Air Diagram AD 4551 and Junction Box 1

In an effort to identify modifications incorporated in to Vampire FB.9 R1382’s Junction Box 1, I went searching for a later revision of Air Diagram AD 4551. We already had issue 3; this came from Gina’s Vampire library. My general Google search came to nothing. Not really surprised!

I found a reference using NAA RecordSearch to ‘Vampire FB Mark 5 Electrical Installation’ by chance while I was having a look for something else on Vampires. The FB.5 and FB.9 are largely the same, the essential difference is that airconditioning (an ACRE 8 cold air unit) is fitted to the FB.9. I imagine that this file is in the Australian archives because the RAAF had a single Vampire FB.5, A78-3 (formerly RAF registration VV465).

So I ordered a digital copy in February; the order cost just under $40 including GST and took 12 days to process. That copy is available at the NAA here:

http://RecordSearch.naa.gov.au/scripts/AutoSearch.asp?Number=3398245&O=I

So it turns out that the file contains AD 4551 Iss. 3. The AD 4551 pages are scanned at a suitably high resolution and overall the result is very clean. I had a look through this just to make sure that Iss. 3 was Iss. 3! Apart from the NAA version not having some small hand mark-ups that our copy had, I didn’t see any edition differences.

When working through the Gun Firing circuit to convert this in to a wiring/routing diagram for Junction Box 1, I had trouble reading some pin IDs on our version. The hardcopy in Gina’s library is a bit tatty (some tears) and grimy; also in the original photographic repro process, the pages weren’t flat so some of the schematic is blurry.

Gun Firing circuit scanned from Gina’s version of AD 4551.

The GF circuit from the National Archives file.

So I took a look at the NAA version to see the pin ID and found a lot more than what I was expecting. There was in fact a significant difference in the actual circuit. The version we already had included Mod 3146. Looking at the circuit diagrams you should be able to see that they are fairly different. There may be other differences too, in other circuits. No idea yet if this was a relevant discovery for R1382, but at least the NAA file is now there for anybody who is interested or may find it useful!

Alternative Fuel Gauge Panel

Five years ago I saw a photo that showed a rather unusual single-seat Vampire fuel gauge panel. The regular panel, when you look at the front face of it is mostly just gauges, placards and the base panel which is made of Tufnol – fibre reinforced phenolic.

This mystery panel had been seriously messed with! The top line of gauges now sat in a folded aluminium part that was attached to the Tufnol. This component in itself didn’t make for a bad looking assembly, but overall it was rather rough looking.

What was this assembly? I thought it was a rough repair, but why so complicated? Why not just replace the panel!

Turns out there were two mods involved. Firstly (RAAF mod 160, DH mod V.204) the Mk.II 8-day clock was replaced by the V.308 stopwatch clock, with the centre fuel tank gauge moving to the old clock position, and the new clock being installed in the centre-top position. The folded aluminium part was required to reinforce the Tufnol that had been dramatically weakened by the much larger hole for the clock, and to provide sufficient space for it.

Somebody didn’t like that idea, so the larger clock was then moved over to the right hand instrument panel, and the centre fuel tank gauge was then moved  back to its original position. (RAAF mod 231, DH mod V224.)

I think that most aircraft bypassed this mess, with the larger clock immediately being installed in the RH panel, as the aircraft came in for servicing and mods.

However, it turns out that A79-14 is a case that was fitted with the mongrel panel (not the panel I originally saw); see the photo below.

Although I still don’t understand why the original panel wasn’t replaced during either mod, given how much work I imagine was involved, I think it is nice that this oddity is preserved. Perhaps for some lessons on how things should have been done properly the first time (new clock in RH panel straight up), or otherwise on the diversity in modifications in our remaining Australian-built single-seat Vampires.

A New Dawn… and the Vampire F.30/FB.31 Fuel Gauge Panel

Well this is it. I have entered the ethereal world of blogging. Pleasingly, there is a real world behind it, and I am going to start by looking at an aspect of the Vampire F.30 and FB.31 cockpit – the fuel gauge panel. The single-seat Vampire instrument panels are largely standard parts across various marks, the fuel gauge panel being a good example. As such, the same panel was used in the early single-seaters and the late-service configuration. In the former, the panel carried five fuel gauges and the clock. In the latter, the panel carried just the five fuel gauges; the basic panel assembly is the same, so for the late configuration the clock hole was empty. (The clock was moved to where the film footage counter for the G.45 gun camera used to be.)

The basic panel was made from Tufnol and had two aluminium reinforcing angles riveted to the vertical edges. The panel also carried descriptive placards and wiring junction boxes.

The five fuel gauges are as follows (indicator values in gallons):

Description     Range/Capacity     Stores ID                        Smiths ID        Panel Location

Port Outer       0 – 57/65               G6A/1969 or /2588          1352FG          Lower Left

Port Inner      0 – 47/52               G6A/2039 or /2587          1351FG          Upper Left

Main               0 – 80/96               G6A/3661 or /2580          1350FG          Top Centre

Stbd Inner     0 – 47/52               G6A/2039 or /2587          1351FG          Upper Right

Stbd Outer      0 – 57/65               G6A/1969 or /2588          1352FG          Lower Right

4 Jan 2013: fix: gauges were wrong way round for inbd and outbd.