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Thermal Shrouds Question
The AFV ASSOCIATION was formed in 1964 to support the thoughts and research of all those interested in Armored Fighting Vehicles and related topics, such as AFV drawings. The emphasis has always been on sharing information and communicating with other members of similar interests; e.g. German armor, Japanese AFVs, or whatever.
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MarkHolloway
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PostPosted: Tue May 08, 2007 5:20 am
Post subject: Thermal Shrouds Question

Exactly what are main gun thermal shrouds for? I was told that it's so the heat from the gun tube does not interfere with the thermal sights but I think shrouds were around before thermal sites.

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piney
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PostPosted: Tue May 08, 2007 6:01 am
Post subject: Re: Thermal Shrouds Question

I was told by a tanker friend that it was to keep the barrel as temperature stable as possible to enhance accuracy. don't know if he was correct or not

Jeff Lewis
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MarkHolloway
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PostPosted: Tue May 08, 2007 6:10 am
Post subject: Re: Thermal Shrouds Question

Piney,

I've heard that too. Was told that the sun beating down on the tube makes it hotter on top than on bottom. Shroud makes the temp even all the way around.

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Joe_D
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PostPosted: Tue May 08, 2007 10:12 am
Post subject: Re: Thermal Shrouds Question

Hi 'Weed, Jeff.
Was told that the sun beating down on the tube makes it hotter on top than on bottom. Shroud makes the temp even all the way around.


Yes, the shroud allows the tube to maintain a relative even temperature all around thus causing the metal to expand and contract evenly. This reduces boresight loss by tube bending and increases accuracy from round to round. Prior to thermal shrouds, we would boresight first thing in the morning and then re boresight at least 2 to 3 more times during the day based on how warm it was and how hard the sun beat on us. During firing the tube also heats up and the shroud reduces the bending of the tube by about 50% IAW the "Book". One dirty trick on the A1's was to pour water over or urinate on another crews tube without them looking during gunnery so they would loose their boresight Twisted Evil . The Master Gunner School actually demonstrated this phenomena by pouring water down the tube from the breech after firing a few rounds. Then they do an MRS update (That little device on the end of the M1 Tubes) and fire another to demostrate that it will correct for boresight loss. The longer a gun tube is, the more important the shroud becomes. Very important for long range gunnery.

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Sabot
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PostPosted: Tue May 08, 2007 12:59 pm
Post subject: Re: Thermal Shrouds Question

The thermal shroud also contains the heat around the gun tube. This way the thermal radiation (heat) eminating from the gun tube does not distort the image on the thermal sight. This only effects tanks with thermal sights though.

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Roy_A_Lingle
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PostPosted: Wed May 09, 2007 12:00 am
Post subject: Re: Thermal Shrouds Question

Hi Mark! Hi Folks!

I remember prior to the 1973 Middle East War, there was a chart that listed the max effective range of US Army Anti-tank weapons.

While the TOW was listed as 3,000 meters, the 105mm on our M60 MBTs was only listed as effective out to 1,200 meters. One thing that always confuzed me for the longest time was that the M60 tank was capable of 4,400 meters when it rolled out of the factory doors.

That was also during the time when there was a lot of talk about ATGMs being better than MBTs because they could hit targets at greater ranges than a tank and cost less.

When the 'lessons learned' came out after the 1973 war, the US Army was very surpised that IDF tankers had a very high number of hits on targets at greater than 1,200 meters with 105mm cannon.

A number of things where changed with US MBTs and tanker training. The three things I remember most was the AOS was installed on the M60s, the thermal shround was added (something the Brits had been doing ever sense they fielded the Chieftain) and the Master Gunner Program was started.

Some very old history, as I remember it.
Sgt, Scouts out!

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JimWeb
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PostPosted: Wed May 09, 2007 4:20 am
Post subject: Re: Thermal Shrouds Question

- Roy_A_Lingle

A number of things where changed with US MBTs and tanker training. The three things I remember most was the AOS was installed on the M60s, the thermal shround was added (something the Brits had been doing ever sense they fielded the Chieftain) and the Master Gunner Program was started.


Excuse me we had them on Centurions as well!

Cool

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Roy_A_Lingle
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PostPosted: Wed May 09, 2007 4:30 am
Post subject: Re: Thermal Shrouds Question

Hi Jim! Hi Folks!

- JimWeb
- Roy_A_Lingle

....something the Brits had been doing ever sense they fielded the Chieftain.....


Excuse me we had them on Centurions as well!

Cool


If I remember right, the British Chieftain was the FIRST MBT to use thermal shrouds. In time just about everyone who used a 105mm gun tube based on the L7 design added shrouds. I remember a lot of Centurion photos with tubes that only had paint on them.

Sgt, Scouts Out!

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JimWeb
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PostPosted: Wed May 09, 2007 5:51 am
Post subject: Re: Thermal Shrouds Question

- Roy_A_Lingle
Hi Jim! Hi Folks!

- JimWeb
- Roy_A_Lingle

....something the Brits had been doing ever sense they fielded the Chieftain.....


Excuse me we had them on Centurions as well!

Cool


If I remember right, the British Chieftain was the FIRST MBT to use thermal shrouds. In time just about everyone who used a 105mm gun tube based on the L7 design added shrouds. I remember a lot of Centurion photos with tubes that only had paint on them.

Sgt, Scouts Out!



And I can remember a lot of M60 tubes without them... BUT the thermal jacket was first issued on the Centurion Mk 10 - four years before Chieftain entered service. All marks after that had them issued but not neccessarily fitted.

Cool

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Joe_D
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PostPosted: Wed May 09, 2007 12:25 pm
Post subject: Re: Thermal Shrouds Question

Hi Roy, Jim,
What's interesting is the Thermal shroud did not get fielded with US Tanks until the M60A3 came around. Kinda funny since everyone else had them long before. I think it had a lot to do with the whole package upgrade to A3. Putting a shroud on an A1 would help you with maintaining your boresight but besides that not much else. I can understand why you would need one on the Cheiftain, just look at the length of the tube.
Maximum effective range on the A1's was officially 1800 meters. The FCS could make firing solutions out to 4400 but to be able to consistently hit (98% excluding Gunner error) 1800 was it. The A3 would also calculate solutions out to 4400 but it's MAX was 3000 meters with the same gun. Amazing what a modern FCS can do. Some of the things it compensated for that the A1 didn't were Air Density (Elevation and Air Temp), Crosswind, Cant, Ammo Temp, and a consistent accurate Rangefinder good for+/- 5 meters.
About the Master Gunner Program, Yes, it started to make a big difference. But then you had to get larger CVC helmets when their heads swelled up Mr. Green

Joe D
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mike_Duplessis
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PostPosted: Wed May 09, 2007 1:49 pm
Post subject: Re: Thermal Shrouds Question

Didn't i read somewhere that Merkava has (had) a bit of a problem in regard to thermal imaging distortion. Basically, you're out in the hot desert in a big steel box with the engine compartment between you an the target. Those 'heat ripples' off the hot engine deck make the setup less than ideal.

okay, I may be all wet on this. This may be a problem recounted from the '82 Lebanon war (25 years ago!) for all I know!
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Roy_A_Lingle
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PostPosted: Wed May 09, 2007 11:53 pm
Post subject: Re: Thermal Shrouds Question

Hi Mike! Hi Folks!

- mike_Duplessis
Didn't i read somewhere that Merkava has (had) a bit of a problem in regard to thermal imaging distortion. Basically, you're out in the hot desert in a big steel box with the engine compartment between you an the target. Those 'heat ripples' off the hot engine deck make the setup less than ideal.


I don't know about the Merkava, but that sounds possible to me. In my current job, one of things I do is use thermal cameras. When the cameras were new, heat from near by street lights didn't bother them. But as the cameras aged, nearby heat sources start interfearing with them and the picture quality goes to pot when the camera is pointed in the direction of a street light.

Sgt, Scouts Out!

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Roy_A_Lingle
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PostPosted: Thu May 10, 2007 4:32 am
Post subject: Re: Thermal Shrouds Question

Hi Jim! Hi Folks!

- JimWeb

....the thermal jacket was first issued on the Centurion Mk 10 - four years before Chieftain entered service.
Cool


I didn't know that, possible because I am not British, I just remember the Chieftain as the first tank I ever saw with thermal shrouds and always wondered why the US didn't also use them.

Thanks for the update Jim.
Sgt, Scouts Out!

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JG300-Ascout
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PostPosted: Thu May 10, 2007 5:21 am
Post subject: Re: Thermal Shrouds Question

...and to add to the list of mysteries like "Green Tigers in Africa" and "Pink Panthers in Vietnam" there's always the......









...wait for it......








"Thermal Shroud of Turin"


(Thank ya' very much....)

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