DH.98 Mosquito B Mk IV - The Wooden Wonder

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Mosquito B Mk IV Series 2

Mosquito B Mk IV

Short description

The Mosquito B Mk IV is a dedicated bomber variant of the Mosquito FB Mk VI that is already ingame. This, unlike the Fighter-Bomber variant, is completely unarmed. That means that it doesn’t have any weapons to defend itself. It however trades off the weapons for a bigger bomb load and a dedicated bomb sight.

Development and Operational History

The 24th of August 1936, the British Air Ministry issued specification P.13/36, which called for a twin-engined bomber. It specified that the bomber should have a top speed of at least 275 mph @ 15.000 ft (442 km/h @ ≈4.600m), and a range of 3.000 miles (≈4.800 km) with it being able to carry a bomb load of 4.000 lb (≈1.800 kg). It should be defended with two turrets, one in nose and another in the tail. This specification, while not only setting the basis for the Mosquito, it also let to the development of the Avro Manchester and the Handley Page Halifax.

However de Havilland were not convinced that it would be possible to produce a plane, that would be able to archive the required speed with just 2 Merlin engines, unless there were made sacrifices by reducing the bomb load or vice versa. However an engineer at de Havilland, Eric Bishop, suggested that if they made the airframe out of wood, and removed all armaments of the aircraft, that with the reduced weight, they would be able to meet the required speed without compromising the bomb load. This would also have the advantage of being able to make use of alternative non-strategic construction material and unused skilled labour.

The 20th September 1939, Geoffrey de Havilland wrote to Air Marshal Sir Wilfrid Freeman, the Air Council’s member for Research and Development, outlining the idea for a wooden unarmed twin-engine bomber with the reference DH.98. He wrote the following: “We believe that we could produce a twin-engine bomber which would have a performance so outstanding that little defensive equipment would be needed”.

The 7th October 1939, the design team responsible for the development of the DH.98 under chief engineer Eric Bishop, were relocated to Sailsbury Hall, were they began the development of the aircraft.

The Air Ministry were however concerned about the radical idea of the aircraft. Some of their concerns were about its ability to continue being faster than the enemys aircraft. There were also the concern about its 2 man crew in regards to fatiqure, and suggested that they increase the crew to 3. Last but not least, they were concerned about it being unarmed. To apease the Air Ministry, de Havilland built mock-ups with a gun turret aft of the cockpit.

The 29th December 1939, company representatives together with people from the Air ministry and RAF operation command, examied a full scale mock-up, where the project recived backing. This led to the 1st January 1940, in a meeting which included Geoffrey de Havilland, Air Marshal Sir Wilfrid Freeman and Jon Buchanan (Deputy of Aircraft Production), where they ordered a single prototype to specification B.1/40/DH.

Specification B.1/40/DH, called for the aircraft to be fitted with RM.3SM Engines (Merlin 21) and a bomb load of 1.000 lb (≈450 kg). It should have a maximum speed of 400 mph @ 24.000 ft (640 km/h @ 7.300 m), cruising speed of 325 mph @ 26.500 ft (525 km/h @ 8.100 m), a range for full tanks of 1.500 miles @ 25.000 ft (2.400 km @ 7.600 m) and a service ceiling of 32.000 ft (9.800 m).

1 March 1940, Air Marshal Sir Wilfrid Freeman, issued a contract under the specification B.1/40/DH, which was an order for 50 airframes of a bomber-reconnaissance variant. This contract also included the order for the priviously mentioned prototype. Later during May 1940, the Air ministry issued the specification F.21/40, which called or a fighter variant of the DH.98 armed with four 20 mm cannons and four .303 machine guns, it were also to include an airborne interception (AI) Mk IV (Airborne radar). By june 1940, it had gotten the name Mosquito.

In 1940, after the evacuation of British troops from France, Lord Beaverbrook as the minister of Aircraft Production, stopped the production of the Mosquito to instead focus production of five existing aircraft. However in July 1940, the Mosquito was reinstated as a priority after the promise of the delivery fo 50 airframes by December 1941. It turned out that only 20 airframes were built in 1941, the rest of them were delivered by mid March 1942. By that time the original order had changed, so that the 50 delivered aircraft would be 20 photo-reconnaissance variant and 30 fighter variant.

Prototype W4050

16th January 1941 during testing of the prototype W4050, it managed to outpace a Spitfire Mk II @ 6.000 ft (1.800 m), it ended up being 20 mph (30 km/h) faster that the Spitfire. In Febuary 1941, it was tested to a top speed of 392 mph @ 22.000 ft (631 km/h @ 6.700 m), compared to the top speed of the Spitfire Mk II, which were 360 mph @ 19.500 ft ( 580 km/h @ 5.900 m)

The 21st June 1941, the Air Ministry authorised the mass production of the Mosquito, where it ordered that of the last 10 of the photo-reconnaissance variant should be converted into the bomber variant. These 10 convereted aircraft would become the Mosquito B Mk IV series 1. Of the total 273 Mosquito B Mk IV that would end up being produced, the rest of them would be produced as the Mosquito B Mk IV series 2. The difference between the Series 1 and Series 2 of the Mosquito B Mk IV, is that the Series 1 could only carry 4x250lb bombs, where the Series 2 could carry 4x500lb bombs and during April 1943, they were converted to being able to carry the 4000lb “cookie” blockbuster bomb, by modifying the bomb bay doors to fit it. A few of the Mk IV were converted to carry the Highball bouncing bomb, which was a smaller version of the Upkeep bouncing bomb, which were used during the dambuster raids.

4.000 lb "cookie" bomb being loaded into Mosquito B Mk IV

In May 1942 the Mosquito B Mk IV entered service with 105 Squadron, where they would perform low-level and shallow dive daylight attacks, on 19th September 1942 the Mosquito would perform its first of many attacks on Berlin. 25th September 1942, 4 Mosquito B Mk IV would perform a raid on Oslo, where they were to bomb the Gestapo headquaters in the city. The raid itself ended in failure, however the following day, the 26th, BBC announced the raid, which were when the British public would first learn of the RAFs new aircraft.

30th January 1943, on the day that marked the 10th anniversary of the Nazi party being voted into power, Hermann Göring were scheduled to perform a speech at 11:00. However 3 Mosquito B Mk IV from 105 squadron, attacked the main Berlin broadcasting station, which kept him off air for more than an hour. Later on in the afternoon a second attacked performed by 139 Squadron also in Mosquitos interrupted a speech performed by Joseph Goebbels.

During some of the raids the Mosquito would perform, it would be flying literally at rooftop level, and dropping bombs through the windows of buildings. Other operations the Mosquito performed, would be pathfinder operations. Were they would mark the initial targets during night time operations with pyrotechnics, whereafter the main bomber force would come in do the rest of the job.

Some were also used in non military roles, such as in BOAC service. Where they would perform transport of special cargo, from for example neutral Sweden. Some of the things they carried were precision ball berings or special cargo in the form of VIP, including Danish nuclear physicist Niels Bohr.

The Mosquito, the worlds first multirole aircraft, would see service to the end of the war, with multiple different variants and marks being produced, including being produced by Canada and Australia.

Engine: 2x Rolls-Royce Merlin 21
- Take-off Power: 1.280 hp (954 kW) @ 3.000 RPM
- Combat Power: 1.490 hp (1.111 kW) @ 12.500 ft (3.810 m)
Maximum Speed: 380 mph (610 km/h)
Crusing speed: 265 mph (426 km/h)
Service Ceiling: 34.000 ft (10.000 m)
Climb Rate: 2.500 ft per min (12,7 m/s)
Length: 40 ft 9 ½in (12,43 m)
Wing Span: 54 ft 2 in (16,51 m)
Height: 15 ft 3 in (4,65 m)
Empty Weight: 13.400 lb (6.084 kg)
Gross Weight: 21.462 lb (9.744 kg)
  • 4x 250 lb G.P / S.A.P. / M.C. / I.B. Bombs
  • 4x 500 lb G.P / M.C. / I.B. Bombs
  • 2x 500 lb S.A.P. Bombs
  • 1x 4000 lb H.C. Bomb
  • 1x 2700 lb I.B. bomb
  • 2x Mk1A SBC
  • 4x Hudson SBC
  • 1x Highball bouncing bomb
  • 1x A Mark III*** Aerial Naval Mine


De Havilland Mosquito | BAE Systems

de Havilland Mosquito - Wikipedia

de Havilland Mosquito operational history - Wikipedia

List of Air Ministry specifications - Wikipedia

De Havilland Mosquito: The wooden fighter-bomber that could do it all - youtube

Mosquito History - http://www.mossie.org

The de Havilland Mosquito as an Unarmed Bomber - www.historyofwar.org

Air Staff requirements for a twin-engined Medium Bomber Landplane. Spec. P13/36 - The National Archives

Mosquito B, High-speed Bomber, De Havilland - airpages.ru

Old Mosquito Drawings - Air & Space Magazine - twitter.com

BC - Bombs, Mines, Incen’s - https://lancaster-archive.com

Bouncing Bomb - Wikipedia

Mines of the United Kingdom / Britain - NavWeaps

The Mosquito Pocket Manual: All marks in service 1941-1945
  • By Martin Robinson
  • ISBN: 978-1-4728-3432-4
The Merlin: The Engine that won The Second World War
  • By Gordon A. A. Wilson
  • ISBN: 978-1-3981-0325-2


ROYAL AIR FORCE BOMBER COMMAND, 1942-1945. | Imperial War Museums

ROYAL AIR FORCE BOMBER COMMAND, 1942-1945. | Imperial War Museums

ROYAL AIR FORCE BOMBER COMMAND, 1942-1945. | Imperial War Museums



Image of the W4050 prototype, is from De Havilland Mosquito | BAE Systems


Interesting that it can carry a 4000lb bomb. I imagine that looks pretty funny on a Mozzie.

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It actually doesn’t show much, it just gets a bit of a beer gut


It’s crazy that it’s not in game

Don’t care which variant but we 100% need a bomber 'squito for somewhere around 3.3. It’d be so fun in GRB, dashing into the battle faster than fighters can keep up, obliterating some unsuspecting tanks with a cookie, and dashing out again.

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I want a true bomber variant of the Mosquitto so badly. It would be great fun, hoping that it can come after the split BR in June

Should have been in the game 10 years ago. Would love more mossies overall

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It’s a disservice that gaijin have only given us the submarine mozy and an amalgamation of 3 in one with the other. I’ll want, no,m. We need the night fighter version with 4 20mm, radar and more powerful engines along with the bomber variant which was known to be faster than any fighter at the time after it had dropped its bomb. It’s why they were so loved. Especially with the recent buff which made them slightly less of a bus, all we need now is for gaijin to unfuck fuel sliders and allow us to take less than 40minutes of fuel.

It’s ridiculous that this isn’t in game yet, and the gap it leaves in the tree is sorely felt.


Finally an aircraft I can identify with…


I actually forgot they changed its flight model, I’ll need to go fly one. It got better did it?

It’s not as floaty anymore, and turns enough to cause a blackout now. So yeah I would say it go better. Although I mainly use the 57mm as the other one just isn’t for my taste as it’s trying to be far too much all at once, doesn’t help how gaijin just added whatever they could to it instead of simply adding different vareints so now we have in which has a bomb bay while still holding onto its 20mms…. I just wish we had more.


Added the aerial naval mine “A Mark III***”

I found mention of the Mosquito being able to carry the A Mark III naval mine, which were using the same dropping gear as the 4.000 lb bomb.
The only sources i have been able to find about it, is a website that mentions it in a small paragraf, another is it being listed in the index of “Mine Disposal Handbook Part III British Underwater Ordnance”. However i have not been able to find the complete handbook, with it in it.

There is also mention of the 1.500 lb A Mk I - IV, which might be the same as the A Mark III. The source list it as a 1.500 lb mine, with a filling content of 750 lb Amatol high explosive. It does in the same chapter of the journal mention a mining operation with Mosquitos. Source: Royal Air Force Historical Society Journal 45, page 137 - 152

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