Balistic: rifle vs armoured car

[bonzillou]

excellent pictures

Edited 21 March , 2020 by bonzillou

[david murdoch]

Another interesting point for the armoured cars  - mentioning the vulnerability of the tyres. As early as spring 1916 they mention the use of NAP (natural air pressure) tyres - in theory puncture and bullet proof. These seem to have not been available in great quantities as they are seldom seen in use and most middle east photos show cars carrying various spare tyres of different patterns and  sometimes several complete and wheels.

bonzillou.

My grandfather was an NCO with 8th L.A.B in France and then 8th L.A.M.B  (8th and 9th L.A.Bs combined) He went with them to Mesopotamia directly from France  - they moved the cars by rail from the north down to Marseilles at the end of 1917.

 

Edited 21 March , 2020 by david murdoch

[david murdoch]

Another interesting photo showing armour  - this is actually a Lanchester, but had same admiralty pattern turret. This one looks like it's been hit by a shell or shell fragments.   

[bonzillou]

and I like the "two tyres with chains" on last picture.

[JMB1943]

On 20/03/2020 at 13:08, david murdoch said:

William Beardmore and Co. in Glasgow were one of the main suppliers of armour plate due to them already being set up as a major supplier of armour plate for Clyde built warships. From 1895 they had a 12,000 ton press to make American Harveyized armour plate and a lot of experience in the development of case hardened plate. Also due to the original Rolls Royce armoured cars  being produced for the RNAS. Admiralty pattern turrets for the armoured cars were produced there. 

 

Pascal,

 

Mention of the Wm. Beardmore Co. reminded me that they had been a supplier of the Hadfield steel (Manganese 12% w/w in steel) that was used for the manufacture of GW steel helmets for the British Army.

The acceptance standard for a helmet was that it should resist penetration by a pistol bullet at 600 feet/sec.

This was presumably a conical roundnose bullet (Lead; weight = 265 grains; muzzle velocity = 600 ft/sec) fired from a Webley revolver.

A photo of a severely indented helmet shows that the Webley bullet has not quite penetrated. See Helmets & Body Armour in Modern Warfare, by Bashford Dean, p. 129, Fig. 86; available on-line. Note that the caption to Fig. 86 says  "indentation caused by glancing machine gun bullet". However, in my opinion, the appearance of the indentation appears more consistent with a direct impact.

Below is a theoretical comparison of the kinetic energy (KE = mv²/2) deposited on target for the .455 inch Webley roundnose vs .303 inch SMLE pointed bullet.

 

                                                       .455 Webley                     vs    .303 SMLE

                              mass (grains)          265                                      174

                   muzzle velocity (fps)          600                                     2440 (assumed falls to 2400 fps at 30 yds)

                Test thickness (helmet          0.036" (0.91 mm)                7/16" (11 mm) hard steel plate

 

                                              mv²          265 x 600 x 600                  174 x 2400 x 2400       

                Result: severe indentation (almost penetration?)       penetration

                                Ratio of KE rifle to pistol = 174 x 5,760,000 / 265 x 360,000 = 10.5 :1

                                Ratio of metal thickness = 11 / 0.91 = 12 : 1

 

This result convinces me that the data that I had previously supplied from the War Office publication regarding the SMLE is correct.

You may want to have your French doubters look at this, and supply a counter-argument, or correct any mistake in my reasoning.

 

Regards,

JMB

 

[david murdoch]

Looking up armoured plate ballistic trials, there are various photos online regarding warship armour. These were carried out on sample plates as quality control and proof tests for the customer, so stands to reason the same type of trials would be carried out on thinner plates to prove they met the specification required. Back then as now armour plate production processes were classified. I found this in an article regarding thinner plate and small arms. The plate being much thinner than that used on armoured cars, but gives some figures relating to a standard .303 round. It's reasonable to presume the armoured car plate would be proof tested with standard rounds at various ranges for acceptance by the Admiralty. Obviously it was found fit for purpose (at the time) and the later models of cars did not uprate the armour - though this was probably a trade off against weight that the chassis could stand. Also it's one of the reasons pretty well all the armoured cars were moved out of France  - due to the road conditions and lack of mobility they became very vulnerable and the Germans moved quickly to mass produce armour piercing small calibre rounds. So the adding of Uralite cladding (basically asbestos fibre) is an interesting early development in composite armour on vehicles. As I mentioned those cars that later went to Mesopotamia had it removed by 1918 either as weight reduction or it was deemed unnecessary for the conditions seen there. There are photos of some armoured cars (one particular L.A.M.B ) where the turret and cab are coated with asbestos cement  - this has been noted as being for insulation rather than armouring. 

 

 

[bonzillou]

22 hours ago, JMB1943 said:

 

This result convinces me that the data that I had previously supplied from the War Office publication regarding the SMLE is correct.

You may want to have your French doubters look at this, and supply a counter-argument, or correct any mistake in my reasoning.

 

Regards,

JMB

 

Of course your data is accurate and thanks for all these informations.

The doubters will keep doubting!

[bonzillou]

this has been noted as being for insulation rather than armouring. 

 

that is interesting too

Edited 23 March , 2020 by bonzillou

[david murdoch]

"Mention of the Wm. Beardmore Co. reminded me that they had been a supplier of the Hadfield steel (Manganese 12% w/w in steel) that was used for the manufacture of GW steel helmets for the British Army.

The acceptance standard for a helmet was that it should resist penetration by a pistol bullet at 600 feet/sec.

This was presumably a conical roundnose bullet (Lead; weight = 265 grains; muzzle velocity = 600 ft/sec) fired from a Webley revolver.

A photo of a severely indented helmet shows that the Webley bullet has not quite penetrated. See Helmets & Body Armour in Modern Warfare, by Bashford Dean, p. 129, Fig. 86; available on-line. Note that the caption to Fig. 86 says  "indentation caused by glancing machine gun bullet". However, in my opinion, the appearance of the indentation appears more consistent with a direct impact."

Here is a picture of proof tests on Hadfield steel Brodie helmets against shrapnel balls.

[JMB1943]

David,

 

Thanks for all of the info that you have posted, also the wonderful photos of various armoured cars.

There are a couple of questions for you,

1) do LAB & LAMB relate to Light Armoured (Motor) Brigade ??

2) In my post #30, I grossly over-estimated velocity as 2400 fps at 30 yds--clearly too high from your data in #31; do you have ballistics tables for the 303 that would give me the true value?

Regards,

JMB

Edit: 2)  I have calculated from your info above, that V = 2009 fps at 30 yds.

Edited 23 March , 2020 by JMB1943
Add info

[david murdoch]

6 hours ago, JMB1943 said:

David,

 

Thanks for all of the info that you have posted, also the wonderful photos of various armoured cars.

There are a couple of questions for you,

1) do LAB & LAMB relate to Light Armoured (Motor) Brigade ??

2) In my post #30, I grossly over-estimated velocity as 2400 fps at 30 yds--clearly too high from your data in #31; do you have ballistics tables for the 303 that would give me the true value?

Regards,

JMB

Edit: 2)  I have calculated from your info above, that V = 2009 fps at 30 yds.

I'm sure the actual proof tests for armoured car plate probably survived among a lot of Beardmore's archives - possibly in the Mitchell Library in Glasgow. 

Edit - sure to be here. https://archiveshub.jisc.ac.uk/search/archives/88294517-f1f7-330b-b044-74ba6273b5eb

From looking up Lee Enfield data  2400 fps is the most commonly noted muzzle velocity - the tests (against the thinner plate) state  2050fps at 10 yards. The armour thickness was originally intended to counter German S bullets  - basically from any range up to point blank.

Regarding armoured car units L.A.B = Light Armoured Battery - when the army took over the Royal Naval Air Service cars they formed these 4 car L.A.B units, but looks like they quickly found they were too small to be very effective. Going by the War Diaries they were lucky to have two or three operational at any given time. So 8 car L.A.M.B - Light Armoured Motor Battery were formed each with it's own mobile workshop unit attached. As previously mentioned 8th and 9th L.A.Bs were combined to form 8th L.A.M.B and sent to Mesopotamia directly from France. Some  of the others left the UK for the Middle East as 8 car units. The L.A.M.B Brigade was formed in Mesopotamia in 1918. This was a central command for armoured car operations for 8th,13th & 14th (and later 6th & 15th L.A.M.Bs). It can be seen in the diary how all the units operated in sections (2 cars) and operated together - likely dependent on which vehicles were servicable at any given time. Almost never see a whole unit of 8 cars on one operation.

8th and 9th L.A.Bs were also unique in that they had towed Hotchkiss 3 pdr guns. There is also  plenty mention of these in the war diaries in France but they were not taken to Mesopotamia.

Edited 24 March , 2020 by david murdoch
Adding information.

[Open Bolt]

Very good David. Would you recommend a book on the armoured cars of the Great War? I see there is one by Bryan Perrett. Perhaps you are putting one together.

[stripeyman]

13 minutes ago, Open Bolt said:

Very good David. Would you recommend a book on the armoured cars of the Great War? I see there is one by Bryan Perrett. Perhaps you are putting one together.

Obtain a copy of 'War Cars' by David Fletcher, he of the Tank Museum, it is excellent.

[Open Bolt]

16 minutes ago, stripeyman said:

'War Cars' by David Fletcher

Thank you, yes the name is familiar.

[david murdoch]

War Cars covers various developments in early armoured card and also includes lists of the Motor Machine Gun Batteries and armoured car units compiled by the late Charles Messenger. 

David Fletcher also has a book specific to the Rolls Royce. Both of them helped me greatly when I was just getting started in my research.

 

https://www.amazon.com/Rolls-Royce-Armoured-Car-New-Vanguard/dp/1849085803

 

https://www.amazon.com.br/Rolls-Royce-Armoured-Car-1915-44-models/dp/1785210580

[Open Bolt]

Excellent - my thanks.

[bonzillou]

thanks David for the pics and the data

[pjwmacro]

I'd agree with David's recommendation of David Fletcher's War Cars book. It's excellent and available on Amazon for reasonable prices. I haven't read the Rolls Royce book. Bryan Perret's book is interesting, (I am reading it at the moment!) but very focused on the units which were in Russia and Dunster force ops. It doesn't have much about the cars themselves, or more general info about the MMGS and MGC(M) or the less well known batteries.

 

Also second the thanks to David for sharing both his expertise and some fascinating pictures.