Designer: Brian D. Wendt

Motor Manufacturer: AeroTech, Inc.
Propellant Type: Composite (Ammonium Perchlorate)
Motor Designation: I211

Motor Diameter: 38 mm
Motor Length: 240 mm
Propellant Mass: 0.251 kg
Total Motor Mass: 0.473 kg

Total Impulse: 435 Ns

Burn Time: 2.1 s
Maximum Thrust: 353 N
Average Thrust: 210 N
Specific Impulse: 177 s

Notes: Construction of Isabelle was an ongoing project throughout the spring 2002 launch season. This rocket served as the vehicle to achieve Tripoli Rocketry Association Level One certification with its first and only launch. It was an excellent introduction into the handling and performance characteristics of high-power composite motors. The Binder Design kit used very similar construction techniques to the Estes kits with which we were already familiar. Since there was no requirement for fiberglassing, heat-curing or use of carbon composites, the technical advancements were confined to the stress and recovery considerations of using the larger engine. Also, no flight computers or barometric/acceleration recovery triggers are required for a Level One certification, so these were omitted.

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Designer: Brian D. Wendt

Motor Manufacturer: Estes Industries
Propellant Type: Black Powder
Motor Designation:  C6-0, Booster
 C6-7, Sustainer

Motor Diameter: 18 mm
Motor Length: 70 mm
Propellant Mass: 0.0216 kg
Total Motor Mass: 0.0444 kg

Total Impulse: 17.64 Ns
Burn Time: 3.72 s
Maximum Thrust: 14.09 N
Average Thrust: 4.74 N
Specific Impulse: 83 s

Notes: J-III is the third iteration of the venerable Josephine series, which began with Principia’s first rocket back in the fall of 2001. The first vehicle of the fleet to incorporate multiple stages, J-III flight tested several important design characteristics unique to the class, such as stage coupling and interstage vents which prevented the booster from separating before the core had ignited. This vehicle also validated chute-less recovery of the booster stage, which relies on the aerodynamic instability of the separated booster to reduce its terminal velocity and allow for a safe landing.

The Cambridge Dictionary of Space Technology defines a rocket as a propulsive device using a mixture of propellants which, upon ignition, provide a reaction force to propel a vehicle such as a missile, aircraft or spacecraft.

Typically, two separate chemical propellants are used, a fuel (such as liquid hydrogen or kerosene), and an oxidizer (such as liquid oxygen or nitrous oxide), which provides the oxygen to sustain a burning reaction. Rockets differ from similar propulsion systems such as gas turbine engines (jets) in that they carry both their fuel and oxidizer on board, thereby needing no intake oxygen to operate. Also, the performance possible with rockets make them ideal for vehicles such as spacecraft, which need to achieve large changes in momentum and high final velocities.

A rocket operates according to Newton’s third law of motion, which states, generally, that for every action there is an equal and opposite reaction. In a chemical rocket, the fuel and oxidizer are combined in a combustion chamber, where they are exposed to a source of ignition, causing a violent chemical reaction which produces hot, rapidly expanding gases. These gases are accelerated through a throat and nozzle, where they are ejected at very high velocity, thereby imparting a change of momentum to the vehicle.

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by Robert C. Truax, January 1999

Copyright © 2000 Aerospace America.   Reprinted with permission.

The story of turbopump rocket development is an interesting one of trial and error. Many sidelines were explored before the objectives of light weight and high performance were finally attained with the main engines for the Shuttle. Russian rocket development followed a somewhat similar path, and the end result was very similar: a topping cycle with high combustion chamber pressures.

But turbopump engines, whether high pressure or low, were a mistake from the very beginning. They simply are not worth what they cost in time and money. In all the early development efforts, pump-fed systems were preceded by a pressure-fed version. In every case, the mission was accomplished and the program goals met before the development of the pump system was completed. After the X-I broke the sound barrier with its pressure-fed rocket engine, who ever heard of the D-558-2 — powered by a pump-fed engine?

Technically simple two-stage launchers with pressure-fed engines and ocean recovery offer the economical operations that have escaped our high-technology turbopump rockets for more than four decades.

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