Here is an interesting bit of development work being let by the DOD which I found while reading through a list of contracts:
United Technology Corp., West Palm Beach, Fla., is being awarded a $49,405,000 indefinite-delivery/indefinite-quantity contract for research and development for the Robust Scramjet. The Air Force will issue delivery orders totaling up to the maximum amount indicated above, though actual requirements may necessitate less than this amount. At this time, $220,000 of the funds has been obligated. Further funds will be obligated as individual delivery orders are issued. This work will be complete by September 2010. Solicitation began April 2003, and negotiations were completed September 2003. The Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio, is the contracting activity (F33615-03-D-2418).
A SCRAMjet is a Supersonic Combustion Ram jet, an engine which is of use only for hypersonic speeds. It would needed for missiles or near-suborbital warcraft.
PS: For those not familiar with the space community, the Air Force Research Lab at Wright Patterson (AFRL-WPAFB) is where very interesting future-looking propulsion systems work is done. If you want to talk about things like antimatter engine design, these are the lads.
*giggling like a Japanese school girl* oooh, Antimatter engines and suborbital warcraft, the part of my brain that loves scifi is just shivvering in delite *crossing fingers for orbital weapons satellites*
Hmmm… for some reason I can’t seem to edit my article now, some database strangeness going on at Hosting Matters I presume… In any case, here is the text I can’t add:
Additional note: there is also Air Force Rocket Propulsion Lab which I believe is in California and to be more accurate, that is where a lot of the antimatter geeks were the last I talked to anyone about it.
Does anyone else think they are aiming too low?… sure if you are going to travel thru an atmosphere what you really want is to slip thru it without touching anything: No friction, no drag, no buffetting,etc,etc… If they really wanted to make hypersonic atmospheric travel viable they would be offering some … “indefinite-delivery/indefinite-quantity contracts for research and development”… to aim for the best possible hypersonic travel vehicle anyone has the smallest chance of turning from dream to reality.
What would really make hypersonic travel easy would be a forward facing particle attractor/deflector that doubles as a shield and particle accelerator. This device would take any approaching particles/objects and accelerate them past the skin of the craft, flinging them off the back without letting them touch anything on the way past! 😉
Okay Joe, go out and invent one and I guarantee you’ll be a billionaire 😉
BTW, there is a DARPA project looking at suborbital craft.
Ok Dale. where do I apply for the research grant? 😉
DARPA
Dale – must be the rift in the time-space continuum…
Aviation Week / Space Technology had a good article a while back. The U.S. military is working toward a hypersonic vehicle which uses hydrocarbon fuels (such as JP-8). This is cheaper and more stable than various other exotic options – thereby allowing for the development of practical weapons. The problem comes from the combustion time in the scramjet. Hydrocarbons normally don’t burn quickly enough.
However, the breakthrough came by passing the fuel just under the vehicle’s skin. This cools the skin while heating the fuel to the level that it begins a cracking process allowing the fuel to fully combust in the chamber.
It sounds as if the Air Force is comfortable with the basic technology now to begin exploring practical applications of it.
David, if you can produce a link to that article, I would be most interested in reviewing it. It seems at first blush like a very sound concept. But the control of mixture an ignition point would appear to be daunting challenges.
Dale, I still recall the day when almost all this stuff went on at JPL in Pasadena (at least as far as engines were concerned). I am fascinated in my readings today at the vast array of “alphabet soup”, mostly under the DoD, but also the DoE, DoT, and others, engaged in high technology programs. As you might guess, there is considerable overlap. It would be nice to have a round-up of all these agencies, their designated area of endeavor, and their current projects.
actually, there were a total of three such contracts. Note that only $220k has been obligated, so further funding will depend upon congressional and service appropriations.
David,
The fuel circulation/feed system you describe has been in use for some time…the first production line aircraft to use it was the SR-71/Blackbird. the fuel used is JP-7 and the gas turbines are P&W J-58s, which are semi-ramjets. The highly heated fuel does not “crack” but vapourizes much more rapidly allowing a more rapid flame propagation resulting in higher combustion pressures and complete burn before the gases enter the turbine section.
Our current technology is way too primative to even allow the manufacture of a demonstrator “antimatter/matter” propulsion device.
Shaun: I hope you did not infer that it was anything like near term. I only said that these may be some of the same people who study such concepts. I know for certain the USAF group at the Rocket propulsion lab do indeed study such concepts because that is the group the late Dr. Robert Forward (who gave me all the contact info for those people) worked with on some of his concepts.
Antimatter engines are 50 years out, if not more, but people are looking at the requirements now. Obviously you can’t build one in +50yrs unless at some point you started looking at the design problems. The biggest of these is, of course, the fuel factory. That little issue is so many orders of magnitude beyond current global antimatter production rates that it hardly bears discussion.
Here’s a link:
http://www.aviationnow.com/avnow/search/autosuggest.jsp?docid=140914&url=http%3A%2F%2Fwww.aviationnow.com%2Favnow%2Fnews%2Fchannel_awst_story.jsp%3Fview%3Dstory%26id%3Dnews%2Fmdcrj0903.xml
“Above Mach 5, the inefficiencies associated with slowing the air for mixing and combustion are large and result in a loss of net positive thrust.
“In contrast, a supersonic combustion ramjet, or scramjet, begins to operate at flight speeds of around Mach 4-4.5 and, theoretically, can continue to operate up to about Mach 25. . . But getting the fuel-air mixture to ignite when mixing time is less than 1 millisec. is extremely difficult. Early scramjet researchers used highly reactive fuel additives to enhance the mixing and combustion process, but these chemicals can’t be used on board ships or submarines because the materials are highly toxic. . . .
“To overcome these problems, Pratt & Whitney, working with the Air Force and NASA, is developing a scramjet powered by conventional, unadulterated, liquid hydrocarbon fuels such as JP7. To accomplish this, they direct the liquid fuel through the scramjet’s walls and use the heat generated by supersonic and hypersonic flight to “crack” the JP7 into “lighter,” more volatile components. These gaseous components are then introduced into the supersonic airstream and ignited, producing thrust (AW&ST June 24, p. 95).”
The problem, as I recall, from the good old days of NASP, is firstly the plumbing as you have to have good old turbo jets and then ram jets to get you to SCRAM spped, and then materials, because you’re playing to hit Mach 25 in the upper atmosphere, which is going to make the aircraft surfaces insanely hot.
Dale mentioned the other plumbing problems with using fuel for cooling in another section.
It would be nice to seem them trialed though.
Personally, I wish they’d kept working on the DC-X concept.
David,
There is no cracking of the fuel(s). None of the constituent parts of the fuel can be allowed to fall-out of solution or vapourize before injection into the combustor or even before combustion. Vapour in the fuel system between the supply tank and injector(s) will cause uneven heat transfer from hot surfaces, eratic fuel pressures and eratic flow into the combustor. Constituent parts of the fuel falling out of solution will also lead to similar problems as well as seized pumps. BTW these fuel feed systems operate at extremly high pressures when pumping the fuel into the combustors. When the fuel is injected into the combustor it must do so in a way that results in an even burn and temperature rise across the combustor, resulting in an even pressure rise of the gases as they exit the combustor……also known as thrust.
Dale,
Yes and no…….the primary impedament to antimatter drive systems is the “belief systems” that permeate the scientific communities these days, once these are replaced by a single system based on calculation then things will again rapidly move forward.
Most of the challenges are understood, the manufacture of actual antimatter in useable quantities and how to collect the resulting energy release and convert it into a medium for usefull work have yet to be solved. Using mercury as the “fuel”, storage,transfer and injection into the reactor vessel using magnetics is well understood with only flow control needing work since the injection stream will likely be down at the atomic level.
I understand the Ruskies did a lot of research work into antimatter.
I can’t see Earth based manufacturer of anti-matter to be practical, nor for that matter all that desirable.
OTOH given the energy input requirements you could build something space based which would be fine. It would certainly make sense for space exploration as a fuel.
Yes, I agree. Anti-matter manufacturer will be much easier in space based solar power facilities. At present it is an enormously inefficient process and even when we first create it it gram quantities it is going to take orders of magnitude more input energy than what is contained in the antimatter.
As to dangers… Bob Forward pointed out that it is actually not as dangerous as many SF novels made it appear. Think about it. In a fission or fusion bomb, you have a volumetric chain reaction. In a lump of antimatter you only have energy release proportional to surface area and the density of matter impinging upon it. Thus a lump of antimatter will tend to turn into a very gamma ray hot jumping bean that builds up in intensity as it breaks up into smaller chunks. Bad enough to be in the near vicinity, but nothing like a nuclear weapon because the energy release appears over many seconds or even minutes rather than in milliseconds.
It would depend on the weapon design. I’ve seen the effect of dropping a 6kg lump of Sodium into a lake (via giant catapult) and that “jumping bean” scaled up would do significant damage.
What I suspect you’d do is a MRV style warhead with smaller anti-matter cluster bombs, you’d separate in the atmosphere and have them settle over an area thus doing huge wide area damage.
The damage would be more blast related of course, but there’d still be a pretty far bit of gamma radiation to deal with.
You’re talking about something entirely different. I’m talking about the perceived danger of antimatter in and of itself, whether manufacture or in a rocket engine. We aren’t going to get the equivalent of a nuclear explosion out of a rocket engine failure.
More on cracking JP-7 in hypersonic vehicles:
http://www.popsci.com/popsci/aviation/article/0,12543,364514-4,00.html
Damn it. Here it is:
Cracking JP-7
Dale, would you please edit that URL in David’s post so this thread is a managible read?
David: I think you’ve pretty well annilated Shaun here, and I’ve just skimmed the material. I must say, the idea of cracking a complex hydrocarbon into simpler (and, supposedly, more volitile) components “on the fly” in any kind of a controlled manner seem nearly as far-fetched as a sustained matter-antimatter reaction. But not inconceivible.
On the matter of matter-antimatter propulsion, some months ago, Glenn Reynolds posted the idea on InstaPundit for a “low-tech” deap space vehicle that might be launched by China or one of the other “emerging” astronautical nations that would be powered by successive nuclear blasts (and hense, built very heavy to endure the shock). I was thinking, why not, rather than a sustained rection, have a pulsed matter-antimatter engine in which miniscule quantities of fuel are injected into the reaction chamber in a very rapid pulse stream?
David,
A brief technical history of JP-7 can be found here :-
http://www.centennialofflight.gov/essay/Evolution_of_Technology/fuel/Tech21.htm
Jargon used in av fuels can be found here :-
http://www.chevron.com/prodserv/fuels/bulletin/aviationfuel/3_at_fuel_specsandtest.shtm
The technical explanation for the introduction and combustion of fuel in a scramjet combustor can be found here :-
http://www.aiaa.org/images/about/02_TC_Highlights/aiaa-pc.pdf
P&W contributing to the “deliquency of minors”….I do not know when the full report will be available :-
http://www.eng.fsu.edu/feeds/fa03/fa03/eml5935/09232003-session/materials/09232003-Nagel.pdf
Hotrodding your SR-71’s J-58s can be found here :-
http://www.dfrc.nasa.gov/DTRS/1997/PDF/H-2179.pdf
BTW….MIL-DTL-38219 is the spec for JP-7 as first published in 1970.
Comic books aside….there is no cracking of the fuel.
Kevin: You’re talking about an Orion. That’s an invention of Dr. Freeman Dysan. The concept was tested (using only high explosives) in the 1950’s and was put forth as a quick way to colonize the solar system. But it was nuclear and it was military and JFK had other plans. It got killed by the test ban treaty.
An Orion is simple to build and with it you could fly thousands of tons direct from Earth to Mars. Hundreds of crew. And you could have done it in 1960 because the spaceship used shipyard technology. Big, heavy welded steel construction. Not much high tech to it.
As to the suggestion on a stream of antimatter bomblets… doesn’t quite work as you are suggesting. Antimatter emits energy only at its surface. You would have to ensure there was sufficient hydrogen reaction mass density and enough time for the particles to fully burn from the outside in. In practice this means making them very small to maximize surface area. You don’t really get an impulsive effect, it’s just a normal rocket engine. Orion depends on the shockwaves against the pusher plate at the bottom.
The operation of various types of anti-matter engines is *way* too complex to go into in a comments section. A good starter is Bob Forward’s book, “Mirror Matter”.
You’ll find a lot of information on these topics on my http://www.islandone.org web site. It’s just about the definitive propulsion site on the web, thanks to a friend in Poland who keeps up one major section of it.
[I posted this as three messages because for some reason my browser was getting error messages back when I tried to post it all at once]
“As to dangers… Bob Forward pointed out that it is actually not as dangerous as many SF novels made it appear. Think about it. In a fission or fusion bomb, you have a volumetric chain reaction. In a lump of antimatter you only have energy release proportional to surface area and the density of matter impinging upon it. Thus a lump of antimatter will tend to turn into a very gamma ray hot jumping bean that builds up in intensity as it breaks up into smaller chunks. Bad enough to be in the near vicinity, but nothing like a nuclear weapon because the energy release appears over many seconds or even minutes rather than in milliseconds.”
What happens if you use gaseous antimatter and gaseous matter? Mix it together in a chamber, and you’ll have plenty of contact and reaction going on.
Or am I talking out of my hat?
When we can produce visible quantities of antimatter, we’d better have ships to propel with it – because we’ll need to scatter to the four winds in fairly short order afterward.
“An Orion is simple to build and with it you could fly thousands of tons direct from Earth to Mars. Hundreds of crew. And you could have done it in 1960 because the spaceship used shipyard technology. Big, heavy welded steel construction. Not much high tech to it.”
You’d still have to launch the thing from Earth. And isn’t setting off several nuclear bombs within the Earth’s atmosphere kind of unhealthy?
“I understand the Ruskies did a lot of research work into antimatter.”
Thank God they never got anywhere with it.