BobKatianh,
The parts “bible” is AP1086 – Priced Vocabulary of RAF Equipment – but wartime editions appear to be almost non-existent. There are some extracts available, but my guess is that these will not be of much help. Have a look at the “Wreckage of Lancaster ED908 (60-Z)” thread. You may find something of interest there.
http://forum.keypublishing.com/showthread.php?120747-Wreckage-of-Lancaster-ED908-(60-Z)
BobKatAir Ministry,
That’s absolutely marvellous – thank you so much for all your time in researching the Spares List – very much appreciated. It is interesting to see that the part was used all three systems: fuel, hydraulics and pneumatics. I think I have the diagrams for all of the systems in AP2062A and, as you say, there are some illustrations which I have already posted of it in situ in some of the areas you describe.
Now we know exactly what it is, there seems little purpose in further speculation as to the actual use of the piece found in ED908. A splendid outcome – I couldn’t have hoped for more. Many thanks again.
BobKatAir Ministry,
I have been wrestling with the British Standard Pipe (BSP) measurements, but I think I now have it.
According to your particulars, the AGS 904 sleeve has a hexagonal nut with a 0.595in (15.1mm) diameter on the flat sides.
Item B is a ¼” BSP which seems to be a ‘standard’ reference for the inner pipe with the following attributes:
Thread outer (major) diameter = 13.157mm (0.518in)
Thread inner (minor) diameter = 11.445mm (0.451in)
19 Threads per inch (TPI)
Laurent has provided us with measurements of 15.1mm [A] for the hexagonal nut diameter and 13.1mm [U] for the thread outer diameter. The dimensions of the piece show that we have a thread of 19 TPI. I have asked him if he can supply the missing measurements [Y and Z] from your chart, but this isn’t really necessary now. We clearly have item B from your list.
Were your specifications from a wartime manufacturer’s catalogue, or was this a post-war version?
All we need now is for someone to confirm what it was used for in the aircraft.
It has occurred to me that Laurent’s other coding – 2SS (?) could be 28S which was the AM code for AGS screws. 28F was for couplings.
BobKatThanks very much, lanc35. A good thought – I have looked through my copy, but nothing gives the view that would be useful.
However I have come across a picture of one of FM104’s outboard engines undergoing restoration with a ‘T’-joint piece of pipe, with the same sort of silvery brownish colouring, but behind the fireproof bulkhead, not in front as I had thought (it is difficult to get the perspective from the diagram), which looks as if it could be from the pneumatic system.
With regard to item 22, this was identified by the people at Lincolnshire Aviation Heritage Centre, so I am assuming that this is a piece of the fuel pipe as they have suggested.
Air Ministry, it looks as if you have come up trumps! Many thanks.
I think Laurent’s reference ‘OU’ was meant to be ‘ou’ = ‘or’. So we probably have AGS 904 7B, or, looking at the photo, maybe AGS 904 / B. The external measurement of the hexagonal nut is 0.59 inches which fits with item B, although the thread measurement doesn’t look quite right – nearer half-an-inch than a quarter – a bit odd. Aluminium alloy fits Laurent’s description. So I think we are definitely in the right area.
The next question is what is the sleeve for? It is clearly a pressurised pipe joint. I agree with you that it is unlikely to be for fuel. The Lancaster Manual says that the hydraulic system works at 800-900lb/sq.in, and the normal pressure in the pneumatic system is 300-320lb/sq.in. My guess is that our piece is pneumatic.
BobKatItem 39 – more research
The attached diagram shows a number of pneumatic three-way couplings on the left, and some hydraulic couplings on the right. There may well be others, but perhaps our piece 39 can be identified using the diagram as a guide?
The only similar fuel pipe joint I have discovered looking through AP2062A is the one already shown for item 22.
If we start from the premise that item 39 is not part of the fuel system, then, as far as I can tell, we are left with the possibility of it being part of either the pneumatic or hydraulic systems.
On the diagram:
Pneumatic:
A is alongside the Heywood Compressor and appears to be in the engine nacelle;
B is on the pipe along the leading edge of the wing behind the fireproof bulkhead;
C is along the same pipe but centrally placed above the main spar;
D and E are within the fuselage close to the emergency air bottles;
Hydraulic:
F and G are along the fuselage below the pilot’s seat; and
H is by the inner side of the port inboard fuel tank.
Knowing that item 39 was found close to item 22 and not far from item 25 (the fuel stopcock) – the three pieces are almost in a direct line – the balance of probabilities suggests that it may be part of the pneumatic system on the starboard wing – either item A or B. However this is inevitably pure guesswork. It would be enormously helpful if someone could locate a photo of any of these things in situ or provide some information about the metal used for the pipework. I can only hope!
BobKatPeter, it seems that we may be on the right track.
As you know, I am no mechanic, but as the fuel pipes simply provide a conduit between the fuel tanks and the engines, they would, I assume, not operate under any significant pressure, whereas the pneumatic or hydraulic systems would. This being so, it would seem logical that the pipework might be made of different metal to withstand the greater pressure.
I have to say I am a little uncertain of Laurent’s description of item 39 as being made of aluminium. The colouring on the photograph is not completely silvery, but perhaps this would be affected by the joint being under the ground for many years? It could be that my translation from the French is confusing – maybe an alloy is what is meant. Would this be likely?
I guess part of our difficulty is that most of the surviving Lancasters are Canadian built, and these and others have probably been subject to post-war modifications. As a result it is presumably not easy to determine exactly what metal may have been used in 1943 for the pneumatic or hydraulic systems at the time when ED908 was built?
Can anyone add anything to this discussion please?
BobKatPipework
Peter,
I have been having a close look through AP 2062A. It is clear that there are similar joints to those pictured in both the pneumatic and hydraulic systems. I assume these would be likely to be made from different materials?
The piece identified as being a fuel pipe coupling (item 22), with some of the pipe still attached, appears to be made from copper which I assume would be as expected?
Item 39 is said to have more the appearance of aluminium. Would this, or something similar other than copper, be used for either of the other systems?
BobKatPeter, many thanks. This seems to confirm that there was only one priming pump for each wing. So, we seem to have a mystery.
Either we have what appear to be two almost identical pieces – one from each wing – or we have two similar pieces of pipework connections, each with a different function?
If anyone has any thoughts as to what other function this coupling might have, I should be glad to hear.
BobKatItem 39: fuel pipe joint?
I now have the measurements of item 39. It is 70mm wide. The external diameter of the pipe joint (measured by the screw thread) is 13.1mm; the width of the hexagonal nut is 15.1mm and the end nut is 15.5mm.
It was found close to item 22 which, I am told appears to be made from copper or brass, whereas the recently found item appears to be aluminium.
Further research indicates that ‘R3’ is a code used by Avro and ‘AGS’ is ‘Aircraft General Standard’.
I attach a diagram from AP 2062A showing the position of the fuel pipe joint next to the priming pump. If this is correctly identified, a bit of a mystery arises. As I understand it from AP2062A, there was only one priming pump in each wing which served both the inboard and outboard engines. Eye-witness reports say that the port wing separated from the aircraft after the mid-air explosion. Unless the port inner engine remained attached to the stump of the wing and the fuselage, and it was only the wing tip with the outer engine that was lost, then it would be expected that only the remains of two engines and one of these priming-pump joints would be found at the main crash site. Were there other similar connections in the fuel (or another) system, or did the number of priming pumps change?
Are there any Merlin 28 experts who can throw any light on the subject please?
BobKatNew items found: 39 and V1
Attached are pictures of two more items found.
The first, number 39, is a connection joint looking almost identical to number 22 (post # 226). Unlike the earlier item it has some part numbers visible which Laurent has recorded as: (1) R3 827 or 927; (2) 235 3549 or possibly 2SS 3549; and (3) AGS 9047R OU B. I assume it is a fuel pipe connection. I do not have its dimensions but I have asked Laurent for these.
The second item, which I have numbered V1, was found about 300 metres from the launch ramp in the direction of London. It seems possible that it is associated with the flying bomb or the launch mechanism.
Any ideas anyone?
BobKatOboe Ground Stations
Dave Wallace and I have been continuing our research into the demise of ED908 and, at the same time, looking at the use of Oboe Ground Stations. Some interesting facts have emerged about the sortie to the Forêt du Croc.
The Headquarters Pathfinder Force (No.8 Group) Operations Record Book states that on 19 July 1944 sorties were planned (amongst others) to the V1 Storage dump at Thiverny and to the V1 site at Forêt du Croc. The Thiverny mission was due to have taken place in the morning of the 19th, but was delayed until the evening. Dave’s father and my wife’s uncle, James Foulsham, flew in tandem to Thiverny in their Mosquitos successfully to mark the target with flares. The Forêt du Croc sortie was cancelled and re-arranged for the next day, 20 July. This meant that instead of the planned night-time sortie, it became a daylight operation. There is no mention of the weather in the Operations Record Book, but no doubt this played a part in the changes to timings being made. The urgency of dealing with the threat from the V1 launch sites would also have been a factor.
When I first started my research into Oboe, I found it difficult to find much information about the use of Oboe Ground Stations, so I thought it might be useful to record a little of what we have found. Oboe signals could only be transmitted to one aircraft at a time. This meant that if target indicators or bombs were to be dropped at the same time on the same target by more than one Oboe-controlled aircraft, then different combinations of Ground Stations would be required to control the aircraft on their beams. In simple terms, the aircraft flew along a ‘tracking’ beam and a signal was given by the ‘releasing’ station when the two beams intersected over the target. It was also possible for the Mosquito aircraft to be controlled by the same two Oboe Ground Stations if they flew at intervals about ten minutes apart, allowing each aircraft to pick up the beam and drop its bombs or flares, before the next picked up the tracking signal. Each aircraft had its own call sign.
For the Thiverny sortie on 19 July, Foxall/Wallace (pilot/navigator) were controlled by a tracking beam from Hawkshill Down I paired with the releasing station at Worth Matravers I. Arriving about a minute later, Foulsham/Swarbrick were controlled by a tracking beam from Hawkshill Down II paired with the releasing station at Tilly Whim III. They were therefore flying the same path along two different beams from the same tracking station (Hawkshill Down near Dover), and given release signals from two different stations (Worth Matravers and Tilly Whim) located close to each other near Swanage.
On the fateful mission to the Forêt du Croc on 20 July, Wolstenholme leading the first wave in his Mosquito was controlled by a tracking beam from Hawkshill Down V paired with the releasing station at Beachy Head operating on Channel 13. However he did not have a successful run, losing the beam because of a poor signal, and he switched off at 1617.01hrs. His wave’s attack was aborted. This would explain why the second wave, flying above the first and due to bomb a minute later, crossed over the first from starboard to port. Foulsham in Lancaster ED908 was controlled by a tracking beam from Hawkshill Down II paired with the releasing station at Beachy Head operating on Channel 11. Foulsham was reported as successfully releasing his bombs at 1617.46hrs, moments before the aircraft, already with an engine on fire, lost its port wing after a mid-air explosion.
I have a number of other Oboe Ground Station pairings used for attacks into Germany and France. If anyone is interested, let me know, and I can post them.
BobKatThanks Peter – your picture was much clearer than mine. It certainly looks like a match – our piece seems to be from the row with the ridged edging. I think we can consider this as having been identified unless someone directs us to an alternative position – I certainly cannot see any other part of the fuselage panelling that has similar dimensions to our piece on the photographs I have. Thanks again for pointing me in the right direction.
BobKatPiece 38A
Thanks for your thoughts, Peter.
Assuming the aircraft did not crash on its back (which I believe to be the case), only the starboard wing would have remained attached until impact with the ground. This would have been on the far side of the main crash site from where these pieces were found. If we have ruled out the bomb doors (which would probably have still been open), then we are left with the tail-plane or fin as a distinct possibility. I attach a picture which shows a few panels from the tail fin with the characteristics we have – closely spaced rivets on the short side and more widely spaced along the length. This looks to be a possibility?
……….
I have now counted the rivets – the piece found seems to be an identical match to the rear fin panelling pictured. Perhaps we have identified our piece?
BobKatPieces 38A and 38B
Peter,
I have heard from Laurent: “there is no plexiglass, everything is made from aluminium! The sheet metal seems to have suffered the force of the explosion!”
I have looked at a few pictures of the external skin of the aircraft and note that generally the rivets are more widely spaced than is the case with ours. Does this suggest that we have a piece which required extra strengthening? It looks more like a piece from the bomb doors, but as this part of the skin was, I think, all attached to formers rather than stringers, this would seem to be ruled out. So what would have been attached to stringers (on the assumption this is what we have) as opposed to formers?
Or am I looking in quite the wrong direction?
BobKatThanks, Dave. I think we are now all agreed that the “stripes” are not D-Day markings, but exhaust stains. Sorry to have caused confusion!!
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