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New XCOR Rocket Engine Passes First Test
apsmith writes "XCOR Aerospace just successfully test-fired their new liquid oxygen/kerosene rocket engine. This is significantly more powerful than the engines used in the XCOR EZ-Rocket vehicle, and will be further developed for use in the Xerus suborbital vehicle. XCOR is one of the serious X-Prize contenders, and partly funded by John Carmack of Id and Armadillo Aerospace (Carmack's in-his-free-time X-prize contender)."
Oxygen, by itself, won't hurt you. If the O2 tank leaks, you end up breathing a slightly more oxygen-rich atmosphere. The EZ-Rocket carries the O2 tank in place of the passenger seat, primarily because it won't kill the pilot if it vents.
The fuel (alcohol in earlier prototypes, kerosene for this one) is carried in a separate tank slung below the fuselage. It's outside the aircraft frame.
If you've taken fire safety training, you know that there are three components that are required for a fire - fuel, oxidizer, and heat. Remove any one, and you don't have a fire. When you're fueling you car, the gasonline doesn't spontaneously ignite with the oxygen in the air, right? Add heat and you've got a fire, though.
So, if you keep the fuel, oxidizer and heat in controlled environments, you'll survive the flight just fine. If the O2 tank ruptures, you should probably worry more about schrapnel or the overpressure.
The current shuttle uses liquid oxygen, by the way, along with(surprise) liquid hydrogen. Together they fuel the orbiter's engines. The boosters on the side are solid-fuel motors and once they're lit, they don't go out until the fuel's burned.
Incidentally, every rocket fuel of one kind or another has to have some oxidizer, or it won't work in space(think that one through.) Most rockets for non-space applications have oxidizers, too, because it's hard to get oxygen from the air mixed in with fuel fast/well enough to be useful(this is why ramjets were so 'neat', they don't need to carry oxidizer, but can generate enormous amounts of thrust at incredible speeds.)
The orbiter also uses hydrazine for the auxiliary power units and firing thrusters(I think), and a half dozen other things that go 'boom' or are very nasty. That's the whole point behind rocket fuel- burning it has to release a LOT of energy for its weight.
Please help metamoderate.
Challenger... I rest my case.
LOX (Liquid OXygen) is used because it is both cheap, freely avilable and less dangerous than most other oxidisers. For more info on propelants in general, see here. For LOX + kerosene in particular, the link is here. Off course, if you want to get away from the nasty cryogenic oxidicers, you could always go for hydrogenperoxside and kerosene (se data here). Off course, H2O2 is more expencive and way more poisonous than LOX, but it's give and take... In large quantities, 95 per cent hydrogen peroxide then cost approximately $1.00 per kg - LOX on the other hand cost about 0.08$ per kg. Or you could get exotic and use Liquid Fluorine and Kerosene wich gives a Isp: 322.00 sl. compared to a Isp: 300.00 sl. for LOX/Kerosene (se data here) - but then LF was kosting 6.00$ in 1959, and I don't think the price has dropped.
So in short, LOX has a few drawbacks, but the benefits of using it outweights them. Oh, and Encyclopedia Astronautica is a good place to find this sort of info.
Everything in the world is controlled by a small, evil group to which, unfortunately, no one you know belongs.
--Mike
Oxygen Poisoning info
It looks like oxygen toxicity begins at about 10 times sea-level partial pressure of oxygen (article cites 29 lb/sqin). How stuff works explains that the process is very dependent on both pressure (not % of atmosphere!) and time. Early astronauts used 100% oxygen atmospheres at a low pressure without any problems.
If I have been able to see further than others, it is because I bought a pair of binoculars.
We are not currently an X-Prize contender. If the X-Prize is still available when our Suborbital vehicle is complete, it is conceivable that it could be modified to meet the requirements of the X-Prize. XCOR is more focused on the immediate possibility of revenue generating service from the Xerus spaceplane.
:)
For more information about our Suborbital program, visit our suborbital page at:
http://www.xcor.com/suborbital.html
--Mike Massee
XCOR Aerospace
Actually, if you were a scuba diver and used oxygen enriched breathing mixes (aka Nitrox), you'd know that the risk of a CNS OxTox hit (a central nervous system seizure due to oxygen toxicity) significantly separates from zero at a ppO2 between 1.6ata and 2.0ata... pretty far from 10.0ata.
Much of my scuba diving is limited by this number. I usually dive EAN32 (32%O2 68%N2) for my recreational diving, and at 128fsw (the local pressure equivalent to a column of salt water 128 feet tall with 1ata on the top), the ppO2 is 1.6ata. That's the MOD (Maximum Operating Depth). Don't go deeper than that. Even accidentally. So I limit my dives on EAN32 to 110feet to stay away from that invisible boundary where risk starts to accumulate.
You're right that whether you get hit is variable on pressure and time, it also depends on the individual's body, how fit they are, how rested they are, if they've done recent exertion and lots of other variables we don't understand. You can be tested (in a hyperbaric chamber) and make it to 4.0ata for an hour on one run and then a month later get a CNS hit on the way past 2.0 at the start of the run.
Also, a CNS hit isn't really harmful itself. When you're lying down in a hyperbaric chamber and you get hit, you go into a mild convulsion, lose conciousness, they drop the pressure, you wake up none the worse for wear. What hurts is when you need to be concious to keep doing something important (like keep the breathing regulator in your mouth on a scuba dive, or like continue to pilot the vehicle).
Finally, there is another kind of injury from elevated oxygen levels, where your lungs get burned from long exposures (long is hours and days, depending on how elevated the pressure is). This is why when you're in the hospital and need extra O2, they don't put you in an pure O2 environment and leave you there. The tissue in your lungs degrades and that injury can eventually be more serious than whatever you were on the supplemental O2 for. This is sometimes called Systemic OxTox, though it has a few names.
In either case, as others have mentioned, you're more likely to be burned by the LOX freezing your skin or the shrapnel from the bursting container than by breathing the extra O2. It also may not help the situation that the suddenly reduced temps in the cockpit cause all of the windows to frost up just as you're losing engine power...
Regards,
Ross