ID guns on these MCC trucks

[chrisgrove]

Pole trail limits elevation - hence reduces the range! Nice pics of Martin Parry conversion.

Chris

[Mike Cecil]

Yes, that's partly true, but there comes a point of elevation with a fixed cartridge (like the 18pdr) where further increasing the elevation actually decreases the range. I agree that the single pole trail design limited the elevation in the 18pdrs case to only +16 degrees, which in turn meant that for the 18pdr cartridge, the maximum range attainable was also limited.

The main problems with the limited range of elevation (-5 to +16 degrees on the 18 pdr Mk1) were crest clearance (getting a round over elevated terrain) and the inability to elevate sufficiently for 'plunging fire', ie getting the round coming back to earth at a high angle, which was much more effective when bombarding emplacements and fortifications.

Mike C

[Mike K]

Wiki does it again:

http://en.wikipedia.org/wiki/Ordnance_QF_18_pounder

Nasty , the way the shell exploded, delivering a wave of lead/antimony bullets up to 300 yards away .

Mike

[Mike Cecil]

Yes, Mike: I've just read through it, and its a good coverage of the gun and ammunition. Not much reference to Australia (esp WW2 use in the ME and Pacific) but that's a minor point in the overall scheme of things.

The explosive action of the Shrap shell 'ejects' the balls/shot from the casing, which then falls to earth, often remaining intact. Many were subsequently souvenired, and thus it is probably the most commonly available variant of the 18pdr in collections because of that.

Mike C

[David Hardway]

Hmmmmmm i know these pics of the approx 10 Morris CDSW tractors to come to NZ there are remains of at least 5 still known to exist just not really enough to build a decent truck

Dave

[David Hardway]

Heres some more from the same sequence note the threadbare tyres on the limber

Dave

[Lang]

MikeC,

Good info as usual.

I think your info on reducing the range with elevation is suspect - you can't beat physics - 45deg is maximum range for any projectile, thrown rock, motorcycle jumping busses or garden hose. Shot-put and javelin athletes aim for an exact 45deg launch.

I seem to remember "howitzer" referred to a weapon capable of higher angles than 45deg - very useful for high crest clearance or tossing over a hill ie the shells go further and further as the gun gets to 45deg then start coming back in - try it with a garden hose. In theory, if you can get it high enough (mortars have no trouble) you can drop a shell down almost vertical behind a building 100 metres away - or maybe back down your own barrel!.

They had a reasonable range because they had quite a good muzzle velocity. For those whose memory needs jogging like mine these days, the weight of the projectile has absolutely nothing to do with its range. If we had a target at 100 metres a 22 aimed direct would hit it about 5 inches low, a heavier 243 would hit it about 1 inch low and an even heavier 18 pounder would hit it about 8 inches low. It is all to do with the time in the air while gravity is pulling them all down at 32 ft/sec/sec so velocity is king.

I can't figure out why they only had 16deg unless they were designed as a direct fire weapon - it would make them almost useless as an indirect fire support weapon. Any ideas? I suppose they came from an era where the commander still stood on a hill and directed the battle visually.