Hawker Typhoon and the Napier Sabre

by Paul H Wilkinson

Considerable mystery has surrounded the newest fighting and bombing planes developed in England for the Royal Air Force. Perhaps none of these new craft has been such a closely guarded secret as the Hawker Typhoon single-seater fighter. Recently, there have been references to this particular plane in the British press and a sample Napier Sabre engine with which it is equipped has been sent over to the United States. As we in this country release some data at least on our latest fighters, it should prove interesting to see how the new British fighter compares with the best we can produce.

Basically, the Hawker Typhoon is a development of the well-tried Hawker Hurricane, both of these fighters being designed by Sydney Camm. The Typhoon is slightly larger than the Hurricane and is more strongly constructed to take an engine giving approximately 50% more power and requiring a corresponding increase in tankage. The similarity in design is noticeable in that both airplanes are low-wing monoplanes with bullet-like fuselages and excellent streamlining.

With regard to airframe construction, the Typhoon probably embodies a change from conventional Hawker steel tubing and fabric construction to all-metal stressed-skin construction so as to withstand the high operating speeds and high stresses to which the airplane is subjected. The landing gear follows Hawker practice and folds up sideways into the lower surface of the wings while the tail wheel retracts neatly into the lower extension of the fin. The unusual shape of the fin and rudder is due to the necessity for providing ample control surfaces to offset the relatively large side area presented by the high narrow fuselage when the plane is turning.

Various arrangements of armament are possible on a fighter of this type. The successful use of eight .30-caliber machine guns in the Hurricane undoubtedly has been continued in the Typhoon with the guns mounted along the leading edges of the wings. Additional armament in the form of two or four 20-mm shell guns mounted in the wing stubs gives the Typhoon considerably greater striking power than its predecessor. Armor plate and shatter-proof glass are provided for the protection of the pilot and there are self-sealing gasoline tanks. The radiator appears to be located in the nose of the plane directly behind the spinner on the propeller with the propeller shaft from the engine passing through the center of it.

The power plant of the Typhoon is the new 24-cylinder Napier Sabre which is credited with an output of 2,000 hp. Designed by Major Halford who was responsible for the designs of the Napier Dagger and the Napier Rapier, the Sabre hardly can be said to be experimental although its cylinders are arranged in H formation. Liquid-cooling for its relatively small cylinders is an innovation, however, as is the reported use of sleeve valves. Unusually high crankshaft speeds and the use of a two-speed supercharger make the 2,000-hp output possible from this new engine only slightly larger in overall dimensions than its predecessor, the 24-cylinder 1,000-hp Napier Dagger.

In estimating the weight of the Typhoon, various factors have to be taken into consideration.

Summing up, it is seen that these four groups of items added approximately 2,600 lb to the weight of the Hurricane when it was developed into the Typhoon. Since the weight of the Hurricane with full fighting equipment is 6,100 lb. the weight of the Typhoon therefore is about 8,700 lb. This is equivalent to a power loading of 4.35 lb/hp which is appreciably less than the 4.7 lb/hp power loading of the Hurricane.

Performance figures of the Typhoon have not been released but they can be estimated fairly closely from the performance of the Hurricane II powered with a 1,300-hp 100-octane Rolls-Royce Merlin. The increase in engine power output from 1,300 hp to 2,000 hp should have resulted in an increase in maximum speed from 350 mph to approximately 410 mph for the Typhoon. Likewise, the initial rate of climb should have been increased from 2,500 ft/minute to 3,500 ft/minute due to the decrease in power loading. An increase in service ceiling from 35,000 ft to 40,000 ft undoubtedly has been attained with the more powerful engine.

The flight range of a fighting plane depends to a great extent upon the mission for which the plane is used. Undoubtedly, the Typhoon primarily is intended for the defense of England. Its major uses therefore are as an interceptor for localized defense against hostile bombers and their escort fighters, or as a front line fighter against hostile bombers and fighters just across the Channel. It does not appear to have sufficient range for use as an escort fighter even with medium range bombers. A flight range of three hours' duration cruising at 325 mph, or two hours' combat most of the time at full throttle, therefore appears to be a fair indication of the capacities of Great Britain's new Hawker Typhoon as a fighting machine.

This article was originally printed in the August, 1941, issue of Aviation magazine, vol 40, no 8, p 108.
The original article includes a rather fanciful drawing of a fighter plane; it lacks the Typhoon's "chin."