Multidimensional spline-interpolation-extrapolation methods for approximating hydraulics of steering actuating units for rocket stages

The paper discusses development principles of multidimensional approximation methods for hydraulic properties of throttling windows in slide hydraulic valves of electro hydraulic amplifiers of steering actuator, that are based on cubic spline-interpolation-extrapolation (SlE) of functions. A distinctive feature of the methods that were developed consists in that math simulations do not require complex analytical dependences of the properties, but rather only tabular representation of experimental data is used for their approximation in the course of calculation. The high efficiency of cubic SIE-based multidimensional approximation methods presented in the paper has been proven and demonstrated in math models for static analysis of autonomous one-stage electro hydraulic steering actuators with two- and four-throttle electro hydraulic amplifiers. Thanks to these methods the calculations of static properties of steering actuators within wide ranges of working fluid temperatures and power supply voltages are at present accurate to within ±2%.