Finding its bearing: Orbit plot with starting shaft location (red dot) marking each revolution as shaft spirals to its center during propellant fluid film pressurization. (Credit: Blue Origin)
By Jeff Bezos
Although the BE-4 turbopump is smaller than your refrigerator, it generates 70,000 horsepower from a turbine running at nearly 19,000 revolutions per minute that pumps cryogenic propellants to pressures just under 5,000 pounds per square inch. To react the forces generated by the rotating turbine and impellers inside the pump, production rocket turbopumps to date have used traditional ball and roller bearings. For BE-4, we’re doing something different – we’re using hydrostatic bearings.
A hydrostatic bearing relies on a fluid film supplied by a high-pressure source to provide support for the shaft and cause it to float without contacting the static structure except at startup and shutdown. The BE-4 main turbopump uses hydrostatic journal bearings for radial support and hydrostatic axial bearings to carry axial thrust. The system is bootstrapped. The high pressure fluid films for the bearings are supplied by the propellants themselves – liquefied natural gas and liquid oxygen – tapped off from the pump discharge flows.
Material selection is a critical consideration for this approach, as ...