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Ah, I have discovered a relatively simple identification cue to tell the difference between an FSED XM1 and an LRIP or later Abrams...

If the lower, rear part of the turret has a vertical "slab" (my word) - like on this one (see also Hunnicutt's Abrams p 200) - its an FSED XM1.



LRIP & later Abrams dont have that vertical slab - see this pic & Hunnicutt's Abrams p206.



So the Abrams at the Fort Hood East Gate is an FSED XM1 - one of only 11 built. However, it appears that Operational Test III (OT-III) at Fort Hood (ie 2-5 Cav, etc) used LRIP, not FSED, tanks (see Hunnicutt's Abrams, p 202-203). Although FSED Abrams were tested at Fort Bliss during OT-II...

Neil

So I'm to assume that this is a relatively rare M1? Any one know what became of the other eleven? And I'm still curious as to what the stampings on the side skirts stood for.

Yes, its pretty rare. Its a "true" XM1. XM1s include the original XM1 competitor vehicle (the turret exists, not sure what happened to the hull), and the 11 Full-Scale Engineering Development (FSED) pilot vehicles (PV).

PV1 is in front of the Patton Museum at Fort Knox
PV4 has the Chrysler competitor turret on it for some reason & at least was in storage at TACOM in Warren, MI
PV11 was used for live-fire testing & may or may not still exist "behind the fence" at APG...

There's another "XM1" at TACOM.

The Fort Campbell "XM1" could be FSED PVs...

The APG "XM1" is probably an LRIP vehicle - these were sometimes called XM1s as well...

Neil

How do you determine which tank is 1,2,3, or so on?

- SFC_Jeff_Button

How do you determine which tank is 1,2,3, or so on?

Jeff

Research, Research, Research! Also a little luck that someone has documented it in print!!!

Thank goodness for Hunnicutt's indepth work. It really helps provide a sound basis for most armor related, historical information and data. (I'm sure most on this DG will atest to...)

Don

Yes, but... Hunnicutt's purpose was to explain the development & fielding of a particular tank or weapon system. This means that individual pilots or prototypes (pictures, RNs, SNs, etc) are occasionally mentioned... But in general, the fates or disposition of all pilots or prototypes are not given, and the location of stampings is certainly not. That being said, they're a great reference!

But in cases like these, we need to fill in the details. Unfortunately, I dont have a good way yet to determine the PV number or SN externally yet.

Don, any chance you could poke around the Patton Museum's XM1 next time you're there?

Neil

- Neil_Baumgardner

Yes, but... Hunnicutt's purpose was to explain the development & fielding of a particular tank or weapon system. This means that individual pilots or prototypes (pictures, RNs, SNs, etc) are occasionally mentioned... But in general, the fates or disposition of all pilots or prototypes are not given, and the location of stampings is certainly not. That being said, they're a great reference!

But in cases like these, we need to fill in the details. Unfortunately, I dont have a good way yet to determine the PV number or SN externally yet.

Don, any chance you could poke around the Patton Museum's XM1 next time you're there?

Neil

Did it yesterday, but a 'tad' too cold (temps in 20's) to do any real 'hunting'. No stamp tags on skirts, no obvious markings. I'll do a little more indepth snooping next time.

Don

I would ask the museum directors but they cant even keep track of where their Shermans are, (seriously, I had to tell them what motor pool they were in and they still cant find a field piece). Their anxious for me to assist them but they don't want to do much for me. I think Dontos is the "key" to our research at this time. I will try and get back to the XM-1 when I get some free time and look her over again.

Jeff,
Those stamps on that XM-1 should be ID marks for the Ballistic skirts. C/A should mean "Chobham Armor". Remember that when the M-1 was first made it was not designed with the new armor by either Chrysler or GM. It was later demonstrated to the US and was adopted for the program. From what I remember the pilot vehicles were the first to be equipped with this material. That's why the turret's appearance changed so much from the prototype. Can't bend it or shape it, had to made in slab form. The Chrysler skirts were marginal protection and served also to reduce dirt ingestion of the turbine engine

Joe D

- SFC_Jeff_Button

How do you determine which tank is 1,2,3, or so on?

Some of the PVs had numbers stamped into the hull in various places. I recall that one of the tanks that was at TACOM had PV4 stamped into the hull. The Fort Knox example has no numbers at all, AFAIR, which leads to the question "how do we know it's PV1?" Unless museum records prove that, I don't really know.

Jeff, I'd be real interested to hear if you can find anything on that Hood tank that shows which PV it is - it is definitely a rare tank! I'd guess only about 5 or 6 of the original 11 still exist, and most of those were modified from their original configuration, due to testing improvements. An example of this is the "paddle wheel" track retainer on the sprocket. This was installed on all (I think) 11 PVs as a result of the initial OT-II test at Fort Bliss, when the tanks threw track a lot. The second part of OT-II was at Fort Knox, using the paddle wheels (and other improvements).

Other than that, this Hood PV looks pretty original, on the outside. It still has the ammo feed chute for the TC's 50-cal, the old-style MRS held on by a bunch of bolts, the original front skirts with circular recesses for the latches, etc.

As Neil mentioned, the tanks used for OT-III at Hood and later in initial fielding were the first 110 LRIP tanks, not the PVs. These were also technically XM-1s, since the tank had not yet been type-classified. I was involved in this fielding, and I do not recall ever seeing a PV at Hood at that time (I think I would have noticed, being kinda "into" the tank history at that time).

I will try to find my notes and photos from the early 80s. Honestly, I can't remember now if the LRIP tank S/Ns started with a letter, or just the number. They were all made at Lima, so maybe it was just a number without the L. But I do remember refering to L8 at that time - L8 was not fielded, but was used for various tests (it had an under-armor APU added to the left-rear sponson). I wonder whatever happened to L8 ... it had so many mods, I doubt if it was ever fielded to a unit ... not in that configuration, anyway (if anyone finds an early M1 with an odd box with louvers sticking at the back at the upper left rear, it's L8).

My notes from way back when also told where all the PVs were, at that time. Will try to dig that stuff out.

Geoff Walden

- Geoff_walden

- SFC_Jeff_Button

How do you determine which tank is 1,2,3, or so on?

Some of the PVs had numbers stamped into the hull in various places. I recall that one of the tanks that was at TACOM had PV4 stamped into the hull. The Fort Knox example has no numbers at all, AFAIR, which leads to the question "how do we know it's PV1?" Unless museum records prove that, I don't really know.

Geoff, do you remember where PV4 was stamped?

As for the Knox example, we at least know its a PV since it has the vertical "slab" on the rear turret - maybe Don can chime in as to what the museum records say... And I thought I had found "something" on it that proved it was PV1...





Neil

- Geoff_walden

My notes from way back when also told where all the PVs were, at that time. Will try to dig that stuff out.

Geoff, if you could find that list it could be a goldmine! Next though, since the Chrysler turret got put on PV4.... What happened to the original chassis?

Neil

I guess a return trip to the "PV" M1 is in order for tomorrow! I'll climb up on it and all over the top of the hull and turret. Any mark I find I will photograph. I will also re-stick my arm inside and try to get a few different shots of the interior.

- SFC_Jeff_Button

I guess a return trip to the "PV" M1 is in order for tomorrow! I'll climb up on it and all over the top of the hull and turret. Any mark I find I will photograph. I will also re-stick my arm inside and try to get a few different shots of the interior.

Jeff

There is usually a data plate on the interior turret wall at the TC's position. If you can get a shot of it (if one is there) you might be able to get some information.

I'll dig around and see if I can find an image of its location, and post it a little later.

Don

- SFC_Jeff_Button

I guess a return trip to the "PV" M1 is in order for tomorrow! I'll climb up on it and all over the top of the hull and turret. Any mark I find I will photograph. I will also re-stick my arm inside and try to get a few different shots of the interior.

Here is a reference image for the turret data plate.



Don