Flight, August 1924

THE BLACKBURN-NAPIER "CUBAROO"
A Long-Distance Torpedo-'Plane with 1,000 H.P, Napier "Cub" Engine

   WHATEVER may be the position of Great Britain in the matter of modern single-seater fighters, there can be no doubt that in one class of aeroplane, at least, this country is well ahead of all others. We are referring to the class known as a torpedo-'plane, and of which several interesting types have already been produced and put into service. Another step forward in the development of this class of machine has undoubtedly been made with the new Blackburn-Napier "Cubaroo," recently finished by the Blackburn Aeroplane and Motor Company of Leeds. This machine, which is claimed to be the first in the world to be specially designed for the Napier 1,000 h.p. "Cub," was demonstrated at Brough, the Blackburn Company's seaplane station on the Humber, on Thursday of last week before a gathering of Air Ministry experts and representatives of a number of foreign governments. By the courtesy of the Napier and Blackburn firms we were privileged to witness the flying tests, which were carried out by Flight-Lieutenant P. W. S. Bulman, M.C., A.F.C., of the Royal Aircraft Establishment, Farnborough.
   The weather was about as disagreeable as possible when the party alighted from the train at Brough station; not only did it rain cats and dogs, but the impression of many of the visitors must have been that it rained "Cubs" and "Lions." At the Brough factory the great machine was having a few finishing touches put to it in one of the large sheds, and while the rain pattered on the corrugated roof the visitors were conducted around by Mr. Rhodes of the Blackburn Company and by General Festing, who has now joined this firm as foreign representative. The Napier Company was represented by Messrs. Winter and Jones, who were ready with any information required relating to the huge Napier "Cub" engine.
   Although the Air Ministry has decreed that external views of the machine may be published, it is not permissible to give other than very brief particulars of the Blackburn "Cubaroo." A very fair idea of the size of the machine may be formed by an examination of some of the accompanying photographs. The span of the biplane wings is 88 ft., and the overall length of the machine 54 ft., while the height is close on 20 ft. The total loaded weight is over 9 tons, out of which approximately 3 1/2 tons is useful load. Of performance figures it is not permissible to speak, but it may be stated that long range rather than high maximum speed has been aimed at, and that in addition to its load of "frightfulness" the "Cubaroo" carries fuel for an exceptionally wide cruising range.
   The biplane wings are designed to fold back so that the machine shall occupy as little space as possible, this being a matter of very considerable importance for the sort of work for which it is designed. As our photographs will show, the joints and hinges in the wings occur at the outer undercarriage struts and, of course, at the sloping interplane struts meeting the top plane. As usual in such designs, a jury strut is placed between top and bottom front spars when the wings are folded.
   Two separate undercarriages of very wide track, and each consisting of two four-foot Palmer wheels, support the machine on the ground, the space between the two undercarriages being quite clear for the torpedo which is slung under the fuselage. Of the mounting of this torpedo, and the devices for heating it, etc., nothing may be said, but a general idea can be formed from an inspection of the photographs.
   The "Cubaroo" is designed for a crew of three, two of whom are accommodated in the pilot's cockpit ahead of the top leading edge and above the rear portion of the engine. The third member of the crew conducts most of his business in the rear cockpit, which, it will be seen, is well raised and gives a very, wide field of fire for the rear machine gun. It may be mentioned that ladders lead from the lower rear cockpit to a central cabin, and from this again to the pilot's cockpit. The view from the latter is exceptionally good, as the pilot is placed well above the engine, over the cowling of which he can look forward and downward at quite a considerable angle.
   An unusual feature of the fuselage design is that over the rear portion a triangular cross-section is employed, while the forward part is of trapezoidal section. There are, we believe, several reasons for this form of body, but into these it would be imprudent to delve too far, and we must leave it to our readers to draw their own conclusions as to the why and wherefore of an arrangement rarely met with in modern machines.
   The 1,000 h.p. Napier "Cub" is, as is well known, of the 16-cylinder "X" type, with four cylinders in each row. In front view the engine is not symmetrical, inasmuch as the two upper cylinder banks are placed at a smaller angle than are the two lower rows. This fact has been made full use of by the designers of the "Cubaroo," and the two upper cylinder banks are entirely cowled in, only the exhaust collector projecting past the sides of the engine housing. The relative narrowness of the engine across the top cylinder heads has also allowed of keeping the nose fairly narrow at this point, thus improving the pilot's view. A curved radiator fits over the top of the nose, and it seems likely that for winter flying the front cockpit may be kept comfortably warm without other heating than that provided by the proximity of the engine and radiator.
   A number of interesting features are deserving of mention, but in view, of official restrictions the temptation must be resisted, and there remains little else to be said except to give some personal impressions of the flight carried out during the visit to Brough.
   During the late afternoon the weather moderated somewhat, and the "Cubaroo" was brought out of the shed and the wings extended. This operation completed, and various minor adjustments having been made, the machine was wheeled out on the aerodrome, Mr. Bulman got into the cockpit, and the small gas starter was set in motion. For a time nothing much appeared to happen, but presently the large airscrew began to turn slowly, and in a couple of minutes, starting from cold, the "Cub" fired and began to tick over merrily. Then followed a wait of some ten minutes while the large engine was warming up. Finally, Mr. Bulman was satisfied, the chucks were removed from under the wheels, and the "Cubaroo" taxied across the aerodrome.
   Turning into the wind, the machine stood for a few moments while the pilot surveyed the aerodrome. Then the "Cub" roared and the machine slowly gathered speed. After what appeared an extremely short run for such a large machine, the "Cubaroo" "floated" into the air (no other word describes the take-off), and the huge aeroplane climbed steadily. Flight-Lieut. Bulman then commenced a series of evolutions such as steeply banked turns, slow and fast flying, etc., and we doubt if ever a pilot has given press photographers such an excellent opportunity for getting "close-up" pictures of a machine in the air. Time after time he circled very low, slipping slowly past the small mound on which the onlookers were standing, and then, opening out the engine, climbing in a right-hand turn to repeat the manoeuvre.
   The Napier "Cub" appeared to run without a stutter, and the smoothness with which it picked up after being throttled down was particularly noticeable. The speed range of the machine seemed very good, although it should, of course, be remembered that the machine was flying light, and that with full load the performance would scarcely have been as good. Nevertheless, from the way in which the machine handled on the occasion of our visit, and making due allowance for the skill of Flight-Lieut. Bulman, there is little doubt that the defence forces of this country have received - or, rather, will receive when the type is put into production - a most valuable addition in the Blackburn-Napier Cubaroo torpedo-'plane. More than that it is scarcely possible to say at the moment, but the Blackburn Company is to be congratulated upon the production of such a formidable weapon of defence, and the Napier Company on the 1,000 h.p. engine which has made it possible.