A Method of Measuring Helicopter Landing Loads

Summary

Tests have been made to examine the dynamic response of representative heliport structures to helicopter landing loads. The loads applied by an S.5S helicopter were measured by British European Airways and the corresponding strains, reactions and deflections occurring in the instrumented test platform were recorded by the Building Research Station.

This paper describes the specially designed recording equipment fitted to the helicopter and discusses the data obtained from over 400 heavy landings. It is concluded that:—

• (a)The tyre deflection method used to measure applied load was better than the others considered.

• (b) Overall accuracy achieved was in the order of ± 10 to 15 percent.

• (c) Accuracy could have been improved if more time had been available to eliminate the effects of follower bounce and to establish the exact degree of sideloading present on the mainwheels.

• (d) There was inconsistency in oleo performance which had a marked effect on the time-history of load application.

• (e) The time-history of load application also depended on whether or not the rotor was running and providing lift.

• (f) In very few of the landings from a low hover and in none of the 30 or so run-on landings did all four wheels touch together; this is the most critical loading of the structure.

• (g) Despite the large number of heavy landings earlier in the trial the undercarriage finally failed at 19 fps which was considerably in excess of its design velocity.