Clustered n Staged

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.


Well-Known Member
Mar 2, 2009
Reaction score
This is a rocket that I came up with for the EMRR "Elevate 11" contest. One of Nick's earlier suggestions was to build a rocket with 11 stages (yeah right) but it got me thinking about building a staged rocket that could maybe use 11 motors. Maybe even a booster with 10 motors, lifting a sustainer with the 11th motor... :rolleyes:

I messed around for a while in Rocksim and came up with the design below.

The central motors are 24mm, and the "strap-on" boosters, which are permanently attached to the booster section are arranged in 3 sets of 3 13mm motors. 6 of the 9 "stap-ons" will use A10-P motors and 3 will use standard A10s or A3s and will eject small streamers after the rocket has staged.

Sims to about 2400' with a full load in the booster and a D12-7 sustainer.

EMRR 11one.jpg

EMRR 11two.jpg
First thing I did was gather up the necessary parts.

The sustainer fins were left over from an early attempt to clone a Thrustline Mighty Mick from a Rocksim file attached to an EMRR review. I printed out the template and cut out the fins, but they just looked wrong. Luckily John Rowan-Stern re-appeared on the scene and got me going in the right direction, and now I had a use for my orphaned fins :D

Elevate 11 Rocket 002.jpg

Elevate 11 Rocket 003.jpg
First bit of construction was to build the central 24mm motor mounts. I cut 2 motor tubes from some spare BT-50 and glued everything together. The mounts are identical except for the Kevlar shock cord tied around the sustainer mount, and routed through a shallow notch in the forward centering ring.

I installed thrust rings in both mounts but decided to leave out the hooks and go with friction fitting for the motors.

Elevate 11 Rocket 007.jpg

Elevate 11 Rocket 011.jpg

Elevate 11 Rocket 012.jpg
Next up was some tube cutting. The booster body is 3.25" of BT-55 which yields a 0.50" gap between the booster and sustainer motors.

The "Strap-On" boosters are all cut from BT-5 and are either 5" or 3" long.

Once the booster section was cut the central motor mounts were installed in both the booster and sustainer.

Elevate 11 Rocket 018.jpg

Elevate 11 Rocket 021.jpg
At this point I had two parallel paths going. On one hand I was attaching the fins to the sustainer, and on the othe I was creating the booster "pods" by combining 3 sections of BT-5 side by side.

The main reason for grouping the "strap-on" boosters this way was to make sure there was enough room for the sustainer fins to slide freely between the booster pods, and also to leave enough room for a launch rod. Of course in the end I will tell folks I did it that way because it looks cool... :cool:

I used a section of BT-55 as a form to glue the boost pods together. I taped a 5" section of BT-5 along a reference line, and then glued a 3" section to each side. Finally I added a fillet of glue on the inside of each seam.

Elevate 11 Rocket 027.jpg

Elevate 11 Rocket 024.jpg

Elevate 11 Rocket 023.jpg
At this point the sustainer is basically finished, a pretty slick rocket on its own. The nose cone is a BNC55-ACP from Semroc

Elevate 11 Rocket 031.jpg