Scratch - Ares I (1:54) {Scratch} Original Design / Scratch Built

Contributed by Scott Ripplinger

Manufacturer: Scratch
(Contributed - by Scott Ripplinger - 06/02/08) (Scratch) 1-54 Ares I

Brief:
A single stage scale of NASA's upcoming Ares I launch vehicle. The rocket separates in the center for recovery. A 38mm motor mount allows flights on H, I, and J motors.

Construction:
The lower body tube is a 2.56" phenolic tube and the upper section is a 3.9" phenolic tube. The nose cone and reducer sections are custom made from balsa. The engine flare at the base is made from layered plywood. Centering rings are also plywood on a paper 38mm engine mount. The fin section is made from a removable section of acrylic tubing. The fins are also acrylic and epoxied in place with the joints fiberglassed. There is also a standoff on the fin unit with a rail guide. A rail button is fitted on the upper section to match. A custom made ejection baffle is in the lower tube and also provides attachment points for the shock cord.

Custom wood parts (nosecone, reducer, and engine fairing) were turned on a lathe. Constructing the fin unit was a little difficult because the epoxy did not bind well to the acrylic surface. If I were to do it again, I would use a solvent acrylic cement.

Flight and Recovery:
One flight on an Aerotech H123W-S. Good flight overall with a slight turn windward. Motor is retained using a customized flanged aft closure from The Rocket Man. The parachute used was a 45" Top Flight nylon chute. It was a little undersized and the rocket came down fast, but it survived with minor damage.

On 'ChuteSummary:
This was a great project for me. I probably could have benefited from some more experience before taking on a custom scale build, but things turned out well in the end. It flies great and got a lot of people in my club excited. I may want to make a few modifications before flying it again, but I look forward to using it for years to come.

The main drawbacks with this rocket as I built it are that I ended up with some inflexibility on the recovery system. The 45" chute barely fits with all of the shock cord due to the ejection baffle taking up too much space and placed too high. The fin unit is also fragile, but (with some effort) it can be replaced if needed, since it is removable. One of my major concerns before launching this rocket was stability issues. I didn't plan ahead very well and ended up with a bottom heavy rocket. I addressed this by stuffing a couple of T-shirts in the empty upper section to even it out. In the future I hope to upgrade this to a dual deploy or even just move the parachute to the upper section to be deployed with an altimeter. Another thing I would redo given the chance is make some more space in the lower section for the parachute. The baffle installed really restricts the space so I may not be able to move to a larger parachute in that section.

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