A Striking Development in Aero Engine Design



A Striking Development in Aero Engine Design


so inevitable has become the perfection of new ideas in relation to modern sc’ence and engineering, that the news that the first British heavy oil aero engine has passed its Air Ministry tests loses much of its surprise. A few years ago when it was prophesied that the heavy oil engine would come into use on automobiles, sceptics scoffed at the idea—but the pioneer work went on just the same. First lorries and transport vehicles, and then such cars as the GardinerBentley, and the Cummins Diesel car appeared, and it is inevitable that the type will one day be turned into a commercial proposition for private motor cars.

The aeroplane engine presented an even greater pull for the scoffer, for in. the air weight is all important, and Diesel or semi-diesel engines are of notoriously heavy construction. But if the experimental staff of our great engineering firms paid any heed to the pessimists no progress would ever be made, so they go on quietly with their work. Now the seemingly impossible has been achieved, and the RollsRoyce ” Condor ” Compression Ignition engine has successfully passed the Air Ministry’s civil engine type

test of 50 hours. The conversion of the Rolls-Royce “

Condor” petrol engine to the compression ignition system was initiated by the Air Ministry and has been developed at the Royal Aircraft Establishment, Farnborough, with the co-operation of Rolls Royce Ltd., which produced such components of the engine as required modification. Compression ignition engines have usually been designed with a substantial increase in strength and weight in anticipation of increased stresses, but in the case of the” Condor” the problem was approached from the other direction, viz., to ascertain how much increased strength was required to be added to an existing petrol engine to secure completion of the normal type test requirements for civil use when employing heavy oil as fuel. The engine has now completed the standard civil type test modified to suit C.I. engines, the duration of which is 50 hours. It is the only C.I. engine which has completed this test in this country with the exception of the Beardmore ” Tornado” which was installed in the airship R.101 and was of a considerably higher weight to power

ratio, being designed to suit airship conditions.

The ” Condor ” engine is now being subjected to experimental flight tests in a ” Horsley ” aircraft at the Royal Aircraft Establishment with a view to exploring the pro• blems of the operation of C.I. engines in flight, including the effects of altitude and low temperatures and ease of handling and control. It is hoped also to establish by practical test the theoretical advantages of low fuel consumption and cost under cruising conditions and to find out the extent to which the size of the radiator and weight of cooling water carried can be reduced as compared with standard petrol engines.

This is only one of a number of experiments which are being made with C.I. engines either by or for the Air Ministry. The chief technical details are given below :—

POWER.-480 b.h.p. at normal charge and r.p.m. 500 b.h.p. at maximum charge and normal r. p. M. ROTATION OF AIRSCREW.—Left

Hand tractor. R.P.M.-1,900 normal ; 2,000 maxi

mum. (Columned on next page). WEIGHT.-1,504 lb. with starter and accessories but less airscrew

boss. CYLINDERS.-12 in two banks of 6 at 60°V—water-cooled. 2 inlet

and 2 exhaust valves. Bore and stroke 5i” x 71″, stroke/bore 1 : 1.363. Compression ratio 12i : 1. Maximum pressure 800 lb. per square inch.

CYCLE OPERATIONS.-4 stroke solid injection.

OVERALL DIMENSIONS.—Length 741 inches ; width 30i inches ; height 45i inches.