Max height of a 105 round??

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#1
Debate in the Bar from a couple of Infantry lads.

The argument...If a 105 light gun was at sea level then what is the maximum height that a 105 HE or WP round could go. The argument stems from how high would an aircraft need to be to ensure that it could not be hit.

same question posed for a 81mm Mortar round.

Answers on a postcard please!!!!

Bob
 
#3
If you're looking for a 'safe altitude', then MLRS firing ATACMS will reach an altitude of approximately 164,000 ft.

Clearly we hope that the BSM* are on top of their real estate...

*Not Battery Sergeant Major, before someone witters...
 
#4
All depends on the met ;)
 
#5
I remember someone once saying that if it was firing in high angle, on charge super, it would clear the equivalent height of mount everest,(29028 ft). Whether this is an urban mith or not I don't know, all I do know is I wouldn't want to be the poor wheelman spammed with digging a trench for the breech to have clearance.
 
#6
BeastAppreciationSociety. said:
I remember someone once saying that if it was firing in high angle, on charge super, it would clear the equivalent height of mount everest,(29028 ft). Whether this is an urban mith or not I don't know, all I do know is I wouldn't want to be the poor wheelman spammed with digging a trench for the breech to have clearance.
Broadly correct - yes.
 
#7
Well my guess was 20,000 feet for a 105 and 12,000 for a 81 mortar.

I suppose if the aircraft was right over the target then it could be a lot lower as the round would be relativly low and moving laterally at that point.
 
#8
The problem you have with the light gun is there are limits in QE for the higher charges (the breech tends to hit the ground and you can wreck other bits of the recuperator (sp) system) once I'm back in work on monday I can give you the official number from firing tables.

I know when we are doing firings they stop the aircraft from coming overhead at all......I have a number in my head, I think 7,000m, but I might be getting ft and m mixed up...or just plain confused. Will give am answer on monday if no-one else has.
 
#9
I assume all the altitudes already given are correct, however, you all forgot to factor in the Royal Artillery, so, the rounds would always fall about 100m short of their actual intended target :D (Ubique - All over the shop)
 
#10
Ali_Gee said:
I assume all the altitudes already given are correct, however, you all forgot to factor in the Royal Artillery, so, the rounds would always fall about 100m short of their actual intended target :D (Ubique - All over the shop)
And the bogs you built don't flush :p
 
#11
Well when planning Air intregation with Fast air and guns we use 15,000 ft as a vertex for 105mm , 10,000 for 81mm.
thia can be found in TAMS . If you want to explian to your INF chums that fast air can fly underneath arty rounds and
do so often .All depends on the impact area /fast airs target, of and how good your FAC is. ''Cleared hot'' !!!!
 
#12
Darth_Doctrinus said:
If you're looking for a 'safe altitude', then MLRS firing ATACMS will reach an altitude of approximately 164,000 ft.
I doubt that height could be achieved due to the inability of the LLM to reach the angle required. :)
 
#13
Ali_Gee said:
I assume all the altitudes already given are correct, however, you all forgot to factor in the Royal Artillery, so, the rounds would always fall about 100m short of their actual intended target :D (Ubique - All over the shop)
Firstly, it is bracketing, secondly with the splinter distances that really is not far away at all. :)
 
#14
GunnersQuadrant said:
Ali_Gee said:
I assume all the altitudes already given are correct, however, you all forgot to factor in the Royal Artillery, so, the rounds would always fall about 100m short of their actual intended target :D (Ubique - All over the shop)
Firstly, it is bracketing, secondly with the splinter distances that really is not far away at all. :)
Actually a huge number of people would disagree with this simple statement. 100 metres is a significant distance for 105mm; and lies outside LSD for 155mm as well. I accept that SSD is outside that limit, but crap fragmentation, particularly with US systems, would not provide any sort of measure of guarantee of a 'hit' and even less therefore of a 'kill'. This lies at the root of the IFPA argument, and the current agonising about whether we go for Excalibur type systems, unitary warhead coupled to GPS guidance, or more rockets - with all their inherent problems with zone etc etc.

I certainly don't believe there are many people here on ARRSE who can offer anything particularly intelligent to this debate per se - unless they work for DEC(DTA) - but I'd certainly be interested to see what people generally thought about solving this problem. LIMAWS (G) or (R)?? :)

FWIW I suspect that we will adopt a typically Gunner solution - a little of both, thereby achieving very little in capability terms - as usual.

GQ - I'm intrigued to hear that we can't fire ATACMS at certain elevations of the LLM - can I get a feel for why you say this, so I can sound knowledgeable at coffee tomorrow? A quick search through my pams and this (admitedly typically dodgy) Wikipedia link indicates otherwise. Or am I being a steamy biff (as usual)? Are you back now, by the way?
 
#15
GunnersQuadrant said:
Ali_Gee said:
I assume all the altitudes already given are correct, however, you all forgot to factor in the Royal Artillery, so, the rounds would always fall about 100m short of their actual intended target :D (Ubique - All over the shop)
Firstly, it is bracketing, secondly with the splinter distances that really is not far away at all. :)
I'm surprised that such a wise and experienced Gunner as yourself didn't look the grunt in the eye and with a knowledgeable air, just say "zone". Any further dicontentment can be addressed by the "occasion to occasion" effect.

Always leave those who practice the lesser arts mystified.

Of course, in my day, if your powder was a bit damp, the cannon balls would drop all over the place. Thank heavens for Capt Harry Shrapnel's Patent Shell is all I can say.
 
#16
getting back to the original question.

According to the firing tables (though admittidly not the most upto date version) the max vertex of a shell for the 105mm L118 gun is approx 7500m, which is actually fired at a lower chanrge than top charge due to the limitations on the QE of the gun. If you ignored the limitations and dug a damn big hole for the breech then you could probably get higher, but also probably end up with a buggered gun.

do i sound too much like a spotter now? I'll go away now.
 
#17
An interesting thread, I have to admit that I had never realised how high artillery shells go... I'm trying to find more interesting ways to teach physics, applications of science etc. to make it better for all students, not just those that are cadets. Can anyone point me at unclassified information in the public domain, regarding the maximum height achieved, and range for different elevations - ideally for both a mortar and a large calibre gun?
 
#18
The basics are quite simple to do, Newtons Laws etc cover the basic details of all ballistic flight. The additions within Range Tables etc, include issues such as Met, spin of the earth, weight of shell, relative heights of firing/impact, different propellant types/sizes.

There are basic computer programmes that model these, which are available on the net i'm sure.

I used to be able to do all the basic stuff from newtons laws and probably can if I think about it a bit. But an interesting task would be to he the students think about all the different factors that may affect the shells flight and see what they can produce, and then compare it against what the Firing Tables say....although firing tables are RESTRICTED the basic contents are probably not. Feel free to PM me if you want anything info, might see if the company has any educational info relating to this you never know.

S_R
 
#19
ComeSunt said:
Debate in the Bar from a couple of Infantry lads.

The argument...If a 105 light gun was at sea level then what is the maximum height that a 105 HE or WP round could go. The argument stems from how high would an aircraft need to be to ensure that it could not be hit.

same question posed for a 81mm Mortar round.
Answers on a postcard please!!!!

Bob
If my memory serves me correct the formula for calculating the height of a mortar round is 4T squared where T = Time of Flight. We used to talk about 10,000 ft being the max height of a mortar round. This would be for time of flight of 50 seconds which is pretty extreme.

For a time of flight of 30 seconds which is probably more representative it's only 3,600 ft high.

Hope this helps
 
#20
abeaumont said:
An interesting thread, I have to admit that I had never realised how high artillery shells go... I'm trying to find more interesting ways to teach physics, applications of science etc. to make it better for all students, not just those that are cadets. Can anyone point me at unclassified information in the public domain, regarding the maximum height achieved, and range for different elevations - ideally for both a mortar and a large calibre gun?
Google Artillery Firing Tables Vertex Height and you'll find links to some presentations (mainly .ppt) that might be of use.

Some of them list "non standard conditions", which covers a multitude of factors that can affect the flight of a shell, although the ones I looked at didn't include muzzle velocity and the factors that affect it.
 
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