An Overview of Roadrunner Motors

Roadrunner offers two propellants in reliable single use 29mm motors. Roadrunner propellant (no letter designation) is a moderately quick burning propellant, producing white/grey smoke and a bright white flame while Roadrunner Rapid propellant (R designation) is a short burn, high thrust propellant producing a moderate amount of smoke and good tracking smoke.

Testing, testing and still more testing has proven Roadrunner motors to be extremely reliable. Suffice it to say that many, many, many motors were burned in:

  • propellant development
  • casing material testing
  • nozzle size determination
  • failure testing
  • hot and cold testing
  • reliability testing
  • obtaining performance data
  • flight testing
  • more flight testing :)
  • certification and production testing

However, rough handling during shipping or otherwise can damage phenolic, usually evidenced by a small hairline crack. Therefore it is always a good idea to closely examine each phenolic motor casing for signs of damage before putting it in your lovingly built and finished rocket. (Slight chipping of the thrust ring, which sometimes occurs during shipping, is cosmetic damage only).

Of course, if motors don’t ignite, they aren’t much good. Although the igniters included with Roadrunner motors ignited the motor first time, every time, tests using other igniters were performed. Each Roadrunner motor was ignited using 1) a Copperhead, 2) a First Fire Jr, 3) a Quickburst Twiggy (at 22 gauge, larger than Roadrunner’s recommended igniter size), 4) a Quickburst Popper and 5) an Ellis Mountain igniter. Blastoff without a hitch. The Roadrunner propellant ignited slightly (but noticeably) slower on the Quickburst Popper. Although not a statistically valid sample, it does appear that Roadrunner motors are easily ignitable with commercially available igniters.

Will they fit in your rockets? The labeled motor fit into every 29mm motor mount tube on hand with no problems, including tubes from from Loc/Precision, Public Missiles (PML), Aerotech, Binder Design and BSD. The extra length of Roadrunner motors, due to not using a molded closure, means that in kits with a built in motor stop you should check the CG/CP relationship prior to flight. Guidelines for building an Aerotech kit without the motor stop are available here.

Now you have no excuses. Get out there and fly Roadrunner motors today.