Necessity for strength tests to supplement calculations and to check the assumptions on which the calculations are based. Historical outline. Examples of certain types of defect which are revealed by strength, test.

Assumed aerodynamic conditions. Approximations reproduced by test loading. Methods of support during test. Measurements, testing routine and technique.

The usual tests are described:—Flight test, C P . forward; Flight test, C P . back; Nose dive test; Tests of auxiliary and controlling surfaces; Ailerons, elevators and rudder; Tailplane and fins; Fuselage, down load, side load, torsion ; Undercarriage, discussion of stresses which may arise during landing, pointing out presence of frictional horizontal force causing rotational acceleration of the wheels; Static tests of undercarriages, dropping tests; General description of rib tests.

Description of shot bags and general principles of load application with a view to efficiency and safety.