An analog simulation representing dynamic shock absorption characteristics of a conventional oleopneumatic landing gear strut has been developed. This simulation includes both airplane and strut dynamics. The basic equations of motions are those used for a two-degree-of-freedom system. The hydraulic, pneumatic, and mechanical aspects of the shock strut dynamics have been analyzed. The metering orifice and snubber orifice discharge coefficients have been treated as a function of Reynolds number, orifice shape, and orifice orientation. The snubber valve hydraulic force during compression and rebound has been accounted for. Other factors considered in the system simulation are internal friction in the shock strut, wing lift, inclination of the landing gear, and the effects of wheel spinup and drag loads. A special circuit was devised on the analog simulation which allows the operator to vary the shape of the metering pin, observe the effects on shock strut load instantly, and optimize the load stroke curve(s). The simulation has the capability of high-speed, iterative operation. Good correlation has been established between flight/drop test data and the simulation predicted results. The simulation therefore provides an important design tool for optimizing pin profile, as well as evaluating existing shock strut designs.
[1]
Benjamin Milwitzky,et al.
Analysis of Landing-Gear Behavior
,
1953
.
[2]
Walter C. Hurty.
A Study of the Response of an Airplane Landing Gear Using the Differential Analyzer
,
1950
.
[3]
S. J. Davies,et al.
An experimental study of the flow of water in pipes of rectangular section
,
1928
.
[4]
L. J. Kastner,et al.
A Reassessment of Metering Orifices for Low Reynolds Numbers
,
1965
.
[5]
D. Katz,et al.
Fluid Dynamics and Heat Transfer
,
1959
.
[6]
G. W. Hall.
Analytical Determination of the Discharge Characteristics of Cylindrical-Tube Orifices:
,
1963
.
[7]
H. L. Langhaar,et al.
Steady Flow in the Transition Length of a Straight Tube
,
1942
.
[8]
E. Markland,et al.
Discharge Coefficients for Incompressible Non-Cavitating Flow through Long Orifices
,
1965
.
[9]
James H Walls.
An experimental study of orifice coefficients, internal strut pressures, and loads on a small oleo-pneumatic shock strut
,
1955
.