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Nontoxic hypergolic liquid bipropellant rockets. - Adventures in Engineering — LiveJournal
The wanderings of a modern ronin.

Ben Cantrick
  Date: 2006-03-23 07:49
  Subject:   Nontoxic hypergolic liquid bipropellant rockets.
Public
  Mood:der uber-nerd


Specifically, our non-toxic hypergolic miscible fuel is comprised of three parts: a colloidal transition metal oxide, a low-molecular weight alcohol, and a sensitizing agent. The metal oxide rapidly decomposes 98% hydrogen peroxide into hot molecular oxygen, steam, and heat. The heat and oxygen that are generated rapidly combust the alcohol while the sensitizer destabilizes the hydrogen peroxide and provides additional fuel combustion value. The sensitizer is added to modify the local pH and to increase the polarity of the alcohol, which makes larger portions of the metal catalyst soluble.

http://roger.ecn.purdue.edu/~rusek/papers/nawcbiprop.html

Found this while I was looking for ways to make a PMFF/nitrous hybrid engine hypergolic. The neat trick here is that they dissolve some metal ions in the alcohol, so when you spray the alcohol and peroxide together, the peroxide instantly flames up due to catalyst action. Nice.

Isp is around 270s with the correct butanol isomer(s). That's very nearly as good as hydrazine. The fuel to oxidizer ratio kinda sucks at 4:1, but you can use methanol instead at about 2.5:1 and still get 260s. It's a pretty good small rocket system. The propellants are pretty non-toxic, reasonably dense, and liquid at room temperature. Ignition is fast and highly reliable. Peroxide distillation rigs used to be quite risky, but some smart guy figured out that you could distil under vacuum and now they're quite safe if built right.


(This is the part where everyone except willow_red just smiles, nods, and proceeds to ignore me. Okay, everyone? On three: One, two, THREE! (Smile) (Nod) (Wander away))
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Ben Cantrick
  User: mackys
  Date: 2006-03-23 21:16 (UTC)
  Subject:   (no subject)
During my browsing last night, I read about ramjets and scramjets. They had a chart of what velocities they worked at. Basically, the ramjets won't work until about .8 mach, and the scramjets won't start working until about mach 5-8. (Escape velocity is about mach 32.) Any single-stage space plane is going to have to mount all three of: conventional turbines, ramjets, and scramjets. And have some way to protect the turbines when it's going mach 30, cuz no fan blade is going to survive that.

I still think it's a better idea to have a conventional jet carry the ram and scram-jet spaceplane up to about 80k feet and let it light off from there. It's requires two vehicles, but at least both of them are within our current engineering abilities. As opposed to a single stage to orbit spaceplane, which I don't think we have the tech ability to make right now. A two stage also means that you can carry larger payloads since you don't have to carry near as much fuel since you're already off the ground and up to speed before you start spending the fuel that takes you out of orbit.

I don't have a lot of love for NASA recently. In the Apollo era, they were doing something that nobody had done before, and I respect them intensely for that. But in the last 20 years they've stagnated and become hopelessly bureaucratic. I don't want people thinking "two stage to orbit" = "NASA space shuttle". Instead, think of two stage to orbit as being like Burt Rutan-Scaled Composite's White Knight/Spaceship 1 pair. If Rutan thinks two-stage is a good way to do things, that's good enough for me.
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MegaZone
  User: zonereyrie
  Date: 2006-03-23 23:19 (UTC)
  Subject:   (no subject)
Have you seen the latest AvWeek, with the 'Blackstar' cover and articles?

I really hope that thing is, or was, real. :-)

(And I understood the post too.)

Oh, check this Blackstar info.
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Ben Cantrick
  User: mackys
  Date: 2006-03-24 01:28 (UTC)
  Subject:   (no subject)
I did see the Blackstar story. Pretty darn cool. I have to wonder if the military abandoned the idea after seeing SpaceShipOne work. And how long before DARPA makes Rutan very rich by buying a copy of the SS1 plans. ;]
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(no subject) - (Anonymous)
Ben Cantrick
  User: mackys
  Date: 2006-03-24 07:45 (UTC)
  Subject:   (no subject)
Maybe this is Aurora. But i kind of doubt it.

I thought Aurora was supposed to be a pulse-jet anyway.
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Willow: DI Impactor
  User: willow_red
  Date: 2006-03-23 15:13 (UTC)
  Subject:   (no subject)
Keyword:DI Impactor
Nice! While hypergolic fuels are always going to be hazardous to work with (by definition), it'd be really nice if the components could individually be less toxic. I only skimmed the article, but it seems like this stuff could make storage and handling easier.

As for the Isp, the test stand didn't do all that well, but with good chamber/nozzle design, this thing gets in the realm of some of the EELVs (anywhere from 230s to 290s). This could work well as an upper stage or a deorbit engine. Thanks for the link.
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osmium_ocelot: flare
  User: osmium_ocelot
  Date: 2006-03-24 00:20 (UTC)
  Subject:   (no subject)
Keyword:flare
nope, don't understand the technical aspects insofar as the rocketry science notations and such. However, I understand the implications of being cleaner and safer. And it's still pretty nifty.
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