Post 1010 Rocket Project: Motors

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We are planning to use 24mm motors in the F class. To get to the 800ft level we will use the AeroTech re-loadable and single use motors. We need to get the ejection at around 8 seconds after launch. A slightly early ejection is a more consistent altitude than a late ejection. The ejection delay numbers are seconds after burn out, so the total time to ejection is the burn time plus the delay time.

Possible Motors

Motor Type Loaded
Weight Total
Impulse * Burn
Time * Rocket Weight
for 800ft Cost Comment

E9-4/6 Single Use (Estes) 58g 27.87Ns 3.09s 280-300g $15 3 pack

E12-4/6 Single Use (Estes) 58g 27.24Ns 2.44s 280-300g $15 3 pack

E20-4/7W Single Use 49g 35.0Ns 1.6s 320-370g $15 2 pack

E30-4/7T Single Use 49g 33.6/39.5Ns 1.0/1.2s 340-390g $21 3 pack

E28-4/7T Reload 55g 39.7Ns 1.2s 340-400g $18 3 pack

E15-4/7W Single Use 49g 40.0Ns 2.7s 360-410g $21 3 pack

F44-4/8W Single Use 48g 41.5Ns 1.0s 380-430g $17 2 pack

F30-4/6FJ Single Use 54g 47.0Ns 1.5s 410-460g $15

F24-4/7W Reload 62g 47.3Ns 2.1s 420-460g $25 3 pack

F39-6T Reload 59g 49.7Ns 1.3s 450-500g $25 3 pack

F32-4/6T Single Use 64g 56.9Ns 1.7s 480-540g $15

* According to http://www.nar.org/standards-and-testing-committee/nar-certified-motors/. You may also check out the motors on ThrustCurve.org since they have all the same motors, but slightly different values.

Here are the thrust charts from AeroTech.

Assembling an AeroTech reloadable is something we need to learn. You need to follow the instructions closely. Making one error in the assembly may destroy your rocket. One place where we differ with the instructions is at the end. We don't use the red cap to hold the igniter. We use either a rubber band or masking tape.

Here is a cheat-sheet on assembling an AeroTech motor.

Here is a YouTube demonstration of assembling a G motor.