PlaneSpottingWorld welcomes all new members! Please gives your ideas at the Terminal.

Sopwith Dolphin

From PlaneSpottingWorld, for aviation fans everywhere
5F.1 Dolphin
Type Fighter
Manufacturer Sopwith Aviation Company
Designed by Herbert Smith
Maiden flight 23 May 1917
Introduced 1917
Primary users Royal Flying Corps
Royal Air Force
Canadian Air Force
Number built 1,532

The Sopwith 5F.1 Dolphin was a British fighter aircraft manufactured by the Sopwith Aviation Company. It was used by the Royal Flying Corps and its successor, the Royal Air Force, during the First World War.

Design and development

In early 1917, Sopwith's chief engineer Herbert Smith began designing a successor to the Camel. The resulting Dolphin (internal Sopwith designation 5F.1) was a two-bay, single-seat biplane armed with two synchronised Vickers machine guns and two Lewis guns hinged to the front spar of the centre section. The Lewis guns were intended to be fired forward and upwards over the propeller arc, although they could also be swung back to fire almost vertically upwards. These guns enabled a stealthy attack from behind and below the fighter's quarry, in much the same way as the World War II Luftwaffe's Schräge Musik installation.

The Dolphin was the first Sopwith design to use a water-cooled inline engine, the new 200 hp Hispano-Suiza 8B; versions of this engine also powered the Royal Aircraft Factory S.E.5a and SPAD S.XIII.

To provide an optimal view for the pilot, the Dolphin's upper wings were attached to an open steel cabane frame above the cockpit. The pilot sat with his head raised through the frame, thereby giving excellent visibility forward and above. To maintain the proper center of gravity, the lower wings were positioned 13 inches forward of the upper wings, creating the Dolphin’s distinctive negative wing stagger.

Third Dolphin prototype

The first of four prototypes flew on 23 May 1917. It was initially assessed at Martlesham Heath in late June. After modifications to the radiator, upper fuselage and vertical stabilizer, the Ministry of Munitions placed an order for 500 aircraft on 29 June. Deliveries commenced in late 1917, with 121 delivered by the end of the year.

Two developments of the Dolphin were planned. The French firm SACA (Société Anonyme des Constructions Aéronautiques) commenced licence production of the Dolphin Mk II in 1918. This variant, intended for the US Army Air Service, was equipped with a 300 hp direct-drive Hispano-Suiza engine. The new engine was considerably larger than the 200 hp version, and required an enlarged, bulbous cowling that fully enclosed the guns. It also featured an additional fuel tank and a variable incidence tailplane. The Air Service anticipated delivery of over 2,000 Mk II aircraft by the summer of 1919, but only a few were delivered before the Armistice.

Meanwhile, persistent difficulties with the geared Hispano-Suiza engine prompted development of the Dolphin Mk III, which used a direct-drive version of the 200 hp Hispano-Suiza. The Mk III first flew in October 1918 and went into production just as hostilities ended.

Operational history

Dolphin of No. 87 Squadron RAF, with one of two Lewis guns mounted atop the lower right wing panel
Dolphin fitted with two upward firing Lewis guns and Norman vane sights
File:Sopwith Dolphin photo1.jpg
Dolphin with Lewis guns

The Dolphin Mk I became operational with Nos. 19 and 79 Squadrons in February 1918. Nos. 87 and 23 Squadrons followed in March. The Dolphin’s debut was marred by several incidents in which British and Belgian pilots attacked the new aircraft, mistaking it for a German type. For the next few weeks, Dolphin pilots accordingly exercised caution near other Allied aircraft.

New pilots also voiced concern over the Dolphin’s wing arrangement, fearing serious injury to the head and neck in the event of a crash. Early aircraft were often fitted with improvised crash pylons over the cockpit to protect the pilot's head. Operational usage eventually showed that fears of pilot injury from overturning were largely unfounded. Crash pylons thereafter disappeared from frontline aircraft, though they were often retained on training aircraft. Night-flying Dolphins belonging to No. 141 Squadron, a Home Defence unit, had metal loops fitted above the inner set of interplane struts.

The unreliability of the French-built Hispano-Suiza 8B proved more difficult to resolve. Use of insufficiently hardened metal in the pinion gears led to numerous failures of the reduction gearing. Limited production capacity for the Hispano-Suiza engine, as well as competition with other manufacturers for the available engines, also slowed deliveries of the Dolphin. By the Armistice, more than 650 Dolphins were stored awaiting delivery of engines.

Despite these problems, the Dolphin proved successful and generally popular with pilots, being fast, maneuverable and easy to fly. The cockpit was warm, in part because the radiator pipes ran alongside the cockpit walls. The field of view was excellent, though some pilots were disoriented by the fact that the nose of the aircraft was not visible from the cockpit. The Dolphin performed particularly well at high altitude. For this reason, Dolphins were often deployed against German reconnaissance aircraft, such as the Rumpler C.VII, which routinely operated at altitudes above 20,000 feet.

The Dolphin could attack with its two fixed Vickers guns, or from below its quarry, with the two upward firing Lewis guns. In service, most pilots removed the Lewis guns, as they were difficult to aim and tended to swing when the aircraft manoeuvered. Removing them reduced the aircraft's weight and provided a marginal increase in performance. It also allayed pilots' fears that the Lewis guns would inflict serious head injuries in the event of a crash. Some pilots nevertheless retained either one or both upward firing Lewis guns for use against high-flying reconnaissance aircraft.

Some pilots of No. 87 Squadron experimentally mounted their Dolphins' Lewis guns on top of the lower wing, outboard of the propeller arc, so that they could be fired forwards, in concert with the fighter's synchronised weapons. These guns were fired by a similar Bowden cable arrangement to that used for firing Foster mounted guns. However, the 97-round ammunition drums could not be changed once empty, nor could the pilot clear gun jams, and this arrangement did not become standard.

Four Royal Air Force squadrons flew Dolphins in combat. Several other squadrons, including two Canadian Air Force squadrons, were equipped with Dolphins but did not become operational before the end of hostilities. Almost all of these units disbanded after the Armistice. Only No. 79 Squadron, based at Bickendorf, Germany as part of the Army of Occupation, remained active until July 1919. The last Dolphins to see service were ten examples sent to Poland in 1920.

A total of 1,532 Dolphins were produced by Sopwith, Darracq Motor Engineering Co. and Hooper & Co.


No Sopwith Dolphin survived to our times but at least two reproductions exist. A Dolphin reproduction, marked as serial D5329, is displayed at the Royal Air Force Museum in Cosford England. This aircraft incorporates some original parts.

Another accurate Dolphin reproduction is displayed at Old Rhinebeck Aerodrome in upstate New York. Powered by a vintage direct-drive Hispano-Suiza engine, this reproduction regularly flew at Cole Palen's weekend air shows at Old Rhinebeck from 1980 onward. On 27 October 1990, an engine fuel pump failure caused the aircraft to crash into a wooded area. Damage was light, and the aircraft has since been restored, without fabric covering, for static display to illustrate how a typical all-wood-structure World War I aircraft appeared.


Dolphin I
Main production version. Powered by a geared 200-hp (149-kW) Hispano-Suiza engine.
Dolphin II
License-built in France. Powered by a direct-drive 300-hp (224-kW) Hispano-Suiza engine.
Dolphin Mk III
Powered by a direct-drive 200-hp (149-kW) Hispano-Suiza engine.


File:Sopwith Dolphin photo2.jpg
Dolphins of No. 1 Squadron, Canadian Air Force
Template:Country data Canada
  • Polish Air Force (postwar, donated by United Kingdom, operated 1920-1923)
    • 19. Eskadra Myśliwska
22px Ukraine
  • Ukrainian Air Force (postwar, two aircraft donated by Poland in September 1920, returned to Poland in February 1921)
    • 1. Zaporoska Eskadra Ukraińska

Specifications (Dolphin Mk I)

General characteristics

  • Crew: 1
  • Length: 6.78 m (22 ft 3 in)
  • Wingspan: 9.91 m (32 ft 6 in)
  • Height: 2.59 m (8 ft 6 in)
  • Wing area: 24.4 m² (263 ft²)
  • Empty weight: 641 kg (1,410lb)
  • Max takeoff weight: 890 kg (1,959 lb)
  • Powerplant:Hispano-Suiza 8B , 149 kW (200 hp)




  • Bruce, J.M. "The Sopwith Dolphin." Aircraft in Profile, Volume 8. New York: Doubleday & Company, Inc., 1970. ISBN 3-910192-52-1.
  • Cooksley, Peter. Sopwith Fighters In Action (Aircraft No. 110). Carrollton, Texas: Squadron/Signal Publications, 1991. ISBN 0-89747-256-X.
  • Franks, Norman. Dolphin and Snipe Aces of World War I (Aircraft of the Aces). London: Osprey Publishing, 2002. ISBN 1-84176-317-9.
  • Green, William and Swanborough, Gordon. The Complete Book of Fighters. London: Salamander Books, 1994. ISBN 0-83173-939-8.
  • Mason, Francis K. The British Fighter Since 1912. Annapolis, Maryland: Naval Institute Press, 1992. ISBN 1-55750-082-7.

External links

See also

Related lists

Template:Sopwith Aviation Company aircraft

cs:Sopwith 5F.1 Dolphin pl:Sopwith Dolphin

This article is licensed under the GNU Free Documentation License.
It uses material from the Wikipedia article "Sopwith Dolphin".