UPDATE: The M1 Streetbrawler

Tanks take a beating in Iraq

A reader sends me the link to this USA Today story. It has some info on how the M1 tank is holding up to continued attacks in Iraq. 80 have been knocked out since the invasion, though many or most of them will be able to be rebuilt and returned to service.

Five men have been killed inside of M1 tanks when they’ve been hit by roadside bombs, and Murdoc recalls that two of them were in this October 2003 incident. Also, at least one of the tanks destroyed was burned out when the truck transporting it was destroyed in Baghdad and another was abandoned during the original Thunder Run and later partied on by Iraqis for Al Jazerra video crews.

m1slatarmor.jpgA number of improvements are being worked on for the M1 to perform better and even more safely than it currently is, one of the most important of which might be a slat armor protective cage for the rear of the tank, where RPG hits can disable an M1. (The illustration at right is from USA Today.)

As mentioned in the previous MO post on the subject, there are other nifty improvements coming for the M1. Another reader sends this image, which outlines the biggies (click for a better view):

The upgrade program is called the TUSK, for Tank Urban Survival Kit. See this Army News Service story for more details, including a monster-sized version of the pic. One thing that bothers me, after looking at the super sized pic, is that the commander’s weapon mount appears to be a RWS Remote Weapons Station like that on the Stryker LAV.

The RWS is not motion-stabilized, something that recent reports are crticising and something that’s bothered Murdoc since before the Stryker went operational. An alternative is the CROWS Common Remotely Operated Weapon Station, a system very similar to the RWS but incorporating motion-stabilization. The CROWS is already deployed in Iraq (I believe it’s on Humvees, but I don’t know for sure) so there should be some good feedback from the field on it’s performance. Murdoc thinks that either the CROWS or another motion-stabilized station is needed.

Thanks big-time to the readers who are helping keep MO in the know. Keep those cards and letters coming.


  1. Do you need independant stabilization on the RWS beyond the stabilization of the turret itself? I mean, the main gun is already stabalized; doesn’t that provide some level of stabilization to the whole turret? I’m really asking — I don’t know. It just seems logical.

  2. Phelps: No, the whole turret isn’t stabilized. As the tank goes over bumps, around corners, and such, the hull pitches, yaws, and rolls and the turret goes with it. Meanwhile, the main gun (and the gunner’s coaxial machine gun) stay on target due to the motion-stabilization. For the whole turret to be stabilized, it would have to be in some sort of floating mount with gyros and actuators or something to keep it on an even keel. The commander’s weapon mount will shake, rattle, and roll right along with the physical turret, throwing off his aim even with the new RWS mount.

  3. There are two tanks that have been made with ‘oscillating’ turrets as far as I know – where the gun is fixed to the turret and the whole turret swings up and down. I don’t think either was stabilised but I’m not sure. One of them is the French AMX-13 light tank. It has advantages and disadvantages. Imagine trying to stabilise something with 20 tonnes of armour on it. It would give the people inside a nice ride though :) Gun shields == good. I do hope they add stabilisation for those which can be fired from inside the vehicle. As I mentioned on another post, I’m a bit worried for infantry walking next to this tank. Normally ERA is a sheet of explosive wedged between two sheets of steel. I’d hate to think what would happen to someone standing beside it when that goes off. Hopefully the front plate has been replaced with plastic or something which will vapourise rather than fragment.

  4. Hm, that’s a great point actually. Since the main gun IS stabilised, you could use the same information (and some trigonometry – you need to know in which direction the other guns are pointing relative to the main gun) to work out how to move the auxilliary guns so that they stay on target. This could avoid the need to install any extra gyros. It could be done with a single datalink from the main fire control computer, a single azimuth sensor for the remote gun mount and some simple code to adjust the azimuth/elevation as the main gun moves in response to vehicle movement.

  5. Yeah, actually I’ve been thinking about this since I replied earlier. There’s probably a way to do it, and the pitch is already covered by the main gun stabilization anyway. One question about the main gun stabilization: What if the gunner isn’t targeting anything? Is the main gun still motion-stabilized? If not, what would happen when the commander was targeting something with his machine gun but the gunner wasn’t? Still the CROWS already has built-in stabilization (though I haven’t heard how it’s actually performing) that apparently works on a Humvee mount, so it would get the trick done on a Stryker or an M1 probably even better.

  6. My understanding is that this is how the main gun stabilisation works: Firstly, it’s actually the sighting mirror which is stabilised, and the gun is slaved to the mirror. This is because the mirror can respond to movements of the vehicle much faster than the gun. So, the target the gunner sees through the mirror appears to stay in his crosshairs because the mirror is constantly adjusting for the movement of the tank and the turret. Also, the gun needs to super-elevate (i.e. point above the crosshairs because the round will drop in flight), plus it may need to aim left/right due to wind and movement of the respect vehicles. So, the fire control computer calcualtes the vertical and horizontal offsets and is constantly moving the gun to point in a direction such that if it were fired, the projectile would land at the target in the crosshairs. However, because the gun is so heavy it’s only pointing in the right direction some of the time. So, if the gunner presses the fire button, it might not fire right away, he might have to hold it down for a fraction of a second while the gun finishes slewing into position. The gun stabilisation itself is enabled, if I remember correctly, while the gunner has his hands OFF two buttons on the targeting controls. I’m pretty sure the mirror itself is stabilised all the time, otherwise it would be hard for the gunner to see anything while the tank is moving. Also keep in mind that while the gun is being loaded it isn’t being slaved to the mirror – it’s lowered roughly level to make the loader’s job easier I believe – then it swings back into position once it’s reloaded. Therefore I think the best idea would be to use the data which allows the mirror to be stabilised in combination with the direction the remote turret is pointing (since, if it’s pointing sideways, its elevation angle is somewhat independent of the main gun’s elevation angle) in order to stabilise the remote turret gun. This would save the cost, weight, complexity, etc. of a set of gyros or accelerometers. The biggest challenge would probably be the integration with the existing system. I’m pretty sure that, even though the main stabilisation system is designed to be used with weapons that are fixed in orientation with respect to the turret, it could still be used to stabilise weapons pointed in different directions, but I’m not sure.

  7. Wow, that’s great info. I had forgotten about the gun needing to lower to reload, too. And yes, I’m sure it’s technically possible. They could get a Mac Mini or something and a couple of USB cables. And a USB eye massager. http://www.murdoconline.net/archives/001841.html (Not really sure where that last bit came from. I just finished reading the first two chapters of the Stryker Report, which cover Command and Control and Digital Systems. Must be a little punch-drunk…)

  8. Ooops. See? I am punch drunk. I meant to say ‘It’s technically possile but there probably are advantages to pulling an off the shelf, self-contained system, too.’

  9. I was thinking, could they just not keep the ammo box in the turret, with the link belt passing up to the gun through a hole in the top. That way, when the belt starts to run out, you could just link the old belt to the new one. Just an idea.

  10. @Nicolas BTW, the pic does not mention whether the tiles are explosive or not, they could just as well be spaced non-explosive-reactive-armor….well, I’m hoping it is.

  11. They are labelled ‘Abrams Reactive Armore Tiles’. Armore sounds like a hybrid of Armor and Amore. Maybe it’s armour that loves the people it’s protecting :) The ‘reactive’ makes me think it’s ERA but I’m not sure. There may be another way to make it reactive. I heard, though, that the tiles were based off those on the Bradley.

  12. It looks like those plates are only on the side tracks, so maybe the Army solution is ‘walk in front of or behind the tank, not in front of it.’ It wouldn’t be the first time the Army relied 100% on training and 0% on technology.

  13. you dont stand that close to a tank today. this aint ww2. they cant see you, are big targets that draw a lot of heavy fire. tanks also have a large concussion ring when they fire. IIRC soldiers are to stay at least 200 feet from a tank.

  14. The Army News Service web site quotes Lt. Col. Michael Flanagan, product manager for TUSK, as follows: ‘Today it’s a 360-degree fight, and these systems are designed to improve survivability in that urban environment.’ The Loader’s Armour Gun Shield looks like it only covers the front 120 degrees of the fight.

  15. I have been thinking about those shaped explosive devices,supposedly nothing stops them.(molten copper)If you put liquid nitogen under 3000 to 5000 psi in steel containers maybe 1/8 in thick and 1/2 in id. Can someone give me some feedback on this

  16. I’m wondering when somebody’ll make the design change from straight reactive armor to an Automatic Defense System like in the Slammers novels. Including manual triggering for special social situations.