THE ROCKET ENGINE
Aussie Invader 5R is a rocket powered car using a single, very powerful bi-propellant engine. The engine development is underway, but due to legal restrictions, we are unable to show you specifics.
The engine design being worked on for Aussie Invader 5R are pressure fed liquid bi-propellant rockets. The use of pressure fed propellants avoids the more complex set up of turbo pumps and associated ancillaries. As the application is not aerospace related, a slightly higher vehicle mass allowance is possible. The use of pressure fed systems also drastically reduces overall system complexity, cost and development times while increasing reliability.
Many people have asked what does 62,000 lbs of thrust look like and the YouTube video on the left is of a hot fire testing of the Pratt & Whitney, 54,000 pound thrust, Nitrogen Tetroxide and Monomethyl Hydrazine engine from a Boeing program and gives some idea of the power rocket engines can produce.
As your can see from this diagram, Aussie Invader 5R will take about 22 seconds to reach a 1000MPH on a full high speed run. The sound barrier (around 760MPH) is broken in about 13 seconds. The car will slow during the measured mile, as the engine will be throttled back. Losing speed is far more time consuming than acceleration, with speed being lost, during the braking process.
Aussie Invader 5R needs just over 3.5 miles to reach maximum speed and enter the measured mile. The car will take a lot further distance to stop, than it does to accelerate to a 1000MPH, due to the fact the engine will need to be “stepped down” in power. This gradual power reduction is to stop the driver experiencing massive negative 16G and passing out, as the car exits the measured mile.
The engine produces maximum thrust, the moment it is fired, with the car accelerating through the sound barrier and on to the measure mile. Once the car enters the measured mile, the engine is throttled down to 60% of power to hold the cars speed steady and stop it accelerating and over stressing the wheels. Once out of the measured mile the engine is shutdown in a controlled fashion.
The car needs to weigh about 9 tonnes, when the engine is ignited, so the car does not accelerate too quickly and exceed 3G. If it does exceed 3G, it could mean the cars wheels will not be able to spin up fast enough and lose traction, causing the car to slide, skid or become unstable. The cars weight changes drastically during a run, as 2.8 tonnes of propellant is burnt in about 22 seconds!