Sunday, September 21, 2008

The NAR number code for model rocket motors, in words of 6 letters or less

So all model rocket motors have a funny code on them like A8-3 or B6-4. This code tells you the total amount of energy in the motor, the mean amount of force it makes, and the delay time between when the motor burns out and it pops the nose cone off so the rocket comes down safely.
  • The first letter is the total amount of energy in the motor. Here a unit called the Newton-second (Ns) is used. 4.45 Ns = 1 Lbs (pound-second). So, an "A" motor has 1.25 to 2.5Ns in it. Not a lot, but it can send a rocket dozens of feet up. A "B" motor has up to 5Ns, a "C" 10Ns, etc. A "1/2A" has up to 1.25Ns.

  • The second figure, a number, is the mean thrust in N. For example, a B6 motor puts out 6 N, more or less. You can then figure out the burn time: B(10Ns) / 6 = 1.7s.

  • The last number is the delay time, from when the motor burns out until when the charge fires that pops the nose cone off and opens the 'chute and allows you to get and fly your rocket again. So, a D21-7, which I will use in my "3M" rocket to send it to the speed of sound, has 20Ns total energy, 21N mean thrust, and a 7-sec delay. Easy, huh?

This short word idea for a hard idea is not mine; it comes from here.

2 comments:

mandachan said...

waaah brain implosion!
sorry, just got back from nyc, becky took me to go see chicago, it was AWESOME!

mandachan said...

and i appreciate that you put it in words of 6 letters or less, but i still have no freaking idea what you're talking about.

and thanks for poking me towards doing the black sox scandal for my thesis.