If the motion of an aircraft is restricted, near the ground, to zero bank, comparatively simple solutions to the resulting equations of motion can be obtained, enabling the response to an applied yawing moment to be calculated rapidly. In this paper the analysis is made for three simple forms of applied yawing moment. From the results obtained in a particular case it is possible to judge the suitability of the fin and rudder design chosen on the basis of maximum sideslip reached. A general curve of overswing, in terms of the aerodynamic derivatives of the aircraft, enables the maximum sideslip to be calculated rapidly in a particular case.

Because of typogiaphical difficulties the symbols ^ have been replaced by ° with v, r and t throughout the paper.

When Trans-Arctic transportation becomes common, when air routes take full advantage of great circle courses, when we travel from New York to New Guinea via Point Barrow, Alaska, from Chicago to China almost hitting the North Pole on the way, and from San Francisco to Moscow via Spitsbergen, then, and then only, will those concerned with aerial transportation realise the facilities the Arctic affords the aerial navigator.

In his technical note on “Dimensions required for Inspection” (July Journal), Mr. G. A. G. Saywell stated that drawings calling up various machined fittings often lack any reference to “practical” measurement by which the operator, toolmaker and inspection department may “set out” and check the work concerned. This statement does not really do justice to the draughtsman who, in preparing the detail drawing for manufacture, has to give attention to all aspects of manufacturing.

Recently published statistics give the impression that an excessively high percentage of non-carrier aircraft accidents investigated during 1948 were primarily due to human error. Further, an examination of available data covering the past decade gives the same impression in respect of all aircraft accidents occurring during that period. The figures quoted convey in fact the unpalatable implication that, although in nearly a half century of aviation great strides have apparently been made in increasing the reliability of the aeroplane, very little has been accomplished in reducing the element of human error in aircraft accidents. Why is this?

It has been claimed that the possibility of accidents in flying is inevitable by reason of the inherent conditions of flying which necessitate, besides reliance on the technical factor, considerable reliance upon the skill, judgment, memory, and physical and psychological conditions of the human being.

“Potential” leads are used to put strain gauge switches and leads in series with high resistance ratio arms in a modified Wheat-stone Bridge. Thus the effects of switch contact resistance change and temperature-resistance change in leads can be minimised to any desired values. The high resistance ratio arms allow coarse resistance changes at the measuring bridge to measure the small resistance change at the gauge due to strain.

High potentials are applied to the bridge to minimise the effects of thermal e.m.f.

Active gauges and the temperature compensating gauges are in circuit for only a few seconds while the measurement is made.