Ignitability of different propellant types

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ghostfather

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All commercially available propellant types ignite, some easier than others. Some are almost instantaneous, some chug along for a few seconds before coming up to pressure.
The legendary Aerotech Blue Thunder was known to ignite easily, and I've used a few slivers around igniters to give them some extra power to ignite upper stages, and C-slot motors.

With upper stage reliability in mind, I'm trying to figure out roughly which propellant types will be easier to ignite, and the sort of propellants that may need extra attention.

Without being manufacturer specific, these are the propellant types that I use:
  • White or Classic
  • Blue
  • Red
  • Green
  • Black or Smokey
  • Sparky
Also the high thrust versions, like Vmax/Warp9, or the low thrust versions like CTI Yellow have different ignition characteristics.
I realize that the different additives alter the burn characteristics, and I assume also the ignitability. I'm not so much interested in differences between manufacturers which both have a Blue propellant, just in general, which sorts of propellants light up the easiest.
 

0011001100

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I will say that Warp 9 can ignite almost instantly. I fly a J1799N and recorded the liftoff at 960 fps. From first sign of smoke to flame/movement was only 4 frames.
 

dhbarr

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Greens are notoriously hard to light, as are old reds
 

prfesser

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In most cases the faster a propellant burns, the easier it is to ignite. Blue propellants contain a compound--a burn rate catalyst-- that increases the burn rate (and gives the blue color) which is why they're easier to ignite. Likewise with Warp-9 and some red propellants which contain different burn rate catalysts.

Best -- Terry
 

ghostfather

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In most cases the faster a propellant burns, the easier it is to ignite. Blue propellants contain a compound--a burn rate catalyst-- that increases the burn rate (and gives the blue color) which is why they're easier to ignite. Likewise with Warp-9 and some red propellants which contain different burn rate catalysts.

Best -- Terry
Thanks, Terry, that's just the rule of thumb and general understanding I was looking for.
Fast propellants are generally easier to ignite, slow burners are harder to ignite - I can remember it that way
 

boomtube-mk2

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I would think that ignition rates are also affected by how long the propellent grains have been sitting around "Oxidizing".

I know that the "White" stuff, if allowed to sit for a lengthy period of time, develops a coating that is best removed so as to insure a better chance of ignition.
 

ghostfather

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I would think that ignition rates are also affected by how long the propellent grains have been sitting around "Oxidizing".

I know that the "White" stuff, if allowed to sit for a lengthy period of time, develops a coating that is best removed so as to insure a better chance of ignition.
Yeah, any motor more than 3-4 years old gets inspected for cracks and oxidation in the grains. If the grains are cracked, I throw it out as CATO material. A bit of oxidation can be very gently removed with fine sandpaper on a dowel. I've sucessfully flown 10 year old motors after inspection, with a sliver of fresh Blue Thunder propellant on the ignitor to boost it
 
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