Turbopump

Although multiple compression stages are needed, axial flow pumps work well with low-density fluids.

[2]: 172  The first engine fired successfully in September, and on August 16, 1942, a trial rocket stopped in mid-air and crashed due to a failure in the turbopump.

During the second half of 1947, Bosco and his group learned about the pump work of others and made preliminary design studies.

[6] By the end of 1948, Aerojet had designed, built, and tested a liquid hydrogen pump (15 cm diameter).

Initially, it used ball bearings that were run clean and dry, because the low temperature made conventional lubrication impractical.

When temperature gauges showed that liquid hydrogen had reached the pump, an attempt was made to accelerate from 5000 to 35 000 revolutions per minute.

After some testing, super-precision bearings, lubricated by oil that was atomized and directed by a stream of gaseous nitrogen, were used.

The problem was traced to the exit diffuser of the pump, which was too small and insufficiently cooled during the cool-down cycle so that it limited the flow.

In this case the axle essentially has propellers attached to the shaft, and the fluid is forced by these parallel with the main axis of the pump.

Gas turbines are usually used when electricity or steam is not available and place or weight restrictions permit the use of more efficient sources of mechanical energy.

Ramjet motors are also usually fitted with turbopumps, the turbine being driven either directly by external freestream ram air or internally by airflow diverted from combustor entry.