Centurion Project, - It's Back! Part 1 Background

This next build will feature a great interchangeable engine mount design - 
I always liked the Centuri kit, the Centurion.
It was Centuri's version of the Estes Big Bertha, but a bit sleeker. A great demo rocket, perfect for small fields with a B6-4 or C6-5. An early Centuri (no wadding needed) baffle was included. I had built and launched a Centurion in the 1970s.

In April, 2013 I was assembling a Semroc (Centuri) Centurion.
I wanted to incorporate interchangeable engine mounts inspired by Mark Goldstein's work. Four half-round dowels glued inside the body tube would lock the engine mount centering rings in place. 
My concern were the four holes in the bottom centering ring. The holes could allow some of the ejection charge to escape out the back. Mark said there wasn't a problem with ejection with his flights.
I really liked the design idea but hoped to find a another method with a tighter seal around the mounts.



I noticed the Semroc (Centuri) Egg Crate kit was advertised with interchangeable engine mounts, two 18mm engines and a single 24mm. I opened up the PDF instructions and found my answer.
Carl McLawhorn came up with a simple, clean solution. A single strip of basswood glued inside the body tube similar to Mark Goldstein's dowel idea. The lower centering ring had no holes out the back! Only the upper ring had a locking slot cut into the side. To see the instructions: CLICK HERE

I will be assembling two Centurion style models, the Semroc Centurion and the Estes Cosmic Explorer. The Cosmic Explorer is certainly based on the Centuri Centurion, skinnier using a BT-55 diameter tube (1.325") instead of the larger Centuri ST-16 tube (1.64")
The Cosmic Explorer will be a stock build - pretty much. This next blog build will bounce between the two models but concentrate more on the Centurion with the interchangeable engine mounts.