Incoming!

[HareBrain]

Quick question for military know-alls (the rest of the internet has failed me once again). Under what circumstances can you hear an approaching artillery shell? The research I've done so far suggests that even final velocity would still be well above the speed of sound, and thus (I think I'm right in saying) inadible until it hits. So what were they doing shouting "Incoming!" all the time in Vietnam? Or was that only for low-velocity howitzers and mortars? (I need the info in respect of a naval gun c1900).

 

[kopiteste]

Is your info on them shouting "incoming!" all the time in Vietnam from Hollywood? Wouldn't believe everything you see in the Movies.
Did a little bit of research on, dare I say it? Wikipedia. It seems that naval guns in and around the 1900s all had Muzzle velocity of around twice the speed of sound. One had a Muzzle velocity around that of sound but was withdrawn before seeing any significant service due to them exploding.
Could you not have your character seeing the muzzle flash or something to cut out the problem?

 

[Ursa major]

Try googling React to Indirect Fire While Dismounted.

There's even a PowerPoint presentation available. (Append power to your search.)




Whether this happens outside a training environment, I'm not sure.

 

[Null_Zone]

From various family members that have served in the Royal Marines, you don't hear anything until it's happening around you. You can sea the muzzel flashes, you can see and hear the impact but the actual rounds coming in your direction you don't. Afterward your memory simply fills in the blanks and makes associations where they didn't exist.

It is possible to mistake fire at positions behind you for closer range guns firing at you.

 

[J Riff]

Good question... mortar shells have a high arc trajectory, but anything like a howitzer.. you would think wouldn't announce itself. in 1900.. the info must be sitting around somewhere, maybe on a muzzle velocity fan site.
The Whizz-BAng! http://1914-1918.invisionzone.com/forums/index.php?showtopic=133941

 

[TheEndIsNigh]

HB:

No expert but I suspect the following.

Artillery bararges are/were not accurate.

Unlike the WWI where the targets were mostly static and the 'aim' was to get your shells into the trenches (most of the time) and kill those sheltering there.

WWII brought the concept of a gradually moving barrage. The idea being to blanket an area in front through and beyond your enemies position. This could have the effect of driving the enemy out and away from their 'safe' positions or just making life unbearable in general.

Now if the barrage started beyond your position you would hear the shells whistling overhead and knowing the tactic you could reasonably expect the wave of explosives to be coming back towards you some time soon.

I understand this was used to great effect in the North African campaign where the Allies advanced under a constantly rolling barrage that was laid down from behind. At times they were in more danger from advancing too fast into the tail end of their own artillery than from the German defences.

J. Riff makes a good point with the mention of mortars. These are sometime used at relatively close quaters. Where you might hear the sound from the shell as it went up. You may even hear the thud from the launcher as can be heard at firework displays. The thud would be a good hint that something would be arriving soon due to the reasonable expectation the enemy wouldn't be firing at themselves.

With naval barrages the tactic was to soften up the defenders and if possible drive them away from the beach head. These bombardments could last for days which not only denied the defenders sleep, but also tore up the barbed wire and obstacles that were be present to prevent men and vehicles getting of the beach. Oh yes it might also kill quite a few too.

With airborne bombardment where they bombs are dropped in a continuous line the sound from the first bombs would be 'in the wind' before the last bomb dropped so again you should hear the whistle/whine since they are only falling at relatively slow speeds; naturally you would know they were coming your way from the increase in volume.

 

[HareBrain]

Thanks very much, everyone. I had found the info that naval guns had a muzzle velocity of about mach2, but I couldn't find out how much velocity was lost during flight. Seems probably not enough. I'll either have to have the shell go overhead or not be heard before it hits.

 

[Vertigo]

During my (short) time in the army the saying used to be that you don't hear the one that kills you. If it's coming straight at you then it beats the speed of sound and you don't hear it. If it's off to one side then you may hear the expanding sound wavefront before you hear the explosion (whistle...bang) depending on how far to one side it is.

The same holds true for rifles, incidentally. We were taught "crack... thump"; you hear a sharp incredibly piercing crack first, which is the sonic "boom" of the bullet passing you by (hopefully; otherwise you don't hear at all!) this is then follwed by the thump sound which is actually the gun firing and this is what you had to try and determine the direction of to spot the shooter. It was very easy to get familiar with this by working in the butts (the sharp end of the outdoors firing range where you hide behind big banks and manage the targets). Here you will hear the sharp crack of the bullet passing overhead follwed by the sound of the gun firing. And believe me the sonic "boom" is far more unpleasant and damaging to your ears than the actual gun firing.

 

[Boneman]

But... if the attacking warship is a long way away, its trajectory will be to fire the shell upwards, and as long as the distance travelled by going up, reaching an apogee and then descending, is far enough, then you'd hear the sound (travelling flat over the sea) first. Maybe. Muzzle flashes, if recognised by a veteran, would probably be best.

 

[Pyan]

Eyewitness report from the Queen Mary, lost at the Battle of Jutland, 1916:

Petty Officer Ernest Francis was a gunner's mate aboard the battle cruiser Queen Mary. His ship was one of the causalities of the conflict. It was blown out of the water with the loss of almost its entire crew of 1,000. We join his story as he and his gun crew sits in the turret of one of his ship's big guns and prepares for battle:

"The guns were loaded and brought to the half **** and reported, and then came the order to bring the right gun to the ready...Shortly after this, the first salvo was fired, and we started on the great game.

Up till now I had not noticed any noise, such as being struck by a shell, but afterwards there was a heavy blow, struck, I should imagine, in the after 4 inch battery, and a lot of dust and pieces flying around on the top of 'X' turret.

(my emphasis - and apparently the forum software won't allow technical terms for gunnery, as it thinks I'm being rude...)


The Battle of Jutland, 1916