kerosene booster could produce similar launch results with "less dangerous" emissions is interesting.
Colby

Offline kraisee

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RE: Choice of fuel for a launch vehicle
« Reply #5 on: 11/19/2005 05:52 pm »
Quote
PMN1 - 19/11/2005  11:26 AM

There is an article by Stephen S Pietrobon (Small World Communications) in the May/June 1999 Journal of the British Interplanetary Society about replacing the SRB’s with LRB’s

‘The use of high-density hydrogen peroxide/kerosene liquid rocket boosters for the Space Shuttle is investigated as a replacement for the existing SRB’s. It is shown that H2O2/Kerosine outperforms solids, LOX/Kerosene and LOX/LH2 as a general booster propellant due to its high density and moderate exhaust speed. With the same propellant mass and size as that of the current SRB’s, computer simulations indicate payload mass can be increased by a third from 24,950kg to 33,140kg for a 28.45°, 203.7km circular orbit.'


I'm not sure if there aren't some down sides for using H2O2/Kerosene.      I'm not aware that the combination is corrosive, but what are the final by-products of use as a rocket fuel?   LOX/LH2's by-product is water vapour, so that's pretty good IMHO.

Also, there don't appear to be many engines which can use that combination, so I'd guess there's not much in the way of experience with them either.   While the Specific Output of H2O2/Kerosene does seem to be high enough to compete favourably with the SRB's, there's certainly no H2O2/Kerosene engine available yet which is large enough or powerful enough to use, even clusterd, under something as small as an SRB.   Have a look:

http://www.astronautix.com/props/h2oosene.htm

I personally would favour replacing the SRB's with a LOX/LH2 system because that's what is currently in use at the Pads today and thus the infrastructure at the Pads is already in place to handle it.   I liked the old USAF concept of six SSME's on each booster, flyback design.   That allowed for a very straight-forward development program from the current STS systems into the new ones.

Ross.
"The meek shall inherit the Earth -- the rest of us will go to the stars"
-Robert A. Heinlein

Offline PMN1

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RE: Choice of fuel for a launch vehicle
« Reply #6 on: 11/19/2005 06:12 pm »
Axxording to the article he is looking at modifying the RD-170..

CH2 + 3H2O2 = CO2 + 4H2O

CH2 + 1.5)2 = CO2 + H20

At the end of the article ' Previous H2O2/Kerosene engines such as that successfully used in the Black Knight sounding rocket and Black Arrow launch vehile used silver gauze to first decompose the 85% H2O2 in the combustion chamber. For higher concentrations of H2O2 another calaytst is needed such as platinum. Modern H2O2 contains inhibiters which can poison such a catalyst. These inhibitors may need to be removed  for rocket-grade H2O2. No ignition source is required since the very hot decomposed H2O2 will spontaneously combust with kerosene. Due to the high mass ration of H2O2 to Kerosene and the superior heat characteristics of H2O2 compred to kerosene the H2o2 should be used to cool the engine nozzle before combustion. In a staged combustion engine, the pre-combustion chamber needs only to decompose H2O2 to provide the energy for the turbines, simplyfying the engine design. Since H2O2 is non cryogenic this helps reliability (of the 22 Black Knight and 4 Black Arrow launchers, involving 128 Gamma engines, there were zero engine or propulsion unit faliures). The NF-104D research aircraft alos successfully used the AR-2-3 90% H2O2/Kerosene engine to set records that still stand to this day.'

Offline Dobbins

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John B. Dobbins

Offline PMN1

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RE: Choice of fuel for a launch vehicle
« Reply #8 on: 11/19/2005 08:46 pm »
Quote
AndyMc - 19/11/2005  11:55 AM

Hi,

Just googled, and found the article you mention is availabe as a pdf: http://www.sworld.com.au/steven/pub/lrb.pdf

His site may also have some more things of interest: http://www.sworld.com.au/steven/


Thts the one, good find, the article on the reusbale launch vehicle is also in JBIS issue.

Offline realtime

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RE: Choice of fuel for a launch vehicle
« Reply #9 on: 11/20/2005 02:55 am »
Quote
I personally would favour replacing the SRB's with a LOX/LH2 system because that's what is currently in use at the Pads today and thus the infrastructure at the Pads is already in place to handle it. I liked the old USAF concept of six SSME's on each booster, flyback design. That allowed for a very straight-forward development program from the current STS systems into the new ones.
If there were a requirement to replace SRBs, I too would vote for a LOX/LH2 system, but probably not a flyback.

If you use LOX/LH2, you can just place more motors at the bottom of the ET.   Throw fairings over the plumbing so they can use the ET tankage.  If you want reusability do it with some sort of Shuttle-C parachute arrangement.

It's almost impossible to "live off the land" with a motor that uses chemicals more complicated than LOX/LH2.  The processes are complex and require catalysts or produce large amounts of waste byproducts.  Thus, L2H2/kerosene motors don't lend themselves to operations beyond LEO.  They might be useful for small motors that have to remain in storage on orbit for long periods of time, or for a space tug tied to LEO like Parom.

On the other hand, it is not hard to imagine LOX/LH2 fuel being manufactured on orbit from water boosted in bulk by commercial entities.  For this reason, designers may standardize on LOX/LH2, though LOX/CH4 will gain a lot of attention because of the desire to live off the land on Mars.


Offline MKremer

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RE: Choice of fuel for a launch vehicle
« Reply #10 on: 11/20/2005 05:05 am »
Using LOX/CH4 propulsion opens up the opportunity for all sorts of fuel supplies from many types of solar system bodies besides just Mars - comets, some asteroid types, and many other moons have lots of organic compounds that can be harvested and refined to use as fuel for future long-term exploration (and base-building) missions.
(There's lots of H2O in those bodies as well, but turning gaseous H2 into LH2 takes a whole lot more energy than making liquid CH4. Creating or transporting heavily insulated LH2 storage vessels would also be a factor.)

Offline CuddlyRocket

RE: Choice of fuel for a launch vehicle
« Reply #11 on: 11/20/2005 06:38 am »
If you're starting from organic compounds, there are a whole number of fuels that would be even better (from a practical, ease of use standpoint) than CH4, such as ethane, propane, butane, ethanol, etc etc.

Methane is proposed for Mars because of the ease of manufacturing it from CO2 in the atmosphere using H2 feedstock brought from Earth.

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