Parallel Staging? Motor choices and designs?

Hi all, I'm just getting back into the sport, and I'm pondering an ambitious design. I want to add strap on boosters to a larger rocket and see if I can manage a complex launch. The idea that I have is based on a model that I found online here, which is a scale model of the Delta IV Heavy. When with high thrust low time motors in the boosters and a medium thrust long burn motor in the core, the idea is that when the boosters burn out, drag pulls them off to the sides so they can recover on their own, while the core continues onward.

My specific plans involve adding boosters to a rocket I already have completed. As a step back into the sport, I bought a two rocket launch kit with the Estes Amazon and Crossfire. On my first launch day, they both performed perfectly, but due to its size, the performance with B4-4 was uninspiring, and the performance with a C6-5 was suitable, but I still think it can be spiced up. I'm thinking to add on some downward facing quarter circles as hooks at the bottom between the fins, and slots about halfway up the tube for the boosters to hook to. My thoughts are that the slots will provide just enough friction to hold it on, and the downward hooks on the core would make the boosters rock outward and away from the core so that they will fall away cleanly.

The Amazon has 4 fins, so i figure I can set it up to work with 2 or 4 boosters, and I'm thinking that I'll use Estes A8-3 motors in the boosters and maybe the Quest D5-6 in the core. I've never used the Quest motors before, but what I've read sounds extremely interesting, especially with the long burn time.

So here are my questions:
1 or 2 fins on the boosters?
Different motor sizes?
Body tube sizes for the boosters? (I was thinking to match the Amazon, which uses the 1.35" tube)
How do I manage the attachments such that they're sturdy, yet release when necessary?
Any other thoughts?

Thanks!

I don't know how far you have gotten with your project since September, but here is a design I came up with in '98, and launched successfully twice.



The plywood tabs at the bottom of the boosters are shaped to lock in place when the booster is vertical, but they unlock when the jettison charge pushes the top of the booster away from the rocket. The main rocket used an I motor and the boosters used H's - all reloadable motors so it was easy to glue electric matches to the inside of the grain for aggressive simultaneous ignition. I'm sure this would all scale to the size of rocket you have built.

Heli Hacker said:

I don't know how far you have gotten with your project since September, but here is a design I came up with in '98, and launched successfully twice.

View attachment 116667View attachment 116668

The plywood tabs at the bottom of the boosters are shaped to lock in place when the booster is vertical, but they unlock when the jettison charge pushes the top of the booster away from the rocket. The main rocket used an I motor and the boosters used H's - all reloadable motors so it was easy to glue electric matches to the inside of the grain for aggressive simultaneous ignition. I'm sure this would all scale to the size of rocket you have built.

Click to expand...

That is one heck of a design. Can you show the tabs up close?

I am tryign to figure out the mechanism.

cwbullet said:

That is one heck of a design. Can you show the tabs up close?

I am tryign to figure out the mechanism.

Click to expand...

+1. I have tried building a parallel staged rocket a few times, get stuck on the bottom attachment - how they lock vertically and release at an angle.

Thanks.

Sather

One design that I am thinking about doing, is parallel staged. My design will use a "pin" ( a 1/2" steel rod, in my case) and a reciever ( a fiberglass tube that can hold the pin). The reciever is attached onto a bulkhead at the point in which you want the boosters to be centered on the main body. I then use fittings to connect all of the recievers to one point, where a timer controlled bp charge can be placed. Then, holes are drilled in the body tube where the pind will be inserted. The pins are then epodied to a hinge. the hinge attaches to the booster. The same thing can then be done on the bottom of the rocket. The trick is getting both BP charges to blow at the same time. Once all of the pins are in place, drill holes through the recievers and pins for shear pins. When the charges blow, they will push the rocket out.

Take a look at my Titania and Thunderbird. Both rely on the fact that an Estes B6-0 or C6-0 produce significant forward pressure at thrust burnout which, though not officially an ejection charge, is enough to kick a nose-cone and streamer out of a parallel booster.