The Handley Page H.P.42 and H.P.45 were four-engine biplane airliners designed and manufactured by British aviation company Handley Page, based in Radlett, Hertfordshire. They held the distinction of being the largest airliners in regular use in the world on the type's introduction in 1931."Handley Page HP42 'Heracles'." Science Museum, Retrieved: 9 June 2019.
The H.P.42/45 were designed in response to a specification issued during 1928 by the British flag airline Imperial Airways. The two models are very similar, with the H.P.42 optimised for range at the expense of payload while the H.P.45 carried more passengers over shorter distances. Imperial Airways approved Handley Page's proposals and ordered four aircraft of the two variants to serve as the new land-based long-distance flagships of its fleet.
On 14 November 1930, the prototype, named Hannibal made its first flight. Following their introduction into Imperial Airways service, they formed the backbone of the airliner's land-based fleet through most of the 1930s and, along with the company's numerous flying boats. Eight aircraft were built, four of each type and all had names beginning with the letter "H". Three survivors were pressed into Royal Air Force (RAF) service at the outbreak of the Second World War. By the end of 1940, all of the aircraft had been destroyed.
Development
In 1928, Imperial Airways invited submissions from the British aviation industry for a replacement of its de Havilland Hercules and Armstrong Whitworth Argosy landplane airliners for use on its major long distance routes across the Empire.Barnes 1987, p. 306
The tender was split into four requirements of three and four engine aircraft for the European routes, and three and four engine aircraft for the Eastern routes. Quotes were expected for batches of three, four, five and six aircraft. Imperial Airways preferred air-cooled engines while the engines chosen would be provided by Imperial Airways as would the electrical and wireless equipment. Payments would be made progressively throughout production with the final third of the price kept until after delivery and acceptance.Barnes 1987 p307
Imperial specified that the aircraft's stall speed would not exceed , and it was to be able to fly hands-off and be able to maintain altitude with one engine out, for a given range. They also specified that the average passenger would be assumed to weigh .
Imperial Airways offered bonuses for exceeding the specifications and penalties for under performance and late delivery. Aircraft were to be delivered from September 1930 to the end of the year (Eastern type) and December 1930 to end of March 1931 (Western type).
British aircraft manufacturer Handley Page, who had an established reputation for large airliners,Taylor and Taylor 1978, p. 118. submitted tenders to meet all four of the requirements.Barnes 1987 p 307
Handley Page built two very similar aircraft, designated H.P.42 and H.P.45, to meet the different requirements. The H.P.42 was for Imperial Airways' long-range Eastern routes, while the H.P.45 was configured for shorter routes across Europe. Imperial Airways ordered four of each. Imperial Airways commonly referred to the H.P.42 as the H.P.42E (E for "Eastern" routes – India and South Africa), while the H.P.45 was referred to as the H.P.42W (W for "Western" i.e. European routes).Sweetman 1979, p. 26.Woodley 2006, p. 10.
The design was drawn up by George Volkert and Harold Boultbee.
Design The Handley Page H.P.42 was a large unequal-span sesquiplane. It incorporated numerous original features throughout its design.NACA 1935, pp. 2, 6. It had an all-metal frame with fabric covering on the wings, tail surfaces and rear fuselage. The fuselage comprises two sections, the unusually long forward section built up around massive riveted girders and partly skinned with corrugated metal, while the rear was built around welded steel tubes and skinned with fabric. Their construction was noted as being relatively expensive.NACA 1935, pp. 3-4.
The wings were braced by a Warren truss to simplify rigging, which had already been tested on Boultbee's Handley Page Hare. The engines were placed as close to each other as the propeller diameter would allow to reduce any yaw from an engine being shut down. Automatic slots were fitted to the top wing, which benefited from a new construction approach involving single z-section spars and planking, of duralumin.NACA 1935, p. 3. Slot-type ailerons are also used, each with four hinges and supported by four box-section brackets and both statically and aerodynamically balanced, making for relatively light control forces. Inboard of the lower engines, the lower wings were inclined upwards so the spar would pass above the cabin rather than through it. Both the elevators and ailerons were controlled via a large diameter Y-tube with the core controls being duplicated.NACA 1935, p. 6. The biplane tailplane was furnished with three separate fins.
The H.P.42 was powered by four Bristol Jupiter XIFs, while the H.P.45 variant used four Jupiter XFBM supercharged engines.NACA 1935, p. 5. Both models had their engines in the same positions with two engines on the upper wing and one on each side of the fuselage on the lower wing. While not common, it was not an original innovation, having been previously used on some of Blériot's aircraft.NACA 1935, p. 2. The upper engines were placed as close together as permissible by the diameter of their propellers and were mounted on rigid duralumin plates attached to the rear wing spar with welded steel tubing. Fuel tanks were in the upper wing and were gravity-fed.NACA 1935, pp. 4-5. The throttles for the engine included a "lost motion" mechanism which used the first movement from the stop to turn on the fuel cocks.
The fully enclosed crew compartment was located at the nose of the aircraft.Croucher, Martin. "UK team plans to build replica of 1930s aircraft that connected Sharjah to the world." thenational.ae, 12 June 2014. There were two passenger cabins, one forward of the wings and the other aft. The H.P.42E carried six (later increased to 12) in the forward compartment and twelve in the aft. There was also substantial space allocated for baggage. The H.P.42W variant seated 18 passengers forward and 20 aft, at the cost of a baggage capacity.Jackson 1973, p. 238. The cabins featured a high degree of luxury, having been intentionally styled to resemble Pullman railway carriages. Other features aimed at improving passenger comfort including spacious cabins, wide windows, and full onboard services. Initially, as was typical for the period, there were no seatbelts until an unrelated air accident motivated Imperial Airways to install them.Marsh, Alton K. "Huge biplane airliner may fly again." AOPA, 31 March 2014.
Operational history
On 14 November 1930, the prototype, now named Hannibal and registered as G-AAGX, was flown by Squadron Leader Thomas Harold England for the types first flight.Swanborough 1992, p. 143. In May 1931, the aircraft was granted its certificate of airworthiness, permitting its use for commercial flights. On 11 June of that year, the first paying passengers were flown to Paris. The extremely high cost of air travel at this time usually limited flights to members of high society, such as royalty, celebrities, and senior business figures and the H.P.42/45 fleet were viewed as Imperial Airways' flagships and were accordingly provided with a luxurious onboard service and an elaborately decorated interior.Votolato 2007, p. 13. They acquired a favourable reputation with the flying public, particularly for their dependability,Cooke 1959, p. 30. and accumulated a combined mileage in excess of 10 million miles (16 million km) in nine years with Imperial Airways.
A key requirement of Imperial Airways was for its airliners to land safely at low speed, on the grass or unpaved airfields common at the time. Without using flaps, this required a large wing area (almost as much as a 767 that weighs over 10 times as much). During 1951, Peter Masefield wrote, "The trouble about a slow aeroplane with a really low wing loading is the way it insists on wallowing about in turbulent air ... One of the reasons why seven times as many people fly to Paris to-day, compared with 1931, is that the incidence of airsickness in modern aircraft is only one-hundredth of that in the pre-War types."The Aeroplane 14 December 1951, p. 767. Another writer remembered "I had quite often been landed in a '42' at Lympne to take on sufficient fuel to complete the flight (from Paris) to London against a headwind – was its normal cruising speed."Banks 1978, . However, while that was three times faster than a combination of steamships and trains used prior to airplanes, several French aircraft types on the same route were significantly faster, including the Wibault 280, which first flew in the same year, and cruised at . When the H.P.42s were impressed on 1 September 1939, they had recorded almost a decade without any fatalities while in civilian service.Elanor, Humphreys and Humphreys 2005, p. 7.
In 1933, after several had been lost or damaged in accidents, Imperial attempted to purchase two more H.P.42s, to be powered by Armstrong Siddeley Tiger engines, but would not accept Handley Page's quoted price of £42,000 each, which was much higher than the original price of £21,000 in 1931, so, instead, they ordered two Short Scyllas, a landplane version of the Short Kent flying boat.Barnes 1976, p. 322.Barnes 1967, p. 272.
Individual histories Four H.P.42 and four H.P.45 aircraft were delivered, while two of the H.P.45s were later converted into H.P.42s.
H.P.42
G-AAGX Hannibal The first flight of the prototype, Hannibal, was on 14 November 1930. The aircraft was named after Hannibal, the Carthaginian military commander.
On 8 August 1931, while on a scheduled passenger flight from Croydon to Paris the port lower engine failed. Debris from the failed engine struck the port upper propeller, causing it to vibrate so severely it had to be shut down. A forced landing was made at Five Oak Green, Kent where the aircraft suffered further damage to a wing and another propeller, and the tail was ripped off by a tree stump. There were no major injuries amongst the 20 passengers and crew. The aircraft was dismantled and taken to Croydon by road for rebuild."Accident To Air Liner. Damaged In Forced Landing." The Times, Issue 45897, 10 August 1931, p. 10, Column G. Hannibal was again damaged at the RAF temporary landing ground at Semakh on the Sea of Galilee on 17 November 1932, by strong winds. The fuselage and heavily damaged wings were sent by gauge Hedjaz Railway to Haifa, where it was transferred to the standard gauge Palestine Railways and forwarded to Heliopolis for repair.
It disappeared over the Gulf of Oman on 1 March 1940, with eight aboard, including the First World War ace Group Captain Harold Whistler and the Indian politician Sir A. T. Pannirselvam."Loss of "Hannibal." Flight Magazine, Volume XXXVII, Issue 1628, 7 March 1940, p. 217. Retrieved: 4 August 2011. An early report that wreckage of the aircraft had been located, turned out to be incorrect."Plane Wreck Found". Irish Times, Reuter (Dublin), 5 March 1940, p. 6."Hannibal Disaster: Wreckage Not Found." Townsville Daily Bulletin (Townsville, QLD), 7 March 1940, p. 4."Hannibal Search Abandoned." Flight Magazine, Volume XXXVII, Issue 1630, 21 April 1940, p. 271. Retrieved: 4 August 2011. No trace has ever been discovered and the cause of its loss remains unknown.Hobby, R. W. "Imperial Airways HP42 'Hannibal' flight CW197". rrhobby.ca, 2010.
G-AAUC Horsa