Chieftain MK3 Build

[Mark Heaps]

Also the vision block being inserted from inside is correct. The driver had a day scope and a night scope which he could swap from inside.

[Stephen White]

David, long time since I caught up with your marvellous, long running saga. The change in driver’s periscope mounting was the result of introducing the driver’s night sight, an early image intensifier. It was not without amusement. For example, it was somewhat alarming as a commander to have nothing but natural eyesight when your eighteen year old driver could claim to see a lot more. It made for a lot of trust. It took a while for drivers to get used to some of the characteristics of II such as reduced depth perception. Obstacles were closer than they appeared. Similarly, the sight was poor at revealing holes and dips ahead. We were first over an engineer AVLB one night and my driver was unable to see that the Sappers had mislaid it and the drop on the far side was significant. Chieftains do bounce if dropped, whereas turret crew don’t. My dentist had a bit of work to do.

[David Battson]

Stephen, Mark
Thank you for sharing your experiences and anecdotes from living and working with Chieftain, it adds an extra dimension to the subject... and as I've found building Chieftain, you can never have too many dimensions ! Stephen, thank you for clarifying the reason for the vision cover change, I was thinking about modelling the vision block in the picture below which I now guess would have been a bit of a faux pas. Was there an earlier binocular vision device for the driver, how did they see using the infra red lights ?
David

later night scope ?

[Mark Heaps]

David, that is indeed the drivers nightsight, an early image intensifying device. The daysight was a simpler vision block. Best photo I can find online giving its dimensions and appearance is https://www.gettyimages.de/detail/nachr ... popup=true
I believe both were used on a lot of the armoured vehicles in British Army service, at least I think they were interchangeable between CH, CR1, FV430 series and also M109s in British service.
The drivers nightsight could also be put to other uses, I was attached to 137 Bty, 40 Field Regt RA during the first Gulf War. The NOD (Night Observation Device) we had got damaged so the drivers night sights were the only night vision capability we had. I made extension cables for each vehicle so that a night sentry could sit on top of the vehicle scanning the surrounding ground using them. I heard later that the driver did not always get his nightsight back for a nightmove, instead it being kept by the vehicle commander

[Mark Heaps]

Another anecdote.
The "coffee capsule" on the left side of the sight (righthandside when looked from the front) is the washer jet housing.
Swap over two 3-pin plugs on the top left of the Hull Main Junction Box and the washer pump would function as soon as the driver turned his master switch on giving him a wet neck.
Found this out after a previous ECE had not put them back correctly after searching for a Neg Earth fault.

[Mark Heaps]

And to answer Davids question, the night sight also amplified light in the infra-red spectrum giving the driver more vision if he had the IR headlights switched on and they actually worked. Checking that they worked required removal of the IR lens so not always done.
The gunner´s sight had the same capability with the search light with IR filter in place providing illumination of the area out front. Only the commander had only his Mark 1 eyeballs to rely on.
The search light on a Chieftain was a scary bit of kit to work on at times. The circuitry was simple and easy to fix but the searchlight had to be unbolted from the turret and placed on the back decks when the tank was transported by rail otherwise it hung out too far over the track guage. Sö support the weight of the searchlight on the crane, undo the bolts, swing the searchlight out a bit and then someone has to reach in through the gap and undo the cables. Reverse the process on un-loading from the train. Depending on whether the crane-op liked you and how sadistic he was could make it a bit hairy.

[David Battson]

Mark,
Thank you for the information. I am making an early MK3 as it would have been out of the factory in 1970 and wanted to do something more than just the clear drivers periscope. Would the image intensifier in the picture above have been around at that time or was there an earlier version ?
David

[David Battson]

Moving on to the headlights. Whilst the kit bezel size is ok, the rear of the housing is a little too square in shape. To improve the look, new headlight units were turned up. A slot cut out of the bottom of each allows the addition of a squared off section for the light support and cable input.

On the real thing the light units clamp onto pegs welded to a flat mounting bar and the wiring cables come out of the back of the light units which presents a number of tricky challenges to resolve at scale such as fixing strength, alignment and scale wiring detail. As an alternative I followed Phil's method of extending the fixing supports and wiring down into the glacis and made up new hollow fixing supports for a stronger fixing and requiring only dummy wiring detail at the back.

After an order to Component Shop (thanks John for the recommendation) LEDs were fitted to all the lights. The infra red uses a red LED glowing through a glass watch lens painted with cherry red ceramic paint. The white light shines through an off the shelf 13mm solid resin headlight reflector - I'm hoping that there is enough going on optically with the lens to detract from the fact that the lens is plain and doesn't have the diffraction markings of the real thing.

Hopefully there won't be any issues with the LEDs as the bezels are glued in place and dummy fixings added around the perimeter - the gaps intentionally exaggerated to stop the detail being lost under future paint layers.

All four lights were glued in place and aligned at the same time, the mounting bars merely proving height adjustment. Dummy cable plugs were added to the rear of the lights. Dummy cables will be added sometime later on when the mudguard and side light details are finalised.

Rallye upgrade

[Mark Heaps]

Hi David ( and for others contemplating copying you )
The IR lens was so dark red as to to appear almost black, no visible light at all when switched on. When inspecting the tanks, we would have to undo the securing screws on the lens untill we could get enough gap to confirm the bulb was still operational.
Maybe use a non-permanent black pen on the lens for daytime displays and wipe off for low-light, night-time running to give the non-miltary spectators the impression they are watching the scene through an IR viewing device. The military & ex-military spectators will know that the red light illumination is wrong It was IR light being emitted, we did not see it as red through our IR sights.

[Richard Goodwin]

Some really high grade detailing going on there David, keep it up . I am however in agreement with Mark, considering the level of detail and accuracy you're aiming for, black lenses would be more appropriate for your IR headlamps. That said, it's your tank so be theatrical if feel the need

[John Clarke]

Nope, don't agree, red LED's all the way, how else are you going to know if their switched on or not? You'll be telling me next that the big band sounds out of the sound module isn't realistic or you can hear internal radio chatter outside the tank???

[Richard Goodwin]

Nope, don't agree, red LED's all the way, how else are you going to know if their switched on or not?

If you don't fit em, you won't need to turn them on Cost and time saving measure that one

[David Battson]

Thanks chaps for the the thoughts on the IR lights. The lense colour has come out a bit redder in the photo than it actually is, but I will check again when its unmasked and may well darken it up some more. However the LED bulbs are definately staying, everything in scale modelling is a compromise and as John has said it adds a little bit of extra interest and theatre - even if its just explaining to people that "yes I know that you can't see it in real life !".
David

[David Battson]

Headlight guards
As each pair of my new headlights sit slightly further apart than the kit ones, new headlight guards were required to cover them. The guards were made up from brass bar, wherever possible pinned and then soldered together. To get the required shapes, the bar was bent around a jig of steel pegs set in an piece of scrap aluminium plate. Holes were also drilled in the jig for the legs to match the hole pattern previously added to the glacis on the galcis, so that the finished assembly would be an exact fit. To make a mirror image frame for the other side the plate was simply turned over and the pegs pushed through to the other side.

With the light guards completed, I had to complete the look by making up the splash guard that fits between them. On the real thing, the guard is only held in place by two arms clamping back onto the light guards. At 1/6 scale then, not only is the splash plate quite delicate detail for the front of an rc tank, it also has the potential to damage the light guards should it get caught up or hit by something. In an effort to make things more robust, I added three support legs to the bottom of the splash plate which will be embedded into the glacis. These should help hold the splash plate in place and reduce any forces transferred to the light guards.

splash plate and guards.PNG (1.01 MiB) Viewed 1939 times

For now, the light guards and splash plate will be left loose and won't be finished off until the dummy lighting cables are added which in turn rely on the front mudguards being complete and finally fixed down which in turn rely on....etc...etc...
David

[John Clarke]

Very nice, but I'm trying to imagine what sort of forces are you expecting on the splash guard?