On Chimera again ... (designer's notes)

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chykka
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Re: On Chimera again ... (designer's notes)

Postby chykka » Wed 22 Jan 2014 08:18

You know what I'm surprised it made it into the game. However it's fun it is to use with a mass of centurions :P
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Re: On Chimera again ... (designer's notes)

Postby Woodwind » Wed 22 Jan 2014 11:48

Just to clarify the provenance of the two TD programmes mentioned in this thread. The Jagd Chieftain was an Anglo-German project started in 1972. The Chimera was a UK design project run in 1985 by the Armour School at their Armoured Corps HQ.

The Canadian link is still a mystery to me - but their strategy study paper took place only a year after the Chimera was presented to an audience in the UK that included some senior Canadian officers and they might simply have asked to use the concept to fly a few kites in their own study.

I have now dug up some of the paperwork and can answer a few more of those questions. Here goes.

As I re-read it I was reminded that one of the aims was to provide the infantry with heavy tank-destroyer support. I had rather forgotten that aspect of the design - it's worth mentioning though.

We had looked at a number of options but wanted a design that could be in service by the mid-1990s. We discarded missiles as a weapon as we believed that a kinetic energy round should/would be the primary tank-killing projectile.

We saw the priorities of the design as being:

Firepower: Survivability: Mobility (in that order)

Firepower

We wanted similar or better firepower compared to contemporary MBTs, capable of killing the next generation of Warsaw Pact tank at 2000m and to do so against moving targets, on a 24hr basis. We did not see a requirement for Chimera to be able to fire-on-the-move . The (then) experimental L30 120mm gun was selected for reasons of commonality and performance. The mounting provided 8 degrees of depression, 12 in elevation, and 15 in traverse either side of centre. We thought about using an autoloader given the quite low headroom in the fighting compartment but ruled it out as the ammunition is in two parts and thus not easily loaded mechanically. We did go for a carousel ammo storage system which presented the projectiles and charges at the same height via a hatch at the rear of the fighting compartment. Some 46 rounds were carried.

Gun Controls: We used what at the time was the latest thinking in gun control equipment and proposed a merging of some new computing power to achieve an accurate and rapid line-switching capability between targets. We did not have a hunter-killer mode where the commander could easily hand-over a target to a gunner - but we did the next best thing with the TI systems available at the time. The sighting arc was about 30 degrees and we felt that that was adequate when working with other vehicles in a defensive position; the vehicle could always be moved to cover a target outside that arc.

Survivability

The main hull requirement we decided was to provide total protection over a frontal 60 degree arc against current tank guns and missiles and we specified a mix of RHA and Chobham armour - though as previously stated we did not fully understand was the latter was at that time (and the fact that we had non-UK officers involved meant that we could not have even discussed it even if the UK guys had been briefed about it). The rest of the vehicle was to be protected against the usual suspects - 155mm airburst and cannon fire. The hull was designed to withstand a mine under a track. We believed that the flat sides meant that armour upgrades were easily achieved - though we noted that this could significantly increase its weight.

Mobility

From the outset we accepted that there was going to be little innovation in the mobility department. We selected the 1000hp Roll Royce CV12 series engines but did at least adopt the mods that would allow it to be uprated to 1200hp. We wanted a fully automatic gearbox as there was not a dedicated driver in the crew of three. All driving/servicing tasks etc had to be minimised therefore, and it was felt that an auto box was part of that process. We reckoned we would have had 800+ HP at the sprocket for a weight of 53 tonnes which was a decent - if not spectacular - ratio for a TD.

Hydrogas suspension was proposed to eliminate the intrusion into the hull caused by torsion bars; space was a major issue in the Chimera as we soon found out (another reason to have a turreted fighting vehicle).

Hope the above answers some of the questions raised

I have one more document to go through and will get back with any other useful info - though much of it will be a bit boring and technical and probably not worth repeating here. I have also just found some of my preliminary sketches and will try to upload those at some pint.

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Re: On Chimera again ... (designer's notes)

Postby Woodwind » Wed 22 Jan 2014 11:49

Sorry - at some point I meant to say in that last sentence. Though a pint also sounds good!

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Re: On Chimera again ... (designer's notes)

Postby [EUG]MadMat » Wed 22 Jan 2014 12:11

Woodwind wrote:Sorry - at some point I meant to say in that last sentence. Though a pint also sounds good!

Here's some ...
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One of the most interesting thing about this project for me is not a technical point, but the fact you mentionned that it was first envisionned to make use of the tank crews gone in reserve.
That is indeed IMO a good way, if indeed the project was kept cheap enough, to make the best use of their experience and specialization ...

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Re: On Chimera again ... (designer's notes)

Postby Mitchverr » Wed 22 Jan 2014 12:57

Just a few things (though some are more aimed at MadMat for the game in light of what you said :lol:)

So, Mat, "experamental L30", could be a way to improve the Canadian deck more with a bit of an AP buff to their dreaded ultimate stolen killer :D

Now, a big thing that goes around is how slow the L11a5 gun is to load here, in comparason to other 105/120mm guns in use by allies, would the loading system for the chimera have given it an advantage/disadvantage in loading the gun over the other 2 piece ammunition tanks ie the chieftain and challenger 1 in your view? As from what i know of CAT trials, the main problem of the L11a5(just wondering from an 80s view, so i suspect the L30 wouldnt have been "ready" bu then but might have been, i dont know) was really the loading speed of the gun, just curious.


Also, for the "shell trap" in the front, i am just wondering if it was thought possible to design the frontal arc with a gun mantlet on it of some kind, allowing it to not have the trap, though it would be intergrated into the frontal armor allowing a traverse, just something i would have thought of doing, though i know its a little hard with armor that isnt just steel to give it a kind of curved front/shape, not to forget adds weight on the gun making it a little awkward there too.
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Re: On Chimera again ... (designer's notes)

Postby Woodwind » Wed 22 Jan 2014 13:39

The L30 would have of course gone on to be fully developed and is used in the Chall 2 today.

Part of the costing assessment looked at crewing by reservists as there was no way we were going to be able to propose raising several more regular armoured regiments to man these vehicles. The three-man crew also helped to keep costs down and to make it easier to actually find enough crews from the reserves.

Reference the "shell-trap" or ballistic window to use a slightly more technical term, we simply could not fill it without adding a huge amount of weight to the front end. Anything less than protection against tank-rounds over the frontal arc would have been rather pointless in our view. The behind armour metal would have been more than enough to cope with cannon rounds etc. from doing any real damage - although it might have been possible to jam the traverse/elevation mechanism with a very lucky shot by a 30mm RARDEN for example.

Someone asked whether the Chimera concept would have had or indeed did have any influence upon armoured vehicle or strategic thinking. I think possibly it might have - but not a huge amount other than to show once again that a conventional tank with a turret is a far better fighting machine at the end of the day. A TD is OK for set-piece battles with conventional armoured forces moving out from established front lines etc - but we have seen in recent years how these conditions do not occur in many modern conflicts. Whether or not the Chimera was a serious influence on Canadian studies in 1986 I simply do not know as I was unaware of that work till I read about it on a Canadian army forum a few days ago.

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Re: On Chimera again ... (designer's notes)

Postby another505 » Thu 23 Jan 2014 21:58

Wow thank you woodwind!
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Of Salt

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Re: On Chimera again ... (designer's notes)

Postby [EUG]MadMat » Thu 23 Jan 2014 22:12

I've edited the OP with that:
[EUG]MadMat wrote:EDIT: And here is one of the original drawing (december 1984):
http://i.imgur.com/ftWFTeJ.jpg

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Re: On Chimera again ... (designer's notes)

Postby trotskygrad » Thu 23 Jan 2014 23:07

is that reactive armor on the side?
NEXT TIME I SEE A DAMN FLAMEWAR INVOLVING DARTH-LAMPSHADE, FROSTPOOKY, LONERIFLE, FADE2GRAY, TROTSKYGRAD AND/OR ANYONE INVOLVED IN A DISCUSSION BETWEEN THEM I'M GOING TO HAND OUT BANS TO ANYONE USING ANYTHING LOOKING REMOTELY LIKE AN AD-HOMINEM

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Re: On Chimera again ... (designer's notes)

Postby Woodwind » Thu 23 Jan 2014 23:22

No - it was supposed to be a space for some new version of Chobham - or simply a big lump of steel to protect the side of the fighting compartment that would be exposed in a typical fire position. We were not really into ERA at that time.

The background scenery gives a bit of a feel for the strategic backdrop to the concept; East German watch towers on the IGB. Rather fitting for ALB in a way.

Don't forget - this was my own sketch and it predates the final version and the model. In fact, I was a bit annoyed when someone saw it and then told me that I had got it all wrong. It was probably the Canadian officer on the course. I think it was eventually used in the report though.

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