Technical data
Type Mosquito B.Mk.IV
Function Fast bomber
Year 1941
Crew 2
Engines 2*Rolls-Royce Merlin 21 or 23
Power 1,460hp at 1,905m
Length 12.43m
Height 5.31m
Wingspan 16.51m
Wing area 40.57m2
Empty weight 6,078kg
Loaded weight 9,735kg
Maximum weight 11,340kg
Wing Load (kg/m2) 279.5
Power load (kg/hp) 3.88
Speed 620km/h
Landing speed ?km/h
Landing roll ?m
Takeoff roll ?m
Turn time ?sec
Normal range 1,900km
Maximum range 3,283km
Flight Endurance ?h ?min
Ceiling 10,363m
Climb 762m/min
Fuel 2,449l
Guns None
Bombs Up to 1,814kg
Rockets None

De Havilland Mosquito B.Mk.IV

(59k b/w photo from Profile Publications No.209 "De Havilland Mosquito Mk.IV") A Mosquito IV pattern aircraft (serial number DK296) prior to delivery to the USSR, but already in Russian markings (August 1943).

The B.Mk.IV was the first bomber variant of the Mosquito to be produced (from October 1941 on, entering service with No. 105 Squadron on November 15, 1941). The first nine aircraft (W4064-W4072) were designated as Mosquito B.Mk.IV Series 1 (W4066 later became the sole P.R.Mk.IV Series 1). These machines had originally been ordered as P.R.Mk.I photo-reconnaissance aircraft (the first order consisted of 50 machines, in its original form covering the prototype, 20 P.R.Mk.Is and 29 F./N.F.Mk.II fighters/night fighters). Power was provided by two liquid-cooled Rolls-Royce Merlin 21 or 23 12-cylinder vee engines rated at 1,460hp each. The aircraft carried no gun armament and at first the bomb load was confined to two 227kg bombs carried internally. But it was soon found out that if the fins of the British standard 227kg bomb were shortened, the bomb bay of the Mosquito could carry four of them. At first there were experiments with telescopic fins, but drop test revealed, that cropped bomb fins caused no detrimental effect on the standard bomb and this was a much simpler solution which doubled the Mosquito's bomb load as soon as adequate stocks of short-finned 227kg bombs became available.

The first variant ordered from the outset as a bomber was designated B.Mk.IV Series 2 (deliveries starting in April 1942 and terminating in August 1943) and could primarily be distinguished from Series 1 aircraft by its lengthened engine nacelles which extended beyond the wing trailing edge. This had become necessary to correct some tail buffeting caused by disturbed airflow aft of the engine nacelles. Power plants and armament were the same as with Series 1. A total of 300 B.Mk.IV Series 2 aircraft were built, about 30 of them later converted to P.R.Mk.IV Series 2 photo-reconnaissance aircraft.

In April 1943 de Havilland suggested the carrying of one 1,814kg bomb (the so-called "Cookie", a thin-cased, cylindrical high-explosive bomb with devastating blast effect) by the Mosquito. A number of B.Mk.IVs were converted to carry this weapon, which made necessary bulged bomb bay doors. In this configuration the Mosquito's all-up weight was 11,340kg. On February 23, 1944 the first three "Cookies" dropped by Mosquitos fell on Düsseldorf. One modified B.Mk.IV was used for tests with the "Highball" bouncing bomb (two carried), a smaller version of the bombs used to destroy the Möhne, Eder and Sorpe dams. These bombs were brought to rotation by a special mechanism in the bomb bay before being dropped and when hitting a water surface, they "jumped" over the water for a considerable distance which enabled them to hit targets protected by torpedo-nets or similar devices.

The Mosquito B.Mk.IV also did much pioneer work in the use and perfection of electronic navigational and blind bombing aids like "Gee" and "Oboe" and the use of "Window" (aluminum foil stripes dropped to jam German radar).

(44k b/w photo from "Mosquito in Action" Part 1) Another view of DK296.

19k color drawing from "Mosquito in Action", Part 1 of same aircraft.

The only known example of the Mosquito delivered to the Soviet Union is aircraft DK296, a B.Mk.IV which had seen operational service with No. 105 Squadron, RAF. One source quotes that the Russians first showed interest in 1942 to build the Mosquito under licence and therefore this aircraft was painted in Russian markings in August 1943 for delivery as a pattern aircraft. But it was not before April 20, 1944 when it finally left for its new owners. Its further history is unknown. Another source states that there were some more B.Mk.IVs allocated for delivery to the Soviet Union in 1944, but it is doubtful that more than one aircraft of this type was actually delivered.

No other variants delivered to Russia
  • Squadron/Signal Publications, Aircraft No.127 "Mosquito in Action" Part 1 by J.Scutts;
  • Profile Publications No.52 "The de Havilland Mosquito Mks.I-IV";
  • Profile Publications No.209 "de Havilland Mosquito Mk.IV" by M.J.F.Bowyer;
  • "Aero" magazine, Vol.43 (in German);
  • The Mosquito Page
  • Mosquito, de Havilland
  • D.H.98 Mosquito
  • de Havilland Mosquito at "Watson's"
  • de Havilland Mosquito - some articles from 1944!
  • de Havilland Mosquito at the Alberta Aviation Museum
  • de Havilland aircraft - including Mosquito
  • de Havilland Mosquito at its birth-place Salisbury Hall

  • Created for RAM December 18, 1999
    by Thomas Heinz
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