40 mm Bofors AA guns made in GB and US

[Godwin Hampton]

Brian,
Dome Trainers were definitely used by the British Army for gunnery training, with a Bofors in the centre under the hemispherical dome, and a projector sending moving images of planes to be aimed at.

I have a User Handbook for Apparatus, Dome Training, No.6 and "Portobel", dated 1962. The introduction says "This apparatus is an anti-aircraft gunnery trainer developed on principles similar to the Apparatus Dome Training No.4. Used in conjunction with a service dome, it provides a substitute for field training with aircraft co-operation when training anti-aircraft gunners on L.A.A. weapons. It provides also realistic gunnery practice under conditions closely resembling those experienced in actual warfare."

Half a dome survives still in situ at the Malta War Museum, which is housed in a building that was originally built as a Territorial Army Drill Hall. No doubt the dome would have been very useful for evening training sessions, or when the weather did not allow outdoor training. The dome is made out of plywood stuck on to a wood framework, probably produced locally to a W.D. design. It is about 20 feet in diameter, and supported about seven feet off the ground. I have an impression that it would be painted in silver (or aluminium ) paint, probably to produce a more vivid image from the projector.

I do not know when they started to be used, but I would suspect that World War 2 was the ideal time as they were badly needed to train hundreds of gunners in as short a time as possible!

The 1962 "Portabel" was a portable structure made out of proofed fabric that could be inflated to form the dome. Entrace was through an airlock with two sealed doors at each end of a short entry tunnel. A blower kept the whole thing inflated, and made up for any leaks.

The projector provided images of different planes flying under varying conditions, as well as realistic sound. The apparatus also created gun noise and images of clouds, to add realism.

[Ewan WT]

I have just joined the Forum to research the Dome Trainer. This was the first anti-aircraft simulation technology invented by my grandfather, Lt-Commander Henry Stephens, for the Royal Navy in 1940. This is the Pathe News in 1951.

https://www.britishpathe.com/video/dome-trainer

Henry's private journal has been deposited in the Imperial War Museum and the BBC made a documentary in 2025, narrated by the British actor Stephen Fry. YouTube has parts of the documentary.

There was a huge demand for this technology with 43 domes being built across the UK including one at Langham which survives today. This puzzling dome structure was a forerunner of today's immersive experiences including Imax screens, aircraft pilot simulation and computer games. This revolutionary invention saved thousands of lives and shortened the Second World War.

https://www.iwm.org.uk/collections/i...ect/1030031411

https://www.bbc.co.uk/programmes/p02rcd2x

https://www.bbc.co.uk/programmes/p02rc8dl

I would be pleased to have any more information on the Dome Trainer and the gunnery used inside it. At Scapa Flow there is a further installation of what looks like a rear gunner turret developed for air-to-air gunnery. This is not in any of the official records that I can find!

Best wishes,

Ewan Ward-Thomas
Grandson of Henry Stephens, RN

[Pete M]

This is a hugely informative thread and has been very useful to me in identifying a 1937/39 Instructional model of the 40mm Bofors that I am trying to restore. I think the model, like most instructional models used by the British Armed forces, was made by Bassett-Lowke, it is made of brass and is about 1/8th scale. From the information I've gleaned from Terry Gander's book and the wonderful information in this thread I think I've identified the model as a Mk I Bofors on a Mk I carriage, possibly Mk IA (Polish Carriage). The model also has the "Bofors/Polish Course and Speed Corrector" although parts of it are damaged/missing.

I was heartbroken half-way through the thread to discover that Stellan had died, especially so as he was a real driving force in learning new information about the Bofors and also the prime mover in keeping this thread alive. In one post he indicated that he was preparing a book on the Bofors, does anyone know how far he got with that and if anyone has taken it on after his death?

In one of his earlier posts Stellan showed a photograph of some girls with 40mm Barrels and wanted to know which factory this was? I think there's a high degree of probability that it is the 'Hush-Hush' factory that was in Tubney woods just outside Abingdon. The manufacture of the barrels was re-located here after the Coventry factory was bombed. Article on the subject here:

https://www.heraldseries.co.uk/news/...elped-win-war/

On the subject of the wheel nuts, Terry Gander's book, page 49, indicates that the Mk IA (Polish) Carriage's are identifiable from five bolts on the wheel hubs. However, earlier in this thread Stellan indicated that it was the Swedish made carriages that used five wheel nuts and the Polish carriages that used six? Does anyone know for sure? Certainly on page 21 of the Gander book there appears a 1938 photo, taken in A B Bofors workshop, which shows a 1936 model Bofors, ultimately destined for Dutch East Indies, which has five bolts on the wheel hub. This would seem to indicate that Stellan has it correct and that Gander inadvertently transposed the numbers, or did the 1936 model simply involve a re-design to the Polish style?

There doesn't appear to be an option to upload images to this site so I'll have to look into getting some images up on a web hosting site so you can see the model.

[Pete M]

Another quick question regarding the mounting places on the Mk I carriage for the Ground Spikes. On the photos I've seen so far there are two ground spikes mounted, side by side, on the side of the cruciform just to the right of the Travelling Lock for the Gun. I presume there is at least one other, or possibly two ground spikes, mounted on each of out-rigger arms as well?


You can see more clearly what I am talking in photographs of this Dunkirk survivor at IWM. If you look at the second photo, just behind the left-side wheel you can see two Ground Spikes mounted on the side of the carriage, one pointing left and the other pointing right. There's a third ground spike visible on the out-rigger arm.

https://www.iwm.org.uk/collections/item/object/30025446

On the model I have there are a total of three ground spikes mounted on the carriage. One of each out-rigger arm and a third on the side of the main beam of the cruciform, just to the right of the travelling lock, where the photos normally show two ground spikes. Does anyone know if there is a particular Mk, or national make, that has only one ground spike mounted on the side like that?

[Grant Bowker]

You should be able to upload pictures(select "manage attachments" in the additional options area below the text composition area). The most common problems seem to come from oversize images (both pixel count and file size can be trouble). See http://www.mapleleafup.net/forums/showthread.php?t=19 for some more guidance. If all else fails, another member may offer to wrangle the photos to fit.

[Pete M]

Thanks for that Grant, I missed that option and was simply trying to use the Icon at the top of the edit box. Will now go back to my original post and add a few pics.

[Pete M]

Just been watching this interesting video from a Living History group in Malta, some nice original footage on display here.

https://www.facebook.com/watch/?v=191892833148902

[Tony Smith]

Originally Posted by Pete M

.... some nice original footage on display here.

First time I've ever seen Single Round loading!