The engine design being worked on 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 also drastically reduces overall system complexity, cost and development times while increasing reliability.
Image courtesy of Rosetta Stone Operations
The following graphs detail the updated performance characteristics of the simulated Aussie Invader 5R: (click on graph images for larger version)
|Speed vs. Time||Speed vs. Distance||Engine Thrust vs. Time||
Acceleration vs. Time
The engine under development will produce about 62,000 lbs of thrust (around 200,000 hp) and burn up to 2.8 tonnes of propellant (H2O2 and kerosene) in about 25 seconds. The engine will go through a gradual shutdown sequence, as shutting the engine off completely as Aussie Invader 5R exits 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 this YouTube video is of a hot fire testing of the Pratt & Whitney, 54,000 pound thrust, Nitrogen Tetroxide and Monomethyl Hydrazine engine from a Boeing program.
Our engine will be running different propellants, but this video gives a great idea of the incredible thrust rocket engines produce. Our engine will be throttleable by virtue it can a mono-propellant or bi-propellant engine (kerosene introduced), so the car can be kept at a constant acceleration of around 3G right up to entering measured mile, where it will be throttled down to not exceed the wheels safety ratings.
A propellant study was completed by Rocket Lab and the fuel selected for the engine is a kerosene. The engine will be fitted with an ablative nozzle made from a composite and epoxy material combination using a 6061 aluminium flange and a silica-phenolic throat insert 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.
Our motor does not have the need for high pressure fuel and oxidiser pumps, instead propellants are “blown-down” via 4 storage tanks that holds nitrogen at around 4,000 psi when fully pressurised. These tanks are coupled to our propellant tanks via high flow regulators that sets our working pressure at between 450-600 psi. The varying pressure will allow changes in engine power, depending on external conditions.
Please note: Some of this information was supplied by Rocket Lab and reproduced with their kind permission.