LVT-4 Heavy Mortar - Close Fire Support - Done !

[buzzbomb]

Over on BTS there is a '46 group build.
Thought I would share here as well, to keep the AFV topic moving along.

For the Pacific war onwards into 1945 and 1946, what about mounting a 107mm/4.2 Mortar into an LVT for On the beach close fire support?

The USN did mount 3 of these mortars into an LCM for a similar purpose, but to get close with the lads with boots on the ground the LVT would be a pretty good platform


After spending 10 Minutes, flat, building the Mortar, the LVT went together in short order as well. The kit is ok, since the suspension is much simpler than the rather nice AFV Club offerings, the main construction bolted along. Worked on a card Mounting platform for the mortar, which I thought would have a traverse mechanism to work with the base plate.  Then dug out some unused Priest ammo holders as the size is about right for the 4.2 Ammo.


The location and format of the Ammo containers has changed a bit after these pix.


More pix shortly, this is moving along swiftly so far.

[perttime]

That must be the M2 4.2-inch mortar.
Wikipedia says:
Effective firing range   515 m (563.21 yd)
Maximum firing range   4.4 km (2.7 mi)

Is that because you couldn't hit things at longer ranges, due to either mechanical accuracy or exterior ballistics, methods of directing fire, or type of targets you wanted to shoot at?

[Old Wombat]

Time of flight, movement of the base on recoil, target movement, wind gusts & other atmospheric conditions would all be in play there.

Remembering that the projectile is pretty big & heavy, & the mortar tube is light & can't handle a large charge to move it very fast.

[rickshaw]

A better method would be to mount the mortar on top of the track so that it could traverse freely.   Make it lockable to point in one direction at need.  Another method, used later in the M125 and M126 Mortar Carrier versions of the M113 (the first for 81mm the second for 107mm) was to create a platform on which mortar was mounted and which revolved.   That allowed firing in any direction.  A particularly useful means of using a mortar.   Having crewed a M125 during on exercise we, the crew all liked it a lot, compared to humping the mortar 'round.

[perttime]

Time of flight, movement of the base on recoil, target movement, wind gusts & other atmospheric conditions would all be in play there.

Remembering that the projectile is pretty big & heavy, & the mortar tube is light & can't handle a large charge to move it very fast.

Those things can be accounted for.
A mortar is generally not a point weapon, it is an area weapon. I don't remember exactly, but have shot mortars at around a minute of flight time, in somewhat known atmospheric conditions. Firing for effect, a 100m x 100m square was the target. At short ranges (inside 1 km?) we'd change aim after every shell to cover that area. 12 or 18 shells (depending on mortar caliber) in 60 seconds or one minute (depending on offensive vs. defensive).

[PR19_Kit]

Looks like we've got our own Whiffing Mortar Crew here. 

[buzzbomb]

A better method would be to mount the mortar on top of the track so that it could traverse freely.   Make it lockable to point in one direction at need.  Another method, used later in the M125 and M126 Mortar Carrier versions of the M113 (the first for 81mm the second for 107mm) was to create a platform on which mortar was mounted and which revolved.   That allowed firing in any direction.  A particularly useful means of using a mortar.   Having crewed a M125 during on exercise we, the crew all liked it a lot, compared to humping the mortar 'round.

You mean like this ?  Was working on the front mount cradle when I posted the first lot of pix. Even added a foot pedal to lock in place


Went down the path of the rotating turntable, but the desk space of the LVT-4 precludes that option. It would probably work on an LVT-2 though. I see the mortar as demountable as well so that it can be moved in land with the troops as required. The mounting platform will also have lifting eyes so it too, can be removed if required.

Revised Ammo Stowage layout to offer less obstacle to the side MG positions. Still tossing the .50 vs .30. But the .50 do look chunkier.


As this is an "On the Beach" vehicle, I am now looking at raised armour superstructure to give some crew protection to snipers. Probably fold down for when not required


Almost there really. Now only the paintshow mojo to work on

[Captain Canada]

So cool. Love those big ol' beasts !

[rickshaw]

Yes, that was basically what I was saying about running on the track.

As to a platform, that basically stays in the vehicle and when the mortar is dismounted the normal bipod and ground plate are used.   The platform is permanently in the vehicle with just the tube mounted on it.  The bipod and ground plate are attached outside the vehicle.

The idea of the armour to give protection from snipers is a good one.  I hadn't realised the LVT was so short that the crew's heads would be exposed.

[Old Wombat]

Excellent work, BT!

[perttime]

...
The idea of the armour to give protection from snipers is a good one.  I hadn't realised the LVT was so short that the crew's heads would be exposed.

Protection is good. But... how are you going to aim it, with period technology, if you cannot see an aiming point that is located at some distance?
Aiming points within the vehicle would work for an up-close defensive emergency but accuracy at distance would suffer: no good for offensive use.

Keeping the mortar in the vehicle would be good for most situations. At least you can move quickly right after shooting, before other interested parties start dropping shells on you.

[rickshaw]

...
The idea of the armour to give protection from snipers is a good one.  I hadn't realised the LVT was so short that the crew's heads would be exposed.

Protection is good. But... how are you going to aim it, with period technology, if you cannot see an aiming point that is located at some distance?
Aiming points within the vehicle would work for an up-close defensive emergency but accuracy at distance would suffer: no good for offensive use.

Keeping the mortar in the vehicle would be good for most situations. At least you can move quickly right after shooting, before other interested parties start dropping shells on you.

Eye?  Seems to work for most mortars... 

[perttime]

...
The idea of the armour to give protection from snipers is a good one.  I hadn't realised the LVT was so short that the crew's heads would be exposed.

Protection is good. But... how are you going to aim it, with period technology, if you cannot see an aiming point that is located at some distance?
Aiming points within the vehicle would work for an up-close defensive emergency but accuracy at distance would suffer: no good for offensive use.

Keeping the mortar in the vehicle would be good for most situations. At least you can move quickly right after shooting, before other interested parties start dropping shells on you.

Eye?  Seems to work for most mortars... 

I must be missing something here.
I thought you wanted higher armor so that snipers couldn't snipe at the crew.
That means that the crew cannot see what is on the outside. And that means the crew cannot hit much with the mortar, without modern stuff like GPS, gyros, inertial navigation, or whatever some modern mortar vehicles use.

[rickshaw]

...
The idea of the armour to give protection from snipers is a good one.  I hadn't realised the LVT was so short that the crew's heads would be exposed.

Protection is good. But... how are you going to aim it, with period technology, if you cannot see an aiming point that is located at some distance?
Aiming points within the vehicle would work for an up-close defensive emergency but accuracy at distance would suffer: no good for offensive use.

Keeping the mortar in the vehicle would be good for most situations. At least you can move quickly right after shooting, before other interested parties start dropping shells on you.

Eye?  Seems to work for most mortars... 

I must be missing something here.
I thought you wanted higher armor so that snipers couldn't snipe at the crew.
That means that the crew cannot see what is on the outside. And that means the crew cannot hit much with the mortar, without modern stuff like GPS, gyros, inertial navigation, or whatever some modern mortar vehicles use.

I think he meant that the armour was only on the sides, not the front or back...   

[Old Wombat]

Set the vehicle up in a given location; calculate angles & distances to various points using a compass & a map; Marines/soldiers call in fire orders & give corrections; I'm sure someone thought of that somewhere/somewhen else?

No military vehicle works in isolation, it's always part of a greater whole, & is either there to support, or can call on the support of others to fulfill the UNIT'S mission.

Strangely, given the technology of the period, most allied forces had radios in platoon level units & up (some even had them at the section/squad level) which could be used to call in artillery support (including mortars).

The mortar crews did not have to see their targets to hit them!


Carry on, BT!