Sopwith Dolphin

https://en.wikipedia.org/wiki/Sopwith_Dolphin

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. The Dolphin entered
service on the Western Front in early 1918 and proved to be a formidable
fighter. The aircraft was not retained in the postwar inventory and was retired
shortly after the war.

In early 1917, the Sopwith chief engineer, Herbert Smith, began designing a new
fighter (internal Sopwith designation 5F.1) powered by the geared 200 hp
Hispano-Suiza 8B. The resulting Dolphin was a two-bay, single-seat biplane, with
the upper wings attached to an open steel cabane frame above the cockpit. To
maintain the correct centre of gravity, the lower wings were positioned 13 in
(33 cm) forward of the upper wings, creating the Dolphin's distinctive negative
wing stagger. The pilot sat with his head through the frame, where he had an
excellent view. This configuration sometimes caused difficulty for novices, who
found it difficult to keep the aircraft pointed at the horizon because the nose
was not visible from the cockpit. The cockpit was nevertheless warm and
comfortable, in part because water pipes ran alongside the cockpit walls to the
two side-mounted radiator blocks. A pair of single-panel shutters, one in front
of each radiator core and operated by the pilot, allowed the engine temperature
to be controlled.

The Dolphin was the first British fighter aircraft that was capable of carrying
four machine guns, as along with the two Vickers guns in the forward fuselae it
could carry up to two Lewis guns atop the upper wing. The next British fighter
to be fitted with four guns was the Gloster Gladiator, which entered service in
1937, 29 years after the Dolphin.


Role
Fighter

Manufacturer
Sopwith Aviation Company

Designer
Herbert Smith

First flight
23 May 1917

Introduction
February 1918

Primary users
Royal Flying Corps
Royal Air Force

Number built
2,072

The Dolphin Mk I became operational with 19 and 79 Squadrons in February 1918
and 87 and 23 Squadrons 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 consisting of steel tubes over the
cockpit to protect the pilot's head. Experience showed that fears of pilot
injury from overturning were largely unfounded. Crash pylons disappeared from
front line aircraft, though they were often retained on trainers. Night-flying
Dolphins of 141 Squadron, a Home Defence unit, had metal loops fitted above the
inner set of interplane struts.

Despite early problems, the Dolphin proved successful and generally popular with
pilots. The aircraft was fast, manoeuvrable, and easy to fly, though a sharp
stall was noted. In his memoir Sagittarius Rising, Cecil Lewis described a mock
dogfight between his S.E.5 and a Dolphin: "The Dolphin had a better performance
than I realised. He was up in a climbing turn and on my tail in a flash. I half
rolled out of the way, he was still there. I sat in a tight climbing spiral, he
sat in a tighter one. I tried to climb above him, he climbed faster. Every dodge
I have ever learned I tried on him; but he just sat there on my tail, for all
the world as if I had just been towing him behind me."

The highest-scoring Dolphin unit was No. 87 Squadron, which shot down 89 enemy
aircraft. Pilots of No. 79 Squadron shot down 64 enemy aircraft in the eight and
a half months that the aircraft was at the front. The top two Dolphin aces
served in No. 79 Squadron. Captain Francis W. Gillet, an American, scored 20
victories in the type. Lieutenant Ronald Bannerman, a New Zealander, scored 17
victories. The third-ranking Dolphin ace was Captain Arthur Vigers of 87
Squadron, who attained all 14 of his victories in the same aircraft, serial no.
C4159. Another notable ace, Major Albert Desbrisay Carter of 19 Squadron,
obtained approximately 13 of his 29 confirmed victories in the Dolphin. Captain
Henry Biziou scored eight victories in the type.

Engine problems

The scarcity and unreliability of the French-built Hispano-Suiza 8B engine
proved to be the most serious problem in the deployment and use of the Dolphin.
Use of insufficiently hardened metal in the pinion gears led to numerous
failures of the reduction gearing, particularly in engines built by the French
firm Brasier. The engine also suffered persistent lubrication problems. Limited
production capacity for the Hispano-Suiza engine and the priority afforded to
French aircraft like the SPAD S.XIII 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.

The Dolphin did not gain acceptance as a Home Defence fighter, due largely to
the time (approximately 20 minutes) needed to warm the Hispano Suiza engine,
which precluded a quick “scramble.”

Use of the Lewis guns

The official armament of the Dolphin was two fixed, synchronized Vickers machine
guns and two Lewis guns mounted on the forward cabane crossbar, firing at an
upward angle, over the propeller disc. The mounting provided three positions in
elevation and some limited sideways movement. The Lewis guns proved unpopular as
they were difficult to aim and tended to swing into the pilot's face. Pilots
also feared that the gun butts would inflict serious head injuries in the event
of a crash. Most pilots discarded the Lewis guns, though a minority retained one
or both guns for attacking high altitude reconnaissance aircraft from below.

Pilots of No. 87 Squadron, including Arthur Vigers, experimentally fitted some
aircraft with two forward firing, unsynchronized Lewis guns mounted on top of
the lower wing, just inboard of the inner wing struts. These guns could fire
incendiary ammunition, which could not be used with the synchronized Vickers
guns. The 97-round ammunition drums could not be changed once empty, nor could
the pilot clear gun jams, and the field modification did not become standard.

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 (1,410 lb)
Max. takeoff weight: 890 kg (1,959 lb)
Powerplant: 1 × Hispano-Suiza 8B, 149 kW (200 hp)

Performance
Maximum speed: 211 km/h (131 mph) at sea level
Range: 315 km (195 mi)
Service ceiling: 6,100 m (20,000 ft)
Rate of climb: 12 min 5 sec to 3,048 m (10,000 ft)
Wing loading: 36.5 kg/m2 (7.45 lb/ft2)
Power/mass: 0.232 kW/kg (0.102 hp/lb)

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.




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