Thinking of the primary propellants used for typical rocket launches (such as Hydrogen, RP-1, solid fuel), what are the odors of the exhaust and burned fuel components? I'd think that the Hydrogen would produce minimal odor due to essentially just water being the result, but wondering what RP-1 and solid fuel exhaust would smell like.

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    $\begingroup$ Speculative answer: If you've ever used liquid barbecue lighter (I think it's kerosene), you'll be familiar with the odor it gives off when it burns. Way back in the 60s/70s before high bypass turbofans and high security, you could watch jets come and go from airports from balconies on the terminal buildings and you could smell the burning jet fuel (basically kerosene) from those old engines. Same odor as the barbecue lighter. I'll guess that burning RP-1 (highly refined kerosene) will be similar. $\endgroup$
    – Anthony X
    Commented Jan 28, 2017 at 2:16
  • $\begingroup$ Pure LOX/LH2 would be scentless; odors will come from all "impurities" - ablative paints, launchpad materials baked in the exhaust, overheated metal of the engine, dust raised by the exhaust and so on; it would most likely be specific to engine/launchpad combo. $\endgroup$
    – SF.
    Commented Jan 28, 2017 at 4:42

1 Answer 1


So a caveat to this answer; these are qualitative descriptions based on my experience.

LOx/H2: I haven't been close enough to a launch or static fire to say.

LOx/RP1: As Anthony X mentioned, RP1 is highly refined kerosene, so the smell is similar to that of a barbecue lighter. One thing that I noticed is that the smell of gaseous RP1 is significantly stronger than that of the LOx/RP1 combustion products.

Solids: There are dozens of propellant combinations for solids, so I'll just cover the one that I am the most familiar with - APCP. The smell is somewhat sulfuric and foul. After smelling this enough, and getting used to it, it isn't so bad. That being said, this is definitely something you don't want to smell (NO2).


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