Centuri Finless Rocket

As an ex-hippie and a tree hugging greenie, I present a rocket born of spare parts and leftovers. The recycler's rocket!

Start with a Semroc Mercury Capsule kit. I got mine from Uncle Mike.

Semroc's excellent Mercury capsule kit contains not only the parts needed to construct the capsule nose cone, but a shroud and centering rings which allow you to use the capsule with various diameter body tubes. The capsule is a fun build in itself, and worthy of a few lines in a later posting.

I am using my capsule on a build of the Orbital Transport Laboratory (Estes Industries Rocket Plan #73) available from Jimz:

https://www.dars.org/jimz/eirp_73.htm

I decided to use the shroud and rings on another project; the Centuri designed Finless Rocket:

https://www.dars.org/jimz/finless.htm

The shroud from the Semroc kit looked awfully similar to the Centuri PR-7-20 paper reducer listed in the plan parts list.

Taking that as a given, I added the few more parts that I needed. A centering ring from the Mercury Capsule kit, a 45cm (18”) length of BT-20, and a few standard rocket bits such as a motor hook and a couple of launch lugs. The Semroc kit even included one of the launch lugs.

With no fins to cut, fill, and align, this is a very fast build. In fact, you can build it as fast as the glue dries. I used white glue for the motor mount, tacky craft glue for the shroud, and yellow (aliphatic resin) glue on the launch lugs.

Fit the thrust ring and motor hook. Glue on the lower launch lug 180 degrees from the motor hook. Take the assembled shroud and cut a slot for the lower launch lug. My slot was ~16mm long, about 5/8”. Slide the completed shroud over the body tube and fix into place with tacky glue.

Notches for the launch lug and motor hook were made with a hole punch and trimmed where necessary with a #11 blade. Fit the centering ring. Fix to shroud and body tube with tacky glue.

Spot the deliberate mistake when cutting the slot for the motor hook...

Fit the upper launch lug, and the rocket is nearly complete!

Find a BT-20 nose cone in your collection, preferably a hollow one, and add 11.34gm (.40oz) of weight. I used a Custom cone and some split lead fishing weights, held in place with gorilla glue (polyurethane glue).

A length of Kevlar held with an Estes trifold mount completes the rocket. Mine recovers on a 38mm (1 1/2”) Hartle Engineering Sky Grrripper streamer.

Like bubble and squeak this is a fantastic use of leftovers. However, unlike that classic breakfast this rocket flies very nicely on an A8-3.

Skippy!
I did one like this a few years back (not quite as good looking), but with a twist... Add a first stage to the bottom of it with fins and all that meets up to the bottom of the shroud. People won't be able to tell its a 2-stager until it actually stages

rokitflite said:

Skippy!
I did one like this a few years back (not quite as good looking), but with a twist... Add a first stage to the bottom of it with fins and all that meets up to the bottom of the shroud. People won't be able to tell its a 2-stager until it actually stages

Click to expand...

There was a plan for such a rocket, named "Oscar", in an issue of the Model Rocketeer in the early or mid '70s. I always wanted to build one, but never did. Maybe I should dig out the plan and get building.

Nice rocket. I have a bunch of BT5 tubes and some estes shrouds from the old designers kit (or whatever it was called). This looks like a good reason to build an 13mm rocket.

Oh yeah, I'm going to have to know more about "bubble and squeak".

Indiana said:

Nice rocket. I have a bunch of BT5 tubes and some estes shrouds from the old designers kit (or whatever it was called). This looks like a good reason to build an 13mm rocket.

Oh yeah, I'm going to have to know more about "bubble and squeak".

Click to expand...

Downscaled this would make a great 13mm rocket. I used to have real problems with shrouds, now it isn't a hassle, I quite enjoy working with paper/card. It's cheap too!

Bubble and Squeak is traditionally last night's vegetables; mashed potato, carrot, cabbage, peas, fried up for the next morning's breakfast. The name comes from the noise it makes when you cook it. Originally an English dish. Like a lot of foods cooked by poorer people ('peasant fodder') it became trendy in the late 90's. Now you get recipes for leftovers!

https://www.taste.com.au/recipes/314/bubble+and+squeak

rokitflite said:

Skippy!
I did one like this a few years back (not quite as good looking), but with a twist... Add a first stage to the bottom of it with fins and all that meets up to the bottom of the shroud. People won't be able to tell its a 2-stager until it actually stages

Click to expand...

Sweet idea. I may have to follow this up...

Sounds good! Thanks.