Post 1010 Rocketry Project: Motors

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We are planning to use 24mm motors in the E 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	280-320g	$15	3 pack
E30-4/7T	Single Use	47g	33.6Ns	1.0/1.2s	350-390g	$24	2 pack
E20-4/7W	Single Use	49g	35.0Ns	1.6s	350-390g	$23	2 pack
E28-4/7T	Reload	55g	39.7Ns	1.2s	360-410g	$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
F35-5/8W	Reload	64g	57.1Ns	2.0s	480-540g	$22	2 pack

* 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.