25-pdr in Korea

[motto]

What occurs to me about the practicality of that very high angle shot is the attitude of the projectile when it returned to earth. The gyroscopic effect due to spin does not reduce anywhere as rapidly as forward velocity and would, I believe, result in the projectile coming down base first. Presumably HE would be needed to have any effect on a target and the question arrises as to whether it would even detonate if impacting base first.
A mortar has tail fins and lack of spin to ensure arriving nose first.
IMHO firing a 25 pdr in the attitude depicted is no more than a stunt and of no practical use.
There used to be a fellow that was involved in ballistic testing and development of artillery during WW2 that wrote a column for a shooters magazine here in Oz. As part of the testing vertical firing for projectile recovery was carried out. The projectiles were arriving base first and so my doubts about results in this case.

David

[Barry Churcher]

Gilles, do you still need a drag rope?
Barry

[CWO (ret) Gilles Aubé]

Yes i need one é
Gilles

[Dan Martel]

Originally Posted by motto

What occurs to me about the practicality of that very high angle shot is the attitude of the projectile when it returned to earth. The gyroscopic effect due to spin does not reduce anywhere as rapidly as forward velocity and would, I believe, result in the projectile coming down base first. Presumably HE would be needed to have any effect on a target and the question arises as to whether it would even detonate if impacting base first.

David,

Very interesting post. Now, for those of us without a Doctorate in Physics, could you please go over the above again? But slowly and in a mono-syllabic style?

I've always believed that a shell fired at a high-angle would travel in a parabola coming down nose first. That is, the shell's orientation (or attitude, as you say) during its entire flight would remain constant from muzzle to detonation. Are you saying instead that a shell fired at high-angle will go up, stop, and (due to the gyroscopic effect caused by the spinning) come down without achieving a parabolic arc?

I realize that the 25-pdr is a gun and not a howitzer, but aren't howitzers designed to fire at the same high-angle that is shown in the photograph? Are howitzer shells designed differently from gun shells?

Originally Posted by motto

A mortar has tail fins and lack of spin to ensure arriving nose first.

I had no idea this was so. And I've fired mortars. I thought that mortar shells spun. Thanks.

Cheers,
Dan.

[Mike Cecil]

... but it is not being fired vertically. The image shows the barrel at an angle of something like 20 degrees from the vertical. As a result, I think the projectile would travel in a high-angled parabola, and land nose first, and this would appear to be supported by Aust WW2 experience in New Guinea.

The problem of firing in the Upper Register, which the 25pdr with Mk2 carriage was not designed to do (unlike the Mk.3 carriage, which was hinged to allow UR fire) was faced by Australian gunners seeking sufficient elevation to get crest clearance, but still be able to 'drop' on a target the other side of the ridge. Answer: dig a deeper hole and drop the trail into it, just like the image. By variations to the charge weight (both standard charge bags and using different combinations of increment bags), the system reportedly worked quite well. If the projectiles had been landing base first, I wonder if the DA fuse on the HE projectile would activate consistently, if at all.

Incidentally, the Gun QF 25pdr is actually a 'Gun-Howitzer', as it has some of the attributes of both. It was designed to replace both the 18-pdr gun and the 4.5 inch Howitzer in British service.

Fantastic images, by the way!

Mike C

[motto]

The premise for my statement is simple.If fired in a vacuum a projectile will only have two forces acting on it, gyroscopic and gravity. It will fall to earth with its axis still pointing in exactly the same direction it left the barrel. The only force that makes a projectile change its axial orientation to align with the direction of travel is aerodynamic.
In the case of vertical firing this aerodynamic force doesn't come in to play as it is square on the nose. Comes the point the projectile stops climbing but is still spinning at hundreds possibly thousands of RPM.
Falling backwards, it depends on factors such as shape, centre of gravity and RPM remaining as to what happens. If gyroscopic effect is preponderant, the projectile will fall base first. If aerodynamics are stronger, the projectile may turn over or tumble. This could happen at any point during its descent.
I would be very dubious of the outcome at this angle and at what point away from the vertical aerodynamics have the preponderance to ensure arrival nose first is any body's guess.
In regards to mortars, the type I am familiar with are smooth bore and the bombs have straight fins. There is nothing to impart spin. I have vague recollections of mortars with rifling but, if the bombs for these have fins, the spin may be for the prevention of wobble and the fins to keep the bomb pointed in the direction of travel.
I know nothing of howitzer shell construction but maybe they are fused in such a way that attitude on impact doesn't matter or maybe it explains why a significant number were reported to have failed to detonate.
If any body disagrees with any of the foregoing, please speak up as I welcome discussion and am here to learn.
David.

[Dan Martel]

Mike C, good to hear from you again.

As it happens I'm reading The D-Day Dodgers by Daniel Dancocks and came upon the following reference. Just to set the quote into context, it is December, 1944, and I Canadian Corps is conducting its last offensive before the onset of winter weather in the Po Valley of northern Italy. After a disastorous first battle under his command, the new Corps Commander (Charles Foulkes) is planning a set piece battle to force a crossing of the Lamone River.

The first attempt had lasted less than 12 hours before the Canadians were forced to withdraw, losing the better parts of the Royal Canadian Regiment and the Hastings and Prince Edward Regiment in the process. Both battalion commanders, along with the commander of the 1st Brigade, were sacked.

After a new attempt to force a crossing of the Lamone, the Corps will have to cross four canals before reaching its objective, the Senio River. Both of the rivers and all four of the canals had steep banks, high dykes, and were in full flow due to the autumn rains. Plus, of course, the Germans.

At the same time, the First Division was making amends for its earlier setback on the Lamone. In sharp contrast to the silent attack employed by the Fifth Division, the First employed a massive and imaginative thirty-minute bombardment, which ceased for twenty minutes, then resumed in the hope of catching the defenders in the open. This program was orchestrated by the division's chief gunner, Bill Ziegler, who had introduced another innovation. With the enemy taking refuge behind the floodbanks of the rivers and canals, there was a need for more plunging fire, like that of mortars. Since 25-pounders could fire at no more that a 45-degree angle, Ziegler had the trails of the guns dug into the ground, which increased the angle of fire. There were no range tables for this type of shooting, but "we had a lot of mathematical brains," says Ziegler (himself a civil engineer in peacetime), "and we corrected them by actual fire."

Interview between Ziegler and the author, 1989.

It looks like this technique worked and that the shells detonated. Unfortunately there's no reference as to whether or not this was used in North West Europe.

Further to gun and howitzer trajectories, the following quote highlights the danger to troops in the front line from their own artillery, even if the surveying is done correctly. This occurred at the start of the first, and ultimately unsuccessful, crossing of the Lamone.

The operation started poorly for the Hasty Ps (The Hastings and Prince Edward Regiment). The assault companies of both battalions were instructed to keep away from the river bank during the ten-minute preliminary bombardment by the medium guns. This precaution was necessary because the mediums fired their shells in a flat trajectory, and it was almost certain that there would be some hits on the Canadian side. However, the two companies of Hasty Ps moved right up to the embankment, thanks to the darkness and fog and their unreliable Italian maps. At 0500 hours, when the bombardment began, one Canadian shell after another smashed into them; by the time the mediums ceased firing after ten minutes, the Hasty Ps were a battered bloody mess. Forty-eight of them had been either killed or wounded; the survivors were in a state of shock.

War Diary of the Hastings and Prince Edward Regiment. December, 1944.

Best laid plans, and all that.

Dan.

[motto]

Thanks Dan, hard information on artillery usage seems hard to come by but it now appears there was a precedence to what those fellows were doing in Korea which to my eyes doesn't appear to be a combat situation, more of a test firing or tickle up? The situation just doesn't seem that serious.
Unfortunately Bill Ziegler doesn't give any information on what angle they were firing at and we will probably never know if all firings at that angle resulted in detonation.
Perhaps the question of projectile attitude hasn't been asked because the majority of shells do detonate and it's of no more than technical interest.

David

[Barry Churcher]

Gilles, I will send info via PM on the weekend.
Barry

[chrisgrove]

Originally Posted by Dan Martel

Mike C, good to hear from you again.

As it happens I'm reading The D-Day Dodgers by Daniel Dancocks and came upon the following reference. Just to set the quote into context, it is December, 1944, and I Canadian Corps is conducting its last offensive before the onset of winter weather in the Po Valley of northern Italy. After a disastorous first battle under his command, the new Corps Commander (Charles Foulkes) is planning a set piece battle to force a crossing of the Lamone River.

The first attempt had lasted less than 12 hours before the Canadians were forced to withdraw, losing the better parts of the Royal Canadian Regiment and the Hastings and Prince Edward Regiment in the process. Both battalion commanders, along with the commander of the 1st Brigade, were sacked.

After a new attempt to force a crossing of the Lamone, the Corps will have to cross four canals before reaching its objective, the Senio River. Both of the rivers and all four of the canals had steep banks, high dykes, and were in full flow due to the autumn rains. Plus, of course, the Germans.



It looks like this technique worked and that the shells detonated. Unfortunately there's no reference as to whether or not this was used in North West Europe.

Further to gun and howitzer trajectories, the following quote highlights the danger to troops in the front line from their own artillery, even if the surveying is done correctly. This occurred at the start of the first, and ultimately unsuccessful, crossing of the Lamone.



Best laid plans, and all that.

Dan.

You should try 'The Regiment' by Farley Mowat, who was an officer in the Hasty Ps. The Ist Brigade was warned at very short notice to assault across the Lamone, after the first assault by 3rd Brigade attack had failed. The medium artillery was tasked to concentrate on houses immediately behind the high dykes on the far side of the Lamone, targets suited only to 25 pounders which could carry out high angle shoots, despite the objections of the artillery officers to the brigadier. There was insufficient time to give out orders properly. The acting CO of the Hasty Ps (the CO had been ordered by the brigadier to ensure the 2ic commanded for this attack - and three of the company commanders were inexperienced)) having no time at all for a recce, chose his start line as a ditch well back from the river, prominently marked on the only maps available, but which turned out to be visible only on the map, with the result that the leading two companies moved on (in the dark) right up to the friendly side dyke, where they were predictably clobbered by the medium artillery. The remaining two companies, further back, were then ordered to continue the assault, leaving the battalion with no reserves to counter the inevitable counter attack. No plan was instigated by brigade to get tanks, or even anti-tank guns across the river. If ever there was a disaster orchestrated by brigade, division and Corps, this was it. The casualties, of course, were all at battalion level.

As a minor detail, Stan Ketcheson, the acting CO of the Hasty Ps, was not sacked as he was wounded by mortars shortly after the battle.

Oh, and 67 of the Hasty Ps were killed, seriously injured or captured in that battle.

Chris

[CWO (ret) Gilles Aubé]

I am still looking for two 25 Pdr drag rope if someone as any.
Gilles

[Rob Fast]

I am also looking for a couple...tough find. Cheers Rob in Manitoba