I applaud your ambition. Like you, I got a MPC Vostok (along with a MPC Titan IIIC and an OOP Estes Cosmos Mariner) with the intent of getting a good flight out of these bricks. Call me a hardhead. Anyway, some thoughts:
1. A liner tube is a good idea, not only to insulate the ejection gas heat, but also to prevent the pressure from blowing apart the glue seams. If I remember correctly I used a BT-20 + tube, which sleeve fits over a BT-20. Erockets might still have it. I think a BT-40 would also work, if you can find one.
2. RE: rear ejection/dual chutes. That would be difficult. There is a small gap between the outboard booster pods and the main body. You would have to insert a small tube to duct the gases between them. And if you use dual chutes and two pods, you would be trying to simultaneously eject both with one charge. Very iffy, ask anyone who has flown the Estes Gemini DC. If you put both chutes in the main body it would help only if the combined volume occupied by the two chutes is less than the one chute it replaces. Maybe folding the chute a little differently would help: a longer thinner package to fit the diameter of the rocket, rather than the traditional burrito style.
3. Re: Aerotech reloads. Do you already have the hardware ? It can be expensive. Reload motors require the casing, forward and aft closures, and the drilling tool to adjust the length of the delay. You will also need to do pre-flight prep (assembly) and post-flight prep (cleaning) for each motor. I used to think gun enthusiasts were a bit fanatic with their constant cleaning of their firearms, but now I know why: the residue from black powder is highly corrosive. It needs to be removed after every use, or the internal metal will pit and corrode. Originally my thinking was to save money by buying the reloads rather than the single use motors. But do the math: if you save a couple of dollars per launch, it would take 15 to 20 launches before you break even and start to save money. Can you do 20 launches and recover your rocket every time? Maybe if you live in the Kansas wheat fields or Arizona desert. Otherwise I would go single use. No assembly, no cleanup, fire and toss.
I wish I could tell you that these launched straight and true, but they have been shelf queens for the past year. The Vostok has been painted, the Titan and Mariner are still naked. One day I'll light them up, but I have to be in my "what the hell" mode. BTW best price I found for the Vostok and Titan is at Hobbylinc, at around $17 each. I'll try attaching a couple of pictures, but since I'm a newbie to posting they may not go through. Wishing you success in your endeavor.[IMG]MPC Titan next to Dr Zooch Soyuz[/IMG] [IMG]Titan IIIC[/IMG]

Attached Thumbnails