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We approached the highly recommended New Zealand company Rocket Lab Ltd. They conducted preliminary design, feasibility and optimisation studies on our Land Speed Record car regarding the use of rocket propulsion.
To date, Rocket Lab Ltd. have completed several projects for car, culminating in specifications for the vehicles weight, rocket engine design, types of propellant, propellant tanks, engine thrust and optimised trajectories.
Originally it was planned to use four smaller (15,500 lb/f) hypergolic (self-starting) HTP rocket engines, which would allow throttling via the ability to stop and start engines as required. This system was eventually changed to the more conventional system due to import restrictions and the cost in obtaining the oxidiser (H2o2 – Hydrogen Peroxide) from overseas.
| The engine under development for Aussie Invader 5R is based on the highly successful series of Atlas rockets used by NASA for many years. It has been employed in intercontinental ballistic missiles (ICBM) and has achieved speeds of 4,500 mph (7,245 km/h).Under full load the engine will produce about 62,000 lbs of thrust (200,000 hp) and burn about 2,800 kg (2.8 tonnes) of propellant (liquid oxygen and bio kerosene) in about 25 seconds. The engine will go through a gradual shutdown sequence, as shutting the engine off completely once Aussie Invader 5R has exited the measured mile would result in severe negative “G” for the car and driver. | |
| Many people have asked what does 62,000 lbs of thrust look like and the YouTube video below is of a hot fire testing of the Pratt & Whitney, 54,000 pound thrust, Nitrogen Tetroxide and Monomethyl Hydrazine engine for a Boeing program. The testing was conducted in early February, 2011. Our engine will be running on Liquid Oxygen and Bio-Kerosene, but it gives you a good idea of the explosive power of these engines. Our engine will be throttleable, but will deliver a minimum 63% of power on start up. | |
Pressure Fed Liquid Bi-Propellant Engine
The proposed engine design for Aussie Invader 5R is a pressure fed liquid bi-propellant rocket. The use of pressure fed propellant avoids the more complex set up of turbo pumps and associated ancillaries required. As the application is not aerospace related a slightly higher mass allowance is possible. The use of pressure fed systems drastically reduces overall system complexity, cost and development times while increasing reliability. A bi-propellant rocket engine uses two liquid propellants, an oxidiser and a fuel both in liquid state.
The schematic below shows a typical pressure fed rocket engine system along with the required valving and general equipment required.
A typical pressure fed rocket engine system
Propellants
A propellant study was completed by Rocket Lab in February 2009 and the fuel selected for the engine is a bio-kerosene fuel. The engine will be fitted with an ablative nozzle made from a composite and epoxy material combination and will mean there is no need for the fuel to be used in cooling of the combustion chamber walls to keep temperatures within recommended limits. Exhaust gasses will reach about 2,000 degrees centigrade.
Further work was commissioned to evaluate different propellants and their impact on tank sizes for Aussie Invader 5R. It was concluded that the most effective and safest oxidiser would be liquid oxygen, which is less expensive than the original Hydrogen Peroxide and readily available world-wide.
Aussie Invader’s Engine Performance and Design
Photos of Aussie Invader rocket engine injector plate and LOX hat – click images for larger versions |
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Our motor does not have the need for high pressure fuel and oxidiser pumps, instead propellants are “blown-down” via two storage tanks that hold helium at 3,800 psi when fully pressurised. These two tanks are bridged together and coupled to our propellant tanks via high flow regulators that set our working pressure at 500 psi, resulting in a 380 psi injector pressure.
Ignition is achieved via the injection of “TEA” triethylaluminum into the heart of our engine. The motor is not hypergolic (self-starting) and needs a steady flow of TEA to maintain combustion/plume. Our rocket nozzle will be made from a composite and epoxy material combination, using a 6061 aluminium flange and a silica-phenolic throat insert, which is also under development.
This information was supplied by Rocket Lab Ltd and reproduced with their kind permission.
