[AR] Re: LOX/propene engine question
- From: Peter Fairbrother <zenadsl6186@xxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Mon, 4 Jul 2016 22:18:55 +0100
On 04/07/16 18:31, Paul Mueller wrote:
There is a university student team who wants to build a LOX/propene (aka
propylene) engine for their rocket for the Intercollegiate Rocket
Engineering Competition. I had never heard of propene before (and didn't
know it was the same as propylene) so I checked it out on Wikipedia.
Toxicity doesn't appear to be a major concern. The Wikipedia article
also says that Garvey Spacecraft Corp is developing a LOx/propene engine
(and confirmed by http://www.garvspace.com/Current_Projects.htm, last
updated over a year ago).
So it appears that it should be suitable for a student team--just
wondering if anyone has any information to add.
Thanks, Paul M
Yes, it's pretty non-toxic, though like most light hydrocarbons it is an
anaesthetic intoxicant and simple asphyxiant.
Propene aka propylene is widely used by plumbers and the like, sold
under the name MAP-PRO.
When Linde stopped making MAPP gas (methylacetylene/propadiene
stabilised with propane)firms like BernzOmatic and Rothenberger started
supplying propylene under the name MAP-PRO as a substitute.
It works ok-ish for a hotter gas-air flame than propane, but unlike MAPP
it isn't much use for oxy-gas welding. I digress.
The name propene comes because it is an alkene, with a single double
bond between two carbon atoms, the analog of propane, with 3 carbons.
Propylene is the older, less "scientific" name, though I think propylene
is still IUPAC-approved.
There is also propyne [1], a 3-carbon alkyne molecule with a triple
bond, but that is most definitely not suitable for student rocketry.
I have a question though, why not propane? It's only about 2s less in
Isp on a few random RPA check runs, and it's quite a bit cooler-burning.
And while this is unlikely to be a problem unless you are using regen
cooling, propane does not undergo polymerisation, while propene does.
Just asking.
[1] sometimes called methylacetylene - naming can be confusing until you
realise that naming is one-way, so a molecule can have many names, but,
ideally at least, a name can only refer to one molecule.
-- Peter Fairbrother
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