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when it says otherwise mediocere, is that improper? —Preceding unsigned comment added by (talk) 04:29, 17 December 2007 (UTC)


  • I don't think the articles should be merged. Monopropellant is a class of chemicals, whereas the rocket article mainly talks about hydrazine rockets. Also the rocket article is significant enough to remain a separate article due to the reference to space ships and satelites. Having said that, both of the articles could use some clean up to make them more distinct from each other.Hobo 02:19, 27 August 2006 (UTC)
  • I also oppose the merger as per user hobo sbandrews (t) 13:08, 18 March 2007 (UTC)
  • I agree that they should not be combined. Monopropellants may be used beyond rockets such as the new NASA missions to the moon and mars in landers and rovers. Many robotics carry them.


No mention of Hydroxylammonium nitrate or HAN? I tried to briefly find a reference that was freely accesible but HAN is discussed mostly in technical papers such as those found on the AIAA site. When I have more time i'll see what I can write up. I do know it is bonded with Hydroxyl-terminated polybutadiene (HTPB) or Carboxy-Terminated Polybutadiene (CTPB) and requires preheating to 200-300 deg C to decompose. Catylist is a noble metal, similar to the other monoprops that use silver or palladium. —Preceding unsigned comment added by Integracer (talkcontribs) 18:09, 18 September 2007 (UTC)


A rocket propellant consisting of a single substance, especially a liquid, capable of creating rocket thrust without the addition of a second substance. McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

Gas(?): We came across Industrial Accidents reminiscent of the use of Hydrogen Cylinders (6000 PSI)(with the regulator hammered off) used as a missile as in the movie "Chain Reaction". Toy Rockets and Military Torpedoes have been powered by compressed air. Is Dry Ice in a pop bottle a monopropellant rocket?

Solid fuel: Although its tempting to call all solid fuel monopropellant because only one chunk of stuff burns, proportion on components and improper mixing or component ratios are the same issues that one faces with binary liquids. Aluminum and Ammonium Perchlorate powders are mixed with asphalt (old) or rubber (polymerized after mixing and molding) (see; it is a mixture not a monopropellant. The fuel in classic Jetex hobbyist rocket motors ( is Guanidine Nitrate (, a monopropellant. Impurities are added (and engines have safety mechanism) to make them more likely burn fast than explode. Ammonium Nitrate (see the wiki) can deflagarate or detonate, but can be used as monopropellant, and for more energy can be mixed with powdered sugar which is then not a monopropellant, but which can form a solution of Ammonium Nitrate and Sugar (no separate crystals) which is then a monopropellant. (See ; ) Potassium Nitrate and Powdered Sugar is not a monopropellant, but at 220 degrees (decomposes violently at 240) sugar will dissolve the KNO3 and solidify to a solid solution (glass) which is a monopropellant (see et al; ) Ammonium Perchlorate (neat) could be a monopropellant, deflagarate or detonate depending on your luck. Guncotton, Cellulose Dinitrate, would be a monopropellant.

Liquid fuel: Hydrazine is used for space vehicle thrusters, it generates H2 and N2 gasses on contact with (esp Iridium) catalyst; (known by way of my work at Aerojet nee Rocket Reasearch)( Hydrogen peroxide by itself. Solution of Ammonium Nitrate in Methanol. Pure Nitromethane ( ; ), and 40% Nitromethane/Methanol Radio Control car fuel. Ethylene Oxide (favored for fuel air explosives). Methyl Nitrite. Nitrous Oxide. (see All except Nitrous Oxide and Hydrazine can be detonated. Article refers to Torpedo engine monopropellant fuel rather than Rocketry fuels. Similarly, "Top Fuel Dragster" ( use Nitromethane/Methanol because maximum power can be derived from a given engine displacement.

Basically if you need two fluid pumps or if you use one fluid pump and a heterogeneous solid reactant its not a monopropellant. Re: solutions, commonly understood monopropellants like Hydrazine and Hydrogen peroxide are often diluted with water (or the former with methanol) for ease of handling or stability.

I have a few years of amateur rocketry experience as well as many years as an industrial chemist, some of it with direct rocketry experience. Oxidizer and Rocket (empty) weight are important limitations. Convenience and safety are important features as well. I've had fuel mixtures from Zinc/Sulfur to Gunpowder go off while tamping it into the engine (Friction, Static Electricity, or Pressure)(Moisture absorbed from the air can also initiate reaction). There was a disaster when someone in a rail yard inadvertently closed the vents on a rail car of Nitromethane, and it detonated. The sugar/nitrate glass burns with fewer issues and better repeatability. Hydrogen Peroxide (30%) was easy to get at Beauty Supply stores so I used that for my monopropellant rockets, it generated sufficient thrust so I never got around to building one with alcohol fuel. Methyl Nitrite is under its own pressure at Room Temperature.

Water and/or Methanol injection of Aircraft piston and jet engines provides additional power/thrust. This increase in exhaust volume comes at the expense of exhaust velocity (lower exhaust temperature). Note that LOX and LH2 produce a 2500 degree flame however the equilibrium for water decomposition is 2000 degees so thrust is acheived via Hydroxyl radicals and Hydrogen atoms, which continue to react after leaving the rocket engine (hence the huge flame). Shjacks45 (talk) 21:27, 6 March 2011 (UTC)

Is nitrous oxide a monopropellant?[edit]

The article currently asserts "Hydrazine[9], Nitrous Oxide[10], Ethylene Oxide[11], Hydrogen Peroxide[12], and Nitromethane[13] are common rocket Monopropellants.", and provides citations for each. However, the citation for Nitrous oxide doesn't really support that nitrous oxide, by itself, is a monopropellant. Rather, nitrous oxide is an oxidizer, where as a fuel blended with nitrous oxide (e.g., nitrous oxide fuel blend is, in fact, a monopropellant. Can someone else look at this and see if I am interpreting it correctly (if so, we need to change the article). Cheers. N2e (talk) 16:04, 21 March 2011 (UTC)

No, of course it isn't. If it is, please cite some mechanism for it, i.e. HTP has an obvious use as either a monopropellant or an oxidiser, depending on the "cold" or "hot" engine cycle being used, and whether there's a fuel supplied. I know of nothing similar of nitrous oxide. Hybrid rockets and monopropellant fuel blends using nitrous oxide do not make it alone a monopropellant. Andy Dingley (talk) 16:32, 21 March 2011 (UTC)
Thank you for the quick concurrence. I'm not much of a propellant geek so wanted to get a second opinion. I've now removed the erroneous claim from the article.
While your at it Andy, why don't you look through the other claimed monopropellants in the above quotation. Are they all okay? I think they are, but as I said, I am no expert on this stuff. And they are each sourced by the same sort of poor sources as the "nitrous oxide" claim I just removed. Cheers. N2e (talk) 17:41, 21 March 2011 (UTC)
Nitrous oxide (alone, not blended with fuel) is definitely useable as a monopropellant when decomposed with a catalyst. See: or (talk) 11:12, 11 July 2012 (UTC)
"has been suggested as" isn't the same as having a working engine. This is all just hysteria over hydrazine toxicity. The trouble with nitrous oxide as a monopropellant is that although the numbers look good ISP-wise, no-one has yet built a reliable nitrous oxide decomposition catalyst grid (or similar). This is still a long way from being a rocket monopropellant, let alone a "common rocket monopropellant", as this article asserted. Andy Dingley (talk) 12:22, 11 July 2012 (UTC)

Awkward Sentence[edit]

Perhaps this could benefit from some editing: "The most common use of monopropellants[2] is in low-impulse rocket motors[3], such as reaction control thrusters, the usual propellant being hydrazine[4][5] which is generally decomposed by exposure to an iridium[6][7] catalyst bed (Hydrazine is pre-heated to keep reactant liquid) to produce the desired jet of hot gas and thus thrust." Taliska (talk) 00:30, 24 November 2011 (UTC)

External links modified[edit]

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