The HP.43 was tendered to specification C.16/28 for a three engined bomber / transport. Only one was built, J9833, with three uncowled Bristol Pegasus IM3 radial engines, and it first flew on 21 June 1932.
It had heavy and badly harmonised controls and poor performance, and was converted into the HP.51 twin engined monoplane to C.26/31.

Derived from the Hanibal, it had the same wings, with a new fuselage.

Gustav Lachmann took on the technical development of modern methods of aerodynamics and metal construction, and went on to convert the H.P.43 biplane into the H.P.51, with a modern monoplane wing and aircooled engine nacelles. This led to the order for 100 of a production version, the H.P.54 Harrow.

Handley Page HP.42 Article

To Imperial Airways fell the task of establishing British commercial air transport on an economic basis, and with government backing it became possible – at least in a modest way – to begin the procurement of new aircraft and the survey and inauguration of air routes to link the British Empire. Needing more capacity than was provided by its 18-20-seat Armstrong Whitworth Argosy or 14-seat Handley Page W.10 aircraft, Imperial Airways acquired from Handley Page eight aircraft designed specifically for use on the European and eastern sections of the Empire air routes.

Large biplanes, with a maximum wing loading of less than 48.2 kg/sq.m, they were of all-metal construction except for the aerofoil surfaces and aft fuselage, which were fabric-covered. The unequal-span biplane wings were devoid of flying and landing wires, braced instead by massive Warren girder struts, and having ailerons and Handley Page slots only on the upper wing. The tail unit was also of biplane configuration, with triple fins and rudders, and the heavy landing gear was of fixed-tailwheel type. Power plant comprised four supercharged Bristol Jupiter engines, two mounted on the upper wing and one on each side of the fuselage on the lower wing.

For the first time in any British airliner the crew were accommodated inside the aircraft, in a compartment high in the fuselage nose which we would now call a flight deck. Within the main cabins – fore and aft of the wing area where the engine noise originated – passengers were provided with completely new standards of comfort and spaciousness.

Only four of thes Handley Page H.P.42 were ever built, the biggest biplane aircraft ever built. First acquired by Air Transport and Travel, it first flew from London to Paris in 1919 with a single passenger on board – a newspaper reporter.

Those intended originally for eastern use (on the Indian and South African routes) carried six (later 12) passengers in the forward cabin and 12 in the rear, with space for 14.16cu.m of baggage and mail amid-ships. The four equipped for the European routes (based at Croydon) carried 18 passengers forward, 20 aft and had 7.08cu.m of baggage space. The first HP.42 flew on 14 November 1930. It was equipped subsequently for long-range service (H.P.42E, ‘E’ for Eastern) and named Hannibal.

Four Hannibal class H.P.42s, operated in semi-tropical conditions on the long eastern mail routes between Karachi, Cairo and Kisumu.

Anthony Fokker once commented that H.P.42s had built-in headwinds, but their cruising speed of around 161km/h, excellent handling at low speeds and robust structure ensured that they were able to boast a decade of fatal-accident-free flight before being withdrawn from civil airline service on 1 September 1939.

The H.P.42 was developed into two variants: the H.P.42E (Eastern) for long-haul routes to the middle East and beyond, and the H.P.42W (Western or HP.45) for imperial’s flights to Paris and other European cities.

The HP.42E served exclusively in the east, the four HP.42Ws were Croydon-based and differed by being configured for a maximum of 38 passengers, rather than the 24 of the HP.42E.

The HP.42W were first delivered in September 1931.

Hercules, the first HP.42W delivered, by 23 July 1937 had flown 1 million miles / 1.6 million km on routes to Paris, Cologne and Zurich. Just over a year later, it had completed s further 250,000 miles / 400,000 km and had carried 95,000 passengers.

The HP.42Ws were impressed into military service during World War II.

There were four Heracles class H.P.45s, used on Imperial Air¬ways western routes from Croydon to Europe. First of the H.P.42W (‘W’ for Western) for the European services was delivered in September 1931 and named Heracles.
The two versions wore generally similar, except that the Heracles had 550 hp Jupiter X.FBM engines and accommodation for 38 passengers, whereas Hanni¬bal had Jupiter XIs of the same power and seats for only 18 passengers.
The remainder of this family of 1930s ‘Jumbo’ airliners had the names Hadrian, Hanno, Helena, Hengist, Horatius and Horsa.
Together they flew some ten million miles without ever hurting a passenger, until the last of them disappeared on a wartime flight in the Middle East.
With their girder-braced biplane wings and massive fixed undercarriage they had a maximum cruising speed of about 100 mph (161 km/h), but offered standards of comfort and safety that no other transport of the period could equal. As a result, they carried more passengers between London and the Continent in the 1930s than did all other airliners combined, and without ever hurting a passenger until the last of them disappeared during a wartime flight in 1940.
Five also serviced the RAF during the Second World War.

Gallery

HP.42W / HP.45 Hercules
Engines: 4 x 550 hp / 414kW Jupiter X.FBM
Span 130 ft / 39.62 m
Length 89 ft. 9 in / 27.36 m
Height 27 ft
Weight empty: 21,000 lb / 9,620 kg
Weight loaded 30,000 lb
Max. speed 127 m.p.h. / 204 km/h
Cruising speed 95 105 mph / 153-169 km/h
Range: 805 km / 500 miles
Crew: 2
Pax cap: 40

The Hinaidi was a structural rather than aerodynamic development of the Hyderabad (with a primary structure of metal rather than wood in the main production variant) and with Jupiter radials in place of the Lion inlines for slightly better performance with a usefully increased warload. The two Hinaidi prototypes were Hyderabad conversions and thus retained a wooden structure, and first flew in March 1927.

The 12 new-build Hinaidi Mk Is retained the Hyderabad’s wooden construction, and were complemented by seven Hyderabad conversions before the advent of the metal-structured Hinaidi Mk II (first flown 8 Feb 1929), of which 33 were built up to 1932.

The first Hinaidi unit was No. 99 Squadron, which received its aircraft from October 1929. There followed No. 10 Squadron, together with Nos 502 and 503 Squadrons of the Auxiliary Air Force. Hinaidis were replaced by Heyfords from 1933, and declared obsolete during 1937.

The RAF also received three examples of the troop-transport version known as the Clive (formerly Chitral). Each could accommodate 17 fully armed troops, or equivalent freight; folding seats being provided on both sides of the cabin and racks for the rifles. Two gun positions were retained (nose and dorsal). The first Clive was later civil registered G-ABYX and named Youth of Australia (subsequently Astra).

Hinaidi Mk II
Engines: 2 x Bristol Jupiter VIII, 328kW (440 hp)
Span: 22.86m (75ft).
Length: 18.03m (59ft2in).
Height: 5.18 m / 16 ft 12 in
Wing area: 136.66 sq.m / 1470.99 sq ft
Max T/O weight: 6577 kg (14,500 lb).
Empty weight: 3647 kg / 8040 lb
Max speed: 106 kts / 196 km/h / 122 mph at sea level.
Cruise speed: 121 km/h / 75 mph
Ceiling: 4420 m / 14500 ft
Range: 1368 km / 850 miles
Armament: 3 x 7.7-mm (0.303-in) machine-guns, 657 kg (1,4481b) bombs
Operational range: 850 miles.
Crew: 4