It is now a matter of history that the development of an efficient gas turbine for use in aircraft engines had to await the availability of materials with the properties which would give an adequate life under the conditions which have to be imposed for efficient and economic service. These conditions are, of their type, more severe than any so far imposed on materials in other mechanical equipment. For efficient operation the gases employed in the turbine must be at a high temperature and the flow of gas passing through must be large. In aircraft engines also, the turbine must operate at high speed, with the resulting accompaniment of high stresses. It was to the metallurgist that the engineer naturally turned first for materials to meet these conditions of high temperatures and high stresses and, although some attention has been given to non-metallic substances, the problem still remains essentially a metallurgical one.

What are the particular factors of the aeroplane of 1947, which have a special effect on landing gear technique?

1. (i) Increase in the speed of take-off and landing.

2. 1940: 65 to 90 m.p.h.

3. 1947: up to 130 m.p.h.

4. (ii) Increase in wing loading and the use of thin or laminar flow wing sections.

5. 1940: 301b. sq.ft.

6. 1947: more than 50 lb. sq. ft.

7. (iii) Increase in physical dimensions and all-up-weight of the aircraft.

8. 1940: 80,000 lb.

9. 1947: 300,000 1b.

10. (iv) Increase in operational altitude.

11. 1940: 10,000 to 15,000 ft.

12. 1947: 15,000 to 30,000 ft.

This paper gives details of the first flights of the German, Italian and Japanese jet-propelled aircraft and engines during the last war. Only gas turbine jet propulsion has been covered.