Sopwith Dolphin

Infobox Aircraft
name =5F.1 Dolphin
type = Fighter
manufacturer = Sopwith Aviation Company



designer = Herbert Smith
first flight=23 May 1917
introduced = February 1918
retired =
status =
primary user = Royal Flying Corps
more users = Royal Air Force
produced =
number built = 2,072 Mason 1992, p. 105.]

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 new fighter (internal Sopwith designation 5F.1) powered by the 200 hp Hispano-Suiza 8B. Franks 2002, p. 7.] The resulting Dolphin was a two-bay, single-seat biplane. The upper wings were attached to an open steel cabane frame above the cockpit. To maintain the correct center of gravity, the lower wings were positioned 13 inches forward of the upper wings, creating the Dolphin’s distinctive negative wing stagger. Franks 2002, p. 7.] Cooksley 1991, p. 34.] The pilot sat with his head raised through the frame, where he had an excellent field of view. This configuration sometimes caused difficulty for novice pilots, who found it difficult to keep the aircraft pointed at the horizon because the nose was not visible from the cockpit. Franks 2002, p. 8.]

The Dolphin was armed with two fixed, synchronised Vickers machine guns and one or two unsynchronized Lewis guns flexibly mounted to the forward cabane crossbar. The mounting provided three positions in elevation and limited sideways movement. Davis 1999, p. 128.] Robertson 1970, p. 105.]

The first of four prototypes flew on 23 May 1917. Franks 2002, p. 8.] The type was initially assessed at Martlesham Heath in late June. Franks 2002, p. 8.] After modifications to the radiator, upper fuselage and vertical stabilizer, the Ministry of Munitions placed an order for 500 aircraft on 29 June. Production commenced in October 1917, Mason 1992, p. 105.] with 121 Dolphins delivered by the end of the year.

Operational history

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. Franks 2002, p. 11.] 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. Franks 2002, p. 21.] 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 of No. 141 Squadron, a Home Defence unit, had metal loops fitted above the inner set of interplane struts.Lamberton 1960, p. 62]

Despite early problems, the Dolphin proved successful and generally popular with pilots. The aircraft was fast, maneuverable, and easy to fly, though a sharp stall was noted. The cockpit was warm and comfortable, Cooksley 1991, p. 34.] in part because the radiator pipes ran alongside the cockpit walls.

Four Royal Air Force squadrons operated the Dolphin as their primary equipment, while other squadrons used it in small numbers. One Canadian Air Force squadron equipped with Dolphins but did not become operational before the Armistice.

Engine problems

The scarcity and unreliability of the French-built Hispano-Suiza 8B proved to be the Dolphin's most serious shortcoming. Use of insufficiently hardened metal in the pinion gears led to numerous failures of the reduction gearing, Mason 1992, p. 105.] particularly in engines built by the French firm Brasier. The engine also suffered persistent lubrication problems. Davis 1999, p. 129.] Limited production capacity for the Hispano-Suiza engine, and the priority afforded to French aircraft, slowed Dolphin deliveries. Availability of the Hispano-Suiza improved in early 1918, as the French firm Emile Mayen began deliveries on an order placed by the British Admiralty.

When functioning properly, the Hispano-Suiza afforded the Dolphin excellent performance 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 ft. Franks 2002, p. 21.] The Dolphin could attack with its two fixed Vickers guns, or from below its quarry, with the upward firing Lewis guns. The Lewis guns proved unpopular in service, however, as they were difficult to aim and tended to swing into the pilot's face. Mason 1992, p. 105.] Pilots also feared that the gun butts would inflict serious head injuries in the event of a crash. Most pilots therefore discarded the Lewis guns, Mason 1992, p. 105.] though a minority retained one or both guns specifically for use against reconnaissance aircraft.

Pilots of No. 87 Squadron experimentally fitted some aircraft with forward firing Lewis guns on top of the lower wing, outboard of the propeller arc. Mason 1992, p. 105.] These guns were actuated by a Bowden cable. However, the 97-round ammunition drums could not be changed once empty, nor could the pilot clear gun jams. This field modification did not become standard. No. 87 Squadron also explored the use of equipment to supply pilots with oxygen at high altitude. The experiment was abandoned after trials showed that the oxygen tanks exploded when struck by gunfire. Franks 2002, p. 21.]

Postwar service

Dolphins were rapidly phased out of the postwar inventory. Nos. 19 and 87 Squadrons demobilized in February 1919. Davis 1999, p. 135.] The last operational RAF unit was No. 79 Squadron, based at Bickendorf, Germany as part of the Army of Occupation. The squadron remained active until July 1919. Franks 2002, p. 18.]

The last Dolphins to see combat service were 10 examples used by Polish forces in the Polish-Soviet War. From August 1920, these aircraft were primarily used for ground attack duties in the Battle of Warsaw and other actions. These aircraft were soon grounded due to lack of spare parts. Davis 1999, p. 135.]

In October 1920, two Polish Dolphins were loaned to the Ukrainian Air Force (1. "Zaporoska Eskadra Ukraińska") for use against the Soviets. The two aircraft were returned to the Poles in February 1921. [Kopañski 2001, pp. 11–40.]

Production and planned developments

A total of 2,072 Dolphin Mk I aircraft were produced by Sopwith, Darracq Motor Engineering Co. and Hooper & Co. Mason 1992, p. 105.] Approximately 1,500 Dolphins were stored awaiting engines at the time of the Armistice. These airframes were eventually scrapped incomplete. Mason 1992, p. 106.]

Two developments of the Dolphin were planned. The French firm SACA ("Société Anonyme des Constructions Aéronautiques") commenced licensed production of the Dolphin Mk II in 1918. This variant, intended for the French "Aéronautique Militaire" and the US Army Air Service, was equipped with a 300 hp direct-drive Hispano-Suiza 8F. Bruce 1969, p. 20.] Maximum speed rose to 225 km/h (140 mph), with a ceiling of 8,047 m (24,600 ft). The new engine was considerably larger than the 200 hp version and required an enlarged, bulbous cowling that fully enclosed the guns. The Mk II also featured an additional fuel tank, a variable incidence tailplane, and longer exhaust pipes. 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 200 hp Hispano-Suiza 8B prompted development of the Dolphin Mk III, which used a direct-drive version of the 200 hp engine. Cooksley 1991, p. 34.] The Mk III first flew in October 1918 and went into production just as hostilities ended. Cooksley 1991, p. 34.] Many existing Dolphins were also converted to Mk III standard by removing the reduction gearing and fitting a modified cowling. Davis 1999, p. 135.]

Modern reproductions

There are no known surviving Dolphin airframes, 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. In September 1990, an engine fuel pump failure caused the aircraft to crash into a wooded area. In November 2007, Old Rhinebeck Aerodrome began restoring the aircraft to flying condition. When completed, it will be painted in the markings of No. 19 Squadron.

Variants

;Dolphin Mk I:Main production version. Powered by a geared 200 hp (149 kW) Hispano-Suiza 8B. ;Dolphin Mk II:Manufactured under license in France. Powered by a direct-drive 300 hp (224 kW) Hispano-Suiza 8F.;Dolphin Mk III:Powered by a direct-drive 200 hp (149 kW) Hispano-Suiza 8B.

Operators

;flag|Canada|1868:
* Canadian Air Force
** No. 1 (Fighter) Squadron;POL:
* Polish Air Force (postwar, donated by United Kingdom, operated 1920-1923)
** 19. "Eskadra Myśliwska"

;
* Ukrainian Air Force (postwar, two aircraft loaned by Poland in October 1920, returned to Poland in February 1921)
** 1. "Zaporoska Eskadra Ukraińska"

;UK: multicol
* Royal Flying Corps/Royal Air Force
** No. 19 Squadron
** No. 23 Squadron
** No. 79 Squadron
** No. 85 Squadron
** No. 87 Squadron
** No. 90 Squadron
** No. 91 Squadron
** No. 141 Squadron

pecifications (Dolphin Mk I)

aircraft specifications
plane or copter?=plane
jet or prop?=prop

ref=

crew=1
capacity=
length main=6.78 m
length alt=22 ft 3 in
span main= 9.91 m
span alt= 32 ft 6 in
height main= 2.59 m
height alt= 8 ft 6 in
area main= 24.4 m²
area alt= 263 ft²
airfoil=
empty weight main= 641 kg
empty weight alt= 1,410 lb
loaded weight main=
loaded weight alt=
useful load main=
useful load alt=
max takeoff weight main= 890 kg
max takeoff weight alt= 1,959 lb
more general=

engine (prop)= Hispano-Suiza 8B
number of props=1
power main= 149 kW
power alt= 200 hp
power original=
max speed main= 211 km/h
max speed alt= 131 mph
max speed more= at sea level
cruise speed main=
cruise speed alt=
never exceed speed main=
never exceed speed alt=
stall speed main=
stall speed alt=
range main= 315 km
range alt= 195 mi
ceiling main= 6,100 m
ceiling alt= 20,000 ft
climb rate main= 12 min 5 sec to 3,048 m
climb rate alt= 10,000 ft
loading main= 36.5 kg/m²
loading alt= 7.45 lb/ft²
thrust/weight=
power/mass main= 0.232 kW/kg
power/mass alt= 0.102 hp/lb
more performance=

armament=
* 2× 0.303 in (7.7 mm) Vickers machine guns; up to 2× 0.303 in (7.7 mm) Lewis guns
* Up to four 25 lb bombs.

avionics=

ee also

aircontent
related=

similar aircraft=

sequence=

lists=
*List of aircraft of the Royal Air Force

see also=

References

Notes

Bibliography

*Bruce, J,M. "War Planes of the First World War: Volume Three: Fighters". London: Macdonald, 1969, ISBN 0-35601-490-8.
* 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.
*Davis, Mick. "Sopwith Aircraft". Ramsbury, Marlborough, Wiltshire: Crowood Press, 1999. ISBN 1-86126-217-5.
* Franks, Norman. "Dolphin and Snipe Aces of World War I (Aircraft of the Aces No. 48)." Oxford: Osprey Publishing, 2002. ISBN 1-84176-317-9.
* Green, William and Gordon Swanborough. "The Complete Book of Fighters." London: Salamander Books, 1994. ISBN 0-83173-939-8.
* Kopañski, Tomasz Jan. "Samoloty brytyjskie w lotnictwie polskim 1918-1930 (British Aircraft in the Polish Air Force 1918-1930)" (in Polish). Warsaw: Bellona, 2001. ISBN 83-11-09315-6.
* Lamberton, W.M., and E.F. Cheesman. "Fighter Aircraft of the 1914-1918 War". Letchworth: Harleyford, 1960. ISBN 0-90043-501-1.
* Mason, Francis K. "The British Fighter Since 1912." Annapolis, Maryland: Naval Institute Press, 1992. ISBN 1-55750-082-7.
* Robertson, Bruce. "Sopwith – The Man and His Aircraft". London: Harleyford, 1970. ISBN 0-90043-515-1.

External links

* [http://www.oldrhinebeck.org/collection/airplanes/Sopwith%20Dolphin.htm Old Rhinebeck Aerodrome Sopwith Dolphin]
* [http://www.rcaf.com/aircraft/fighters/dolphin/index.php?name=dolphin The Sopwith Dolphin]