testtest

The Noble (but Doomed) M551 Sheridan in Vietnam

The word "doomed" is a silly characterization. Any light-weight armored vehicle has its vulnerabilities, and even the M48 tanks in VN were knocked out. The M551 stuck around well after VN, serving until 1997.

The Sheridan was praised for its performance in Panama, and the Sheridan suffered no mechanical breakdowns in combat and performed extremely well in Desert Storm and Desert Shield in it's intended role as a Armored Reconnaissance/Airborne Assault Vehicle.
 
I served on Sheridans on the East West German border in the late 70s. Admittedly there were problems during VN, but like any weapons system, there were improvements. The big thing that stuck out to me was saying it had "a finicky track." Umm.. no. It was a very dependable track and suspension and rarely gave us problems compared to the M60 series. We could go were the heavies wouldn't dare follow. One memorable case at Hohenfels maneuver area, a column of M60s and Sheridans moved out at night in near blizzard conditions with compacted snow and ice on the tank trail. The heavies tried to climb a grade and came spinning down out of control. Meanwhile, our cav troop went up the hill no problem.

Another error is while the hull armor was aluminum, the turret was rolled homogeneous steel with steel belly armor. Design and engineering development never stands still. As far as fire control goes, we were the first to get laser rangefinders (although not integrated with the fire control) years ahead of the M60 series. It also was one of the most dependable systems on the vehicle. The gun was not a smooth bore, but rifled. Our master gunner equated the 152mm more akin to a direct fire howitzer in contrast to an M60s gun. We were inherently more accurate round to round.

There were other things I could mention, but as Talyn said, the article just skims the surface of the vehicle's performance and history and the author certainly can't call it a failure.
 
While I have the greatest respect for Dale Dye, there are a number of significant and misleading comments in his assessment.
1. The 152mm gun/launcher was most definitely not a smoothbore. It was rifled with a keyway cut at the 6 o'clock position that a key on the Shillelagh Missile ventral side would engage, preventing it's rotation. Conventional rounds were banded for the rifling apart from the Canister round. I will try to attach a fuzzy pic of the bore.
2. He refers to the conventional ammo as "caseless". This is incorrect, it was a combustible case (usually) that was meant to be consumed during firing, with any residual hot particles hopefully blown out with three shots of air from the Closed Breech Scavenger System (CBSS), a system that only just came on line at the last minute in 1969. Having been a "last resort" solution to the case residue problem there were several projects to make the gun adaptable to both a metal case (25 were prepared and fired & shown to be practical after a projected 21 month development period...this was time the program did not have). A glass particle "frangible" case was also explored. No combustion, but tiny bits that the CBSS would hopefully blow out.
3. The assessment about the track system is woefully wrong. Sheridan had one of the most reliable & robust track systems we ever employed....HOWEVER, the author was there for the early fielding when the tracks were being thrown largely due to the drive sprockets shearing off. Mechanics lacked torque wrenches to secure the sprockets and being too "loose", they put the bolts in shear without benefit of enough clamping force. I polled my fellow Sheridan crewmen & mechanics on a relevant page and was met with gales of laughter regarding torque wrenches. It seems they were also lacking in Germany as well. Our 2/11th ACR Sheridans rarely threw a track by '71-'72.
The lack of track support rollers was not an issue, being live track like most German & Russian tracked vehicles came to be.
4. The language about "cartridges meant to detonate in the breech". This is an erroneous statement...the combustible cased cartridges were indeed a fire hazard that could quickly consume the vehicle if ignited, but this is not a detonation. Sheridan DID have a "premature detonation" issue but that refers to the WARHEAD detonating prematurely. This was an issue that nearly killed the vehicle & probably should have. The XM409 HEAT round had a slew of "in tube" premature detonations and at least one just beyond the muzzle as late as 1969. As this was the only armor killer apart from the missile, this was a very serious matter. Combat Developments Command recommended that the Assistant Chief of Staff of the Army be notified in writing of the risk to crews should the vehicle be standardized.
By way of credentials, I was pre-trained on the M551 at the NCO Academy-Ft. Knox (to be a PL in the M551 school). Attended the 4-week Sheridan School at Knox, then served with them on my second campaign in VN. Subsequent to Vietnam, I was assigned to the Armor Board at Ft. Knox (1972-1973) & was on the Hughes LASER Rangefinder that would later be a component of the M551A1 years later.
 

Attachments

  • M551SchoolBoreKeyway.jpg
    M551SchoolBoreKeyway.jpg
    2.3 MB · Views: 16
Welcome to the SA Forum, Ascout. You sound like you know what you're talking about, and we welcome such people here! ;) (y)
 
Welcome to the SA Forum, Ascout. You sound like you know what you're talking about, and we welcome such people here! ;) (y)
Thanks, I do have a certain amount of experience on select armor/cavalry/vietnam-cold war topics.
The article's author has a great deal of influence in certain communities, which is why I commented, as it's worth of correction. His experience was apparently with the "three quarter" Cav, one of the two first units to receive the Sheridan (2/11th ACR as well) largely at the recommendation of Patton & Abrams who both wanted the vehicle "trialed" in combat with Cavalry units.
Neither the vehicle nor the ammo was ready, though the ~1,500 vehicles were already built and laying about at the Cleveland Tank Plant. Abrams heard of their existence and requested a contingent to be sent to VN. This was ill-advised and there were efforts to dissuade the USARV CG but he was having none of it. Quite a few people were embittered by the experience, including a former "Colonel of the Regiment" General Donn Starry, who had commanded the 11th Cav in Vietnam when it became so equipped.
 

Attachments

  • DvrLiceditcrop.jpg
    DvrLiceditcrop.jpg
    99.5 KB · Views: 18
While I have the greatest respect for Dale Dye, there are a number of significant and misleading comments in his assessment.
1. The 152mm gun/launcher was most definitely not a smoothbore. It was rifled with a keyway cut at the 6 o'clock position that a key on the Shillelagh Missile ventral side would engage, preventing it's rotation. Conventional rounds were banded for the rifling apart from the Canister round. I will try to attach a fuzzy pic of the bore.
2. He refers to the conventional ammo as "caseless". This is incorrect, it was a combustible case (usually) that was meant to be consumed during firing, with any residual hot particles hopefully blown out with three shots of air from the Closed Breech Scavenger System (CBSS), a system that only just came on line at the last minute in 1969. Having been a "last resort" solution to the case residue problem there were several projects to make the gun adaptable to both a metal case (25 were prepared and fired & shown to be practical after a projected 21 month development period...this was time the program did not have). A glass particle "frangible" case was also explored. No combustion, but tiny bits that the CBSS would hopefully blow out.
3. The assessment about the track system is woefully wrong. Sheridan had one of the most reliable & robust track systems we ever employed....HOWEVER, the author was there for the early fielding when the tracks were being thrown largely due to the drive sprockets shearing off. Mechanics lacked torque wrenches to secure the sprockets and being too "loose", they put the bolts in shear without benefit of enough clamping force. I polled my fellow Sheridan crewmen & mechanics on a relevant page and was met with gales of laughter regarding torque wrenches. It seems they were also lacking in Germany as well. Our 2/11th ACR Sheridans rarely threw a track by '71-'72.
The lack of track support rollers was not an issue, being live track like most German & Russian tracked vehicles came to be.
4. The language about "cartridges meant to detonate in the breech". This is an erroneous statement...the combustible cased cartridges were indeed a fire hazard that could quickly consume the vehicle if ignited, but this is not a detonation. Sheridan DID have a "premature detonation" issue but that refers to the WARHEAD detonating prematurely. This was an issue that nearly killed the vehicle & probably should have. The XM409 HEAT round had a slew of "in tube" premature detonations and at least one just beyond the muzzle as late as 1969. As this was the only armor killer apart from the missile, this was a very serious matter. Combat Developments Command recommended that the Assistant Chief of Staff of the Army be notified in writing of the risk to crews should the vehicle be standardized.
By way of credentials, I was pre-trained on the M551 at the NCO Academy-Ft. Knox (to be a PL in the M551 school). Attended the 4-week Sheridan School at Knox, then served with them on my second campaign in VN. Subsequent to Vietnam, I was assigned to the Armor Board at Ft. Knox (1972-1973) & was on the Hughes LASER Rangefinder that would later be a component of the M551A1 years later.
Agree wholeheartedly. See my earlier comment. Also, by the mid-to late 70s the HEAT round was devastating to enemy armor. At Graf they put out "new" hard targets before we rolled in for gunnery, usually M-47s hulks. By the time our squadron rotated out, those targets were piles of metallic dust.
 
Another error is while the hull armor was aluminum, the turret was rolled homogeneous steel with steel belly armor. Design and engineering development never stands still. As far as fire control goes, we were the first to get laser rangefinders (although not integrated with the fire control) years ahead of the M60 series. It also was one of the most dependable systems on the vehicle. The gun was not a smooth bore, but rifled. Our master gunner equated the 152mm more akin to a direct fire howitzer in contrast to an M60s gun. We were inherently more accurate round to round.

There were other things I could mention, but as Talyn said, the article just skims the surface of the vehicle's performance and history and the author certainly can't call it a failure.
The LRF comments are gratifying to hear. My first Test Project at the Armor & Engineer Board (Ft. Knox) was the add-on Hughes LRF which began in March or April of 1972. Lengthy project on which I fired many rounds. Relatively trouble free & an improvement on the choke reticle if the target was oblique to the vehicle.
But it was not quite "years ahead of the M60 series"....in fact, the identical system equipped both the M60A1E2 & the production M60A2 even as we tested it on the M551 (it took years to be fielded, I don't know why).
As I was also on the M60A2 Initial Production Test the next year I was already familiar with the Hughes LRF, integral to the tank this time and not added on entirely outside the turret for lack of space.
Your gunner was commenting on the "trajectory of a football" 152mm round, which was not a hypervelocity gun like the M68.
Ultimately, the commitment to Shillelagh was due to limitations in the FCS of main guns of the time. At 2,000 meters, the probability of a first round hit for an average gunner on the M68 105mm was between 0.28 & 0.37 (ARCOVE report, "final report of the ad hoc committee for future tanks & other combat vehicles". Further development of conventional gun systems for armor was essentially abandoned. And look what rules the tank-tank battlespace today.
 

Attachments

  • Hughes.jpg
    Hughes.jpg
    156 KB · Views: 21
  • Screenshot (46)Sm.jpg
    Screenshot (46)Sm.jpg
    84 KB · Views: 19
The LRF comments are gratifying to hear. My first Test Project at the Armor & Engineer Board (Ft. Knox) was the add-on Hughes LRF which began in March or April of 1972. Lengthy project on which I fired many rounds. Relatively trouble free & an improvement on the choke reticle if the target was oblique to the vehicle.
But it was not quite "years ahead of the M60 series"....in fact, the identical system equipped both the M60A1E2 & the production M60A2 even as we tested it on the M551 (it took years to be fielded, I don't know why).
As I was also on the M60A2 Initial Production Test the next year I was already familiar with the Hughes LRF, integral to the tank this time and not added on entirely outside the turret for lack of space.
Your gunner was commenting on the "trajectory of a football" 152mm round, which was not a hypervelocity gun like the M68.
Ultimately, the commitment to Shillelagh was due to limitations in the FCS of main guns of the time. At 2,000 meters, the probability of a first round hit for an average gunner on the M68 105mm was between 0.28 & 0.37 (ARCOVE report, "final report of the ad hoc committee for future tanks & other combat vehicles". Further development of conventional gun systems for armor was essentially abandoned. And look what rules the tank-tank battlespace today.
M60A2 yes, but three years into being on Sheridans, no M60A1s I encountered had LRFs, not even the M60A1 RISE passives. (IIRC)
 
M60A2 yes, but three years into being on Sheridans, no M60A1s I encountered had LRFs, not even the M60A1 RISE passives. (IIRC)
Correct, no M60 or A1 had the LRF's. It was integral to the A2 and the later A3 came out several years after I ETS'd. I never experienced TTS, only the PVS-1 Starlight Scope in VN.
 
Correct, no M60 or A1 had the LRF's. It was integral to the A2 and the later A3 came out several years after I ETS'd. I never experienced TTS, only the PVS-1 Starlight Scope in VN.
We used TTS M60A3s at Ft. Knox to spot for the LRIP M3 CFVs night gunnery. Great sight and was actually more mature than the original M1 sights, though that changed as the M1 systems were upgraded.
 
We used TTS M60A3s at Ft. Knox to spot for the LRIP M3 CFVs night gunnery. Great sight and was actually more mature than the original M1 sights, though that changed as the M1 systems were upgraded.
We were still using the VSS-1 Xenon searchlights when i served. 😄
 

Attachments

  • searchlitesmwater.jpg
    searchlitesmwater.jpg
    318.8 KB · Views: 15
Back
Top