WTF?

Hybrid rocket propulsion system conceptual overview

Nomen est omen. Salami rocket is about building a hybrid rocket with a gaseous oxydizer (N₂0) and salami as propellants.

Oxydizer

I chose N₂O over O₂ because although N₂O carries a lot of conjectural inert nitrogen (64%) oxygen is much harder to handle (tank filling, storage & injection). Additionally the nitrogen, though not participating in combustion, raises the fuel erosion rate and cooles the nozzle enough to reuse it many times. Since the alternatives i found are quite expensive, i use the nitrous oxyde of whipped-cream chargers. By the way, never search for "Sahnespender" at google.

Fuel

Salami: High efficency hydrocarbon based fuel ;)

Simulation

Im using RockSim to simulate the flight stability of the rocket. The behaviour of the N₂0/ hybrid motor is simulated by an external model programmed in C++.

Parts

Overview of the rocket parts

All parts directly participating in the combustion would have to sustain at least 51 bar (vapor pressure of N₂0 at 20°C) but for reasons of safety i assume 200bar as the minimum.

Run Tank: A light-weight container for the oxydizer capable of sustaining enough pressure
Throttle Valve: A valve to allow precise regulation of the oxydizer flow from the run tank to the combustion chamber.
Injector: Aids in vaporizing the (still) liquid oxydizery.
Combustion Chamber: Where the oxydizer/fuel mix burns. Additionally to pressure (same amount as for the run tank) it has to sustain heat.
Nozzle: An opening that dramatically accelerates the hot gas escaping the combustion chamber.
Ignitor: Preheating the fuel and initializing combustion.
Body tube: Enhances airodynamic properties of the rocket and encapsulates the motor.
Motor mount: Anchors the motor within the body tube
Fins: Enhances airodynamic/stability properties of the rocket.
Recovery System (parachute): Enables slow decent after burn-out for safety and reusability
Tail camera: It's all about the nice view
Altimeter: Measurement concludes the fate of the cat
Electric beacon: Transmits a signal to ease finding the landing site.
Filling system: Pipework to fill the run tank with nitrous oxyde from whipped cream chargers.

Run Tank

Run tank

Smart Parts C02 aluminium tank for paintball guns with on/off valve.

Capacity: 591ml (20 oz)
Connector: 1,27cm (1/2")
Max Pressure: 200bar

Throttle valve

An adjustable throttle valve ([1]) intended for use in hydraulics.

Connector: 1,27cm (1/2")
Flow rate: 45 l/min
Working pressure: 350 bar

Injector

SKR-54UC

Diameter: 54mm

Combustion Chamber

Combustion chamber

C02 aluminium tank for paintball guns without on/off valve.

Capacity: 255ml (9 oz)
Connector: 1,27cm (1/2")
Max Pressure: 200bar

Nozzle

SKR-54NZL graphite nozzle

Diameter: 54mm

Ignitor

None selected yet.

Body tube

Cardboard tube, intended for postal delivery.

Dimension: 1000 x 140 x 3 mm

Motor mount & Fins

Motor mount and fins

Wooden centering rings and perspex fins, precisely milled with a CNC machine.

Recover System

None specified/selected yet.

Testing

After a few backyard tests with a rather improvised device, we tested the actual motor at Lindabrunn.

Links

Salami Rocket

Inhaltsverzeichnis