The last of the RAF biplane heavy bombers
The Air Ministry had tried all it knew to persuade the aircraft industry to tender designs of all-metal aircraft – both bombers and fighters – for half a decade, yet it was the industry itself that had been unwilling or unable to comply fully with this dictate, companies producing composite wood-and-metal prototypes accompanied by undertakings to change to all-metal construction if the tender was accepted for production. It was now no longer a matter of the industry calling the Air Ministry’s bluff; the RAF was already disestablishing the woodworking trades. Vickers, for one, was hard at work rebuilding in metal almost every Virginia extant.
And it is worth mentioning here that one very large all-metal aeroplane, ordered by the Air Ministry as long ago as 1923, had flown in 1928 but, contrary to public reports issued at the time, it was not a bomber (and therefore not conventionally eligible for this work). This was the Beardmore Inflexible, a massive aeroplane powered by three 600hp engines. It handled remarkably well in the air but, to be realistic, only confirmed that a large all-metal aeroplane – and a monoplane at that – could be built and that it could fly, but it made no provision for a bomb load. Had there been the slightest suggestion that a bomber version was envisaged, every bomber airfield in Britain would have had to undergo considerable enlargement, not to mention revised hangarage. However, the Inflexible had already made its last flight before Sir John Salmond came to the helm.
The first of the two bomber Requirements referred to previously, B. 19/27, attracted design tenders from Vickers, Fairey, Handley Page, Hawker, Avro and Bristol, prototypes being ordered from the first three of these manufacturers. The second Specification, B. 22/27, brought forth design tenders from Boulton and Paul and de Havilland for even larger bombers, and prototypes of these had been ordered.
Until these heavy bomber prototypes could be evaluated by the Service establishments and squadrons there appeared to be no immediate need to issue further bomber requirements and, owing to the adaptability of the Hart, other categories, such as army co-operation and general purpose aircraft (the latter satisfactorily filled by the Wapiti) could be ignored.
Ironically, neither B. 19/27 nor B. 22/27 succeeded in producing a significant advance in bomber design. B. 22/27 was abandoned when neither of the two three-engine prototypes impressed the Air Ministry or the A&AEE. B. 19/27, however, produced two `winners’, the Handley Page Heyford and the Fairey Hendon. The former was a twin-engine biplane of singular appearance but possessed a mediocre performance; it was also found to display a number of aggravating design blemishes whose rectification delayed entry into service. The latter, a large twin-engine monoplane with a very thick wing, paltry bomb load and pedestrian performance, was ready for service so late that it had long been overtaken by more imaginative aeroplanes, and joined only one squadron – in November 1936!
By 1932, with neither heavy bomber Specification on the table about to produce any significant advance (heavy bomber performance having increased by about 10% in eight years), the Air Ministry decided to issue a new Specification for what, at the time, were referred to as night heavy bombers but which, by the time they reached the Service, were realistically no more than medium bombers. This Specification, B. 9/32, proved to be the long awaited catalyst of bomber advance, producing in due course the Handley Page Hampden and the Vickers Wellington. Neither of these monoplanes flew until 1936, well into the period of RAF expansion.
The performance demanded by B. 9/32 demonstrated the Air Ministry’s determination to introduce monoplanes into the RAF, even though the process was likely to occupy at least five or six years. The Hendon monoplane to Specification B. 19/27 had first flown in November 1930, but had crashed soon after, and although it was to gain the distinction of becoming the RAF’s first monoplane bomber, it was evident that the path being followed by the Fairey Aviation Company into the monoplane era was a cul-de-sac.
In retrospect, the Handley Page H. P. 50 Heyford had the appearance of something that only a mother (or perhaps designer) could love, its heavy-looking biplane structure and spatted main landing gear units suggesting low speed or inefficiency. This impression was heightened by the fact that the fuselage was mounted to the upper wing, strut bracing filling a large gap between the fuselage and lower wing. This layout had a purpose, of course, the lower wing centre-section being of almost double the normal aerofoil thickness to allow bombs to be stowed internally, and brought close to the ground to speed the business of re-arming after a bombing sortie. Other features of the configuration included wings of basic metal structure with fabric covering, a fuselage which was half metaland half fabric-covered, accommodation for a crew of four, robust tailwheel landing gear, and a braced tailplane carrying twin fins and rudders. Power was provided by two Rolls-Royce Kestrel engines, mounted in nacelles beneath the upper wing, outboard of the fuselage and directly above the main landing gear units. The armament had one more unusual feature to add to the appearance of the Heyford, one of its three defensive machine-guns being mounted in a ventral `dustbin’ turret that could be lowered beneath the fuselage, aft of the wing.
The prototype H. P. 38 was flown for the first time during June 1930, and successful service testing resulted in the type being ordered, initially as the Heyford Mk I. A total of 124 had been supplied to the RAF by the time that production ended in July 1936, these comprising 15 Heyford Mk I, 23 Heyford Mk IA, 16 Heyford Mk II and 70 Heyford Mk III aircraft; they differed primarily in installed powerplant. Entering service first with 99 Squadron at Upper Heyford, Oxfordshire, they eventually equipped also 7, 9, 10, 38, 78, 97, 102, 148, 149 and 166 Squadrons until the last of them were displaced by Vickers Wellingtons in 1939. However, they continued in use for some time, especially in training units, until finally declared obsolete in July 1941 as the last biplane bomber to serve with the RAF.
Specifications (Heyford IA)
- Crew: four (pilot, co-pilot/navigator, bomb aimer/air gunner, wireless operator/air gunner
- Length: 58 ft (17.68 m)
- Wingspan: 75 ft (22.87 m)
- Height: 17 ft 6 in (5.34 m)
- Wing area: 1,470 ft² (136.6 m²)
- Empty weight: 9,200 lb (4,180 kg)
- Loaded weight: 16,900 lb (7,680 kg)
- Powerplant: 2 × Rolls-Royce Kestrel II-S liquid-cooled V12 engine, 525 hp (392 kW) each
- Maximum speed: 142 mph (123 knots, 229 km/h) at 13,000 ft (3,960 m)
- Range: 920 mi (800 nmi, 1481 km)
- Service ceiling: 21,000 ft (6,400 m)
- Climb to 10,000 ft (3,050 m): 15.3 minutes
- Guns: 3 × .303 in (7.7 mm) Lewis guns (nose, dorsal and ventral ‘dustbin’ positions)
- Bombs: 2,500 lb (1,134 kg) total