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.

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: 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

The ignitor charge consists of black powder and paraffin wax wrapped in thin papper. It is triggered by an arduino which is remotely controlled.

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.

Filling System

Filling device

A slightly modified CO₂ charging device for paintball guns.

Testing

After a few backyard tests with a rather improvised device, we tested the actual motor at Lindabrunn. Special thanks to kyrah and marius for support, pyromantic inspiration and fuel sponsoring.

Videos

Links

Salami Rocket

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