Survivability of steam locomotives under air attack

[Avimimus]

I was wondering how survivable steam locomotives were (particularly their boilers) during WWII? Especially when attacked by heavy machine guns and autocannons (e.g. M2 Browning & HS-404)

When locomotives fell under attack were they generally defeated by damage to the fittings? By gradual loss of pressure? Or by catastrophic boiler failure?

Does anyone know of any studies?

I figured you guys might know.

 

[Boxman]

Your question reminds me of a portion of a film (see below) that was on Military History Channel some years ago, where the strafing of trains was discussed. I do remember being struck by author Doug Keeney's claim (at the 3 minute 20 second mark) that locomotive engineers would - if possible - release the pressure from the boiler while under attack, so as to prevent it from failing catastrophically and exploding. I'd seen plenty of gun camera footage of steam locomotives emitting enormous plumes of steam while under attack, but never gave much thought to the cause - other than presuming it was the result of strafing damage.

There is some discussion under the video at YouTube as to the validity of Keeney's claim, but, if accurate, talk about keeping your mind while under unfathomable stress! To be able to maintain a mental state that allows one to think and act to rapidly release steam pressure while under a strafing attack has to be up there.

 

[Rickshaw]

In the UK, the drivers of the locomotives of armoured trains were taught to release clouds of steam as a pseudo-smokescreen when attacked.

 

[dan_inbox]

What were the missions of armored trains in the UK in WW2?
In colonies their use is known, but in UK itself?

 

[lastdingo]

There is some discussion under the video at YouTube as to the validity of Keeney's claim, but if accurate, talk about keeping your mind while under unfathomable stress! To be able to maintain a mental state that allows one to think and act to rapidly release steam pressure while under a strafing attack has to be up there.

This can be drilled, same as with the modern frontal collision drill (activate emergency brake -> leave cabin) and Japanese railway earthquake drills.

 

[Rickshaw]

What were the missions of armored trains in the UK in WW2?
In colonies their use is known, but in UK itself?

In the UK they were used for the same thing - defence. Their ability to move an armoured force rapidly to endangered points was well known. It worked in the Colonies, it worked in the UK. Remember, for the first half of the 20th century, the UK was threatened (or rather felt threatened) in two world wars. Trains were invaluable to the defence plans in WWI and WWII.

 

[Avimimus]

I do remember being struck by author Doug Keeney's claim (at the 3 minute 20 second mark) that locomotive engineers would - if possible - release the pressure from the boiler while under attack, so as to prevent it from failing catastrophically and exploding.

Very interesting. I'd wondered about that - It goes to show that it isn't just the thickness of the metal but also the pressure difference that matters!

By the way - I seem to remember reading accounts of American pilots strafing trains from behind in hopes of hitting the locomotive crew.

 

[Mark S.]

From an engineering perspective if you put holes in a boiler depending where they're located you can get two outcomes:

1. The steam escapes and the boiler looses pressure. A graceful degradation without an explosion.
2. The hits reduce or cut off the water supply. This causes more of the heat from the fire to heat and increase the pressure of the steam. With the lost of a large amount of water this should cause a steam explosion if the pressure increases sufficiently.

Don't think you can predict what you'll get because of the randomness of the hits from the projectiles and not knowing the design of the boiler.

 

[Hobbes]

Depending on the design there is a third outcome:
3. the ragged hole in the boiler vessel redistributes stresses in such a way that the material strength is exceeded somewhere and an explosion follows.

 

[Sferrin]

Depending on the design there is a third outcome:
3. the ragged hole in the boiler vessel redistributes stresses in such a way that the material strength is exceeded somewhere and an explosion follows.

Like sticking a pin in a balloon. (Though I'd think they'd have enough margin in the design to avoid that happening.)

 

[Archibald]

From memory of a very old Fana de l'aviation monography on the P-51 (1992), it looks as if the 12.7 mm machine guns of the RAF Mustangs were pretty devastating. The boiler exploded pretty violently, destroying both locomotive and track and stopping traffic, if only for a very short time.

It says a lot about pilots training that they were able to straff and destroy a moving locomotive in a very fast moving aircraft - let's say the locomotive moved at 50 miles an hour, they straffed it perpendicular to the track in an aircraft moving at 200 miles an hour (or more) at tree top level.
I can tell you I wasted a lot of hours in Microsoft Flight Simulator trying to straff and destro the freakkin' locomotives.

 

[CJGibson]

Here's a masterclass in train strafing by Roly Beamont.

It's from Typhoon and Tempest at War by Arthur Reed and Roly Beamont.


Basically find the ends and shoot up what lay between.

Chris

 

[cluttonfred]

Great stuff, thanks for sharing, Chris. I wonder if some of these techniques were actually developed early on in the "rhubarbs" across the channel with Westland Whirlwinds in 1941-43?

Here's a masterclass in train strafing by Roly Beamont.

It's from Typhoon and Tempest at War by Arthur Reed and Roly Beamont.


Basically find the ends and shoot up what lay between.

Chris

 

[Mark S.]

Depending on the design there is a third outcome:
3. the ragged hole in the boiler vessel redistributes stresses in such a way that the material strength is exceeded somewhere and an explosion follows.

A ragged hole may weaken the material but not lead directly to an explosion. A ragged hole sounds like a ductile failure in which the metal fails by tearing. You need to develop steam pressure to have an explosion. A tearing failure will more than likely just release the steam without exploding but then again it matters where the failure is.

 

[dan_inbox]

In the UK they were used for the same thing - defence. Their ability to move an armoured force rapidly to endangered points was well known. It worked in the Colonies, it worked in the UK.

As a means of transportation to bring troops and armor to endangered points, a normal train does the job, no need for "armored train".
In the colonies, armored trains could actually be used as assault vehicles, if only to re-open a railroad line (see Egypt 1882 use attached).
In WW2, I would not expect that the UK would have tried to repel nazi panzers+stukas with an armored train, or would they? Does not sound very promising...

 

[Hood]

Armoured trains were very much in use in Britain during the early part of the war. They were part of the invasion defences and for patrols along coastal areas.

Four battalions of Polish troops were used to man twelve trains from October 1940 until 1942 when the Home Guard took over responsibility for operating them. By July 1943 all the armoured trains in England had been withdrawn, but they lasted in Scotland until November 1944.

And to prove that we Brits are crazy, there was even an armoured train on the Romney, Hythe and Dymchurch miniature railway in Kent armed with a Boys anti-tank rifle and a Lewis gun!

https://www.youtube.com/watch?v=x0sn0HbpKvg
https://en.wikipedia.org/wiki/Polish_armoured_train_units_in_Britain

 

[Rickshaw]

In the UK they were used for the same thing - defence. Their ability to move an armoured force rapidly to endangered points was well known. It worked in the Colonies, it worked in the UK.

As a means of transportation to bring troops and armor to endangered points, a normal train does the job, no need for "armored train".
In the colonies, armored trains could actually be used as assault vehicles, if only to re-open a railroad line (see Egypt 1882 use attached).
In WW2, I would not expect that the UK would have tried to repel nazi panzers+stukas with an armored train, or would they? Does not sound very promising...

In 1940, the UK seriously lacked AFVs. Trains were easily armoured. They could carry guns and men. The UK had an extensive railway system, which provided access to most parts of the country. It wasn't the best solution but it was a solution. Some of the trains were better armoured than others. It all depended on what materials were available and as the war progressed, their efforts improved.

Armoured trains were also used in Canada, the USA, Germany and Russia extensively.

 

[Rickshaw]

Armoured trains were very much in use in Britain during the early part of the war. They were part of the invasion defences and for patrols along coastal areas.

Four battalions of Polish troops were used to man twelve trains from October 1940 until 1942 when the Home Guard took over responsibility for operating them. By July 1943 all the armoured trains in England had been withdrawn, but they lasted in Scotland until November 1944.

And to prove that we Brits are crazy, there was even an armoured train on the Romney, Hythe and Dymchurch miniature railway in Kent armed with a Boys anti-tank rifle and a Lewis gun!

It actually had more than that. It all depends on which period we are discussing. It had by the time it was decommissioned, several Lewis and Bren guns, multiple rifles. It served an important function as well - providing rapid access to a part of the coast that was otherwise inaccessible to trucks/AFVs.

 

[CJGibson]

Armoured trains were considered for the SS-24 and Peacekeeper (MX) ballistic missiles.

Trains still seem to be fair game for strike aircraft. I was on the train to Peterborough a few years back when a pair of Jaguars 'strafed' us.

R. Birkin QC

 

[Sferrin]

Armoured trains were considered for the SS-24 and Peacekeeper (MX) ballistic missiles.

Trains still seem to be fair game for strike aircraft. I was on the train to Peterborough a few years back when a pair of Jaguars 'strafed' us.

R. Birkin QC

They were more than just considered for SS-24.

 

[Avimimus]

Thanks to CJGibson I was recently given a chance to read a report (ORS/2 TAF31 dated July 1945, currently stored in the UK National Archives).

The subject is the effectiveness of rocket projectiles against trains. I thought I'd provide a summary:

- German reports only kept track of strafing vs. bombing. Bombing appears to have mainly damaged locomotives when they were at rail yards (with attacks on moving trains being less likely).

- Strafing appears to have a major psychological impact due to the likelihood of killing passengers and engine crews.

- Visits to 15 locomotive depots and repair facilities (containing more than 585 locomotives) found only four locomotives which appeared to possibly have rocket damage. Staff at three of the sheds reported having encountered a total of 19-25 locomotives damaged in rocket attacks.

- During the previous three months attacks on trains were frequent (for instance 80 out of 120 locomotives at Oanabruck depot had strafing damage over the previous three months). This included 500 rocket attacks with claims by pilots of 176 destroyed and 185 damaged locomotives.

- The authors suggest that rockets may often have missed the locomotive, or impacts may have produced enough debris and steam as to make it look like catastrophic damage was done to the locomotive. However, they agree with the belief of German maintenance crews that even rocket hits were unlikely to permanently destroy a locomotive.

- Only about 2/3rds of senior staff at the repair sheds were aware that rocket projectiles were in use, with only 1/10th reporting having heard of locomotives which were damaged in rocket attacks. They estimated that repairs typically take about one month (twice as long as damage from a strafing attack).

- The reports authors believe that there was no organised policy of concealing the effects of rocket damage, and believed that under-reporting by captured staff would be more likely to originate from mistaking rocket damage for bomb damage (especially given that employment of rockets is often done in a diving attack and moving locomotives are too noisy to hear the sound of the rocket motors).

- The report does not consider the possibility of survivorship bias (i.e. the possibility that rocket attacks were devestating enough that locomotives baldy hit were hauled off for scrap). I'd also wonder if some of the four locomotives they found might have been damaged by dud rockets (given that the RP-3/60lb rocket had an approximately 25% dud rate in service). However this latter explanation would require the dud to penetrate 20mm of curved steel plate.

 

[Jemiba]

.... However this latter explanation would require the dud to penetrate 20mm of curved steel plate.

AFAIK, the same rocket motor was used for the projectiles, that were used to simply pierce the hull of
German Uboats with a solid head ("Rocket Spear"). From what I found, the outer hull of a Type VII C boat
was made of steel plates 22 mm thick. Probably those special projectiles went through the inner hull
then, too, but penetrating a 20 mm steel plate seems quite plausible for a dud to me.

 

[Avimimus]

...which strongly raises the possibility of survivorship bias (i.e. any engines hit by non-duds were so completely destroyed that it appeared as if they were directly hit by bombs).

So, the report can't be viewed as conclusive without more research/analysis. Thanks for the additional data!