THE PROPELLANT TANKS or ORBITAL PROPELLANT MODULE (OPM)
The Propellent Tanks or “OPM” (Orbital Propellant Module – See bottom of page for full explanation of name) is a major part of our cars unique design.
This configuration is the brainchild of Rosco and his team and replaces conventional cylindrical tanks, which were originally planned but rejected after the pressure rating and weight of these conventional designed vessels proved too heavy. It also is too hard to control slosh, which can affect the cars pitch, yaw and stability. The nitronic 40 aerospace materials needed for conventional tanks, didn’t have the pressure rating required for us to deliver of our propellant to the engine at 450-750 psi, with enough safety margin.
Our OPM has a pressure rating of 1000 psi and comprises a module of 7 x 6m long tubes, 4 are for the oxidiser, 3 are for the fuel. These tubes are all fitted with pistons with a ring magnet mounted under the piston crown. An inert high pressure gas, Gaseous Nitrogen (GN2) acts against the pistons forcing the propellants into the rocket engines injector where the meet and create a hypergolic reaction (chemical ignition).
One of the big jobs in building this all Aussie propellant delivery system was in the electronic piston logging location needed to monitor our engines performance and our shifting centre of gravity, along with several other important details. The AT&M electronic strips with LED lights can be seen showing piston travel down the length of of the tanks. The video above is of an initial low pressure system test, using a 100 psi.
This is the Distribution Manifold that takes the propellants from the tanks via a set of tubes to the rocket engine. The propellants are White Fuming Nitric Acid (WFNA – Oxidiser) and Turpentine (Fuel) to the engine, where it mixes and ignites. Producing around 62,000 pounds of thrust (equivalent to about 200,000 hp).
These are the internal pistons with ring magnets and retaining plates. There are a set of highly specialised seals (not shown) that fit in the piston ring grooves and seal the pistons to the tank walls. It is critical no propellant leaks past the seals in this high pressure environment.
This end of the tank set up is where the Gaseous Nitrogen (GN2) is forced into the OPM and this acts on the piston, pushing the propellants into the engine. The force on the pistons can be varied from 450 psi to 750 psi via regulators. The higher the pressure, the power the engine produces. About 2.8 tonnes of propellant can be forced into the engine in just over 20 seconds.
A secondary concept for our propellant tanks design, is it has the potential as an orbiting satellite re-fuelling station. The module could be launched into an LEO (Low Earth Orbit) and with its zero gravity operational features, could act as a “gas station” in space for satellites. Our parent company Apogee Rocket Motor Systems P/L is in discussions with robotics and southern hemisphere launch companies conducting feasibility studies on this concept.