The Bloodhound Project Monopropellant rocket testing underway

Monopropellant rocket testing underway

Engineering News
Monday, 27 July, 2009

A successful static test of the 44.5 kN (10,000 lb) thrust monopropellant chamber was conducted on the 12th of July. The run also served to test the HTP feed system and large horizontal test stand, which will be used for the first firings of the hybrid rocket. The exhaust was absolutely clear, indicating that the catalyst pack is performing well. The chamber was mounted at a height of 6 feet (approximately the same height as it will be installed in BLOODHOUND  SSC). The test produced a huge dust cloud which extended around 300 feet from the test stand.

What is a monopropellant rocket?

A monopropellant rocket is one which uses a single propellant. In this case HTP (High Test Peroxide). The monopropellant chamber uses the same catalyst pack as the hybrid chamber. A stack of 80 x 40.6 cm (16-inch) diameter silver plated nickel disks are used to decompose the HTP into steam and oxygen, the reaction is given as:

H2O2 ⇒ H2O plus O2 plus Heat

The decomposition generates a temperature of around 600 °C, the hot steam and oxygen are expelled through a nozzle generating thrust. In the hybrid rocket this hot oxygen is used to burn a solid fuel, which is contained in a much longer combustion chamber.

How will the monopropellant chamber be used in BLOODHOUND SSC?

The early runs of BLOODHOUND SSC will use a monopropellant chamber rather than the hybrid rocket. The monopropellant chamber is not as efficient as the hybrid, it delivers a specific impulse of 120 seconds rather than the 230 seconds provided by the hybrid. However the monopropellant chamber is much simpler to operate than the hybrid. The monopropellant chamber can deliver over 44.5 kN (10,000 lbs) of thrust, compared to the 122 kN (27,500 lbs) produced by the hybrid. In conjunction with the 89 kN (20,000 lbs) of thrust from the EJ200 the monopropellant chamber will be more than sufficient to propel BLOODHOUND SSC to over 800 mph.

Why is the exhaust clear or Why does the chamber not produce a flame?

As there is no combustion taking place, simply decomposition of HTP. The monopropellant chamber does not produce a flame, just a jet of hot gas. The monopropellant chamber is also being used to test the catalyst pack for the hybrid chamber, the first tests have confirmed that the catalyst pack is achieving a very high decomposition efficiency.