Info on FMC's XM765 AIFV, XM723 AIFV and LVT(X) designs?

[Pioneer]

G’day all
I am looking for line-drawings of the FMC Corporation’s XM765 AIFV and XM723 AIFV (Armoured Infantry Fighting Vehicle) developed in response to the U.S Army’s MICV 70 requirements.
Also of interest is information (Specifications, pics and line-drawings of the FMC Corporation’s LVT(X) design submission

Thanks in advance
Regards
Pioneer

 

[DanielStarseer]

That last one, with the 90mm, I'd like to know more about.
It doesn't resemble any Cockerill, MECAR, or French (DEFA?) design I've ever seen...would like to know if it was derived from US 90mm guns (principally because the US was never really known for low-recoil 90mm guns, as that smallish turret suggests that gun would have to be...).

Such a U.S. equivalent of the PT-76 certainly might've changed the make up of Marine units generally equipped with just those "50/40" turrets on their LVTP-7s. Certainly would've given them better teeth against a number of targets upon landing.

 

[TomS]

The turret strongly resembles the Cadillac Gage 90mm turret found on the V-150/V-300 family. That turret had a Cockerill Mk III gun, but the tube in this picture looks wrong, like it's missing the muzzle brake. Perhaps the cover just disguises it?

 

[jstar]

Don't have a copy hand to reference, but have you tried R. P. Hunnicutt's

Bradley, A History Of American Fighting and Support Vehicles. ISBN 0891416943.

Know it's a good source for M-113 derivative informations.

 

[xiaofan]

Found this on line can't remember which website it is come form,however it looks like an AAV-7 with a 90mm or 105mm turret and it is similar to the FMC's proposed LVT(X), with 90mm assault gun turret (based on M113A2).

 

[TomS]

That looks like a Sheridan turret with a low-recoil 105mm gun.

And so it is: LVTEX-3, in Steve Zaloga's Osprey book on Amtracs

 

[DanielStarseer]

Huh.
Learn something new everyday.

An interesting tale there I wouldn't mind hearing:
"The LVTEX-3 mated an expiremental Navy 105mm low-recoil gun in a surplus Army M551 Sheridan tank turret."

Interesting, because why would the Navy be expirementing with 105mm guns?
USN didn't operate tanks,
and surely they wouldn't have conducted their own research to satisfy a USMC requirement for a low-recoil direct fire support weapon that would arm only so many vehicles (not like it was going to be purchased beyond a few hundred, at most.
Possibly,...but I'd like to know more).

I'd love to know the history of this program (the Navy and 105mm),
if anyone can point me in the proper direction...
(USN having thoughts to bridge the gap in ship gunnery between 127mm and 76mm, maybe?)

 

[TomS]

The Navy has always done a lot of engineering R&D for the Marines, so it's not that implausible that the Navy would have developed a low-recoil 105mm specifically for Marine use.

Steve Zaloga's book on the M551 mentions that Naval Surface Warfare Center, Dahlgren developed a 105mm version of the Sheridan in the early 1980s for possible adoption by the Marines. (See link to Google Books). But there's a picture there that shows this was a more conventional 105mm gun with a multi-baffle muzzle brake. However, some other research suggests that the Marines had studied the Sheridan earlier, as a possible replacement for Ontos, so perhaps the Navy took a look at low-recoil 105mm guns then.

Beyond helping out the Marines, the Navy had a couple of other possible reasons to be interested in the Sheridan (or at least the turret) and possibly adapting it to 105mm. First, the Navy fitted a Sheridan turret on Flagstaff, an experimental hydrofoil, back in 1971. The 152mm gun would not have been an ideal weapon for that vessel, but the light turret was very attractive. Similarly, the Navy had fielded a bunch of heavily armed and armored riverine monitors for Vietnam, including one version with a 105mm howitzer in a turret swiped from the older LVTH-6. Despite being howitzers, those guns were mostly used in direct fire so adapting a tank gun might have been considered as a future development.

PS: Sorry, we seem to have got sidetracked a bit from the original request.

 

[TomS]

Not finding a thread on Sheridan derivatives, I'm going to post this picture of the Sheridan with 105mm gun here. If the mods would prefer creating a new thread, I'll be happy to oblige.

 

[DanielStarseer]

Outstanding,
many thx, Tom.

Something partially on topic, but partially derailing,
with the failings (and cancellation) of the EFV apparent,
I wonder if there are enough reasonably-smart folks left in the defense industry who might consider revisiting these above-mention LVT prototypes for inspiration in developing the hoped-for follow/replacement for what the EFV failed.

Definitely to achieve the desired requirements, a vehicle with a better-shaped front hull (hydronamically-favorable for piercing through the water as in moves forward) is necessary:
I wonder if these prototypes, or the current LVTP-7/AAV-7P (whatever it's called now),
mated to a similar-shaped nose as on that ARISGATOR M113 from the other thread,
then of course a proper engine,
might at least be a good starting point....?

A lot will depend on how large a dismount/squad section the USMC shapes its requirements to,
wherein perhaps even a stretched LVT-based chassis (8 road wheels? 9?) could get us closer than the considerably-wider EFV did...(various sites have folks suggesting a hull with a longer length:width ratio generally gets better speed than a short and wide one.)

Then firepower becomes the argument,
and depending what the USMC wants it to do, 105mm types may not be unrealistic (if we look at Army experience with the various Strykers,
but if I expect the new vehicle to perform any sort of fire support, I would prefer a gun-mortar capable of PGM use, myself...).

Perhaps, if it proves successful enough in early forms, it can evolve into an adaptable chassis, much like the land-based Strykers (or any of the Piranha family,
thus continuing to follow in the footsteps of many LVTs from years past... (we're just going to need the next Hunnicutt to write about them...)

 

[Abraham Gubler]

Beyond helping out the Marines, the Navy had a couple of other possible reasons to be interested in the Sheridan (or at least the turret) and possibly adapting it to 105mm. First, the Navy fitted a Sheridan turret on Flagstaff, an experimental hydrofoil, back in 1971. The 152mm gun would not have been an ideal weapon for that vessel, but the light turret was very attractive. Similarly, the Navy had fielded a bunch of heavily armed and armored riverine monitors for Vietnam, including one version with a 105mm howitzer in a turret swiped from the older LVTH-6. Despite being howitzers, those guns were mostly used in direct fire so adapting a tank gun might have been considered as a future development.

The second generation riverine monitor was to be armed with a Sheridan turret with 152mm gun. This was to be in a special module developed by the Naval Ordnance Laboratory that would be fitted into the ATC Mk 2. For naval application the 152mm isn't such a bad gun on paper as it can fire HE to ~10km and the Sheilligah missile is not wired guided. Wire guidance like TOW has significant range loss over water because the charged command wires fall into water draining the power of the guidance system. Of course the 152mm had significant practical problems with the propellant and missile guidance system. Possibly why the Navy/Marines looked at a low recoil 105mm to replace it.

 

[Abraham Gubler]

The turret strongly resembles the Cadillac Gage 90mm turret found on the V-150/V-300 family. That turret had a Cockerill Mk III gun, but the tube in this picture looks wrong, like it's missing the muzzle brake. Perhaps the cover just disguises it?

You might be onto something here. The LVT(X) requirement was for an Amtrac armed with an autocannon in the 25-35mm range. Perhaps FMC just stuck whatever turret they could find that could fit the ring with some kind of 'big gun' onto this prototype until the 25-35mm gun turret was available?

 

[DanielStarseer]

Cool.
More rare gems of information that a person doesn't easily find online very many places.

As to navalizing the Sheridan bits,
I might also speculate that perhaps there were issues with the semi-combustible propellant cases...?

The river craft certainly wouldn't suffer the rough terrain abuse that a cross-country Sheridan might (water can be rough, but the "background vibration" present in many moving AFVs just might not have been seen in a navalized Sheridan system: the ship turret would be farther away from the engine & transmission vibrations, and no tracks/suspension would shake/vibrate the boat, either).

And, excess moisture, especially in the humid tropical areas, might possibly compromise safe storage (adequately dry) for the projectiles and propellant, maybe...?

Still, an interesting concept, and definitely not the first time AFV turrets were marinized onto ships (or just plain ported over from a derelict AFV).

 

[Brickmuppet]

The Navy tested a modified Sheridan turret on a hydrofoil on the Hydrofoil USS Flagstaff.


There was also the 105mm on the ASPB.
http://www.sikorskyarchives.com/boat2.html

...So there was some navy interest along those lines...at least for brownwater forces. This would seem to easily transfer to AFV guns. It makes sense that they would be looking at ammunition and parts commonality with the leathernecks wherever possible. The 90mm Cockrill is a decent off the shelf solution but 105mm has the potential to use standard USMC ammo.

 

[Abraham Gubler]

There was also the 105mm on the ASPB.
http://www.sikorskyarchives.com/boat2.html

That was Sikorsky's offering for the Mk 2 ASPB which was in competition with the Stewart boat. The role of the 105mm gun was for direct fire bunker busting which the Stewart boat meet with a bow mounted 81mm breech loading mortar.

 

[Abraham Gubler]

I am looking for line-drawings of the FMC Corporation’s XM765 AIFV and XM723 AIFV (Armoured Infantry Fighting Vehicle) developed in response to the U.S Army’s MICV 70 requirements.
Also of interest is information (Specifications, pics and line-drawings of the FMC Corporation’s LVT(X) design submission

All of those pictures above are taken from Hunnicutt's book "Bradley". It does not have line drawings for the XM765 but does for the XM723 and FMC's LVT(X), the later without the turret. In relation to the LVT(X) Hunnicutt mentions that the gun version was armed with the 90mm Cockerill with 8 rounds in the turret and 32 rounds in the hull. Six dismounts could still be carried in this version.

Due to this webpage's policy of limiting scans from in publication or available to buy books I won't scan any of the line drawings. But get a copy of Bradley into your hands and all your questions will be answered.

 

[DanielStarseer]

Outstanding discussion.
For those interested, B&N currently lists Bradley at arounnd $55-60... (after that, my next purchase must be a drool-proof keyboard...)

Seeing those river gunboats, they remind me of more modern designs, such as the CB90 with the AMOS twin 120mm, or that smaller sibling with the NEMO turret.

Noice!

 

[Abraham Gubler]

First, the Navy fitted a Sheridan turret on Flagstaff, an experimental hydrofoil, back in 1971. The 152mm gun would not have been an ideal weapon for that vessel, but the light turret was very attractive.

Reading Friedmann's "US Small Boats" and the Sheridan turret was fitted to the Patrol, Gun, Hydrofoil because the USN leadership wanted a gun for this role. The role of the PGH was to destroy enemy (Soviet) torpedo and missile boats - in effect the 1960s and 70s version of the original role of the destroyer - and was to combine high speed with an appropiate weapon system. The original PG concepts used and trialed the French SS12 missile system which was found to be excellent for the role. However the leadership insisted on a gun so the Ashvellie class had a 76mm cannon. The later PGHs trialed the Sheridan turret so they could use a guided missile while keeping to the mandate of gun armament.

PS: Sorry, we seem to have got sidetracked a bit from the original request.

There is good sidetracked... But I will work up a thread in the naval section for ujnbuilt US small combatants and riverine vessels.

 

[Pioneer]

Gents, I've been reading over older subjects/topics, and I have to sincerely apologies for my non reply/input into this topic I initiated so many years ago

I have to agree with DanielStarseer - "Outstanding discussion"

Considering that you are inherently interested/across 'Armoured Amphibious Assault Vehicles, can I ask the forum a question pertaining to the FMC LVTP-7/AAV-7 please?

Is the size/bulk of the LVTP-7/AAV-7 derived from its need/want to carry and deliver it's twenty troops, or is it due to its need to operate in sea swells from ship to shore?



Regards
Pioneer

 

[TomS]

The LVTP-7 is actually a bit smaller than its predecessor, the LVTP-5, but is faster and somewhat more seaworthy due to better hydrodynamics and propulsion. I'd say the size was a balancing act between having sufficient capacity to split a full reinforced rifle platoon across three vehicles (Marine platoons tend to be much larger than their Army equivalents) and fitting enough vehicles in a well deck to carry th necessary assault wave.

 

[Pioneer]

Thank you for your reply TomS

Regards
Pioneer

 

[Pioneer]

On the subject of the FMC (and Chrysler design LVTPX12 for that matter) LVTP-7, I'm somewhat confused.
Did the Chrysler designed and built LVTPX12
compete directly against FMC in the same competition? Or did FMC build the full production variant that became the FMC LVTP-7 for Chrysler?

Also if I may, I can't help notice Chrysler LVTPX12 was designed and built with one-man power-operated turret, armed with a M39 20mm cannon and 7.62mm machine gun. Does anyone know the make and model of this turret/cannon arrangementent and why did the USMC drop it from the production LVTP-7??


Regards
Pioneer

 

[Elan Vital]

I have found the engineering report of the Chrysler study of the LVTPX12. Really love these LVTPX reports, they are so rich in data on automotive equipment and engineering.

 

[Louis432]

hi all I have a question, guys: is it possible to install an M40 106mm recoilless rifle on a vehicle like the AIFV(YPR765, CM21etc)? Is there a photo or picture, project of anything similar?

 

[Apophenia]

hi all I have a question, guys: is it possible to install an M40 106mm recoilless rifle on a vehicle like the AIFV(YPR765, CM21etc)? Is there a photo or picture, project of anything similar?

As noted elsewhere, the vehicle that you're looking for is the YP408 TLV (Terugstootloze Vuurmond) prototype.
-- https://www.dafyp408.nl/DAF_YP408_TLV.htm

 

[TomS]

As noted elsewhere, the vehicle that you're looking for is the YP408 TLV (Terugstootloze Vuurmond) prototype.
-- https://www.dafyp408.nl/DAF_YP408_TLV.htm

Also the CETME TC-7/106.




It's been carried on the BMR600 wheeled APC but also I believe at least trialed on an M113. It could easily have been carried on an AIFV-type chassis.

 

[Firefinder]

ANother set up be the one on the US T114 Battalion AntiTank version of the M114 scout.

Had a 3 shot autoloader with the M40 106mm in a turret with the ability to reload undercover. And was Amphibious, for river crossing, as well

 

[Magus]

hi all I have a question, guys: is it possible to install an M40 106mm recoilless rifle on a vehicle like the AIFV(YPR765, CM21etc)? Is there a photo or picture, project of anything similar?

It's possible to mount an M40 recoilless rifle on just about any chassis. You just have to either mount it externally, or (as on the T114 BAT seen above) use a turret design where the rear of the rifle sticks out the back of the turret. Because the nature of a recoilless rifle means it's necessary to have the propellant gas (or less commonly a solid counterweight) eject out the back, and you can't very well have that happen inside the crew compartment.