The severity of the tests to which an engine is put before it is passed for commercial work may be gauged from the following details of the "200 hours" endurance test to which the new Armstrong Siddeley Tiger IX 880 h.p. engine has just been subjected (Four of these engines are fitted to the Ensign passenger ioned above). The engine un for 20 periods of ten hours each non stop. For one of these periods it ran throughout at maximum power. In each of the other nineteen periods it ran for fifteen minutes at maximum rate and for 9 hours 45 minutes at maximum cruising revolutions, As the Ensign cruises at 170 m.p.h., the 200 hours test was equal to three England-Australia flights.
Among many improvements introduced into the engine, it may, be mentioned that the two lower piston-rings have a slight angle ground on the bearing face in order to control the film of oil on the wells of the cylinder. Ofter the t angles were still cient!
Text read from the printed page and cleaned; old type leaves the occasional error.