Staged Rocket

I want to build a staged rocket but I don't like the available kits where the sustainer sits right on top of the booster motor. I would like the booster section to be in the neighborhood of 6" to a max of 12" in length.

I was thinking about kitbashing a Big Bertha for this project. I had planned to use a BT-20 tube for the motor mount that would run the entire length of the booster section. I figure this will better direct the second stage ignition charge into the sustainer motor. Plus I'd be able to fit a streamer or small chute into the space between the BT-20 and the main body of the booster. My question is how would I get that booster recovery devise to deploy?
My first thought is to use a "drogue" string attached to the streamer and lightly tape it inside the sustainer. Thinking that during separation, the string will pull the streamer out. Another idea is to drill a few holes in the upper section of the mmt letting the gasses escape and do the job while hoping the hot particles that ignite the sustainer motor stay in the BT-20.
Any thoughts??

Kevin

Kevin,
You are describing gap staging. I have two ideas on doing something similar. One is to airstart the sustainer (using electronics). The booster will use an ordinary motor - ie, one with ejection charge - which will deploy the booster's chute.

The other idea is to use a cluster in the booster. The center motor will be vented forward to ignite the sustainer while one or all the outboard booster motors will eject the booster chute.

Be sure to select the overall burn-time_+_delay-time of the booster motors to ensure the chute is deployed after the center booster motor has burnt out and (hopefully) ignited the sustainer.

Doug

I'm not quite ready for air starts yet. I'm still in the Estes-beginner phase of model rocketry. Some sort of cluster arrangement might work though. The Big Bertha I was going to use was originally purchased for a 3-motor cluster conversion until I came up with this staging idea.
Side bar note: Right after I posted this staging question, I went to the hobby shop and bought an Aerotech Mustang. Now if I can just find some motors I can get my feet wet in mid power!

Kevin