Brief:
T' modification done t' this kit originally was constructin' me own centerin' rings and modifyin' t' bulkhead t' have only one hole for a single motor configuration instead o' placin' three motor tubes in t' mount for a cluster and a 3-hole bulkhead. This initially didn't fly well, so after another modification I now have a shorter version o' t' U.S. Well, blow me down! Rockets Aero Roc 3. Begad! It can fly on either 29mm or 24mm motors with t' included motor adaptor.

Modifications:
After first flight failed, I decided t' saw off t' body tube above t' new bulkhead, ya bilge rat, remove t' modified bulkhead and motor tube and replace them with t' now shorter body tube, t' manufactured centerin' rings, shiver me timbers, me modified bulkhead, shiver me timbers, and a 29mm motor tube. I ordered t' motor mount parts from U.S. Well, blow me down! Rockets. Arrr! T' parts package be from what I believe t' be t' Interroc kit. Ahoy! I had t' do some precise linin' up with t' bulkhead and tubes since thar was still left over glue residue from t' previous build. Aye aye! Ya scallywag! It worked out alright I think.

Construction:
T' original kit has two equal size body tubes, me bucko, balsa nose cone, and three fin configuration. Begad! Blimey! Interestin' features include a paper canopy recovery and a large payload section.

T' PROs o' this is you get a lightweight, durable rocket that can utilize 24mm and 29mm motors which could potentially send this baby out there! CONs o' this build is it was really nay necessary at all. Aye aye! Begad! For t' same price, me bucko, you could get an Interroc kit with a four fin configuration and it will actually give you three motor mount options: 1 x 29mm, me bucko, 1 x 24mm and a 3 x 24mm cluster configuration. I only did this mod because I already had an Aero-Roc and wanted t' save loot on motor usage. Three motors at a time adds up!

Flight:
It flew pretty straight and true. Avast! Blimey! Very light rocket for t' size motors it can handle so make sure you add weight t' t' nose. Avast, me bucko, me proud beauty! It's pretty easy, arrr, just drill a few holes in t' under side o' t' balsa nose cone and add some clay or putty, but once again I'd stress savin' time and loot and just get t' Inter-roc rocket first.

Summary:
For rocket modifications, me hearties, I'd steer clear o' U.S. Rockets just for t' simple fact that t' kits are kind o' pricey.