Bomb Aimers S C I panel

Dur……

I’ve been looking over some AP1660A circuits and I’ve just realised that the ‘Mid Turret’ that is referred to as being interlocked is the one that drops below the aircraft. This is because the circuits I was looking at are for early MKI aircraft which did not have a dorsal (mid-top) turret. Clearly you would expect the gas to easily enter the mid lower and rear turrets.

Only 7 months late perhaps, but it does actually help to date the circuits!

James

That’s the one on the routing chart alright.

James

I`ve been through some of the junction boxes to hand and found the one for the position in the Bomb bay in question.The side is marked `SCB` with a very small custom made input with a lot of empty terminals inside.

Hi Hindenburg

The circuit diagram says that your item is the Engine Bulkhead Junction Box Z.

You will find it on AP1660 A Vol 1, Section 6, Chap 1, Fig 1 drawn in each of the engines.

Don’t know what mod 501 was, but any small change(s) could have rendered it unusable. I’ll bear it in mind at Hendon when I go.

James

[ATTACH]203526[/ATTACH]

Thanks James,I`ve got dozens of Junction Boxes mainly from forward fuselage interior and bomb bay, but `E` doesn`t spring to mind,I do have a couple with `SCB` on however.Got a large unusual Junction box with `Not to be used on Stirling aircraft pre mod 501` but I`ve got a feeling it`s something to do with the engines or general services..I`ll dig it out.

A couple more notes from 1660A:

* Fig 4 States “S.C.I Containers” (so they are containers of something)

* The junction Box E is mounted on top of the SCI panel

* Apparently the instructions for the SCI are written on the front of the panel

Not sure if these help any but if you google “Smoke Curtain Installation”, one of the possible names that Air Ministry suggested, there is loads of info.

This shows why it was called ‘curtain’

http://www.criticalpast.com/video/65675040385_USS-New-Jersey_lightship_Martin-bomber_smoke-screen

More stuff at TNA and IWM on film

If this is the SCI then the control panel could be guessed at a little further. You would not want the SCI containers to be released as part of the normal bomb salvo so those positions would need to be excluded in some way from any bomb release controls. You may want to re-use the containers or bring back the unused ones so any jettison facility may be restricted to manual jettison specifically at those stations. You may want to activate the SCI individually or in a long sequence so there may have been some sort of timer in the panel rather than have the bomb aimer try to guess the timing – get it wrong and you have a hole in your curtain.

I’m sending an email to RAF Museum at Hendon, it’s likely that the SCI was a multi-aircraft device and so may have its own AP.

Oh and if you were wondering, as I was, how the smoke was so slow to dissipate, this from Wikipedia:

“Titanium tetrachloride

Titanium tetrachloride (FM) is a yellow, non-flammable, corrosive liquid. In contact with damp air it hydrolyzes readily, resulting in a dense white smoke consisting of droplets of hydrochloric acid and particles of titanium oxychloride. The titanium tetrachloride smoke is irritant and unpleasant to breathe.

It is dispensed from aircraft to create vertical smoke curtains, and during World War II it was a favorite smoke generation agent on warships.

Goggles or a respirator should be worn when in contact with the smoke, full protective clothing should be worn when handling liquid FM. In direct contact with skin or eyes, liquid FM causes acid burns.”

and another quote from Wiki about the chemical used:

“It has been used to produce smoke screens since it produces a heavy, white smoke that has little tendency to rise”

James

Hi Hindenburg

I wouldn’t want to hang in the turret myself, looks a bit flimsy!

I’m out for a few days but will look at this later – some clues though:

1. The letters on the terminal strips in the TB’s are redundant and not shown on the circuit diagrams, so you can ignore them, except where there are terminals that have different electrical functions but have been given the same number (tsk), then their letter should be counted.

2. Wiring shown dashed means that it is also used on other circuits

I can’t find much about the safety – the wiring diagrams need redrawing to expose the reality of the circuitry.

Let me quote the museum at Hendon with regard to AP1660A

“We have the following volumes available on AP1660A;

Vol 1 = Sec 1 – 6 (017805) & Sec 7 – 11 (017745)
Vol 2 Part 1 = R018754
Vol 2 Part 2 = 023042
Vol 3 Part 1 = R024286″

You can look up what those parts are in the index of AP1660 (any version I should think). Another quote:

“With regards to R018754, this is a very large manual which are loose leaflets containing amendment sheets in no order. I would recommend you view the manual before you request a copy. Now ‘large’ compared to the other volumes should perhaps read ‘enourmous’!

I’m going to Hendon soon to have a look at the parts I don’t have. One of the above is a really dull list of amendments but I’m hoping that R018754 might contain a lot of useful stuff, perhaps instructions about adding removing turrets, safety switches, JB’s??

Anyway, just some info to think about.

Cheers
James

[ATTACH]203269[/ATTACH] I have early and later JB 15 `s (turret supply) James ,the older one on the left. The star marked terminals are 17 to 20 though. Any idea where the safety was fitted on the mid upper…?

[ATTACH]203268[/ATTACH] There was a provision for the early Stirlings to be fitted with FN25 Ventral Turrets…………………..

Hi John

Always happy to give my opinion! 🙂

Circuit diagrams are usually badly drawn because no-one is trained to make them clear, (viz, to explain the operation) and because there is a need to make the circuit ‘physical’ for installation and fault finding purposes.

Sadly the two objectives often fall over each other and confusion results.

The circuits for most of the Stirling are little more than motors and lights operated by switches, it just looks a mess.

James

I think we’ll need your help James when it comes to wiring up our cockpit :diablo::D

John

Looks like 2 and 2A are actually more associated with the -ve connection for the Mid, Rear and LOWER Turret!

Can’t find JB terminal 10 on the Schematic, only the routing diagrams. Dead end sadly!

James

[ATTACH]203247[/ATTACH] interesting that JB/C mounted in the bomb bay suppyling positions 1,2, and 3 is also crossed out on it`s label.
In JB 15 ,which supplies the mid-upper, I can see 4 terminals not connected but marked with a `star` ..wonder if that`s anything to do with the S.C.I safety mod.?

According to the SCI Routing Chart the terminals in JB 15 for the safety switches should be labelled 10, 2A and 2.

Rather bizarrely the two wires from JB 15 that are supposed to go to the Mid-Turret safety switch go separate ways, one goes down conduit C34 which heads towards the tail and passes through JB 16 – possibly this is local to the Lower Turret. The other does go to the Mid turret on conduit C52. That’s odd. In fact reading it again it doesn’t mention that there actually is a Lower Turret safety switch – was there ever a Lower Turret?

Perhaps the link text should read Mid-Turret and not Lower Turret? That makes sense electrically, but then you would expect both wires to the safety switch to be in conduit C52?

However, if there were two safety switches then you would expect two wires to head to the back of the aircraft and two to the Mid-Turret! Then the link mentioned would be between 2 and 2A which make more sense with regard to the numbering.

Finally there seem to be 4 terminals on the safety switch – hopefully having two independent switches between terminals 1 and 1 with the switch between 2 and 2 being unused.

Very confusing!

James

[ATTACH]203247[/ATTACH] interesting that JB/C mounted in the bomb bay suppyling positions 1,2, and 3 is also crossed out on it`s label.
In JB 15 ,which supplies the mid-upper, I can see 4 terminals not connected but marked with a `star` ..wonder if that`s anything to do with the S.C.I safety mod.?

Yes JB/B…sure they were only fitted on the B.A. panels on early Mk1`s..then went onto starboard B.A. position wall forward of the B.A. panel.

Hi Hindenburg

That certainly shows that positions 4,5 and 6 were different, can you conclude that your junction box is therefore early MKI?

What junction box is that from? Is it JB B?

I’ve looked up Bomb Fuzing etc and it seems that normally 3 signals were taken to each location, Front Fuzing, Rear Fuzing and Firing (Release?). There are only 2 signals taken to the SCI positions. There seem to be three sets of three switches on the SCI panel. So are some just unused? Were the extra switches added ‘just in case’? Do they do something else?

Just read that positions 4,5, 6 and 17 were able to carry 2,000lb bombs – co-incidence?

James

[ATTACH]203190[/ATTACH] interesting regarding what positions were for S.C.I fitting ,James.This is the label on the bomb aimers junction box from a Mk 1 aimers panel.

Certainly true, but you would imagine that the rear gunner would be more susceptible than the upper, but there isn’t an interlock for his position.

James

Maybe the rear gunner was not so at risk because he had doors on the turret and can`t slew the turret forward into the the slipstream face on?Interesting that it might have carried chemical weapons though.I saw a slipper tank with spray nozzles allegedly from a crashed HE111 once apparently used for chemical delivery.

[ATTACH]203172[/ATTACH] part of the wiring diagram with the panel in question top left.The left hand side of the panel appears to be a containers jettison unit that has been modified( the type with the red prees button under hinged flap and oval light under flap) as fitted to the Stirlings main instrument panel.Many thanks for all this info James,you`re a star.