de Havilland Mosquito - Unbuilt Versions and Variants

[Schneiderman]

Griffon DH.98 of November 1939 to ascertain exactly how much it was scaled up by.

The Griffon powered 'DH.98 Mosquito', was the DH.102. It was bigger than the DH.98 and according to what's written, was a "scaled down" DH.101. There wouldn't have been very much in common though, between the DH.98 and DH.101/102.
I've been trying to make a model of both of these using a copy of the DH.101 drawings which Tony Buttler kindly supplied to me after I had asked him a number of questions about the DH.101 when it first appeared in a brief article in Air-Britain's AeroMilitaria some years ago. I worked out that the DH.101 was scaled up 1.2 bigger than the DH.98 and then the DH.102 was scaled down again so it was about 1.1 bigger than the DH.98.
Here you can see the difference between the DH.98 and the DH.101

According to Tony's article in Aeroplane Monthly Winter 2013 the 101 was to be powered by Napier Sabres and the 102 either by Merlin 61 of Griffon

 

[Hood]

Having now read the article it looks like the tail-turreted Mosquito was to be the larger Griffon-powered airframe. Versions with two and four-gun tail turrets were studied. Tedder and Sholto-Douglas both favoured ordering two prototypes but DH and Freeman successfully got this rescinded to concentrate on the unarmed Merlin version.

Could this snippet from the film be the long-lost Griffon DH.98 with a tail turret? The turret was to be a Nash and Thompson FN4A and the shape of the turret does seem identical. The larger airframe would also go some way to alleviate the C.G. issue, though I can't find any dimensional data for C. C. Walker's larger Griffon DH.98 of November 1939 to ascertain exactly how much it was scaled up by.

The Griffon powered 'DH.98 Mosquito', was the DH.102. It was bigger than the DH.98 and according to what's written, was a "scaled down" DH.101. There wouldn't have been very much in common though, between the DH.98 and DH.101/102.
I've been trying to make a model of both of these using a copy of the DH.101 drawings which Tony Buttler kindly supplied to me after I had asked him a number of questions about the DH.101 when it first appeared in a brief article in Air-Britain's AeroMilitaria some years ago. I worked out that the DH.101 was scaled up 1.2 bigger than the DH.98 and then the DH.102 was scaled down again so it was about 1.1 bigger than the DH.98.
Here you can see the difference between the DH.98 and the DH.101

The Griffon DH.98 of November 1939 is a couple of years earlier than either the DH.101/DH.102. Those were developed to meet Spec. B.11/41 and Spec. B.4/42 respectively.
It's possible that they revisited the 1939 concept and the dimensional scaling might have been similar to the DH.102, but that's still guesswork and leave open a margin of error.

 

[nuuumannn]

An early study for a defensive turret in the Mosquito.

Picture courtesy from lark

A wee snippet since my article has been published in Aeroplne Monthly, this is a Boulton Paul concept of a defensive turret, which Alec Brew forwarded on to Ben at Aeroplane Monthly, along with detailed imagery. New to me at the time!

 

[nuuumannn]

Oh yes, was it absolutley necessary for the gunner to be there, would it have been possible at the time to have the gunner's position further forward as in say the US North American XB.28?

Not really possible with the state of turret development in the time before the war. Nash & Thompson had not produced a remotely operated turret up to 1939. To do this an entirely new turret would have had to be designed, which would have delayed the project. The Bristol turret was chosen for the night fighter because of its light weight, it weighed less and was dimensionally smaller than the Boulton Paul A turret.

It's worth remembering that the XB-28's Original NAA-designed turrets were not actually functional, service ready turrets. At the time the USA was behind in turret development and gained expertise from Britain in 1941, including examples of BP turrets, that was shipped to the USA. The familiar Briggs-Sperry ball turret used on B-17s and B-24s for example employed the same electro-hydraulic working gear as fitted to Boulton Paul turrets.

 

[nuuumannn]

The Griffon powered 'DH.98 Mosquito', was the DH.102. It was bigger than the DH.98 and according to what's written, was a "scaled down" DH.101. There wouldn't have been very much in common though, between the DH.98 and DH.101/102.

Different concept to what's being discussed here. When the DH.98 was being designed, Bishop proposed alternative engines in 1939, including Sabres and Griffons. The following is from an article I had published in a local magazine about the development of the RAF's "Speed Bomber" as Edgar Ludlow-Hewitt called it:

"Further concern for the lack of armament was voiced by Sholto Douglas and shared by AVM Arthur Tedder, both of whom agreed that de Havilland's proposal, given the company number D.H.98 would only be of interest as a bomber if rearward defensive armament was fitted. Despite de Havilland writing that the fitting of a rear facing turret would hold back production, by mid-October 1939 his team considered the fitting of a tail turret to the Merlin powered proposal. Calculations showed that between 20 and 30 mph would be lost from its top speed. By mid-November however, approval for the construction of two turret equipped prototypes was given. [these were to be the Griffon-engined designs, the Merlin engined tail-turret armed aircraft was not advanced on]

At this time de Havilland still held onto his unarmed bomber concept, offering two different versions of the D.H.98, the first being unarmed, which would demonstrate the basic features of the design and the second being the production bomber armed with a tail turret. At a meeting held on 22 November at the Air Ministry and attended by Freeman, Liptrot and Bishop among others, Freeman expressed his opposition to arming the D.H.98 with a turret and suggested de Havilland concentrate on an aircraft that could not be outrun by any contemporary enemy."

 

[TsrJoe]

I was wondering if any drawings survive of any pre studies leading to the prototype DH. Mosquito ?
I recall mention of a faired cockpit mockup which was initially studied and sounds rather intriguing (would make for an interesting model)

Cheers, Joe

 

[TsrJoe]

ref. DeHavilland Mosquito (all marks), Jonathan Falconer & Brian Rivas, Haynes Publishing, 2018, ISBN. 978 0 85733 360 5

 

[TsrJoe]

Not a 'proper source i know but a couple of interesting snippets noted on the 'Wikipedia' page on the DH. Mosquito https://en.m.wikipedia.org/wiki/De_Havilland_Mosquito

In April 1938, performance estimates were produced for a twin Rolls-Royce Merlin-powered DH.91, with the Bristol Hercules (radial engine) and Napier Sabre (H-engine) as alternatives.[11]

Do any drawings exist of the alternate engine studies ?

On 12 November, at a meeting considering fast-bomber ideas put forward by de Havilland, Blackburn, and Bristol, Air Marshal Freeman directed de Havilland to produce a fast aircraft, powered initially by Merlin engines, with options of using progressively more powerful engines, including the Rolls-Royce Griffon and the Napier Sabre. Although estimates were presented for a slightly larger Griffon-powered aircraft, armed with a four-gun tail turret, Freeman got the requirement for defensive weapons dropped [26]

Griffin engined Mosquito ?

With design of the DH.98 started, mock-ups were built, the most detailed at Salisbury Hall, where E-0234 was later constructed. Initially, the concept was for the crew to be enclosed in the fuselage behind a transparent nose (similar to the Bristol Blenheim or Heinkel He 111H), but this was quickly altered to a more solid nose with a conventional canopy.[31]

sounds different ?

I was wondering if any drawings had been published of the proposals noted (would make for interesting modelling subjects!) Cheers, Joe

 

[TsrJoe]

a tad speculative but an interesting hypothesis ...

Mosquito Genesis - Life Immitates Art?

www.dingeraviation.net