Quantum Leap

Thanks for your help Jim,I am not using the CPR setup,I am building an avbay,I had planned on lighting the sustainer from the interstage coupler but now I am not so sure I want to.I would agree with what you said about not being a good value built stock.I am going to glass the sustainer fins tip to tip.Don't know why I don't plan on flying K to J,more like I TO I.I glassed the inside of the interstage coupler tonight.



More done on avbay

There are several reasons that I don't like lighting the sustainer from below. I don't like "toasting" my rockets, I don't like lighting a motor inside of a confined space, I don't want drag separation to cause the motor not to light, and I like to separate the two parts but still control the length of time before the sustainer lights. On my QL, I just ran a tube through the sustainer fin can for the wires for the separation charge and the ignitor. The pic below shows how the tube sits such that it doesn't interfere with the interstage coupler.

I run the wires through the drouge section and I include a couple of extra feet of wire so that there's no chance that the rocket will stay together if the breakwires don't break. The other pics show how I do the breakwires. The only trick is to make sure that the wires are secure on both ends so that you don't rip out an altimeter.

One other suggestion. When you get things built to the point where you have a weight, check the G's off the pad with your booster motor. You should shoot for at least 8 or 10 G's. The "I" motor you listed might not get you there. My QL is heavier than yours will be, but the smallest motor I have ever used is an I-540.

Jim

JimJarvis50 said:

There are several reasons that I don't like lighting the sustainer from below. I don't like "toasting" my rockets, I don't like lighting a motor inside of a confined space, I don't want drag separation to cause the motor not to light, and I like to separate the two parts but still control the length of time before the sustainer lights. On my QL, I just ran a tube through the sustainer fin can for the wires for the separation charge and the ignitor. The pic below shows how the tube sits such that it doesn't interfere with the interstage coupler.

Jim

Click to expand...

My original plan was to wire a separation charge in parallel with the sustainer igniter,I have not mounted the separation charge holder in the coupler yet.(I did'nt know I was going to have to do that until after the coupler was built)I have the PML accufire timer.I had thought about running a tube down the sustainer motor mount before I glued it in and did'nt do it,luckily the aft centering ring is'nt glued in yet and I can still drill a hole in the fore centering ring so I am going to go back and do that in case I decide to move the staging electronics to the sustainer.

For my separation charge, I just take an ematch and put it on top of a wide piece of masking tape. Then, I put the BP on and near the head of the ematch, and then put masking tape over the top of the ematch and trim the tape where there's no BP. I cover both sides of the resulting 1"-diameter disk with several more layers of tape. For a QL, you only need a charge of about 0.2 grams. The charge just flops around in the cavity under the motor.

Jim

I, too, am a bit late to this thread.

This is a great build, and it's a fun rocket!

I did a build article on my Quantum Leap for Sport Rocketry; an earlier version can be found as an article in a newsletter here (973K pdf). There's also an accompanying risk analysis article. I agree with the sentiments here that the sustainer is better ignited from an altimeter in the sustainer. I put that altimeter down on top of the motor mount, in a bay that was also ported to let the motor ejection be a third backup. There's a brass tube for the igniter wire that ends at the bottom centering ring; I use heavy wire from the altimeter bay to the motor nozzle and then connect the igniter to that.

I didn't use a separation charge--I let the booster drag separate, but I've seen staging done well both ways. I did coat the inside of the interstage with epoxy, but it hasn't been burned by the flights to date.

My main suggestion would be to think the whole flight sequence through, focus on designing your preparation to achieve that sequence (especially the deployment), and write a checklist so nothing gets forgotten, backwards, or mistaken. And then follow the checklist (I didn't once, and ended up recovering under drogue because of it. The rocket was damaged much less than my pride )

I've had 6 two stage and one single stage flight so far. As I said--fun rocket!