RDX as a propellant (sprint missile derivated)

[Setharier]

I found no topics concerning on this. I am wondering of making rocket with maximum boost and acceleration and saw discussion and video on other site(other language) where this sprint missile was discussed and rdx as it's propellant. They said it was "cheated" not to detonate but still burn at extreme speed, making over 60G acceleration possible. I came in interest with high-accelerating amateur rockets which I could build up for new year's eve and now when I am in corner of making RDX I could start preparing super-rockets also :D

On the other hand, is there other propellants that could be used boosting rocket into several dozens of G's?

Is this too high-tech for home pyro/chemists or has it already discussed around? Black powder boosters are more easy, but more boring also and the ones I've attempted were blown up or flew quite badly. (RDX is not valid for search and sprint came up with only some dogs and self defence stuff.)

[486]

There is this new plastic cased ammunition that uses HMX as propellant, they had an article on it in the american rifleman this month. It said nothing but that it uses HMX as the propellant, maybe more can be found elsewhere on the internet.

Wikipedia article on HMX (http://en.wikipedia.org/wiki/HMX)

[Secong Nature]

Hexamine DiNitrate may be a more suitable propellant. It's slower burning than RDX but is easier to make with more available materials, meaning you can make alot more for less money.

You could try dispersing it through double base propellant or BP to increase burn speed.

[Alexires]

Setharier - Do you have a link? Otherwise, translate and type it for us, or copy pasta a babelfish translation in.

I remember hearing that dudes in Vietnam used to use C4 as a hexamine replacement when cooking and also a chewing gum...

I would guess that it would have been the plasticiser burning, but we all know RDX is fairly stable. I wouldn't be overly surprised given that information. Perhaps you were refering to something like this (http://publications.drdo.gov.in/gsdl/collect/defences/index/assoc/HASH2946/8508c3ad.dir/doc.pdf). To understand if something like this is feasable, you should look for DDT stats for RDX and this will tell you its suitability as a propellant.

[Setharier]

In the text it is first said "It went in 4.6 seconds up to 8754 mph", the answer "well then americans may have even advanced in 40 years. In the following link the sprint missile goes to 0-12km/s in five seconds"

http://www.srmsc.org/vid0010.html

"I remember that missile has RDX fuel which has been made not to explode. The missile first stage is still anyway blown off."

The source isn't the most credible, definitely, but it gained my attention. If one could really build up a small missile with thrust of several dozens of G's, I really am interested in and for sure many others are. Just for launching something really fast really high in the new years' eve, and not to forget building (remote controlled) rocket launcher device :)

[Roy Paci]

I borrowed an old textbook that reffered to an NG/NC composition as a propellant... Can't remember the ratios. Any ideas?

[slarter]

One of the Trident Missiles uses 90,000 lbs of HMX for propellant. They made them in Utah and the ones that were flawed were taken out in the desert for disposal.

[Positron]

I am wondering of making rocket with maximum boost and acceleration

That's as easy as keeping the thrust/weight ratio high. Harder to do on larger rockets. I've gotten extreme acceleration out of the simple Estes "D" and "E" engines, using a thin cardboard tube for the body, small-ish fins glued on with epoxy, and balsa-wood nose-cones. No recovery system. Such rockets will "disappear" when you hit the launch button :D with only a trail of smoke to show where it went.

The answer to your question about high-performance rocket propellants is "The Preparatory Manual of Explosives". It contains a wealth of information concerning military propellants utilizing RDX, HMX, Ammonium Perchlorate, and others. I would type the information for you if I hadn't misplaced the damn book :rolleyes:. It will turn up soon, but hopefully some kind individual will give you the info before that.

Anyhow, if I recall correctly, the PMOH does not have too much information on applying the propellants directly to rocket engines. In other words, I don't remember much too much info (there is some...) given on the propellant's Specific Impulse, Burn-rate, Igniteability, Combustion Temperature, Burn-rate Vs. Pressure, etc. that allows you to properly design a nozzle (and combustion chamber) around it.

You DO realize that you will have to design a nozzle, right? And turn one (probably made out of graphite) on a lathe, right? You do realize that you can't just press it in a tube and expect it to perform...

Anyhow, if you're willing to completely learn and absorb www.nakka-rocketry.net, you may be able to pull it off. It's an excellent website...and, he's developing a damn nice Ammonium Nitrate/Aluminum propellant too :cool: Knowing him, he will probably characterize this propellant to the tee, and happily give us all of the information to use ourselves for free. He's doing a hell of a service for Amateur Experimental Rocketry. (Other than buying a CD from him, I'm not affiliated with him in any way.)

Is this too high-tech for home pyro/chemists or has it already discussed around?

Making the propellant is the easy part. Designing and making a nozzle to properly utilize the propellant is a completely different story.

EDIT: It may not be too hard to make your own graphite nozzle, for high-temperature propellants. Looks like the design is much less sensitive than for those propellants similar to the KNO3/Sucrose "rocket candy" blends (much smaller nozzle exit areas are required for higher-ISP propellants, which is nice).

[festergrump]

Sprint Missile Derivaded? Maybe you mean DERIVED instead? Or is this a new word you learned while "conversating" (conversing) with your friends? :rolleyes: Don't get upset and loose your head because someone came along and correctimated you.

Sorry, I couldn't resistulate, the humorosity factor was gargantuanalistic... :p

[Cobalt.45]

They said it was "cheated" not to detonate but still burn at extreme speed... I think you (they?) mean "chelated", not "cheated".

[Positron]

I do believe-ificate that the hilariousness-icity of festergrump's postingness more than makes'es up for my waste-ified time-ification.

[hickey]

There are some information in the use of HMX in high performance propellants in this book
Propellants and Explosives Thermochemical Aspects
http://www.filefactory.com/file/806f3a/n/g5g5e_rar

Further.... if you surf the patent files you can find volumes of information related to the use of RDX and HMX in both gun and rocket propellants.

[Yafmot]

Back in the '90s, I worked for a refractory metals and high performance ceramics outfit down in LA. We got a subcontract from Saco Defense for a program to develop a cannon barrel that was resistant to the erosive effects of Nitramine-based propellants. One powder formulation in particular was especially destructive to bore liners (even stellite!), shooting-out the bores in about 75 rounds. This is not acceptable performance in an automatic weapon.

Most of these propellants contained more than 50% RDX. The mechanism contributing to the bore erosion had to do not so much with heat per se', but wth hot nitramine particles coming in contact with the interior surface. While the isochoric flame temperature was somewhere around 3,000 Kelvins, the surface temperature of the still- burning nitramine particles was somewhere above 4,000. These things were bouncing around inside the barrel like pinballs, at supersonic speeds, and wherever they impacted the bore surface it would scorch a little pit. so it didn't take long to wear down the forcing cone and rifling to the point where the barrel was unusable, spraying all over the range.

What we came up with, initially, was a subscale barrel in .50 BMG which, using the same propellant, lasted through a 10,000 round burst with no detectable wear. The guys at Saco and ARDEC thought we were God. They had tried every trick in the book, 718 alloy, hard chrome, Stellite, and nothing seemed to work.

What we came up with was a liner of pure Rhenium, CVDd on a sacrificial monolithic graphite mandel, with a 4340 chrome moly sleeve shrunk onto it. The graphite was then burned out with an Oxyacetylene torch, modified to extend down the bore. Soon, a few were made in 25 mm for the Bushmaster cannons on the Bradleys.

The "big barrels" cost $10,000 apiece, but were still a bargain when compared to the conventional barrels that cost two grand and wore out in less than 100 rounds. Why they never went into full production is hard to figure.

Anyway, you can expect similar problems if you try to make rocket nozzles out of conventional materials. Carbon-Carbon may hold up for a "one shot deal," but if you are shooting for a reloadable motor with a reusable nozzle, solid Rhenium is damned expensive. And if you're thinking about a Rhenium coating on a CC or graphite nozzle, forget it. We tried that shit (against my better judgement) with a hypergolic satellite positioning thruster, and it failed catastrophically at about 20 seconds of burn time, due to CTE mismatch.

For a gun propellant, though, the nitramine content provided about a 40% increase in muzzle velocity, which translated into about a 25% increase in KE downrange.

Good luck, intrepid scientist!