Flight, July 1933

THE HANDLEY PAGE "HEYFORD"
2 Rolls-Royce "Kestrel" Engines

   SINCE the original Handley Page H.P.38 was designed, built and flown, there has been a change in load factors, etc., and the new "Heyford" night bomber, which is in effect the production version of the H.P.38, therefore differs considerably in some respects from the prototype; so much so that it has been given a new works series number, and is identified as the H.P.50. Before the construction of the "Heyfords" ordered by the Air Ministry was undertaken, the Handley Page works at Cricklewood were thoroughly overhauled and re-equipped with new and improved machinery. Very extensive use has been made of jigs, and the result of all these improvements, which one suspects to be largely due to Mr. Hamilton, who joined the firm as works manager about the time when the work on the "Heyfords" was begun, is at once evident in the form of vastly improved workmanship and finish. An interesting article could be written on the workshop methods used in producing the "Heyfords," but that would be outside the scope of these notes, which are intended to deal with the finished machine rather than with the methods by which it has been produced. As it is, we have not the space this week to describe the "Heyford" completely, and we have, therefore, decided to divide the article into two instalments, the first, which follows, dealing with the structural aspects of the "Heyford," and the second, which we hope to publish later, to describe the finished machine, its lay-out and general equipment.
   In the notes which follow it is advisable to bear in mind that the "Heyford" is an unorthodox aeroplane in the arrangement of its large components. The fuselage and two engine nacelles are placed immediately under the upper plane, while the lower centre section is uninterrupted by any such large bodies, and is, in fact, used as a receptacle for the bombs. This arrangement has introduced certain changes in structural policy.

The Fuselage

   Structurally speaking, the fuselage is built in four separate sections joined together by bolted joints. Beginning at the nose, there is a forward portion which is of metal monocoque construction. Then follows a single-bay portion, with very stout diagonal strut bracing in the side panels, which is in line with the wings. Aft of that is the main rear fuselage portion, with vertical and horizontal struts and tie rod cross bracing. Finally, the fuselage terminates at the stern in a small unit which carries the tail and castering tail wheel.
   The front, monocoque, portion of the fuselage is of very neat and simple construction. It carries no very heavy weights (crew and their equipment only) and therefore a heavy primary structure has not been necessary. The longerons are built up of an outer curved corner strip and an inner strip of “Omega" section. In the forward half of the monocoque the lower longeron "omegas" are fairly shallow, while in the rear half they are deeper, to meet conveniently the tubular longeron of the rear fuselage portion. The "omegas" of the top longerons are shallow and of uniform depth throughout.
   Top and bottom longerons are connected by vertical formers of small, light-gauge strip of "omega" section. Like the longeron strips they are of Duralumin. The covering is "Alclad," riveted on in fairly large panels. The skin is reinforced by external stringers of shallow channel section, and the side of the rear half of the monocoque is reinforced by an internal diagonal member riveted to the skin and to the vertical formers. The deck and bottom of the monocoque are of a construction similar to that of the sides.
   Two half-bulkheads divide the monocoque into three compartments. The bulkheads are composed of vertical channels from floor to roof, double walls attached to the side skin by L-section strips, and internal channel stiffeners. The front bulkhead, which forms the forward wall of the pilot's cockpit, has a two-fold door which, when closed, keeps the draught from the forward gunner's cockpit from entering the pilot's compartment.
   Aft of the monocoque is the single-bay fuselage portion which carries the wings. This has steel tubular longerons and diagonal struts in the side panels, while the top horizontal panel is braced by swaged rods and the floor panel by streamline wires.
   The rear fuselage main portion, which is really typical of the general construction, has steel tube longerons and struts, with tie rod cross bracing. The joints combine welding, bolting and riveting in a somewhat unusual manner. Welding is used solely as a means of locating the strut fittings on the longerons. Two flat plates have their edges welded to the longeron, or to a sleeve over the longeron, and between the free edges of these plates are inserted the strut ends, secured to the plates by tubular rivets.
   Extensive use is made of sleeve joints for struts and longerons. The ends of struts or longerons are inserted in the sleeve, at the other end of which may be another tube or a fitting. In either case the attachment is by thin studs through tube and sleeve, a large number of studs being used, radially disposed to clear each other. If a damaged strut or longeron is to be replaced, all that has to be done is to undo the nuts of these "spoke studs," when the sleeve can be slid along and the tube removed from the structure.

The Wings

   Owing to the unusual arrangement of the fuselage, engines and bombs, the wing structure of the "Heyford" shows local variations in the type of structure used. The top centre section, upper and lower end portions, are, generally speaking, of one type, while the bottom centre section is of quite different construction owing to the need for accommodating the bomb load.
   Duralumin is the material used in the main wing spars and ribs. The spars are of built-up box section, as shown in our sketches. The ribs are of tubular construction, joints being made by flat plates and tubular rivets. The compression or drag struts are of a section similar to that of the spars, but of slightly smaller overall dimensions.
   In the bottom centre section the spars have bulb-section booms joined by a single thin flat web, reinforced by channel-section stiffeners on front and back. Both booms of the front spar, and the upper boom of the rear spar, are of heavy gauge, and are formed on the draw-bench. The bottom boom on the rear spar is of much lighter gauge, and has its free edges curved for stiffness.
   The ribs of the lower centre section are somewhat more elaborate than those used generally in the wings. The wing section used is fairly deep, to accommodate the bombs, and the concentrated loads are, of course, very much greater. The ribs, therefore, have channel-section flanges of fairly large dimensions, and the tubes of the rib wab are of much larger diameter than those of the normal ribs.
   The engine mountings of the "Heyford" are steel tube structures, using partly welded joints and partly "spoke stud" joints similar to those in the fuselage. The engine mountings are made as complete units, even including the interplane struts, and are built in elaborate jigs. The undercarriage telescopic struts are hinged to the front interplane strut inside the engine mounting. Each wheel is carried on a fork, and the single telescopic strut allows the wheel to rise and fall inside its "spat." A castering tail wheel is fitted.


   HAVING dealt, in our issue of July 6, with the structural features of the Handley Page "Heyford" night bomber, we will turn to the finished machine, which presents many points of interest, caused mainly by the novel conception of the general arrangement of large components such as fuselage, engines and bombs. Hitherto the accepted formula for night bombers, at any rate as far as Great Britain is concerned, is the biplane cellule with fuselage on the bottom centre section and engines on or but a short distance above the lower wing. This arrangement, which has served us well enough in the past, is open to criticism on several points, mainly in connection with the defensive armament, i.e., the position of the machine gunners. The customary twin-engined night bomber has a forward gun position in the extreme nose and another gunner's position in the extreme stern of the fuselage. It will be obvious that the top wing, placed as it is a considerable distance above the fuselage, somewhat blankets the view and field of fire of the forward and rear gunner. In a rearward direction the machine is well protected by the gunner in the extreme tail, but it is not, perhaps, altogether satisfactory to have one member of the crew so far away, as communication between him and the rest is likely to be made a little difficult during a "scrap."
   In the Handley Page ''Heyford'' a complete breakaway from the orthodox arrangement has been made by the designers. To begin with, the blind area above the machine has been eliminated by raising the fuselage to the level of the top centre section. In this way the gunner in the nose and the gunner behind the wings can see each other and can cover a complete hemisphere above the machine. Instead of the gun position in the extreme tail, the "Heyford" has a retractable gun turret just aft of the upper rear gunner's position. When this turret is let down, the gunner can cover the whole area behind and under the tail, while the upper gunner covers the area behind and above the tail. This feature was well brought out in the photograph which we published in our July 6 issue. As the interior of the fuselage is so arranged that members of the crew can walk from the retractable gun turret aft of the wings to the cockpit in the nose, communication between members of the crew is rendered much easier.
   The placing of the offensive armament is also different in the "Heyford." All the large bombs are carried in the centre section of the lower plane, where they are out of the airstream and thus do not add to the drag, or at least only add to it to the extent that the centre section which houses them is rather thicker than the rest of the wings.
   The resulting "cleanness" is reflected in a considerably enhanced performance (the "Heyford" cruises at something like 115 m.p.h.), which is further helped by careful streamlining of the engine nacelles and by large "spats" over the wheels of the undercarriage.
   The two Rolls-Royce "Kestrel" engines are, as already mentioned, close under the upper wing. The petrol tanks are situated behind the engines and so shaped as to form a tail fairing for the engine housings. The high placing renders the engines somewhat inaccessible, but light ladders of tubular construction hook on to fittings on the top front spar and are strutted at their lower ends into "keyhole" plates on the lower leading edge. The ladders can be placed in position in a few seconds, and the sides of the engine housing fold down to form platforms on which the engineers can stand while working on the engines. The landing wheels (Palmer wheels with brakes) are, as mentioned in our first article, carried on forks, and are partly enclosed in fairings. In the upper rear part of each wheel fairing is a small door which gives access to the Ki-gass starter, starter magneto switch, and fuel and oil points. The machine is fuelled by attaching the tube from the pump to the fuel point in the wheel fairing. Ordinary filler caps are also provided in the tanks, on the left side of each engine, between the exhaust pipe and the upper wing. On top of each wheel fairing are supports for the vertical and horizontal shafts of the hand turning gear. These are not, of course, permanently attached, but can be shipped and unshipped in a few moments, and carried from one engine to the other.
   The interior of the fuselage of the “Heyford" is reached via a small trap door in the floor, above the trailing edge of the lower centre section. On the vee struts which support the fuselage from the lower plane are fitted steps which render access to the interior very easy. As one enters the fuselage through this trap door, the rear gunner's cockpit end the retractable gun turret are behind one, while ahead stretches the front part of the fuselage with, first, a large stowage compartment, then navigation and wireless compartment, pilots' cockpit, and finally, in the extreme nose, the forward gunner's compartment.
   In the rear gunner's cockpit there is a tip-up seat on the starboard side, and all the usual gear used by a gunner, with ammunition drums on pegs, points for the electric heating of clothes, etc., and so forth. The floor of this compartment is slightly raised, and to the rear is the retractable gun turret, which is entered from the gunner's compartment, and lowered by him. When in the "down" position the turret can be rotated through a considerable range.
   In the front of the gunner's cockpit is a large compartment used for stowing all manner of gear, but with ample gangway space. The floor is corrugated aluminium, but wooden strips are let into the corrugations, so that one actually walks on the wooden strips, which is very much more pleasant than walking on metal.
   Situated immediately ahead of the plane of the front spars is the navigation and wireless compartment, with revolving seat and folding table on the port side. Ahead of the table, and also on the port side, are shelves carried on tubular stanchions. These shelves carry the wireless equipment, the battery of which is placed on the floor, under the wireless set.
   The wireless compartment is separated from the pilots' cockpit by a half bulkhead on the port side. On the inner edge of this bulkhead is the very large tail-trimming wheel. On the starboard side is the seat for the second pilot. This folds flat against the wall, so that a free passageway to the nose is provided. The seat itself folds down and the backrest hinges back. On the port side, just ahead of the bulkhead, is the seat for the first pilot. This is divided into two halves, the half nearest the outer wall being fixed,, while the inner half hinges down to enable the pilot to get into his seat between the back rest, the rim of the tail-trimming wheel, and the pillar rising from the floor, on which are mounted the engine controls. Once in his place, the pilot raises the inner half of the seat, which is provided with a catch. The control wheel is of the cut-away type to give the pilot a good view of his instrument board, which in the "Heyford" is very neatly arranged. The second set of flying controls are built up as a complete unit, and can be detached in a moment when not required. Pedals with heel cups are provided for the rudder control, and are individually adjustable for length, the adjusting wheels being so placed that the adjustment can be made with the feet, and there is no need for the pilot to stoop down to reach them with his hands. A trigger on the control wheel applies the Palmer wheel brakes, and movement of the rudder pedals then gives the differential action.
   A bulkhead with a two-fold door on the starboard side divides the pilots' compartment from the forward gunner's cockpit. This is provided with a "piano stool" type of seat which folds out of the way when not in use. Firing steps are provided at the sides of this compartment, so that the gunner can stand up on them and fire in a downward direction. In the extreme nose of the fuselage is a large window, hinged along its upper edge. A worm gear is provided for opening this window, which affords space for the bomb sight. On the starboard side is the switchboard by means of which the bombs are released, either singly or in salvos. The bomb release on the "Heyford" is electrically operated. On the rear wall of this compartment are the pegs for ammunition drums, etc., and other equipment.
   The extreme stern of the fuselage is closed by a hinged cover, which opens to give access to the supports for the castering tail wheel, the tail-trimming gear, etc.
   The first of the "Heyfords," which was rushed through the shops in order to have it flying at the S.B.A.C. Display at Hendon recently, is now at Radlett Aerodrome having service equipment installed. When this work has been finished the machine will be sent to Martlesham Heath for official performance tests. In the meantime no performance figures can be published. Other machines are in course of construction at the Cricklewood works, and some of these are expected to be flying towards the end of next month.

Flight, June 1934

Handley-Page "Heyford" Mark II

   Although resembling in most of its features the "Heyford" which has recently been issued to the Royal Air Force, the "Heyford" Mark II shows certain detail alterations, such as engine nacelles of improved shape and a transparent roof over the pilot's head. The engines are Rolls-Royce "Kestrels" of 525 h.p. each, and the wing span 75 ft.