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Kurt_Laughlin · ***Power User*** Offline Joined: Jan 24, 2006 Posts: 577

Was it possible for a Shillelagh to hit an aircraft (a helicopter being most probable)? Was the capability ever examined?

KL

Doug_Kibbey

The aircraft would have to be pretty much absolutely stationary or moving no faster than a medium speed ground vehicle, like a dead hover helicopter for that to work. The key to a Shillelagh hit was to hold on target and ignore the movements of the missile from the designated target because there was quite a lag in corrections from the feedback loop of this beam-rider.

Trying to follow something moving with ANY real speed would be out of the question. Attempting to "fly" the missile onto course corrections was emphatically discouraged.

I suspect the lag of the missile as it corrected it's flight down the cone of the beam would make tracking an aircraft, even low performance, basically impossible. Don't know if it was ever attempted. It certainly wasn't discussed with regard to either of the two types of Shillelagh-capable vehicles I served on within my earshot.

MarkHolloway

I was involved in a test at Fort Bliss in 1978 out at the McGregor Range. They were writing the doctrine for Armored Cavalry engagement of aerial targets. I was a turret mechanic for the test. A total of 27 Shillelaghs were fired at a moving helicopter. None hit it but they were all very close. After the firing I found a malfunction in the system that must have occured during the first lauch. I started telling people that the test was invalid due to the error. I was given a 'gag' order not to talk about this fact. Probably because of the large amount of money spent. I think had this error not occured then it would have hit it's target. They also fired the 20mm cannons on the M114A2's and the .50 cals on the M113's. Fort Knox had sent out a prototype tank I think designated M60A1E3. It fired sabot at the targets but I don't remember if it hit it. The M60 had rotary shock absorbers as found on the M1 and the sprocket guard as found on the M1. Anyway, the Shillelagh test was bogus and I wish we could have done it over. This is technical but I'll try and explain. The Shillelagh is 'watched' by an optical tracker (IR). Before firing you do a 'tracker alignment test' where a prism is moved in front of the tracker and it projects a light on the tracker simulating the missile. After this test the prism resets and moves out of the way. In this case the prism failed to reset and it was in front of the tracker during firing. Essentially blinding the system. Otherwise I believe it would have hit it.

Joe_D

That M60 sounds like it was the ATB model,

Was one of the proposed upgrades meant for the A3 program that wasn't accepted. Only thing that actually was implemented was a stronger torsion bar using a newer manufacturing process that was interchangeable with the older system. Was an off shoot from the tube over bar experiment that was never implemented either. The sprocket guard sounds like they were testing a guide free carrier like that on the M1. The firing tests were most likely testing the new XM-21 FCS's ability to engage aerial targets with APDS/APFSDS, being it could calculate lead angles and the velocity of these rounds enabled it to actually apply a workable offset.

Wasn't there an indicator for the gunner to let him know a system MALF happened when the prism didn't reset? If not maybe there should have.

Nice history, maybe a report is out there somewhere explaining everything (Minus your observations Smile

)

Joe D

MarkHolloway

Joe, If the gunner were to run a system self-test it would have shown the error. But in the operating mode the system wouldn't show it. The warning lights just came on when testing the system. I checked the system personally prior to the first missile and it passed. So I've always thought the prism didn't reset after I finished testing the system. The prism was spring loaded and a solenoid had to actuate in order for it to reset.

Doug_Kibbey

- MarkHolloway

Joe, If the gunner were to run a system self-test it would have shown the error. But in the operating mode the system wouldn't show it. The warning lights just came on when testing the system. I checked the system personally prior to the first missile and it passed. So I've always thought the prism didn't reset after I finished testing the system. The prism was spring loaded and a solenoid had to actuate in order for it to reset.

I'm surprised the program director didn't have the missile guidance subsystem check repeated at some point during the test, Shillelagh prices being what they were. I'm not so sure that it was a system malfunction as much as the limitations inherent in the system, though. Had occasion to fire a few Shillelaghs and I have my doubts about tracking and hitting anything at LoPer flight speeds in excess of about 60mph. What was the test aircraft doing....hover, straight and level? Sky or ground in background? At what elevation above horizon?

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