3Cat/8

THRUST: 75 lbf

FUEL: isopropanol

OXIDIZER: NITROUS OXIDE

bURN TIME: 10 - 15 SECONDS

3Cat/8 is a rocket of similar architecture to 1Cat/4, but designed for much higher performance. It has a pair of pneumatic Half Cat valves triggered by a cable cutter severing the pilot line, and it is ignited by an Estes solid motor inside a cartridge that fires through the injector face.

3Cat/8 features a regeneratively cooled combustion chamber. This style of regen circuit was made to maximize manufacturability, and is easily produced with a lathe and mill. For survivability, the pressure and temperature in the chamber is kept low, allowing the aluminum chamber to withstand steady-state conditions without film cooling. No damage was observed on the first flight, where the motor burned for ~11 seconds.

Tests & Launches

Launch 1: 8750’

Launch 2: 1419’

No static test has been conducted on 3Cat/8, since its purpose is to demonstrate that relatively high performance liquid rockets are attainable with a modest budget and manufacturing capability. Most of 3Cat/8’s length is exposed propellant tank, but the airframe is lightweight hand-laid composite taken from an older rocket designed for commercial solid motors.