XYZ

This glossary of historic aviation terms is reproduced from 'The Spotters Glossary' which appeared in 'The Aeroplane Spotter' from January 1940 onwards. 'The Aeroplane Spotter' was the first journal devoted exclusively to the study and practice of aircraft recognition.

We are pleased to have been able to reproduce the entire glossary from A-Z, offering a unique insight into aviation terminology (and therefore aviation history and technology) prior to and during the 1940s.

NB: In the interests of clarity we have substituted current equivalents where words and phrases used in the original publication have fallen from general use (eg, 'aero motor' has been replaced by 'aero engine').

---

"X" Engine: An aero-engine with four rows of cylinders forming in end view the letter "X."

Yawing: An unstable side-to-side motion, about the vertical axis of an aeroplane, which may be described as rotary or angular.

Yield Point: The point where material gives way to excessive strain (such as elongation) without any further stress being applied.

Zephyr: A light warm westerly wind in the Mediterranean.

Zoning: The delimitation of areas urrounding an aerodrome to permit freedom of flight for aircraft approaching or leaving.

Zooming: Utilising excessive forward or downward motion of an aeroplane to gain height suddenly by quickly raising the elevators.