A new potential rocket fuel molecule. Trinitramid.

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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KitemanSA
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Post by KitemanSA »

Giorgio, Happyjack, and mdeminico

Please edit your posts so that only a {Post Deleted} remains! Please? Pretty Please???

Giorgio
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Post by Giorgio »

No problem ;)

zDarby
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Post by zDarby »

1) It seems to be for solid rocket motors, not liquid motors. (Perhaps for hybrids as well?)

2) I've yet to see a reference to what it's 20-30% better than. (STS's SRBs perhaps? Certainly not LH/LOX! At least, not in ISP.)

3) I've yet to see a specific statement as to what it's 20-30% better at. (Ox delivery? Total specific impulse? Energy per mass? Energy per volume? Reaction speed? What?)

4) I believe (though not at all certain) Tibbits is correct: It's an oxidizer, not a fuel. Looking at it's chemical formula, N(NO2)3, it's basically three nitrogen-dioxide molecules connected to a central nitrogen atom. ("[...]The molecule is similar to a propeller in shape.") If such an oxidizer could be synthesized and be stable (my exceedingly elementary chemistry says, "unlikely") my guess is it would be both nicely dense and would decompose quickly into 2*N2 and 3*O2, making the total reaction quick, without any free-floating Ns running around to absorb loads of delta-v... Yes, I'm WAGing, but I think these are reasonable WAGs.

I would also agree with Tibbit's assessment that *IF* 20-30% is in regards to total ISP compared to AP oxidizers in many SRBs, then we can expect vacuum ISPs between 300 & 360 sec. Which would be totally awesome, as it would compare favorably with kerosine/LOX engines!! I must admit, however, that I don't see how this is likely.

He's probably also correct that this will only be seen in military rockets, not civilian ones. Though, this is completely dependent on its manufacturing & handling expense.

Skipjack
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Post by Skipjack »

Yah, so you can build smaller ICBMs so you can fit more of them onto a SSBN. Thats great, I guess...

happyjack27
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Post by happyjack27 »

zDarby wrote: 3) I've yet to see a specific statement as to what it's 20-30% better at. (Ox delivery? Total specific impulse? Energy per mass? Energy per volume? Reaction speed? What?)
energy density, as in per unit mass. the higher payload thing can tell you that.
4) I believe (though not at all certain) Tibbits is correct: It's an oxidizer, not a fuel.
[/quote]
i thought youo said you thought it was a solid fuel? solid fuels are usually mono-whaterver, meaning they don't need an oxidizer.

also, it's NO2'd, i.e. nitrated. nitrated things are usually explosives. such as tri-nitrated toulene, aka TNT aka dynamite.

as for its uses, well, i'd guess it's a solid fuel based on the nitrates thing. which means more dangerous to store (cause you dont need to mix to ignite), and you can't throttle it (its either on or off), etc. which as you say limits its application to more or less military rockets. traditionally, that is. there's no real technical reason solid fuel _can't_ be used for the initial stages of breaking orbit, i.e. a space-rocket.

happyjack27
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Post by happyjack27 »

yep, it turns out to be an oxidizer, according to http://en.wikipedia.org/wiki/Trinitramide . from my understanding that implies that it's a liquid and bipropellant. making it relatively safe to store and throttleable, and thus practical for manned flight.

D Tibbets
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Post by D Tibbets »

The reason I suggested military rockets, is because size and power may be more important than efficiency. I believe some missiles (air to air) have heavy metals in the mixture. This decreases efficiency (ISP) but increases the thrust/ power, allowing for greater acceleration in a smaller package. If this new compound is stable with a good shelf life, it might provide a more dense energy content on a volume basis, so I can see the improvement stated being in this area, rather than ISP.
In one hybrid rocket, the nitrous oxide is the oxider for a rubber compound, but it also can provide rocket power directly (explode) if not handled properly, as found in the Spaceship 2 development. I don't know if this new nitrogen compound could be used in a hybrid engine. Perhaps it could be fed as a slurry, or it could be fixed in the chamber and the fuel injected.

Solid rockets can be mono propellants (like gun powder), or mixtures of fuel and oxidizer. The SRB fuel is aluminum powder, the oxidizer is some perchlorate compound (or something like it) all held together with a binder.

Dan Tibbets
To error is human... and I'm very human.

zDarby
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Post by zDarby »

Not all solid fuels are monopropellants. Many (if not most) are composites of a solid fuel and a solid oxidizer bound in... well... a binder.
(Oh. Right. That's what Tibbits just said. :oops:)

Wikipedia has an excellent entry on solid rocket motors and the fuels of same:
http://en.wikipedia.org/wiki/Solid-fuel_rocket

Its entry on the STS SRBs is, similarly, an informative read:
http://en.wikipedia.org/wiki/Space_Shut ... et_Booster

My understanding about nitrate explosives is that the nitrogens are there to hold the oxygen in a semi-stable place until they're needed for the explosion. They do not participate in the chemical reaction of the explosion at all ---except to release the oxygens on impact and to bind to other nitrogens. (Again, this is only my understanding. The reality may be quite different. I make zero claims to being a chemist. My chemistry is elemental, at best.)

I have yet to find any info on Trinitramide's transition points, densities or chemical properties. (Of course, I really haven't looked that hard.) If they're concentrating on solid fuels, I would guess it's a solid at standard pressures/temperatures. If this is true, it's probably no good for hybrids.

Ok. Let's throw in some numbers. Amonium perclorate ("AP") is what the shuttle's SRBs use for an oxidizer and in mild temperatures it chemically breaks down like this:

2*NH4ClO4 -> Cl2 + N2 + 2*O2 + 4*H2O [wikipedia]

Therefor, a mol of amonium perclorate (117.49 gram [wikipedia]) gives off a mol of O2 that can be used on your fuel; plus gives off the energy of 2 mols of H2O production --increasing ISP somewhat. But, it releases half a mol of Cl2 and N2 each, both of which reduce ISP somewhat. (I can't be bothered to calculate by how much right now.) However, it's telling that 30.1% if APs mass is Cl and 11.9% is N; IE, 42% is mass not adding to the total ouput of energy.

Trinitramide should (I think) decompose like this:

N(NO2)3 -> 2*N2 + 3*O2

IE, one mol of trinitramide (152.023 gram [my calculation, please check]) makes 2 mol N2 --reducing ISP-- and 3 mol O2, to oxidize your fuel. In this case, 63.1% of the mass is Oxygen; and only 36.9% is Nitrogen --dead mass... I assume this difference in dead mass (not a technical term) is where the "increase" comes from... And, yes, I know it's not this simplistic.

Anyway, just another $0.02, which is about what it's worth.

hanelyp
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Post by hanelyp »

Cl2 is a potent oxidizer which will reach to produce HCl and more energy.

Nik
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N2 formation exothermic ??

Post by Nik »

Uh, I understood that such N2 formation was usefully exothermic...

{Shrug} Not a patch on H2/O2 cryo-fuels, of course, of course.

My understanding is that this stuff may be an improvement on the *nasty* hydrazine derivatives now in use for eg attitude thrusters and hybrid rockets.

IIRC, Hydrazine, UDMH and their ilk are why the 'ChemWarfare' guys surround each Shuttle after landing. Even dumping maneuvering thrusters' fuel during approach still leaves toxic, corrosive quantities floating about...

Damon Hill
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Post by Damon Hill »

Actually, I think it's the nitrogen tetroxide they're even more scared of; turns to nitric acid when contacting water. You don't even want to catch a whiff of this stuff--or get it in your eyes. The hydrazines are extremely unfriendly, too. It's partly why rockets are gradually getting away from using such propellants despite their useful properties.

If the trinitramid is reasonably stable--something I read suggests it readily evaporates then decomposes, might be a friendly mono-propellant. I wouldn't take that as being non-toxic until proven otherwise, nor as stable in the detonable sense. We'll have to wait until they can produce it in some bulk quantity--without blowing up the lab.

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