powerandpassionDHP & DHA
Does anybody know if any of the alpha characters relate to factory location ?
Australian Mosquito and Vampire parts have many DHP inspection stamps on them : I have always understood this to signify DEHAVILLAND Preston as the origin of the parts. I interpret this in the context of the rapid adoption of Mosquito manufacture in Australia, when there would not have been the time or contractor base in Australia to meet needs and many assemblies and parts were imported. This is also consistent with the initial supply of UK manufactured Vampire trainers to Australia, before Australian Vampire production ramped up.
Later Swedish Mosquitos, in the Illustrated Parts manual, have many DHA part numbers in them : I have always understood this to signify parts sourced from DEHAVILLAND Australia. If this is correct, as Australian Mosquito production found its legs postwar, many sub assemblies for Swedish Mosquito production in the UK may have been sourced from Australia, as the UK tooled up for the jet age.
Can anyone confirm this and the basics on DHP = DH Preston, DHA = DH Australia, DHC = DH Canada.
What other codes are there, eg for Hatfield production ?
DHP Vampire parts seem to come in a drab green and I have seen the same colour on DHC Caribou parts. Does anybody know what this colour is?
powerandpassionMosquito dataplates
Perhaps there is no ID dataplate on a Mosquito.
After much sleuthing I believe that it is correct that there never was any ID dataplate on a Mosquito that detailed its Air Force identifier or the ‘public personality’ detailed on its paintwork. What does exist are numerous, small dataplates for various sub assemblies incorporated within the one airframe. This conclusion arises from matching these sub assembly numbers to original airframe logbooks preserved by the Australian National Aviation Museum in Moorabbin, Victoria.
I would welcome any constructive criticism or further supporting evidence for the description of the system adopted by DEHAVILLAND Australia below, which I posit was a direct mimic of DH UK and DH Canadian practice. Reproduced below are photos of Australian Mosquito wing and tailplane assemblies in the process of scrapping in 1958 and an undercarriage door assembly dataplate excavated from a scrapping site in later years. These are matched with photos from an original airframe logbook from the era to build the following theory.
The Air Force issued a contract to DEHAVILLANDS to supply a number of aircraft to specification.
DH established a sequential file for aircraft, in the case of the Chronological Log reproduced the aircraft ultimately known as RAAF A52-302 was Aircraft DH 3219 to DEHAVILLANDS. I theorize that this file was retained by DH for warranty and future factory maintenance records, and ultimately disposed off by the factory once a reasonable warranty or service period expired. I have seen photos of part assembled, unpainted Mosquitos in Downsview Canada with a paper fixed to the nose cone, which I theorize was the Canadian factory file identifier. This system would allow for the removal of an airframe from the assembly line for quality or design issues, before it acquired an Air Force identity.
DH utilized an alpha numeric system to mange recording of sub assemblies and components within the airframe, largely supplied by third parties. In practice a Mosquito was a “kit plane”. Sub assemblies included fuselage, mainplane, ailerons, flaps, tailplane, rudder, elevators, radiators, fuel tanks, undercarriage, undercarriage doors etc. Typical codes, as reproduced in the “Particulars of Components” photo below, were Fuselage MN 293, Mainplane MM322, Starboard Aileron MAS 145, Rudder MER 114, Control Column MCU 307, Compression Leg Inner Starboard MUA 1272. In the photos below are close ups of Australian Mosquitos being scrapped in 1958 that substantiate this practice : painted on the Tailplane is the ID MEF 103, Rudder MER 13x and Mainplane MM 327. The photo of the dataplate for undercarriage door shows the code MCA 1025.
As the airframe progressed through assembly it acquired its Air Force identifier, in this case A52-302, which ultimately became its public persona. I understand that in the UK the fuselage identifier became shorthand for the entire assembly, eg MN 293, or RR 299. This was painted on the fuselage, but no identifying plate was fitted in the cockpit with this information. There would seem to be no practical purpose to fit such a plate : the external painted code would serve for all purposes.
Sub assemblies are extensively fitted with dataplates or manufacturer ID codes. A theoretical dug up wreck could be indisputably confirmed in its Air Force identity by cross referencing sub assembly dataplates with the original airframe logbook which recorded this, beyond other contextual evidence. Contextual matching of sub assembly IDs for theoretical remnants in a place like Turkey, Israel or China could assist in matching with fuselage IDs and service records to build a more accurate historical record.
I would welcome any information on sub assembly IDs or manufacturer codes that anybody may have to further build this understanding of Mosquito identification.
powerandpassionSub contractor inspection stmps
Hello,
I’ve found a bunch of inspection stamps on some PBY Catalina parts dumped in Darwin Harbour post WWII that I can’t identify. Starting to do my head in and I was wondering if anyone here might be able to help? Any help would be greatly appreciated 🙂
These Cat parts have numerous Boeing inspection stamps but there are several others that keep showing up – these include “MBA 2” “RMC 2” “SCL 2” “DOL 14” “$” “N” “WSPV 14” and “WOC” / WDC” ? – this last one is hard to read but the shape / writing looks quite distinctive.
Thank you 🙂
These may be sub contractor inspection stamps : it is hard to pursue this logic without understanding what the parts are, but it is reasonable to assume that large quantities of parts were manufactured and internally approved by large numbers of sub contractors, ranging in size from small family businesses to large concerns, then supplied to the final assembly plant. A good example of this are the Bendix wheels that feature on many US aircraft of the era, radially arranged around the spokes are cast in numbers and contractor inspection stamps for casting, heat treatment, machining and assembly.
Thousands of subcontractors were drawn into supplying the war machine and the documentation of these hurried arrangements is limited and opaque. Sometimes the abbreviations on the stamp can be readily matched with a company name. Somebody more familiar with the Catalina story may be able to make some connections with the abbreviations. Some of the stamps refer to overhaul records and maintenance workshops.
“$” is a great stamp. I think this was some toothless old mechanic in a shed somewhere in California who overhauled milking machines and the odd Navy aircraft fuel pump for the son in law quartermaster at the local base.
powerandpassionEd-2 The comments about the various IPB’s were for your benefit.
The documents shown as being held are as follows:
AP1393A Vol. III Part I, 1931
AP1393B Vol. III Part I, 2nd edition, 1934So looks like parts manuals for Mk I & II aircraft.
Aircraftclocks, thank you. Are we talking accessible vodka drinking Cracow Museum here or inaccessible tea drinking UK museum ?
powerandpassionPhysics
Ed-2
The Bulldog A.P. manual calls for NO droop, and a tight cable system.Bulldog Mk IIa Wing:
Total area (two top panels + centre section-no ailerons: 167.3 sq.ft. Aerofoil: Bristol 1A (both upper and bottom)
Ailerons (both): 24.7
Wing chord 76″
Aileron chord 23.5″
Travel: 25^ up & downCheers,
Ed-1
Ed1,
Tuppence worth :
Ratio of aileron to top plane on Bulldog is 1:6.7 (167.3 sq ft top plane to 24.7 aileron) in comparison to Hart family 1: 4.9 (175.46 sq ft to 35.54 aileron). Therefore the Bulldog has a more aggressive aileron, perhaps explaining its reputation as an acrobatic aircraft in the air displays of the 1930’s. The Bulldog aileron chord seems to be double that of the Hart family biplanes.
Hawker Hind has all up weight of 5217 lbs over total wing area of 348 sq ft (top and bottom planes and aileron) = wing loading of 15 lbs/sq ft.
Bulldog II has all up weight of 3503 lbs over total wing area of 306.5 sq ft = wing loading of 11.4 lbs/sq ft.
Therefore the original Bulldog had a more aggressive aileron (and I suspect tailplane arrangement) than an example of the Hart family biplane, acting on a (Bulldog) wing design (steel strip construction) of lighter wing loading. The Bulldog was a performance aircraft pushing material design limits, while the Hart family were a design with higher structural factors and less aggressive parameters (aileron travel, chord and area) helped by a powerful engine.
I believe the original Bulldog had a design fault in the provision of elevator pulleys suspended from the fuselage, in an arrangement that meant that control column forces acted as a lever on the rear elevator pulley, and material fatigue could lead to the detachment of the pulley from fuselage mounting in service. In 1937 a RAAF Bulldog was lost when it failed to recover from a dive, which might be ascribed to this cause.
http://trove.nla.gov.au/ndp/del/article/11051884
I wonder what these ratios/wing loadings are for modern acrobatic aircraft. One gentleman who grappled with lightweight aircraft structures and excessive aileron forces was Jiro Horikoshi, designer of the Zero, who introduced control cables with higher elasticity to take up some of the energy between control surfaces and control column.
There seemed to be a great degree of technology transfer between Britain and Japan in the 1920’s – 30’s, principally with the naval relationship, but also with Bristols and aircraft. I wonder how much the the affinity of Japanese designers for lightweight construction was influenced by Bristol design thought in the 20’s and 30’s. Certainly the Bulldog was built and copied by the Japanese, but maybe Jiro Horikoshi evolved a solution for lightweight structures with aggressive control surfaces that Bristols never got on top of, insisting on a tight cable system.
Ed2
powerandpassionHawker Frise aileron
Following up on the aileron questions: I built the ailerons to follow the standard full wing rib aerofoil. The new question that comes up concerns the leading edge of the aileron, and the gap created on the up aileron. The leading edge of the aileron is rather sharp which brings up the question of aileron snatch. (I do not have a drawing of the aileron rib, thus no info on the radius of the tip, only pictures) I have a copy of the Hartshorn aileron experiment which showed very little difference between the two types. I have not been able to find info from the British side, and NACA does not address the problem in a manner that fits this aileron. (NACA keeps putting the hinge point below the aileron. The picture of the Hawker aileron is a perfect example of the Bristol construction.
So…..does anyone have info on the Hawker ailerons?
Ed,
Pictures below I trust will clear up some detail. I will send you a DXF file which should allow you to output locally a 1:1 Hawker Hart family aileron main rib as per the first picture, which are forming tools for this rib. In the photos the engagement bracket attaching rib to the aileron tube is placed, to give context to the fixing holes in the DXF file, and allow you to place the aileron tube in position. Further photos show the means of connecting the aileron tube to the ribs connecting to the spar. Between the full wing photos and these detail photos I hope there is enough for you to figure it out.
For Hart family biplanes the following data is consistent :
a) Aileron travel 22 degrees up, 18 degrees down
b) Area of top planes including ailerons 211 sq ft
c) Area of ailerons 35.54 sq ft
d) Top plane chord 6ft 0.5in, RAF 28 airfoil.
Can you tell me if the ratios of top plane area to aileron area are consistent with the above on the Bulldog, to establish, perhaps, a principle in the Frise idea of “effective working area” or “ratio of total wing chord to aileron chord”. I wonder if any of the NACA reports allude to this.
Note on the photos that the leading edge and top face of the aileron is clad across its length to give a definate and clean tip to the leading edge. The aileron is balanced with lead weights inside the leading edge, I understand that prior to this there were issues with aileron flutter.
Note on the close up of the hinge that the hinge is ‘sloppy’ within the hinging arrangement to allow for aileron function where the wing is bending in flight, a feature introduced to Sopwiths (Hawkers) in WW1. The hinge immediately adjacent to the centrally mounted aileron gearbox is, however, tight, to maintain a firm connection with this controlling means.
Just passing you a drink on your marathon,
Ed 2
PS – Are you constructing an exhaust collector ring for the Bulldog ?
powerandpassionShort run blades
AA, I have no idea.
If it has then there are, presumably, sound commercial reasons for doing so. In this highly technological age perhaps a change in manufacturing techniques is the reason.
Anon.
Thinking through the evolution of blade manufacture it seems that blades are a good candidate for short run fabrication using 3D laser scanning and CNC from billet. I appreciate that forging blade blanks is a proven and technically sound method, but I sense it was originally driven by economy in material use whereas the problem for modern short run production is amortizing forge tooling costs and forging, where even getting access to a large forging press for short runs is problematical. Modern metallurgy has generated billet remarkable free from defects with grain structures that are superior to anything available to designers seventy years ago. What was unimaginable then is possible now. Obviously somebody needs to invest in the process of bringing regulatory authorities to a point of comfort with this approach, but I can see very little hope for unusual blade types being fabricated within the status quo.
Pictured below are Fairey metal propellors from 1933 (Dr S.A Reed patent), which I understand was the first innovation to break away from the accepted wisdom of timber props. According to Air Annual of the British Empire 1933 the “ construction of the Fairey metal airscrew is extremely simple. A flat forged strip of duralumin, with a hub thickness of 1.5 inches..is cut out to the shape conforming to the plan view of the airscrews. After being profiled throughout the desired aerofoil section by means of a milling cutter or shaping machine the centre twist is applied by means of a hydraulic press. The setting of the outer portions is obtained by means of a twisting machine. Metal shaped bosses are fitted to each side of the airscrew hub.”
In essence this was a machined flat bar 1.5 inches thick with a twist applied to it. I concede this was a forged, flat bar but I would expect that there would not have been off shelf stock bar options in that size then, so there was no other option than to hand forge a block into a flat bar to start the process. How this innovation influenced the later developement of blades with thicker aerofoils made from forged duralumin stock is a self evident progression. But what would a 1930’s designer think of 3D laser scanning and CNC machining and its possibilities? What would they think of modern metallurgy and the purity and consistency of modern materials? In those times the creative mind found its place within the marrow of the industry as today the cautious and acturial mind has risen to the top. No doubt the creative would output five different blade aerofoils in a rapturous day of CAD drafting and CNC machining, and send up the test pilot. Today we may copy with 3D scanning intellectual property for which the generous protection of patents and design registrations has long since elapsed, and the former custodians of this IP show very little interest in single runs of blades because they are not set up in the mind or the factory floor to service this need.
I wonder what a destructive test on a seventy year old NOS blade versus a modern reproduction CNC’d from quality billet would show. The challenge is probably most acutely defined in dealing with replacement turbines for seventy year old superchargers. I don’t know if putting a NOS revolving part that has sat under a chook shed for decades is wise. Gosh I wonder if regulators will ever care enough to let some oxygen into thoughtful short run production of historical aircraft consumables. Probably the most ideal solution for blades is a commercial arrangement with an original equipment manufacturer to supply forged blanks of the right size for finishing in a short run CNC process. Surely there must be someone sitting behind a desk in one of these places who loves to see old metal flung about the sky.
powerandpassionTo answer your first question the RE8 is a candidate according to this web site.
http://www.simonahouse.com/index.php?route=product/product&product_id=129
Now the bit that interests me about this instrument. The supplier code is shown as S on both of these instruments. I have S as being the supplier code for Smith and Sons.
I will need more evident for, if the code was also used by Smiths.Anyway powerandpassion you have given me another supplier code to add to my database on then (read, a short list that I would like to lengthen).
Thank you Aircraft Clocks and Bob, much appreciated.
powerandpassion23E50 hubs
The following is stolen from the most excellent engine history website http://www.enginehistory.org/Propellers/HamStd/hamstd.shtml
In basic terms the 23E50 hub was fitted to everything, so there is a wider possibility of mixing and matching parts.
How are Lancasters and Mosquitos being kept in the air in terms of replacement 6519 props ?
[ATTACH=CONFIG]230599[/ATTACH]
powerandpassionThank you
Sorry, I`ll speak English this time! “Auto Controls” is the term used to refer to the autopilot, so yes, I wouldn`t be surprised if the Lincoln used a similar system. The engine set-up would be different as the accessories were primarily fitted to an auxiliary gearbox on the Lincoln.
The autopilot was powered by an oil filled vane type compressor shown fitted to the opposite bank of the engine in the attached picture, and the cooler on a bracket in the foreground. The other image shows the general services (Heywood) air compressor fitted where the cooler goes, on another engine on the same aircraft. I think the cooler was fitted there to take advantage of the cooling air scoop, to save a redesign.
There are two completely different designs of autopilot compressor, RAE and K3, but both used the same oil cooler.Pete[ATTACH=CONFIG]230389[/ATTACH][ATTACH=CONFIG]230390[/ATTACH]
Pete, thank you for the precise and generous ID, diagrams and context. If anybody wants the cooler happy to swap, PM for ” oil cooler, NS, GSOH, looking for aeroplane for fun times and friendship.”
powerandpassionThank you
Yes, it looks identical to the Lancaster auto controls oil cooler. The stores ref is 27A/1379 (not much help as yours isn`t stamped) and the part number SIS251.
The fact that it has Rolls-Royce and MMOR marks tends to point to the Rolls-Royce / Morris powerplant for the Lancaster too.
It is fitted in place of the Heywood compressor on one of the engines and uses the same cooling air scoop that the compressor would have used.
Introduced in 1941.Edit: A Merlin engine oil cooler weighs at least 30kg!
Pete
Peter, thank you. I have seen coolant radiators made by Morris Motors in other aircraft with Packard Merlins so the cooler may be stand alone. Would Lincolns have the same auto control arrangement? Why is this part of the engine? I understand it is in the position normally occupied by the air compressor but there is no mechanical linkage to the engine. Did RR design the auto controls? What are they controlling? Too many questions!
powerandpassionCurrent spec
There is a reason for the absence of data on Hamilton Standard blades – Hamilton still regard even pre-war designs as secret, and won’t release any blade design data at all. Here is the response I got from them last year when I asked for info on the 6127, the direct equivalent of the DH 54409 blade used on the Whirlwind. Bear in mind this blade was designed in 1936..
Hello Matt,
Thank you for contacting the Customer Response Center.
I was able to locate an Overhaul Manual for the Propeller which is available to registered customers online. I can’t provide you with any design data or specifications as this information is considered to be company proprietary/confidential.
Regards,
Matt Sorace
Sr Service Rep.
Hamilton Sunstrand Customer Response Center
Reading between the lines Beermat ( oh how many times have I mumbled to your cousins in the pubs of the world!) it may mean that the aerofoil is still a current design. In that case a forging die may still exist and getting a forging blank may be possible. In this case all that remains is to convince HS to machine to fit an old HS hub….the 6519 blade fitted all Lancaster and Mosquito, I wonder what the difference with Whirlwind was. From memory all were three bladed? Perhaps the Whirlwind needed a more aggressive aerofoil given less horses under the bonnet? Perhaps the Whirlwind was short distance interceptor while recon Mozzie and Lancaster needed an airliner type prop. I wonder if the humble Dakota prop has the same aerofoil as a Lancaster, but different hub arrangement. There really can’t be too many permutations of piston driven blades, like wing aerofoils. I have some 1930s prop aerofoil data, does anybody know of a book which sets out blade aerofoil data from 1935 to 1955?
powerandpassionDetails
The only relevant manual that went to HARS was AP1538D Vol. 1 dated June 1945 amended to 1950, De Havilland Hydromatic Variable-Pitch Propellers.
This covers 27 props. fitted to the following a/c.
Albermarle, Beaufighter, Firebrand, Halifax, Lancaster, Mosquito, Stirling, Sunderland, Tempest, Typhoon and Wellington.There is no interchangeability list.
I have found Hamilton Standard (HS) Interchangeable Parts List and Parts List for Quick Feathering props. Lots of detail, superbly indexed as all US manuals seem to be, given they were not written in a cellar with bombs falling above. Just working on 23EX, which seems to cover all Merlin multi engined aeroplanes, patterns of commonality emerge with parts from the most common prop variant 23E50, confirming that with much patience , page turning, peering and a bottle of scotch it is possible to build a list of components that like the Ugly in the Good, the Bad and the Ugly it is possible to build a good six shooter from. What is not in this information is what aircraft used what propellor, so more careful peering at multi engined museum pieces would build build an understanding of what quantity of raw material is out there to build Frankenprop. I understand DEHAVILLAND used similar coding systems to HS so would love to get a copy of the AP which is aircraft identity driven. Happy to swap copies of what I find to build universal understanding. None of the HS info I have deals with blades, but I would assume that there must be detailed HS catalogues on blade aerofoils and applications. I wonder if in fact third parties supplied blades to fit HS assemblies? I also understand that blades were forged, for the obvious advantage of grain alignment, but I wonder how much of this was influenced by wanting to save machining time and wasted material primarily. In other words, for one off replacements today, the availability of CNC machining from high quality billet is viable, as wasted material is less costly than forging and forging dies. I am thinking of something like a Beaufighter, where original blades may not be readily available.
powerandpassionThank you again
The DeHavilland Archive at Bankstown went to HARS.
Thank you Avro Avian , Desoto and all, I will chase up the references. Apart from hub interchangeability, around which there seems to be a high degree of commonality, the ultimate question is also on the commonality of blades for modern purposes. If I find out more I will report back. I figure a blade made 70 years ago, even NOS, may not be an ideal thing to spin around at the speed of sound, given the copper in aluminium alloys would have been setting up electro chemical corrosion pathways within the microstructure. Perhaps these days, with CNC machining and modern metallurgy it makes more sense to carve out new blades, paperwork aside. One day somebody will have a NOS blade chunk land in their ice cream, but it will be OK if there is 70 year old paperwork to cover it…I wonder if a multilayer timber prop from WW1 pulled down from behind the bar might be actually safer to spin up…
powerandpassionThank you
23E50 Hydromatic hubs and parts are interchangeable with 23EX stuff. The latter is a licence-built copy of the former.
The same is true of the other sizes as well. Post war, de-H developed the props further and these were stand-alone designs, with little or no commonality with their US counterparts. It’s the war-time stuff which is interchangeable, the idea being that de-H could supply the parts for UK use should US supplies be cut off for this widely used and important product.
Anon.
Thank you Beaufighter and Anon. A supplementary question is on blade choice. Lancaster & Mosquito are given as type 6519 blades, I assume these were configured for multi engined aircraft utilising 23EX hubs , but how might the blades differ from something like a P38 running v12 Allisons? Is there some publication which relates blade choice to application? Given that most modern warbirds are run at partial power in comparison to wartime conditions, will Dakota blades “do” on today’s Lancaster?
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