powerandpassionMore
In the interests of completing the story, ordering my own confusion and promoting the cause of illuminati who love conrods I make the following update :
.
Because I am a dumbkopf I now make the following realizations care of the observation of a practical informer, in reference to the posted pictures of conrods :
1. Three piece RR conrod was due to the adoption of a steel backed & shell design that needed to be separate from the conrod shaft to enable external machining of the plain rod bearing face. Ahhhh! In the Kestrel the plain rod bearing face was cast in CuPb. In the Merlin and Griffin a steel backed CuPb then Pb-Indium bearing was fitted to the machined face of the heavy duty Nickel Chromium bearing support. All needed ‘outside’ machining access.
2. In the Allison V 1710 Gilman’s 1938 patent of steel backed CuPb bearing shells was adopted, allowing a conventional two piece conrod. Less metal, less machining, and from what all the old timers say, a very, very reliable motor.
3. I still think that an additional benefit of the RR approach was a doughnut shaped forging that was stronger than a conventional two piece conrod forging.
4. I am entirely wrong in thinking that the three piece RR conrod was an articulated joint, if I accept the conventional wisdom that the clamping forces of the conrod bearing retention bolts were so specified to prevent this from occurring. I still observe that the Kestrel had a castellated nut and cotter pin at one end and a retention lug at the other end, when a conventional hex head bolt may have sufficed, as it does for other designs. I accept that no part of an aeroplane has more stress or energy imparted to it than the conrod, and the RR conrod is whippet thin. Something in the design allowed it to be so. I really need to sit at the grave of Mr Royce at midnight and see what whispers I can hear rising in the mist. No paper clip passed Mr Royce’s desk without being interrogated and improved. Why did the Merlin persist with a three piece conrod when the Gilman influenced Allison went for something simpler ?
Also now that I have seen a DB 601 conrod I now understand why there was such a fuss made over taking out the Nazi bearing industry and Swedish bearing supply. The DB engines were a far more complex and expensive design concept than the Gilman idea, no doubt strong and reliable, big Bavarian, beer drinking conrods. All these engines, generating the same horsepower bands, but utterly different in their guts.
I guess I am starting to see some of the Schneider racing experience feeding into the RR design mind and the entrepreneurial filching of good design ideas from other sources that is the mark of a dynamic, hungry organization. If 1935 RR was alive today they would be making solar chlorophyll powered turbines to win the 2015 Schneider Solar Challenge…
Ahh the fun I can have with an old conrod, and the stories it can tell !
powerandpassionManufacturing bearings
That’s a very interesting bit of gen, thanks for putting it up.
In the interests of completing the story, ordering my own confusion and promoting the cause of illuminati who love conrods I make the following update :
1923 – Gilman lodges patent for cast in CuPb bearings, granted 1928
1930 – As RR “F” engine resolves into Kestrel, Gilman cast in bearings adopted by RR.
1938 – Gilman lodges new patent for steel backed shell bearings, these bearings incorporated into Allison V 1710, British RR Merlin, Packard Merlin, RR Griffon.
Only the Kestrel had cast in bearings that cannot be removed. Apparently Charles Lindbergh crossed the Atlantic on reliable Gilman cast in bearings in 1928 so early Wright Cyclone ( Bristol Jupiter ?) used cast in bearings.
Unique (?) to RR and entirely separate to Gilman’s innovation is the three piece conrod. Now I am starting to think that this is a RR innovation that had a specific purpose. In the Kestrel rod in the photograph there was a thin sheen of oil on the contact faces when the rod was separated, so no doubt at 3000 RPM the conrod bolts are stretching and, in a fractional sense, this becomes an articulated joint. Now I am starting to think about the extravagant conrod shell bolts and their metallurgy that are a feature of Kestrel and Merlin, that have alternately thin and thick shanks, and a keyhole and pin on the head arrangement to prevent rotation. Rotation could only occur if there was a loss of clamping, consistent with stretch. I thought the thin & thick shank was light weighting but now I am thinking that this allows a factor of controlled stretch. Perhaps RR, struggling with the destruction of whitemetal bearings in “R” & “F” engines came up with the concept of fractionally articulating conrods as a control measure. Certainly it is a unique feature which seems to travel through to Griffon.
There are some pictures of Allison, Merlin & Griffon conrods stolen from enginehistory.org
In my perambulations through the world of conrod bearing design I came across a very helpful and knowledgeable gentleman who made the following notes on Griffon/Gilman bearing shell manufacture :
You may find the following extra notes of some use regarding the actual manufacturing process, as done in Rolls-Royce in 1954 when they were still building a few “Griffon” engines. They are taken straight from the diary I kept while passing through the works as a graduate trainee.
“Lead-Bronze Foundry
Steel-back bearings are cast direct into forged outer casings, with a tin inner sleeve swaged in to hold molten bronze. Bushes are cast into tins. Throughout engine the Cu-Pb basic is reinforced with tin to give required strength. Sn varies from 1% on mains to 10% on little end bushes and exhaust valve guides. Tins, etc, are dipped in molten flux before pouring, and molten pour is quenched to prevent settling of mixture & to improve strength.”
Another note reads:-
“Stress relieving
Eg. steel shells of bearings are heated at 200 degrees C for 3 hours”.
I recollect that, after making the bearings they were checked for circularity on a jig and, if not right, given a few taps with a mallet by an experienced employee for correction!
Regards, Derek Taulbut.
In trying to understand what “tin inner sleeve swaged in to hold molten bronze” meant things got a bit fuzzy, after all this occurred when ERII was still a virgin. I would welcome any recollections from anybody that ever made these bearings and in return will apologize for linking the Sn with HM.
powerandpassionSome thoughts
Hi all,
did the build quality of aircraft suffer during WW2 compared to those built before or after? Mark.
Some thoughts :
In WW2 UK most aircraft inspectors, AID officers, would have been middle aged, either veterans of WW1 or fathers or uncles of combatants. The Aeronautical Inspection Directorate was well developed in the 1930’s, and the combination of professional pride and connection with their own service or the service of younger relations would have been a potent support for quality control. Perhaps the blow outs and quality issues that bedevil some contemporary military projects relate back to oversight from folk that never had to suffer faulty equipment while being machine gunned.
AID inspection, or acceptance/payment for product by the Air Ministry came after inspection by the works. Look at the number of stamps on an old part to see the levels of oversight : raw material, machining tolerance, fit/assembly then AID. Old Bendix wheels from the US have a radiant pattern of numbers on the spokes : metallurgy, casting, machining. So by the 1930s a well established quality control system existed to support the scale up of production in WW2. Aircraft that crashed in the 1930’s did so mainly due to pilot exhuberance.
Of course this system came under immense pressure during WW2, but canny foremen had a way of dealing with assembly workers who had the wrong attitude. I recall reading of Canadian Mosquito production in Downsview when an assembly worker was randomly chosen to go with the test pilot on many maiden flights. Downsview had in house newsletters that constantly reinforced how the smallest detail carelessly omitted could have catastrophic results, which occasionally happened, invariably in view of the plant, part of the feedback loop.
The Soviets just shot folk who would betray the motherland with poor workmanship. Stalin resolved a railway logistics bottleneck issue by decreeing that railway officials should be hung from telegraph poles until the issue was resolved, and had no problem sending aircraft designers to the gulag if they were ineffective.
No doubt on the Axis side these issues were further complicated by raw material shortages. The purposeful choking of bauxite supply from the Dutch East Indies to Japan was a key part of the US island hopping campaign rationale. The struggles of Japanese designs from 1943 onwards due to poor metallurgy are well known. The scatter bombing of Nazi industry after 1943 assisted in creating quality control issues, let alone Czech, French and Pole slave labour searching for ways to quietly destroy quality.
While an airframe might statistically be expected to survive perhaps 100 hours, those that built them cherished the hope that their sons who flew in them would return to resume a fuller sort of life, so they built them strong and well. There were lazy, corrupt and maladjusted constructors, but you had to work hard to be so. Easier later.
powerandpassionHappy to see this aircraft stay in Oz
powerandpassionGilman Patent
Ed, you need to get yourself a copy of Dan Whitney’s excellent book “Vee’s for Victory – The Story of the Allison V-1710 Aircraft Engine 1929-1948” ISBN 0-7643-0561-1. Every aviation petrol head should have a copy. 🙂
AA, thank you for your lead on this, below is the actual patent, care of www.
I will chase up the book.
Certainly a fascinating bloke and connections all the way back to probably the grandpa of Hudson Hornet in Pixar’s Cars ! I think these bearings will never fail and are stronger than most modern high performance bearings, but obviously too expensive for modern production.
I wonder if there is anyone in the US making Gilman bearings for V 1710s ?
Patent was lodged in 1929, renewed by General Motors in 1938. RR was making “F” engine at the time and my 1930 “F” engine manual details white metal bearings, so looks like the commercial development of the RR Kestrel was very much enabled by adopting Yankee technology…
Method of Making Bearings US patent 2130461
In the development of motors designed for high. speed and heavy loads it is important that they be of the lightest weight possible in order that the least amount of power may be required to propel their own weight and, therefore, that metal of the lightest weight possible be employed.
This has resulted in the improvement of metals used for such purposes so that the weight has been decreased without impairing the strength and endurance qualities but more flexibility has resulted, such improved metals being capable of withstanding more or less flexing. Such flexing of the metals as well as the speed of or the load carried by the motor causes a strain upon the bearings used which breaks down lining of such material as Babbitt metal, which has heretofore been generally employed for such purposes, and also results in.the loosening of the bond between the Babbitt lining and the metal of which the shell is composed, thereby materially decreasing the life of the bearing and impairing its efficiency in use. Inasmuch as the value of the motor in service can equal only the life of the bearing it becomes more and more important in the development of this art that bearings be provided which will stand up under the flexing and the great speed and the great load imposed without danger of destruction in the performance of such duty and particularly without separation of the metals of which the shell and the lining are composed.
The object of my said invention is to provide a bearing and a method of making the same composed of metals which will provide a bearing of the necessary strength and rigidity and a bearing surface which will be of comparatively soft wearing quality but at the same time capable of resisting much higher temperature and withstanding much greater strain or “pounding” in service than metals such as Babbitt metal; and also one in which the metals are united by a bond that makes them practically integral and incapable of separation under flexing or any other strain. I have found by experience that a steel shell affords the best foundation for a bearing such as, required for the purpose indicated for the reason that it may be of lighter weight for the same degree of strength than any other metal which I have found suitable for the purpose. I have also found that so-called “plastic bronze” makes a most desirable metal for the lining or wearing surface for the bearing. By “plastic bronze” I mean a composition composed of copper and lead the proportions of which may be varied to suit different conditions and different requirements, a suitable composition being thirty (30) parts of lead and seventy (70) parts of copper. “Plastic bronze” is generally understood to also include, if desired, copper alloys of from 4% to 7% tin with 20% to 30% lead and with or without small quantities, of nickel. It will be understood that in using the term “plastic bronze” herein it is intended to include all such suitable compositions and variations thereof. As is well known the melting point of steel is considerably higher than the melting point of the bronze but the melting point of bronze is very much higher than the melting point of babbitt and the bronze of a composition such as above indicated while affording a most excellent surface for the bearings of high speed motors, nevertheless is of a density and tenacity capable of resisting the wear and heavy duty required.
In the manufacture of bearings of my said invention I employ a method by which the steel shell and the bronze lining or bearing surface are united by fusing the two metals to unite them by a bond that makes them practically integral and permanent so that separation under any strain, load or flexing imposed by the duty of the motor is impossible.
In the accompanying drawing, Figure 1 illustrates a bearing such as contemplated by my invention, the bearing housing usually of aluminum or any other appropriate metal being indicated by the reference letter A, the steel shell by the reference letter B, and the bronze lining by the reference letter C.
In Figure 2 I illustrate a method of forming the bearing which consists in mounting a cylinder D with a bottom d within the shell B and pouring the molten bronze from a ladle E into the space between the cylinder and the inner surface of the shell. It will be understood of course that the ends of the bearing are machined off appropriately after the bearing is finished. The bottom d of the cylinder D is large enough to cover the end of the shell B as clearly indicated.
While I have illustrated this as a method by which the molten bronze may be applied to the shell it will be understood, of course, that any other appropriate method may be employed, whether it be the method of pouring, the method of die casting, or the method of applying by centrifugal force or any other method now known or found appropriate. And I also want it understood that while I have specified “steel” and “plastic bronze” as the two metals preferable in use that these terms are used as meaning any of metals that may be found capable of the use intended. Further, while the method described has been found particularly adapted for the purpose set forth it will be understood of course that it may be modified within the scope of the appended claims. For example, the steel shell and lining metal may be heated together to a temperature where the lining metal will be a substantial degree above its melting point and the steel shell a substantial degree below its melting point or the parts may be heated separately to different temperatures so long as the steel shell is a substantial degree below its melting point and the lining metal a substantial degree above its melting point. The two metals may be united or applied to each other in any manner found practicable, the particular method illustrated and described being one that I have found suitable for the purpose. As will be understood the steel back and the lining metal may be united in flat sheet form if desired and then rolled or otherwise shaped to form a bearing of the shape desired.
In the practice of the method by which these bearings are produced the steel shell of appropriate thickness is heated to a temperature which is approximately the temperature required for melting the bronze metal which is to be used to provide the bearing surface. The bronze metal is heated not only to the melting point but to approximately two hundred (200) degrees above its melting point and then is applied to the surface of the shell by the method heretofore described and illustrated in Figure 2 of the drawing or by any other method found appropriate.
The bronze metal being in a fluid condition and the steel of a temperature substantially the same as that of such bronze metal the two metals fuse and unite firmly together forming a bond that makes the two metals practically integral and incapable of separation regardless of strain, flexing or other duty imposed in use.
After the bronze metal is poured or otherwise applied to the steel shell it is allowed to cool for a short period sufficient to allow the two metals to fuse together but before the lead in the composition of the bronze can settle and separate from the copper by reason of its greater gravity the bearing is immersed in a cold bath and cooled quickly so that the copper and lead content of the bronze composition are held in the metal properly mixed and of the same relative proportions throughout.
The bearing resulting from the practice of the method herein set forth is made the subject matter of another application No. 575,117, filed November 14, 1931, as a division of this application.
While I have illustrated a bearing with the shell lined on its inner surface with the bronze it will be understood of course that its outside may be in a like manner covered with a bronze bearing surface or the bearing surface may be applied to both sides of the steel shell, depending upon the character of use for which the bearing is intended.
By this method a bearing is provided which has been found capable of withstanding the severe requirements of motors designed for the highest speed in airplane and other service and by actual test and comparison such bearings have been able to far exceed in their efficiency in these respects any bearings made by any other processes heretofore known.
Having thus fully described my said invention, what I claim as new and desire to secure by Letters Patent, is: 1. The method of forming bearings which consists in heating a steel shell to approximately the melting point of the bronze lining metal, heating the bronze lining metal to a temperature higher than its melting point, depositing said lining metal while so heated upon the surface of the heated shell, permitting the two metals to fuse and then rapidly cooling the same.
2. The method of forming bearings which consists in providing a steel shell of relatively light, flexible character, heating said shell to approximately the melting point of a plastic bronze lining metal, heating said plastic bronze lining metal to a temperature higher than its melting point, depositing said lining metal while in its molten state upon the surface of the heated steel shell, pausing for a short space of time to permit the two metals to fuse and then rapidly cooling the same.
3. The method of forming bearings which consists of heating a steel body to a temperature higher than the melting point of a composition metal for the bearing surface, mounting a cylindrical core concentrically within said heated steel body, then applying the composition lining metal heated to a temperature higher than its melting point in the space between said core and steel body, allowing time for the two metals to fuse. and then immersing the bearing and core in a cold bath to set the composition.
4. The method of forming bearings which consists in combining a steel shell of relatively flexible character with a lining, of “plastic bronze” by heating the two metals to a temperature that will not melt the steel but will melt the lining metal, permitting the two metals to fuse and then rapidly cooling the same.
5. The method of forming bearings which consists in combining a steel shell with a lining of “plastic bronze” by heating the two metals to a temperature that will not melt the steel, but will melt the lining metal, permitting the two metals to fuse and then rapidly cooling the same.
6. The process of producing a bearing having an outer iron or steel layer, and an inner layer consisting primarily of copper and lead, said two layers being autogenously welded together at their meeting surfaces, which process comprises contacting a molten mass of said copper and lead to form said inner layer, with said outer iron or steel layer heated to a temperature sufficiently high to produce an autogenous weld between the layers; permitting said bearing to stand for a time sufficient for an autogenous weld to form between the layers; and finally drastically chilling said bearing.
NORMAN H. GILMAN.
powerandpassionWell they went back to using S with the Sea Otter and returned to Seagull with the ‘boat with variable incidence wings. Names were usually proposed by the company and then vetoed or rubber stamped by the Air Min so its a puzzle, although not exactly critical. I bet it annoyed Westland, one less W that they could use.
Nup, Westland Walrus was already there in 1925… maybe Walrus was code for something big, fat and ugly, with apologies to all Walri and Walrus lovers out there.
powerandpassionThank you
powerandpassionBingo
At the risk of drifting off the thread topic….
The steel back bearing shells were invented by Norman Gilman and patented by the Allison Engineering Company (later bought out by General Motors) in the early twenties. After trying to come up with a number of solutions to bearing problems in their engines, Rolls Royce ended up obtaining a license from Allison for the steel backed bearing shell technology and paid a royalty on every engine for it (along with just about every other major engine manufacturer…:))
Gold !
(I will start another thread once I hit a new wall on these bearings…)
powerandpassionFound some data on the Bristol 1a, it references to report, B.A. 643
Thanks ac, will pm
powerandpassionFrom http://aerospace.illinois.edu/m-selig/ads/coord_database.html#C
CLARK YH AIRFOIL
16. 16.
Schneiderman, thank you.
While I am on Schneider stuff, do you know if the R engines on Schneider racers had cast in copper bearings at conrod big ends. I understand RR Eagle did and RR Kestrel has, but I have seen references to ‘white metal’ on R engines. I am trying to figure out the logic of cast in copper (gunmetal?) bearings, replaced with removable bearing shells in RR Merlin.
powerandpassionThoughts
According to Bristol drawing # 12356-1 Top Wing Standard Rib and #12497-1 Bottom Wing Standard Rib. After interpolation to the ordinate system, these ribs are the same aerofoil.
David Luff’s book “The Bristol Bulldog” states that the lower wing was a Clark YH. He must have taken this from Andrews book. The aforementioned ribs are for the Type 105 dated 1927.
The YH and 1A are very similar when placed on top of each other. (I have drawn this) Perhaps the YH is the father of the 1A. P&P is admirably spearheading a quest to find more information on the 1A. Correspondence to Bristol Heritage group has so far produced nothing. (please-please let us know if you have said info)
The Bristol 1A ir supposedly the father of the RAF 34 & 35 aerofoils. (This will impress any girl you ever meet.)
Ed 1
Ed, I have 1925 dated patent for Bristol spar used in Bulldog and a lot of steel aircraft literature from the time relates to corrugated spar design. I figure that Bristols designed its spars first, then sought an aero foil to both fit the spar geometry and performance characteristics it was seeking. Perhaps in the process of compromising between limitations of geometry they needed to slightly change the YH to make everything fit, birthing the proprietory 1A without sacrificing YH performance or needing to change their spar dimensions which would require new roll form tooling, not possible on a private venture prototype after years of not winning Air Ministry contacts. Hey I am typing this on an iPhone for the first time and it is ok! I am in a factory yard surrounded by brown snake filled grasslands and it is 40 degrees C. Warm wishes !
powerandpassionThe problem: the depth of the Bulldog aileron on the Mk II series. Does anyone have any insight to ailerons actually being thinner than the adjoining wing? Most ailerons are either
the same size, or slightly larger than the adjoining wing. As there are no known drawings of the Mk II/IIa aileron rib all that is given is an illustration in the A.P. manual showing the
aileron slightly thinner than the wing rib. Did Bristol experiment with this idea? Bristol did one experiment with the Hartshorn aileron, but no information in that paper talks about the
original aileron. I have checked with some of the most knowledgable individuals around who were kind enough to contemplate the question. But nothing definite.
So I am hoping someone out there just happens to know, or knows who knows the answer.
CheersEd
David Luff’s Bulldog pg 57 shows a Hartshorn aileron drawing, with a tapering leading edge that results in three different rib profiles depending where the section is taken. Perhaps this explains the AP drawings showing odd shaped aileron ribs….
powerandpassionBulldog prop
John,
Would you be so kind as to give more physical details. Length, dia. of hub, thickness of hub, dia. of bolt circle, max width of blade, dia. of mounting bolts, dia. of hole. All this will help.
Cheers
Ed
Mate, this is what you want :
Top is Westland Wapiti, middle is Hawker Demon and bottom is Bristol Bulldog. Because you never reply to my posts I will not tell you where they are !:)
powerandpassionHP Clive
I am assisting to ID this prop. It was found in the Oban area. It is 10′ 9″ in dia and has no markings. The rotation is British LH and the usual candidates for such as this would be the Lion, Jaguar, Panther, Pegasus and Jupiter. However all these engines have 8 or 10 bolt hub fittings. This prop has 12 bolt/stud holes. Rolls Royce engines are opposite rotation (RH) though I believe some Falcons and Eagles had LH props but again used 8 stud hubs. The Condor did have a 12 stud hub but I think this prop is nowhere big enough.
I have found one candidate engine with 12 stud fitting and that is the very rare Cosmos Jupiter, later to become the Bristol Jupiter II. Most subsequent members of the Jupiter family used a 10 stud hub fitting Did some early Jupiter’s have 12 stud hubs?
Note the two countersunk brass fittings on the rear of the boss. Are they locators so that the prop if removed will go back at the same position relative to the crankshaft perhaps for gun synchronizing?
Any ideas gentlemen?
John
[ATTACH=CONFIG]225170[/ATTACH]
[ATTACH=CONFIG]225171[/ATTACH]
[ATTACH=CONFIG]225172[/ATTACH]
Attached is photo Of Handley Page Clive 1928, showing what looks like your 12 hole sandwich prop, with the obvious rational for brass locators ensuring a balanced assembly. The photo is from a HP company doc “Forty Years On” 1919 – 1949. Most of the early HP bombers had Falcons which is perhaps where the comfort with 12 hole hubs developed from. Later photos of HP 42 passenger airliner show four blade props, so perhaps the sandwich affair was the typical use of “off shelf” Falcon stock for new application with Jupiter in HP Clive, and once the Jupiter powerplant was established for HP use then a lighter four blade unit was worth investing in for later HP aircraft.
Another thought stems from reading “Flying Years” by CH Keith 1937, which relates to the interwar period in Iraq, and troubles associated with heavily laden takeoffs in ‘thin’ warm, tropical air. Perhaps two blades were used for light applications and four blades for heavy going in the tropics ? Perhaps the secondary blade was kept in the fuselage or workshops for monsoon conditions in places like India/Malaya/Singapore ?
Ed
powerandpassionThe Cloud
Hi,
Titanium Tetrachloride did not need to be ignited – just exposed to air (see Wikipedia)
The Stirling had the capability to take a ‘mysterious’ Bomb Bay load called an SCI – it could do this with Titanium Tetrachloride:
http://www.youtube.com/watch?v=lKU_8hT7rjw
Most impressive!
If your device did use this and if the wind were low it would have left quite a tell-tale trail.
James
James,
Thank you for posting the video link. It is an extraordinary, slightly frightening spectacle. In following through on the web it seems an unpleasant substance, basically fine particles of hydrochloric acid, which explains why it probably wasn’t used as a smokescreen for amphibious assaults such as D-Day or the Pacific islands.
Here is a video of some folk who probably found a vial next to some radioactive waste they might later rub on themselves to see how it will glow at night, win a Darwin award and do a favour to the dogs of the world :
http://www.youtube.com/watch?v=rx7dcM5-Esg
If this stuff was decanted into practice bombs I wonder what the procedure was ? Perhaps it was sealed in small glass cylinders which were safe to handle and insert, and the striker mechanism of the practice bomb simply broke the glass, funnelling the vapour out through the tail tube.
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