- Nov 4, 2009
- Reaction score
I'll be using a 54mm J315 or therabouts.What size motor? 38mm? Should work as the 38's and above come with 1.7g of BP, IIRC...I have used the stock ejection charge successfully on a few flights with a rocket that is 4"x48"..
Unfortunately, I was hoping to figure out if the configuration would work before assembly.Personally, I would use more BP. But it's easy enough to ground test to find out how much you really need. Put the case + forward closure in there with the charge on the closure. I just run the ignition wire down the hole in the ejection well. Then apply power with a battery or launch controller. I've used the Estes E controller for smaller rockets and a HP controller for bigger ones I didn't want to be that close to.
I have a number of e-matches and ignitors I keep around to ground test with. I just bought a pyrogen kit and built a bunch of them for this use. With BP you could probably use use nichrome wire without the pyrogen for a ground test.
I thought about that, but this is my Level 2 attempt, and I'm really trying to follow KISS.I have successfully deployed from a 5.5" rocket many times using no more than 2 grams for apogee deployment. I doubt that you'll need more than 3 grams max. If you want to use even less you could invest into a CO2 system, but it gets pricey for the system starting around $150.00.
Another idea would be to add a removable stuffer tube to take up some volume?
This is a single-deploy rocket, so there is no AV bay.I'm not sure what the difference is between your zipperless design and the "standard" design would be.
My L2 was done zipperless. The lower BT stays with the av-bay and seperates from the fin can. A standard design as I understand it, the lower BT would stay with the fin can and seperated from the av-bay. There's no difference in internal volume, only what part of the rocket the lower BT is attached to.
What ever amount of BP is needed for one design, it should be the same for the other.
Either way, use this calulator. 5 pounds of pressure should be great for 5.5 inch diameter rocket. You have about 24 sq in of nose cone surface so with 120 lbs of force, the nose cone should pop off quite nice.
This is a single-deploy rocket, so there is no AV bay.
With a "standard" design, the upper section is sealed off by the bulkhead at the aft end of the coupler; the chute is in the lower section, in a 17" space, for a volume of 386 cu". This seems to be about right for a 1.2 g charge, at 6 psi, which I figured made sense using the InfoCentral chart.
With a "zipperless", as shown on InfoCentral, the parachute is in the upper section, and the bulkhead is vented to allow the ejection to pass through; the internal volume is thus 864 cu".
Using Chuck Pierce's calculator, that would suggest a charge of about 2.7 g; I'll see how much that would overload the well on the motor.
Just make sure the chute is a very loose fit in the tube, and attached about 1/3 of the length of the shock cord, closer to the motor end of the cord.
Sure; lower section is 42", the upper is 24". The forward centering ring is 19.5" from the front of the lower section, and the coupler is 11".Have you already started construction? If not, increasing the length of the motor mount tube up to the bottom of that coupler you can decrease the volume needed.
Could you give some more information regarding the length of the different sections?
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