| HP.81 Hermes | |
|---|---|
 Hermes IV of Air Safaris atManchester Airport in 1961 | |
| General information | |
| Type | Airliner |
| Manufacturer | Handley Page |
| Primary user | BOAC |
| Number built | 29 |
| History | |
| Manufactured | 1945–1951 |
| Introduction date | 6 August 1950 |
| First flight | 2 December 1945 |
| Retired | 1965 |
| Developed from | Handley Page Hastings |
TheHandley Page HP.81 Hermes was a civilianairliner designed and produced by theBritish aircraft manufacturerHandley Page.
The Hermes was developed during the 1940s in parallel with the closely relatedHandley Page Hastings military transport. It was a low-wingmonoplane, with most examples being powered by fourpiston engines. Originally intended to enter service in advance of the Hastings, development of the Hermes was delayed by the fatal loss of the first prototype during itsmaiden flight on 2 December 1945. Measures were taken to improve the airliner's stability as well as to expand its capacity, which sufficiently impressed theBritish Overseas Airways Corporation (BOAC) into placing a sizeable order for 25HP 81 Hermes IV on 4 February 1947. A pair ofturboprop-powered development aircraft were also ordered by theMinistry of Supply for experimental flights.
The Hermes entered airline service on 6 August 1950, having been delayed by roughly one year due to initial production aircraft being overweight. They would be operated by BOAC, the most prominent operator of the type, for less than a decade before they were sold onto other operators largely due to the rapid advances in airliners made during this era. During its later years of service, second hand Hermes were routinely used by variouscharter airlines. The final Hermes flight was performed sometime during 1969, by which point most of the type had already been scrapped as obsolete. A single example has been partially preserved.
The Hermes can be traced back to discussions held by theAir Staff (United Kingdom) as early as summer 1943.[1] At the time, authorities were considering not only the need for an immediate successor to theRoyal Air Force's (RAF) fleet ofHandley Page Halifax in the transport/freighter capacity, but also the role of an interim civil airliner for thepost-war years. Accordingly, during December 1944, priority orders were placed for various projects, including both the military and civil programmes proposed by the British aircraft manufacturerHandley Page.[1] For the civil airliner,Specification 15/43 was issued by theAir Ministry; this called for apressurised civil transport that was capable of carrying up to 34 first class or 50 tourist class passengers.[1]
During April 1944, at the urging ofGeorge Volkert, Handley Page's chief designer, to settle production priorities, the company's founder and managing directorFrederick Handley Page decided to merge the work of several projects and prioritise the transport aircraft; this also aligned with the release ofSpecification C.3/44, which sought a multipurpose transport.[2] Handley Page's proposal was accepted with no meaningful alterations sought. Shortly thereafter, it was recognised that development of the civil transport posed less of a challenge than the military transport project, thus it was decided that the airliner programme would be flown first.[3] The military transport aircraft, which would share a relatively high level of similarities with the civil project, would enter service as theHandley Page Hastings, while the civil transport became known as the Hermes.[4][5]
Despite the intentional similarities, there were distinct design differences between the two aircraft. Unlike thetailwheel of the Hastings, the Hermes was planned to have a nosewheellanding gear, although the first twoprototypes were completed with atailwheel undercarriage.[5] Despite the differences, both aircraft remained similar enough that they were produced using the same primary assemblyjigs. The first prototype was effectively an unpressurised "bare shell", while the second featured apressurised cabin and was fully equipped in most respects.[5] On 9 November 1945, a mock-up conference was held at the company'sCricklewood facility, attended by various airline officials and industry figures. Rapid progress on the first prototype's construction enabled it to commence ground trials atRadlett on 1 December 1945.[6]
While Handley Page had intended for the Hermes to be introduced in advance of the Hastings from an early stage of development, a delay to its production was necessitated after the first prototype (HP 68 Hermes 1), registeredG-AGSS, crashed during itsmaiden flight shortly after takeoff on 2 December 1945.[6] It is believed that the aircraft had encountered severe longitudinal instability due toelevator overbalance. Handley Page's chief test pilot and the chief test observer were both killed in the incident, while the prototype was completely destroyed by a post-impact fire.[7]
In order to sufficiently resolve the instability that caused the fatal crash, development of the civil Hermes was protracted, while work on the Hastings progressed more smoothly.[8] This delay presented the opportunity to undertake design revisions and improvements; it was decided that the second prototype's length would be extended to produce the HP 74 Hermes II. The prospects of powering the type withturboprop engines was also investigated around this time, but ultimately decided against.[9] The first Hermes II (G-AGUB) performed its first flight on 2 September 1947; it quickly proved to not only have greater stability, but to also possess a superior lift coefficient to the Hastings as well. On 4 September 1948, the type received itscertificate of airworthiness, clearing it for service.[4][10]
On 4 February 1947, firm orders were placed by theBritish Overseas Airways Corporation (BOAC) for 25 of the definitiveHP 81 Hermes IV. This model was furnished with atricycle undercarriage and powered by fourBristol Herculesradial engines, each capable of generating up to 2,100 hp (1,570 kW).[11] Additionally, a pair ofHermes V airliners were also ordered, the primary difference of this model was the use of fourBristol Theseus turboprop engines instead. Further turboprop-powered developments of the Hermes were also proposed to potential customers as a competitor to types such as theBristol Britannia.[11]
Despite the first Hermes IV (registeredG-AKFP) performing its first flight relatively quickly on 5 September 1948,[4] and quantity production being promptly established, BOAC was somewhat unsatisfied by the airliner, primarily due to the early aircraft being overweight.[12] This was in part due to the use of Hastings components and ad-hoc modifications to accelerate flight trials; it was promptly agreed that weight-saving modifications were to be made prior to BOAC issuing its final acceptance of the Hermes. Design alterations to reduce weight included the adoption of lighter floor members.[13]
On 6 August 1950, the Hermes IV finally entered service with BOAC, taking over from theAvro York on the West Africa service from London Heathrow toAccra viaTripoli,Kano andLagos, with services toKenya andSouth Africa commencing before the end of the year.[14][15] The Hermes IV was used by BOAC on routes to West and SouthAfrica. They were quickly replaced, however by the reliableCanadair Argonaut in 1952, although some re-entered service in July 1954 following the grounding of thede Havilland Comet, being retired again in December.[16][17]
This was not the end of the Hermes in airline service, however, as surplus aircraft were sold to independentcharter airlines, withAirwork purchasing four in 1952, others being operated byBritavia andSkyways, particularly in the trooping role.[18] Many of these aircraft were fitted with Hercules 773 engines, which could be operated on loweroctane fuel than the original Hercules 763s, being designated as Hermes IVA. They returned to Hermes IV standards when fuel supplies improved.[18][19]
Later, the Hermes were flown on inclusive tour holiday flights from the UK. The last operational civil Hermes,G-ALDA, flown by Air Links Limited, was retired on 13 December 1964, and was scrapped nine days later.[20][21]
The two turboprop Hermes V were owned by theMinistry of Supply and made their first flights in August 1949.[22] They were used for development of theBristol Theseus turboprop engine. The first aircraft was lost in a wheels-up landing atChilbolton airfield on 10 April 1951, but the second continued development flying with theAeroplane and Armament Experimental Establishment (A&AEE) atMOD Boscombe Down and theRoyal Aircraft Establishment (RAE) atFarnborough Airport until its retirement during September 1953.[23]
The prototype Hermes II was given military markings in October 1953 asVX234 and was used for various research and development programmes, including the testing of airborne radar for theRoyal Radar Establishment atRAF Defford, Worcestershire. It was finally retired in 1969, at which point the aircraft had been the final Hermes in operation.[24]
The fuselage of a Hermes IV (the formerBOAC aircraft G-ALDG namedHorsa) is preserved at theImperial War Museum Duxford.[25]
All 29 aircraft were built atRadlett Aerodrome,Hertfordshire,England.
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Data fromJane's All the World's Aircraft 1950-51[36]
General characteristics
Performance
Related development
Aircraft of comparable role, configuration, and era
