Re: MBT-70
 

Actually it's closer to 1/2 mile. The MGM-51 had a minimum range of 730 meters. As I understand it, the ballistic track of the missile caused it to drop out of the sight/tracker's field of vision within the minimum-range envelope.

Adrian

Re: MBT-70
 

"Pop out of twin hatches and fire at the target"....?!
Sound like a trailer from Star Wars. No wonder the whole vehicle was a failure.

Re: MBT-70
 

Still, it was a very cool tank. The prototypes that never make it into service are actually more interesting than the stuff that does the real fighting. How many German Maus superheavy tanks saw combat service in WWII? Zero. How many books where written about the Maus? Dozens.

Re: MBT-70
 

Isn't the shelleleigh what they use in the Airborne light tanks that the 82nd has? I thought they hated them ...

Re: MBT-70
 

The MGM-51 Shillelagh actually had a full six inch diameter warhead twenty years before the TOW 2 was fielded, and packed a 15 pound warhead, almost twice the weight of the five inch warhead of the original TOW. It was closer in size and penetration to the first generation HOT missile. Those who fired it say the range is actually greater than the listed 3,000 meters, since it was infrared command guided and had no wire. One point I'd like to make about that factoid: there are restrictions on firing wire guided ATGMs over standing water. We've seen that fascinating CNN footage of a British Striker (?) firing a Swingfire missile at the abandoned Iraqi tank during OIF...the missile flies over a shallow pond, and several yards short of the far bank where the target tank was parked, the missile suddenly dips toward the water, strikes the surface, ricochets off the sandy shore, and manages to hit the target. If the target was further back from the shore, the missile surely would have missed its mark, having gone ballistic until the motor shut down. The Shillelagh and other non-wire-guided missiles aren't hampered by such water obstacles.

Basileus

Re: MBT-70
 

Why is there the restriction? How does the water below flight path affect the guidance system?

Re: MBT-70
 

I think the bigger issue was hating the system and the vehicle it was attached to. The M551 Sheridan was in many ways too light to handle the power of the missile, and so were its systems. Launching the missile had a tendancy to shake things in the turret loose and/or outright damage sensitive components. Furthermore, because of the vehicles weight the 152mm conventional (non-missile) ammunition that was carried meant that the vehicle had a very large engagement blind spot between which it could not hit a target with its main gun, but before the missile's minimum range. Of course the M60A2 was said to have suffered from the same blind spot.

Re: MBT-70
 

I may be speaking total BS here, but isn't that related to the fact that the wires aren't coated with some insulant due to weight constraints?
The signal-bearing wire is coiled inside the missile body (or around it in some earlier examples) and doubled or quadrupled for redundancy and equilibrium issues, so the specific weight of the wire is a critical issue to the missile performance. So electric insulation may have been disregarded and therefore lead to critical signal shunts over water.

Another possible case, which would be more consistant with the Striker anectode cited above, is that the wire just sinks into the water (sounds probable for even thin copper wire) fast enough to drag the missile back and down. That would be linked to the fact the the wire uncoils freely while the missile moves, but would also run against this fact, except at top ranges, because of the amount of reserve coiled wire available for unattended sinking before it affects the missile's flightpath.

Just my two cents, extracted from whichever data I could digest on the subject! So if anyone has better facts on this or wants to speculate further...

Re: MBT-70
 

It wasn't the missile, it was the conventional rounds that broke the fire control system. Every time the main gun fired a conventional 152mm round (that's a howitzer-sized round coming out of a 15-ton light tank), the recoil would cause at least two or three roadwheels worth of track to completely leave the ground. The shock would usually result in something breaking. The missile itself imparted negligible recoil.

AFAIK the M60A2 didn't suffer this damage, but the overly complex combination of gun and missile fire control was a maintenance nightmare, the missile couldn't be tracked at night or in inclement weather, and such conditions also rendered the primitive laser rangefinder nearly worthless. Later, when the Tank Thermal Sight was mounted on the 82nd Airborne's Sheridans, there were no problems firing at night or in moderate weather.

According to a former Sheridan crewman, the dead range issue was ironed out. Conventional rounds had an effective range around 1,000 meters, well above the minimum range of the Shillelagh (about 730 meters). In WinSPMBT, the gun has a maximum range of 20, and the missile has a minimum range of 20, which works out.

Basileus

Re: MBT-70
 

I concur with your former conclusion in that Striker footage, PlasmaKrab. The wires are too thin to have much insulation, hence standing water, chain link fences, power/phone lines etc. may short out the wires. The rather sudden dive the missile took toward the pond's surface didn't look like a voluntary course correction. As far as depth of the pond, I don't think the weight of the wire would impact missile guidance, as wire guided missiles are routinely fired from helicopters without adverse effects, even with rotor downwash.

Basileus