The Cerberus multi-headed aerospike engine has 8 component 'FIDO' enginlettes, each of which needs to be independently fed with fuel and oxidiser,
and the assembly shown on the right is one of the modules that provides such functionality. The total weight is 1.25Kg.
It consists of a duplicated set of turbine fuel-flow meters, shut-off valves, and flow-control valves - one each for the fuel and oxidiser. The oxidiser path needs particular attention paying to it
since the design calls for the transport of two oxidiser types during different phases of flight.
During ascent, high pressure compressed air is fed from the onboard aerodynamic compressors and storage system after first being cooled to reduce its temperature and increase its density.
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Fuel Flow Assembly
Photo Credit: NAs / Peter Jones
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As the air thins, the oxidant is switched to liquid Nitrous Oxide (N2O) which poses its own special problems, not least of which is ensuring the flow components operate down to below -88 °C (184 K).
The continuously variable flow-rates of both the fuel and oxidiser with respect to each-other is an important facilty to have since the two oxidisers need mixing in different proportions to the fuel to achieve stochiometric (balanced) combustion.
This fine-controllable and individual nature of fuel/oxidiser delivery also provides the means to control the direction of thrust in pitch and yaw without gimballing any engines. To alter the thrust vector, the flow is asymetrically delivered across diametrically opposed FIDO units causing the aerospike to shift off-axis in the required direction.
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