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.

The storage of aircraft is sometimes regarded as a matter of secondary importance, but to maintain good efficiency and reliability considerable attention must be devoted to the aircraft during the time when it is not actually in flying condition. Storage in an indiscriminate manner leads to a rapid deterioration, with a consequent financial loss and the introduction of other elements which may be exceedingly dangerous when the aircraft is afterwards flown.

A complete aeroplane or seaplane, or any of its components, calls for separate and distinct methods of treatment and these methods have now been formulated, being based chiefly on experience gained by operations of trial and error.

Not only the aircraft, but also the buildings in which it is proposed to store aircraft, must carefully comply with certain conditions, as however much care is taken with the aircraft, a badly constructed or unsuitable building may counteract all efforts to maintain the aircraft in a serviceable condition and be the cause of scrapping valuable machines.