4.2" beds

[tankbarrell]

Many years ago I picked up a smoke BE round from Salisbury Plain and having found it again recently, it turns out to be a 4.2 BEDS dated 1946.
Firstly, what does the DS stand for, does it have some sort of sabot to fit the smaller diameter bomb into the tube?
Secondly, does anybody have a tail that might be available to suit?

Thanks,

Adrian

 

[spotter]

I dont really have any info other than the following taken from "Weapons of the WW2 Tommy"

Shortened extract....
"The 4.2 inch base ejection mortar bomb was introduced into service shortly after the 3inch version in 1945.It had a narrower body than other 4.2 inch bombs and was designed to house the same standardized filling containers used with the 3 inch bombs,The added length of the bomb allowed it to hold an additional container.so for example a 3 inch bomb might hold two thermite charges but the 4.2 could hold three of them,Due to the thin but long lentgh of the bomb ,a special tail unit with spin stabilizing fins was used in place of the standard tail unit,An adapter was located mid body to serve both as a compression guide band for the bomb and to keep it centered in the barrel when fired"

 

[tankbarrell]

Spin stabilized, hadn't realised that. In theory, that will make a tail unit easier to identify, though not any easier to find!
Thanks for the extra info.

 

[AE501]

BEDS is Base Ejection Discarding Sabot. The bomb had a collar round it enabling you to use a common 3" Mortar Smoke.

 

[tankbarrell]

Not sure I understand. I can see how fitting a collar to a standard 3" might allow it to be fired from the 4.2" but the bomb I have is as shown in Spotters pic and is clearly specially made. Is it that it uses 3" smoke cannisters?

 

[AE501]

If you put a 4.2" diameter sabot and corresponding tail unit on a 3" Mortar bomb it becomes 4.2".
What you have is a later development made when the very theatre specific need for an immediate bomb for the Burma theatre of operations 1944-'45 had gone away.
The 4.2" BEDS never made it into the British 4.2" mortar publications of the time, because it was never really required in a European war.

In Burma they were trying to drag and pack mule the British 3.7" pack How and the US 75mm Pack How up and down razor ridges, avoiding and then trying to surprise the enemy. The answer was a heavy 4.2" mor, which arrived for British RA regiments after the Australians already had it (see Google).

What was required was a smoke bomb that matched the range table for the HE bomb so that you could mix and match and even move before the first bomb landed. A good crew could get 12 bombs in the air before the first landed. The problems encountered with this are covered below and how the BEDS bomb was born. I think the paper size must have been foolscap because the top of the drawing is missing, but what you need is there.

This was taken from an Indian Ordnance publication because they were the ones who inherited any remaining bombs, when we pulled out in 1947 leaving everything.
My good friend Norman provided the Indian info, when I told him the story.

They also were used in Korea where the terrain was similar, but without the afforestation.

I am still trying to get the copied text in here. It will have to follow. I may get timed out.

 

[AE501]

Here is the text as promised.

 

[TimG]

AE501,

Whilst it might not have made it into the 4.2" Mortar publication it did make it into the RAOS Pamphlet 12, Mortars and PIAT Bombs, dated 1956. Apparently there was a Drill version of the BEDS as well. Presumably we had still had stocks until then?

TimG

 

[AE501]

By the 1960 Edition only 4.2" Mortar HE and associated drill bombs remained.

I should also have pointed out that the US 4.2" Mortar was a completely different animal and there was no compatibility.

 

[tankbarrell]

Thankyou very much, that explains it all perfectly. I suspect whilst finding a fin will be very hard, locating sabot rings will be next to impossible!

 

[HAZORD]

You could have someone with a lathe make you a sabot. The fins would be hard to make.


I appreciate all the info on this round. I've probably had my copy for about 25 years. I took some photos so you can see the details.

The body is dated 45 and the sabot is dated 46. I believe the fuze is a fired 309. Not sure if it is the correct one for the round.

 

[AE501]

Hazord. Thanks
I thought never to see one of those again.
I think you may have had finger trouble. The fuze should be a 390 Mk 2 or 2A.

 

[HAZORD]

I didn't write it down when I looked at it. Checking now, it's a 390 Mk 3

What is the silver round in the middle? It has remnants of dark blue paint in spots.


Sent from my NSA/FBI tapped iPhone using Tapatalk

 

[AE501]

The Fuze 390 Mk 3 replaced the other two marks in the 4.2" BEDS. Both eventually became obsolete, but the Mk 3 was used in the 105mm L7 Tk gun.

As you know the first use for 4.2" Mor was to counter the threat of possible use of chemical ammo by Germany, in North Africa.
This double guide band design was then used for White Phosphorous Screening Smoke Mk 1 and a Mk 1 HE bomb. The HE bomb was too short range so the streamline bomb was produced.

A whole range of smoke bombs used the design. Yours with the blue markings would have been a Bomb 4.2" Coloured Smoke, but more markings would be necessary to show which one. Had the colour been red it would have been a Smoke BE Skytrail.

It looks as though the fuze in it is a 410?

 

[tankbarrell]

I can make a sabot and the tail, though having an original to copy would be better. Those pics are a great help though, any chance of some salient dimensions?

 

[HAZORD]

I thought you might want some dimensions. I'll measure and sketch it up.

By the way, the sabot rotates freely around the body.

 

[TimG]

Apparently another factor in the design process that governed it's final shape is that 'the powers that be' wanted it to utilise the same (or modified) No3 container, as used in the 25 PR BE - tried and tested. It ended up using a No.7 container which is the same diameter (2.59") but longer.

And the UK did have substantial stocks of 4.2" BEDS in the the '50s

TimG

 

[AE501]

TimG, you have access to the earlier 1956 RAOS Vol 4 Pam 12, or has it become AER Vol 3 Pam 12 by then. Is it a slightly smaller format page size, with two holes at each end rather than the equispaced holes of the AER version. If it is Vol 4 LOXONBAR system, does the binder have a bootlace system which is held in place by a flat spiral steel spring which you wind the bootlace round?
Does the pamphlet indicate a BEDS bomb, with a built up section to the same size as the discarding sabot, which would have been ballistically matched, but non discarding, but still called BEDS?

 

[TimG]

AE501,

RAOS, Volume 4, Pamphlet 12, Part 3. 10th January 1956. Three holes

The only image of the 4.2 BEDS is a diagram showing Method of Filling to DD(L)18992.

There are also diagrams of the Tail Unit No. 8 and Sabot No.1 - Steel.

"..Increased range was achieved by designing a bomb of Diameter H3.476-in, L3.471-in., the full bore diameter being made up by fitting a discarding sabot at a distance 4 1/2" in from the nose of the body..."

TimG

 

[HAZORD]

Tim, is there a chance you could post the diagram of the Sabot No.1 Steel?