Landracing Forum
Thrust-powered Land Speed information => Discussions on absolute land speed records => Topic started by: Blue on November 20, 2010, 06:27:50 PM
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AI-5 has recently changed from Peroxide/bio-fuel to LOx/bio-fuel. This is a BIG change in favor of performance and safety. The next issue of taking on development of a 100,000 lb-ft thrust throttleable chamber is a huge challenge. Combustion stability for a given chamber size, pressure, mass flow, and thermodynamic condition is usually a point design for complex hydrocarbons and I wish them all the best.
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How do they plan to refuel in the one hour turnaround?
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How do they plan to refuel in the one hour turnaround?
The bio-fuel is no problem to refuel, it's a room temperature storable. The LOx requires several hours of pre-cooling to get the tank and insulation down to temperature the first time. After that, it's already cool and can be re-filled after a run with little more effort than the bio-fuel. The LOx will boil off over time, it's a question of insulation. Certainly the turn time requires them to re-launch before much would boil off. Locating the fill ports far from each other should be enough for safety.
The real issue will be combustion stability of a throttleable engine running a complex hydrocarbon never before used in a rocket. The development of this one facet could dwarf the rest of the program.
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I've never heard using LOX and in favor of safety put into the same sentance before
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Even the bio-fuel can be a problem if the run temperatures are below 43 degrees F. It starts clouding and becomes hard
to ignite. We tried it and went back to karosene. I wish them lots of luck but it sure seems scary when you begin mixing
those fuels in the environment we run in. Rosco has some smart people on his team so I'm sure they'll figure it out.
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...... Peroxide/bio-fuel to LOx/bio-fuel......
Forgive my ignorance, but I took physics for my school science requirement, not chemistry. I know what Peroxide is, but what is LOX?
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I thought LOX was what you eat with bagels and cream cheese.
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...... Peroxide/bio-fuel to LOx/bio-fuel......
Forgive my ignorance, but I took physics for my school science requirement, not chemistry. I know what Peroxide is, but what is LOX?
I believe it stands for Liquid Oxygen. I remember see it on tanks/vessels as NASA was filling rockets.
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I thought LOX was what you eat with bagels and cream cheese.
Great avitar, I am a Stan Mott fan myself, but I prefer the Pignatelli over the Cyclops
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The real issue will be combustion stability of a throttleable engine running a complex hydrocarbon never before used in a rocket. The development of this one facet could dwarf the rest of the program.
They should review TRW's work with pintle injection rocket engines.
A bit large for current RRS test stands... but I'm thinking they likely already have a RRS member in their group.
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I've never heard using LOX and in favor of safety put into the same sentance before
Peroxide at high concentrations has a far worse safety record than LOx. Outside the rocket community, LOx is transported and handled with an excellent safety record.
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I've never heard using LOX and in favor of safety put into the same sentance before
Peroxide at high concentrations has a far worse safety record than LOx. Outside the rocket community, LOx is transported and handled with an excellent safety record.
I have not dealt with peroxide so it may be very dangerous, all though I did date a girl once that had absolutely no fear of it. I have been in fuels for the air national guard for 23 years, and of all the fluids that go on aircraft, hydrazine is the only thing that scares me more than LOx. Glad we don't deal with peroxide.
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Interesting discussion regarding using liquid oxygen (LOX) versus high concentration hydrogen peroxide (HTP) as the oxidizer in a rocket-propeled ALSR vehicle.
I have considerable experience with both. Obviously both are aggressively active oxidizers, one cryogenic and the other not. The cryogenic LOX causes design problems in delivering the oxidizer at high pressure into the rocket fuel system. Because of the low boiling temperature it must be pumped, not pressurized by air or nitrogen gases. The oxidizer system materials must be compatible with the very low temperatures, both for insulation and also material properties affected by the cryogenic temperature. A proper pump is quite complicated and costly. It really complicates what should be a relatively simple fuel/oxidizer delivery system.
Also, safety is an issue. I was involved in correcting the combustion problem that killed three NASA atronauts in the Apollo capsule during a static test. Using almost pure oxygen, a spark caused materials to burn violently which normally would not burn at all in air. Result, three dead astronauts and many months delay in the space program.
HTP is also a material that will cause fuels to burn vigorously. It must be handled carefully to keep the containers and delivery system clean. Proper material selection is also critical to avoid rapid decomposition - aluminum alloys, stainless steels, certain plastics - all common materials work fine. A simple blowdown oxidizer delivery system can be used and no cryogenic issues are there. It was used in the field at drag strips for several years with no major handling problems that I know of. Drag racers are not exactly expert at laboratory levels of cleanliness, but with minimal training had an exemplary safety record handling the HTP.
The Material Safety Data Sheets for both materials give a good comparison.
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Just curious. Didn't the Russians figure out that solid rocket fuel is safer and easier to handle? Why not use it?
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I believe they are planning to use simple helium pressurization for the LOx and no pump. This has worked well for many years in many programs especially for short burn times. Yes, LOx is an aggressive oxidizer; but unlike HTP once it consumes the combustable that it hits, it's done. The HTP keeps going on its own.
Any energetic oxidizer is dangerous in an enclosed space. The Apollo crew would not have been saved by using HTP, RFNA, or NT; the culprit was our lack of understanding of the danger posed by 100% oxygen atmospheres under G. At zero G it turned out to be a non issue.
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I have no experiance directly with these fuels, but occasionaly run into Sammy Miller, son of Sam Miller. He claims that the proper handling of Peroxide is the issue with it that gave it a bad reputation. He currently uses it in his business of steaming the ground in oilfields, this thins out the heavy oils and alows it to be recovered.
Sam never had any problems running this fuel, but a lot of others had disasters with it.
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Any energetic oxidizer is dangerous in an enclosed space. The Apollo crew would not have been saved by using HTP, RFNA, or NT; the culprit was our lack of understanding of the danger posed by 100% oxygen atmospheres under G. At zero G it turned out to be a non issue.
Sorry to resurrect this old thread but I'm new here and just catching up!
That's interesting - why does G have any affect on how dangerous LOX is?
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I believe the issue was the system pressures used. Under zero G conditions the space craft was designed to have 100% O2 atmosphere at 4.8-3.5 psi.
On the pad they were using 100% O2 at 14.7 psi. Very different fire environment.
Also as determined in space station experiments under zero G flames behave very differently than they do in a normal gravity environment.
http://nssdc.gsfc.nasa.gov/planetary/lunar/apollo1info.html
http://chemistry.about.com/od/chemistryfaqs/f/firegravity.htm
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The Germans used 85% hydrogen peroxide, called "T-Stoffe", in their ME-163 rocket fighter. Handling the stuff was hazardous and required rubber suits to protect the crew during refueling.
Regards, Neil Tucson, AZ
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The Germans used 85% hydrogen peroxide, called "T-Stoffe", in their ME-163 rocket fighter. Handling the stuff was hazardous and required rubber suits to protect the crew during refueling.
Regards, Neil Tucson, AZ
They didn't have OSHA, they had Adolf :-D
Sid.
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As I recall, if they crashed on take off the HTP fuel had a nasty habit of dissolving the pilot if there were fuel leaks.
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I think the pilot may have to have been dead before the HTP would react with a clothed body and oxidise it completely.
The horror stories abound in the handling of this oxidant but using care, clean non reactive containers, safety water deluge and covering skin and protecting eyes does keep the job safe, with ambient temperature unpressurised product. Slight contamination by touching materials which have been sprayed with unreacted HTP may cause the skin on fingers to go white - you notice this before the skin temperature rises :-). Sluicing with water stops the reaction taking place and then it is just like bleaching hair.
After WWII the British rocketeers were even talking of putting hands into drums of HTP (before rapidly washing it off) without ill effects. Once pressurised the HTP spray could be more of a risk and organic materials react and then burn, so soles of shoes can get a bit warm and melt/catch fire.
Because it can be used as a monopropellant or as the oxidant in a hybrid system HTP has been used across the world in rockets and in Russian torpedos. {The Kursk however was lost through a faulty HTP torpedo episode so do take care.}