Handley Page Type O

The Handley Page Type O was an early bomber aircraft used by Britain during World War I. At the time, it was the largest aircraft that had been built in the UK and one of the largest in the world. It was built in two major versions, the Handley Page O/100 (H.P.11) and Handley Page O/400 (H.P.12). 

The first O/100s to be deployed to France were received by 7A Squadron of the RNAS 5th Wing at Dunkirk in late 1916. Their first combat came on the night of March 16, 1917 when a single aircraft was sent to bomb a railway junction at Moulins-ls-Metz. The improved O/400 started to enter service in April 1918, gradually allowing the re-equipment of more squadrons, being used for both support for the ground forces on the Western Front, particlularly during the German Spring Offensive, and for stategic bombing under the control of the Independent Air Force. After the war, O/400s remained in British service until replaced by the Vickers Vimy towards the end of 1919. About 10 war-surplus aircraft were converted for civilian use in the UK and India by Handley Page.

Handley Page Type O
Class Aircraft
Type Bomber
Manufacturer Handley Page Limited
Origin United Kingdom - UK (Great Britain)
Country Name Origin Year
United Kingdom - UK (Great Britain) 1915
Country Name Operational Year Retirement Year
Australia View
China View
India View
Poland View
United Kingdom - UK (Great Britain) 1916 1922 View
United States of America View
ManufacturerName Production From Production To Quantity
Handley Page Limited 600 View

The four prototypes and first production batch of six aircraft were built at Cricklewood, with the first aircraft delivered by road to Hendon on 9 December 1915. The first flight of the first prototype, serial number 1455, was made at Hendon on 17 December, when a short straight flight was made, the aircraft taking off without trouble at 50 mph (80 km/h). A second flight was made the following day, when it was found that the aircraft would not fly faster than about 55 mph (89 km/h). This was blamed on the drag caused by large honeycomb radiators, which were changed to tube radiators mounted on either side of the engine nacelles. A third flight on 31 December revealed a number of control problems: ailerons and elevators were effective but heavy, partly due to excessive friction in the control circuit and the rudders were seriously overbalanced. After minor modifications, the aircraft was flown to RNAS Eastchurch, where full-speed trials were made. On reaching 70 mph (110 km/h), the tail unit began to vibrate and twist violently: the pilot immediately landed and an inspection showed severe damage to the rear fuselage structure but reinforcement failed to cure the problem. The enclosed cockpit and most of the armour plating were also removed. The second prototype, 1456, was completed in April 1916 and had an open cockpit in a longer nose, with room for a gunner's position at the end. To save weight, most of the armour plating was deleted. This was the arrangement for later production of the machine.

After a series of proving flights at Hendon, 1456 was accepted by the RNAS and was flown to Manston for further trials. These revealed that despite a reduced balance area on the elevators, there was still a tail oscillation problem. A lack of directional stability caused by the increased forward side area was partly cured by adding a fixed fin but to find the cause of the tail oscillation, the Admiralty called in F.W. Lanchester from the National Physics Laboratory. He agreed that simple structural weakness was not the root of the problem and that resonance of the fuselage was the probable cause. Static tests on a third prototype, 1457, which had a redesigned, stiffer, fuselage structure showed nothing. This aircraft had an amidships crew position and on 26 June, Lanchester was flown as an observer. The tail oscillations started at 80 mph (130 km/h) and Lanchester observed that the tail was twisting by 15° to either side and deduced that the cause was asymmetric movement of the right and left halves of the elevators, which were not rigidly linked but connected by long control cables. He recommended that the halves of the elevators be connected, removal of the elevator balances and additional bracing between the lower longerons and the lower tailplane spar, measures which were wholly successful.

The fourth prototype, 1458, was completed with the same fuselage structure as 1456 and provision for armament, with a Scarff ring mounting in the nose, a pair of post mountings in the mid position and a gun mounting in the rear fuselage. This was also the first 0/100 to be fitted with uprated 320 hp (240 kW) Eagle engines. After completing acceptance trials, 1456 and 1457 were retained at Manston to form a Handley Page training flight. The first prototype was rebuilt to production standard and 1458 used to test a new nacelle design. This was unarmoured, had an enlarged fuel tank and the fairing was shortened, eliminating the need for the tip to fold. This nacelle design was used on all aircraft built after the initial batch of twelve. From 1461, an additional 130 imp gal (590 L) fuel tank was fitted in the fuselage above the bomb floor. A total of 46 O/100 aircraft were built before being superseded by the Type O/400.

The most significant difference between the two types was the use of 360 horsepower (270 kW) Eagle VIII engines. Unlike the earlier version, this engine was not built in right-handed and left-handed versions, because production of engines of both types for engine type approval had been difficult: wind tunnel tests at the NPL established that the counter-rotating propellers were a cause of the O/100's directional instability, and so it was realised that only one version was necessary, simplifying production and maintenance; the torque effect was overcome by offsetting the fin slightly. The O/400 had a strengthened fuselage, an increased bomb load and redesigned tankage: the nacelle tanks were deleted and fuel was carried in two 130 imp gal (590 L) fuselage tanks supplying a pair of 15 imp gal (68 L) gravity tanks. Deletion of the nacelle tanks permitted a smaller nacelle and simplified supporting struts, the reduction of drag producing an improvement in maximum speed and altitude. The revised nacelle was tested in 3188, which in 1917 was flown at Martlesham Heath with a variety of engine installations. An initial order for 100 of the revised design, to be powered either by Sunbeam Maoris or Eagles, was placed on 14 August but cancelled shortly afterwards. Twelve sets of Cricklewood-built components were transferred to the Royal Aircraft Factory, where they were assembled into the first production O/400s. More than 400 were supplied before the Armistice. Another 107 were licence-built in the USA by the Standard Aircraft Corporation (out of 1,500 ordered by the air corps). Forty-six out of an order for fifty were built by Clayton & Shuttleworth in Lincoln.

The first O/100s deployed to France were received by 7A Squadron of the RNAS 5th Wing at Dunkirk in late 1916. Their first combat came on the night of 16 March 1917, when an aircraft was sent to bomb a railway junction at Moulins-lès-Metz. At first the O/100s were used for daylight attacks, damaging a German destroyer on 23 April 1917, but the loss of an aircraft to fighter attack two days later resulted in a switch to exclusively night attacks, usually by one aircraft against German-occupied Channel ports, railway targets and airfields. O/100s were also used for anti-U boat patrols off the mouth of the River Tees in September 1917.

The improved O/400 started to enter service in April 1918, gradually allowing the re-equipment of more squadrons, being used for both support for the ground forces on the Western Front, particularly during the German Spring Offensive and for strategic bombing under the control of the Independent Air Force. The O/400s could carry new 1,650-pound (750 kg) bombs, which were aimed with the Drift Sight Mk 1A bombsight. In service, they were deployed in force, with up to 40 aircraft participating in a raid.

One O/400 served with 1 Squadron, Australian Flying Corps in the Middle East. There, flown by Lt. Ross Smith, it was used for night attacks against the Turkish and supplying the small number of aircraft flying in support of Lawrence of Arabia. As part of the Dardanelles campaign an O/100, 3124, was flown to Moudros on the Greek island of Lemnos. On 9 July 1917, squadron commander Kenneth Savory used it to bomb the battle cruiser Goeben at anchor in Constantinople, winning a bar to his DFC. After being used for anti-submarine patrols and to bomb Adrianopolis and Panderma, it was lost and the crew taken prisoner on 30 September when, flown by John Alcock, it was forced to ditch due to a broken oil-pipe on a raid against railway marshalling yards near Constantinople.

After the war, O/400s remained in squadron service until replaced by the Vickers Vimy toward the end of 1919. War-surplus aircraft were converted for civilian use in the UK and nine were used by Handley Page's pioneering airline, Handley Page Transport. Eight O/400s were fitted with passenger accommodation and operated by the 86th (Communication) wing, formed at Hendon to provide quick transport between London and Paris for officials engaged in the negotiation of the Treaty of Versailles. Two were finished in silver dope and named Great Britain and Silver Star and fitted as VIP transports, while the others, seating eight, retained their dark green finish.

Six aircraft were assembled post-war for sale to Republican China under the designation O/7, principally for use as transports. These were delivered to China and re-assembled at Nanyuan near Beijing. The aircraft flew their first service, carrying both airmail and passengers, between Beijing and Tientsin on 7 May 1920. These services were disrupted by the outbreak of civil war, with the aircraft being taken over by various warlords. Before 1924, Handley Page used an alphabetical system for aircraft designations and the Type O followed the Type M and Type N. Type O aircraft are very frequently misnamed as "Handley Page 0/100" and "0/400" with a numeral "0" instead of the letter "O". The company designations "H.P.11" and "H.P.12" were applied retrospectively after the change to the use of type numbers in 1924.

Role Bomber
Manufacturer Handley Page Aircraft Company
First flight 17 December 1915
Introduction 1916
Retired 1922
Status Retired
Primary users Royal Air Force
Royal Naval Air Service
Number built 600

General characteristics

  • Crew: 4 or 5
  • Length: 62 ft 10 in (19.16 m)
  • Wingspan: 100 ft (30.48 m)
  • Height: 22 ft (6.71 m)
  • Wing area: 1,648 ft (153.1 m)
  • Empty weight: 8,502 lb (3,856 kg)
  • Max takeoff weight: 13,360 lb (6,060 kg)
  • Powerplant: 2 x Rolls-Royce Eagle VIII piston, 360 hp (268 kW) each


  • Maximum speed: 97.5 mph (84.7 knots, 157 km/h)
  • Range: 608 nm (700 mi, 1,120 km)
  • Service ceiling 8,500 ft (2,600 m)
  • Rate of climb: 23 min to 5,000 ft
  • Endurance: 8 hours


  • Guns: 5 x 0.303 in Lewis guns (2 on nose Scarff ring, 2 on dorsal position and 1 at ventral hatch)
  • Bombs: Up to 2000 lb (900 kg) of bombs

End notes