RMS Question

Looking at the reloadable motors. What does the S, M, and L notification mean on the engine. For example: G104T-L. What does the L mean? I assume it is relative to the delay.

Short, Medium and Long. I'm not exactly sure what that translates to in seconds though. Probably around 4, 7 and 10.

Mark

Your assumption is correct Mark. when you get into High Power and ask for a H128W with a ten second delay, don't be surprised if the vendor looks at you funny! HPR guys use the "Short - Medium - Long" designation instead of 6 - 10 - 14 seconds. I guess it is because it's much easier to remember, especially when you are preping a HPR flight. There is too much to do...check your cords, pack main chute, prep altimeter, build motor, etc... The last thing you need to deal with is extra numbers.

So it's time to update the ole' vocabulary there bro and have some fun along the way!

Carl

Originally posted by CTulanko
HPR guys use the "Short - Medium - Long" designation instead of 6 - 10 - 14 seconds. I guess it is because it's much easier to remember...
Carl

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Remember that the delays can be off by 20% and still be within tolerances. Short/medium/long is more appropriate because people tend to get hung up on the individual numbers. RockSim doesn't help either when it tells you that you need a 4.71s delay.

Also, remember that unlike black powder motors, composite motor delays start burning at the same time as the motor. Because different motors operate at different pressures, the delay column propellant will burn at different rates for different motors. This is why there are so many delay packages in the RMS+ system. When you add up all the various sources of error, it's lucky that delays can be kept within 20% of their stated value.

HPR guys use electronics. Motor ejection is only for rockets which are too light to zipper and too soft to damage anything they hit after a recovery failure.

Also, remember that unlike black powder motors, composite motor delays start burning at the same time as the motor. Because different motors operate at different pressures, the delay column propellant will burn at different rates for different motors. This is why there are so many delay packages in the RMS+ system. When you add up all the various sources of error, it's lucky that delays can be kept within 20% of their stated value.

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Ohh, I want to explore this a little bit. Are there any RMS delays that can be interchangable?

Say I want to take an F40-4 and an E28-5 and swap the delays. Am I putting myself into a totally unknown situation?

- Nick

Originally posted by EMRR
Say I want to take an F40-4 and an E28-5 and swap the delays. Am I putting myself into a totally unknown situation?

- Nick

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Yes, it's not a good idea (and probably makes the motor uncertified). I don't know any specifics of these two motors, but the delays are probably not interchangeable.