"Effects of extreme cold on artillery" Topic

I recently read the excellent book 'The Day We Almost Bombed Moscow', about the British involvement in the Russian Civil War.
One thing that intrigued me was that, during the extreme cold of winter, the French 75s wouldn't work and the British 18-lbers had to set their sights to 3750 yards, in order to fire 2000 yards.
I can understand a weapon not firing at all (presumably frozen solid) but am struggling to understand why an artillery piece's range would be effected by the cold. I realise that altitude will have a (slight) impact on range – rugby penalty kicks and cricket hits for six carry noticably further in (eg) Johannesburg than (eg) Durban – but I am at a loss to understand why cold would have such an impact. Any ideas? Is cold air that much denser? Or is it something to do with diminished explosive power of the charge?
Has anyone ever bothered to model this in a wargame? One would assume that similar effects were experienced on the Russian Front in WW2?

One source I read states that cold rounds in cold tubes could result in as much as a 20% decrease in range. Deep snow/ice will impact the burst radius at the point of impact as well.

Cold air is denser, but only by a couple of percentage points (look at an old-fashioned weather map with isobar notations and you can see the difference.) Another factor could be metal (both barrel and shell) contracting so propellant gases are escaping around the shell?

Dom Skelton

Yes – I thought cold air wouldn't be MUCH denser… certainly not enough to drop range by almost 50%.

damosan / Dom Skelton

I think your theories about the impact of the cold on the metal of the barrel might along the right lines… any metallurgists on TMP?

The French 75's probably wouldn't work because their recoil mechanism's failed – Ian Hogg described them as machined like a Swiss watch – extreme cold could make any hydraulic fluid more viscous, and if it got REALLY cold, could freeze it & burst the cylinder, without even firing the gun.

The British 18 pdr.'s recoil system was more 'robust' and could use almost anything as its hydraulic fluid, from straight water thru' glycerine mixes – basically anti-freeze.

we had several exercises in winter time, with M-30 (it was used in WWII) and D-30 howitzers. No problems with firing the guns, no problems with hydraulic systems (D-30 uses hydraulics to position the gun, too). The only real problem we saw that you need much more time to fix the "legs" of the howitzer, as three ca 50 cm "pins" need to be hammered into stone-hard frozen earth ;)
Metal, used for barrels'inside is supposed to handle both low and high T conditions, lubricants/hydraulic liquids are normally chosen for -34-37C on most of the Russian territory and -43 in colder regions. It is also true for most of the pressure vessel equipment, seal materials, controls, etc (yes,I'm a mechanical/process engineer).

Severe cold affects seals on weapons (leakage) and hydropneumatic recoil mechanisms (freezing up), so barrels and recoil systems have to be 'warmed up' through firing several practice rounds, propellants can be affected by low temperatures so that muzzle velocity is reduced, fuzes (both impact and proximity) can be less efficient, cleaning barrels becomes more difficult (have to use solvents), ice particles get into operating mechanisms, and ballistics can be affected by severe temperature changes, of anything up to 100 metres or more per 1,000 metres, HE shells bursting in 10 cm snow or deeper will suffer from 'smothering'.

Barin1 and bashibosh (what a double-act that would be)

Thanks for those excellent posts. So does the impact refered to in the book ring true to you? Or does this sound unusual?

Also, aren't most artillery shells designed to explode a few feet above the ground, to spread shrapnel over a wider area… which would mean that soft ground / snow etc wouldn't effect them? Sorry if that is a daft question – I was an infantryman, not a gunner.

BullDog69

There are mainly three types of arty rounds (actually fuzes): an airburst capability (proximity fuze I think it is called), point detonating, and a time delay fuze that allows the round to dig into soft soil etc. Therefore you can have different affects on target, depending on what you want to do to the target. For troops in the open most likely Air burst, for troops dug in you would use the delay fuze, for other targets such as vehicles, buildings etc Point detonating. In snow and really soft soil the delay and Point detonating may get smothered by the snow/soil.

No RP fuses in WWI, so the only air-burst would be set by hand (the fuse time or length) when firing at a direct fire target.

What they are describing as a snow impact factor is for contact fused HE (i.e., the round hits the ground and explodes).

Dan

Artillery shells in the early 20th Century had impact fuzes, i.e. they detonated the explosive charge on striking the ground, or mechanical proximity fuzes, i.e. they were set to detonate the explosive charge after travelling for a certain period of time, so that they exploded in the air above the ground. Shrapnel shell is the best example of the latter; HE shell of the former. For fighting in snow bound conditions, artillery would be advised to use air bursts rather than ground bursts in order to maximise their effect against targets in the open.

Yup – that makes sense and was pretty much what I thought.

And for Renaissance navies, it would get cold enough to freeze the balls off your brass monkeys.

Actually, it doesn't take much of a dimensional change to really screw up any firearm. You have to use different bullets in 7.62x54R versus .30-06 or 7.62 NATO, and that's a .005" diameter difference in the specification, less than a sheet of paper.

Cold is no different: I've seen it with a rifle during late elk season. temp was about -20F, and the first shot only went about 75 yards. You could see the contrails off the rifling. Second shot went about 150 yards, and the third shot finally took the animal (mmm, elk steaks).

Now, I'm not sure whether that was because the projectile contracted so much more than the barrel that there was leak-by, or that the barrel contracted more than the round for a near-jam. I'm guessing that it had more to do with the barrel.

Possibly dis-similar metal contraction rates?

Does anyone have the co-efficients of temperature handy for lead vs steel (for rifle bullets), or steel vs cast iron (or whatever else shelles might be made of)?

If the projectiles are contracting further in cold temperatures than the barrels are, then you will have greater windage, hence shorter range.

The cold would effect the burning rate of the propellant and that would effect range & accuracy.

jdg

Another factor may be that the sights go out of calibration.

I'm surprised to hear about the problems with the 75mm gun. The only French 75 I've ever seen still in service was being used by a National Guard unit for avalanche work. By definition, that would be rather cold, but perhaps they found a work around.
Grelber

Grebler

I am probably very wrong on this, but I seem to remember reading that avalanches often occur when temperature rises, often as winter turns to spring. It is therefore possible that the 75 you are refering to was used in relatively warm temperatures compared to those faced in Murmansk.

What I find odd is that I have never read about this in accounts of the Germans fighting in the Russian winter in WW2. No one (yet) has mentioned anecdotes about this, but one would have thought that – if it is a genuine problem – then those fighting on the Russian Front would have experienced it at its worst? Could it have been perculier to the British 18-lber for some reason?

I waws in the US Field Artillery for 21 years, most of it in fire control.

2 things will effect the range from the cold. First is air density. Not only is the resistance higher, but there is also a large amount of increased drag. This effects it more than you might think.

The second is that cold powder does not burn as well. Even a few degrees will drop muzzle velocity.

However, a 50% reduction in range sounds to severe. Yes a cold tube does not shoot right, but a couple rounds fixes that right up. Soldiers have been known from time to time to embellish things just a bit to show how hard things where on them. Perhaps this is some of that.

Or perhaps the old powders where much more effected by cold than the newer ones I have used.

And at the end here another though comes up. Powder that has laid around in storage for a long time can be very erastic. If it has not the newest then that could have dropped MV, but would have nothing to do with the cold.

C. Bellamy, in his book Absolute War, publ. 2009 Pan ppbk edition, p. 80, quotes Marshal Voronov on the Russo-Finnish War: "Artillery material was of particular concern. During the freezing weather in Finland, the semi-automatic mechanisms in the guns failed. New types of lubricants had to be developed immediately." Bellamy has a section later on (pp. 322-324) about the effects of winter warfare on the Eastern Front on the Germans, but it adds little more to the points already made above, except to state that problems began at -20 degrees Centigrade (-4 degrees Fahrenheit) and that the temperature around Moscow in 1941 fell to -28.6 degrees C (-19.3 degrees F).

"The only French 75 I've ever seen still in service was being used by a National Guard unit for avalanche work."

Are you sure this wasn't the 75mm pack howitzer? I would be amazed to learn that a French 75 was ever in service post-WW2 with the National Guard.

50% range reduction is excessive. Cold does effect ballistics but we compensate for that in MET data applied to the firing tables. The first spotting round would be off target but the gun would quickly get on target as it warmed up. There is not any wargaming effect if that is what you are looking for (unless you are doing skirmish artillery duels).

CC, the worst I ever had was about 500M short on a first shot. I suspected that the gun crew had put the prop temp gage in on inside the truck up by the cab, so it and they would be a bit warmer when I called for a temp reading. then when they hopped out to shoot, they grabbed a colder can.

Have you ever had something worse? I suspect you have done more cold shooting than me. Germany was very cold, but everything we used was SP, so never had to much trouble with cold inside the guns. In the states I had towed guns several times, but never experienced a range cut in half.

I just had a thought, could the cold have somehow effected thier ability to go up to proper elevation? It sounds odd, but something has to be odd for there to be such a big range drop.