# Copy the other guy's stuff



## gjs238 (Jun 2, 2010)

What equipment was copied from the enemy?
What did the Germans copy? Russians? US? Brits? Etc.
Aircraft, firearms, widgets - anything.

Example:
US: Bazooka > German: Panzerschreck (enlarged improved)


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## Thorlifter (Jun 2, 2010)

It was post war but the Russians copied the B-29 down to the nuts and bolts and released the Tupolev Tu-4.


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## Colin1 (Jun 2, 2010)

Thorlifter said:


> It was post war but the Russians copied the B-29 down to the nuts and bolts and released the Tupolev Tu-4.


They did the same with the C-47


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## timshatz (Jun 2, 2010)

I think the M60 Machine gun was a compilation of ideas from various other machine guns (MG42, Lewis Gun, ect).


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## Colin1 (Jun 2, 2010)

Lessons learned from captured Fw190s
were fed into the Tempest V program, from windscreen and canopy design, ducted spinners on annular radiator experimental installations to the more general radial-engined layout with the stacked, individual exhaust stubs.


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## imalko (Jun 2, 2010)

Colin1 said:


> They did the same with the C-47



Quite, it was build as Lisunov Li-2, but they used different engines for their version.

Also, the advent of T-34 led towards development of German Panther.


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## davparlr (Jun 2, 2010)

A whole slew of German technology was copied/used by allies after the war.


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## Colin1 (Jun 2, 2010)

davparlr said:


> A whole slew of German technology was copied/used by allies after the war.


V2 technology in the US and Soviet space programs


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## Messy1 (Jun 2, 2010)

Metallurgy was "borrowed" from the British by the Russians. Read an account where Russians were given a tour of a British jet engine factory, and they wore soft soled shoes that would pick up metal shavings. The shavings were analyzed back in Russia to figure out the ingredients in the alloys the British were using and having success with in their jet engine program.


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## Colin1 (Jun 2, 2010)

Messy1 said:


> Metallurgy was "borrowed" from the British by the Russians. Read an account where Russians were given a tour of a British jet engine factory, and they wore soft soled shoes that would pick up metal shavings. The shavings were analyzed back in Russia to figure out the ingredients in the alloys the British were using and having success with in their jet engine program.


...and then the bloody Socialists under Atlee handed them the Rolls-Royce Nene


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## evangilder (Jun 2, 2010)

The Russians did not copy the C-47, they license built them for free. They purchased several DC-3 airliners before the war. 21 were bought for Aeroflot. Licensing arrangements were made as part of the deal.


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## bobbysocks (Jun 2, 2010)

i understand the japanese built a C47 as well....and made a zippo lighter copy but it didnt work as well as the original.


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## gjs238 (Jun 2, 2010)

US: M1 Garand > Japan: Type 5 Rifle (experimental w/minor changes)
US: M1 Garand > Italy: Beretta BM59 (post war, improved, more of an evolution than a direct copy)

Also produced under license in several countries post war: Italy, Japan, perhaps others.


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## evangilder (Jun 2, 2010)

bobbysocks said:


> i understand the japanese built a C47 as well....and made a zippo lighter copy but it didnt work as well as the original.



The Japanese purchased licensing rights for the DC-3 in February of 1938 as well.


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## vikingBerserker (Jun 2, 2010)

The G5N Shinzan has a lot of stuff copied from the DC-4E


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## N4521U (Jun 2, 2010)

Am I wrong? The Japanese were manufacturing a propeller hub assembly for the US before the war? And the Zero was based on a Hughes design that the US military rejected? Bill


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## evangilder (Jun 2, 2010)

There is a lot of rumbling that the Zero was based on the Hughes H-1 racer, but there has never been any definitive proof of it. There are similarities, but that can happen with a lot of aircraft.


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## r2800doublewasp (Jun 2, 2010)

Alot of German stuff was copied/built from remaining parts after the war by Czechoslovakia, ie the me 262 (avia s92) the me 109 (avia s-199, fitted with jumo 211) and the German halftrack Sd. Kfz. 251 (ot 810)


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## evangilder (Jun 2, 2010)

Spain also built 109s and He-111s. In an interesting bit of irony, the Israelis had some of the Czech 109s.


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## tomo pauk (Jun 3, 2010)

N4521U said:


> Am I wrong?
> ...
> And the Zero was based on a Hughes design that the US military rejected? Bill



One can trace pre-Zeros ( pre-Oscars) in A5M 'Claude' Ki-27 'Nate' - clean lines all the way.

But then, Ki-61 looks wery much like He-100 with enlarged wings 'normal' radiator.


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## Njaco (Jun 3, 2010)

evangilder said:


> Spain also built 109s and He-111s. In an interesting bit of irony, the Israelis had some of the Czech 109s.



another bit I believe is that the first 109 had a British engine and the last version, built by Spain, also had a British engine.

Wasn't the Erla hood a somewhat copy of the bubble canopies used by the Britiah and USA?


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## gjs238 (Jun 3, 2010)

I suppose perhaps the Allies were hesitant to commit copyright/trademark infringement since they would end up paying after the war was resolved.

Nevertheless, what should the Allies have copied from the Axis?
What should the Axis have copied?

Given the time constraints, what was practical to reverse engineer and copy?


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## tomo pauk (Jun 4, 2010)

Germans copied Russian 120mm mortar - being very impressed both when launching receiving fire from those babies. Good decision by Germans...

Allies copied German electric torpedo.


As for stuff that should've been copied... French 155mm GPF would've been looked as blessing from German artillerymen, ditto for Russian 152mm gun-howitzer 122mm gun. Also the 7,5cmL43/48 cannon 10,5cm howitzer barrels would've benefited from carriage from ZiS-3.
Western allies could have put to a good use tapered bore AT cannons, due to availability of tungsten, and recoilless guns would've been nice to have.
KV tanks' chassis copied by Germans pronto, with 8,8cm in the turret from day one.
Russians would've loved the DB-601 for their Yaks co, while Germans could've used Russian 37mm (mounted on Yak-9T) to tackle B-17s from great range. Late war B-20 and NS-23 (think that was the name) would've been nice for 109s 190s. 
One really great thing that Axis AA forces would've loved were the Western Allied radars VT fuses, and perhaps mounting those 8,8s at trucks (in Russian Italian fashion) would've been good.


How about nuke?


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## tomo pauk (Jun 7, 2010)

Now how I've forgotten the beauty, the R-2800 for Axis... And P-51, at least the airframe.


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## davebender (Jun 7, 2010)

T-44 - Wikipedia, the free encyclopedia
T-44 and later Soviet tanks copied torsion bar suspension from the German Panzer Mk III, Panzer Mk V and Panzer Mk VI. 

Ruhrstahl X-4 - Wikipedia, the free encyclopedia
Germany was working on a wire guided air to air missile which didn't quite make it into production. Post-war France produced the missile in modified form as an anti-tank weapon.

http://en.wikipedia.org/wiki/SNECMA_Atar
The post-war French SNECMA Atar jet engine was derived from the BMW003 engine. Much of the development was done by former BMW engineers. I find this project interesting as the WWII era BMW003 engine did not pan out. However if Germany had survived then something similiar to the SNECMA Atar might have powered a next generation German jet fighter.


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## Zniperguy114 (Jun 7, 2010)

The Russian PPSh-41 was a copy of the Finnish KP-31, the only true difference is the calibre and the number built.


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## stona (Jun 8, 2010)

Messy1 said:


> Metallurgy was "borrowed" from the British by the Russians. Read an account where Russians were given a tour of a British jet engine factory, and they wore soft soled shoes that would pick up metal shavings. The shavings were analyzed back in Russia to figure out the ingredients in the alloys the British were using and having success with in their jet engine program.



Errr!,but didn't we (the British) give them some nice state of the art Rolls Royce Nene jet engines to get the ball rolling. I believe the Nene was the most powerful jet engine in the world at that time (1947), though I stand to be corrected. Not really my thing jets.
Not terribly difficult to reverse engineer.
Cheers
Steve


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## Messy1 (Jun 8, 2010)

Steve, I am not sure the time frame that the event I wrote about happened, I was pulling it from memory. I was thinking it was towards the very end, or right after the war ended. I cannot even remember the book I read that in to be honest. I would like some more info if anyone has anything concrete on that subject.


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## red admiral (Jun 8, 2010)

> T-44 and later Soviet tanks copied torsion bar suspension from the German Panzer Mk III, Panzer Mk V and Panzer Mk VI.



What nonsense. Torsion bar suspension had already been around for years, and in use with Russian tanks for years before the T-44.



> Germany was working on a wire guided air to air missile which didn't quite make it into production. Post-war France produced the missile in modified form as an anti-tank weapon.



A "modified" form as in a completely different weapon.



> The post-war French SNECMA Atar jet engine was derived from the BMW003 engine.



No it wasn't. It was an entirely new design developed by the Franco-German team having access to British and American jet engines. Not something that wartime Germany can suddenly conjure out of nowhere.


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## Shortround6 (Jun 8, 2010)

The early Atar, while it was designed by/with the the German team that did the BMW 003 does have a number of differences. 
Several books do state that the Atar was developed from the 003 but there seems to be quite bit of development.
Atar was 886mm in Dia. vs 690mm.
Atar was somewhat shorter, 2845mm vs 3630mm.
Atar weighed 850Kg vs 624Kg.
both used a 7 stage axial compressor but the Atar had a compression ratio of 4.2:1 and an airflow of 43KG/sec at 8,050rpm compared to the 003's 3.1:1 compresion ratio and 19.3kg/sec airflow at 9,500rpm.
Burner sections were different with better materials in the Atar (stainless steel instead of aluminized sheet steel and 20 flame cups instead of 16. A few other differences?
Single turbine disc in each engine but again different materials and a slightly lower inlet temperature on the Atar. Atar also has a bigger temperature drop through the turbine indicating higher efficiency. 
Take-off was 2200kg thrust static at sea level. This is for the Atar 101V of late 1948/early 1949. 

It seems to be a bit like saying the Griffon was developed from the Merlin.


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## FLYBOYJ (Jun 8, 2010)

stona said:


> Not terribly difficult to reverse engineer.



Actually not really true.

The Soviets needed to know what some of the materials were in the raw state, possibly annealed prior to heat treating. That's where we hear about the story of visiting Soviet engineers who wore soft soled shoes so they can gather up examples of metal chips from machines at the RR factory. Once they figured out what the material was they how to figure out how to make it, heat treat it, and process it again not an easy task. The same held true for dozens of other components including rubber parts, gaskets, hardware and even safety wire. In some respects, the Soviets reverse engineering effort might have been just as brilliant as actually developing the engine themselves!


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## Shortround6 (Jun 8, 2010)

the soviets did have the advantage that once they analyzed a metal sample they could order a metal supply factory to produce that exact alloy without worrying about trade secrets or proprietory alloys.

Different British suppliers had slightly different alloys, some of which worked better than others in certain applications or needed slightly different heat treatment to get the same performance.
things got better in the 50s-60s.


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## FLYBOYJ (Jun 8, 2010)

Shortround6 said:


> the soviets did have the advantage that once they analyzed a metal sample they could order a metal supply factory to produce that exact alloy without worrying about trade secrets or proprietory alloys.


But figuring out the alloys was the hard part - all that had to be done "by hand." Melting the samples gathered and figuring out the alloying elements without the help of complicated machines and computers, that was the challenge, and I'm sure many of the engineers assigned to do this task worked under duress.


Shortround6 said:


> *Different British suppliers had slightly different alloys, some of which worked better than others in certain applications or needed slightly different heat treatment to get the same performance*.
> things got better in the 50s-60s.



I'd like to know where you got that information from or what specific parts, materials and their alloy specifications we're talking about. When a component is designed a specific material specification is called out on the engineering drawings and within that material specification is the alloying requirements. For example, if a component was to be made from 7075, it doesn't matter if the aluminum is bought from Reynolds or Alcola, 7075 is going to be made from _"5.1-6.1% zinc, 2.1-2.9% magnesium, 1.2-2.0% copper, and less than half a percent of silicon, iron, manganese, titanium, chromium, and other metals"_

The British would do the same on some of their earlier material specs for turbine engines and the only major difference you're going to find is the amount of impurities that may be in the raw state of the material. Using my example of 7075, as long as the ingot meets the basic alloying requirement for the spec, it doesn't really matter what supplier the material comes from.

Now those 'suppliers' *manufacturing parts *will not determine what material their part will be made out of unless they were granted full design authority and that was rarely done.


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## Shortround6 (Jun 10, 2010)

FLYBOYJ said:


> I'd like to know where you got that information from or what specific parts, materials and their alloy specifications we're talking about. When a component is designed a specific material specification is called out on the engineering drawings and within that material specification is the alloying requirements. For example, if a component was to be made from 7075, it doesn't matter if the aluminum is bought from Reynolds or Alcola, 7075 is going to be made from _"5.1-6.1% zinc, 2.1-2.9% magnesium, 1.2-2.0% copper, and less than half a percent of silicon, iron, manganese, titanium, chromium, and other metals"_
> 
> The British would do the same on some of their earlier material specs for turbine engines and the only major difference you're going to find is the amount of impurities that may be in the raw state of the material. Using my example of 7075, as long as the ingot meets the basic alloying requirement for the spec, it doesn't really matter what supplier the material comes from.



did the British "spec" 7075 aluminium or did they "spec" something like "B.B. 111" As in Bermabright 111?

See: iii | flight advertisements | ill birmabright | 1944 | 1049 | Flight Archive

or: flight advertisements | hiduminium applications | aluminium alloys | 1944 | 2487 | Flight Archive

The British were into proprietary alloys. Now another supplier might be able to supply the same thing or maybe not unless they paid royalties to the first company?
Remember Bristol tried over 40 alloys and hundreds of heat treatments and manufacturing processes to get the sleeve of the sleeve valve to stay round. It took a bit of high level coercion to get them to share this knowledge with Napier when Napier ran into trouble with their sleeves.
Many British companies had small engineering staffs and sometimes relied upon suppliers to suggest or recommend special alloys for specific applications. 
Sometimes they didn't know why something worked, they only knew that it did and if they tried substituting something else it failed. 
Most, if not all Bristol Hercules engines used imported Swedish roller bearings on their crankshafts. No British supplier could meet Bristols standards? or there was something about the Swedish bearings that was different but not readily identifiable?
There is a story about one of the Shadow factories tooling up to produce aero engines. The Car manufacturer who ran this plant wanted to "Buy British" when it came to the machine tools but the parent plant insisted on Swiss gear cutters for the reduction gears. Finially it was decided to try the British gear cutter on a trial bases before buying the majority of machines. The trail set of gears failed about 70-80 hours into the standard British type test. The way the two different gear cutters worked stressed the gear teeth differently as they were being cut. 

BTW, I didn't dream this up on my own. I believe the proprietary alloys thing was mentioned by Herschel Smith in his book "A History of Aircraft Piston Engines" but perhaps he was wrong and I am seeing things that were not there. 

The British aero industry and it's suppliers may have been very different in the 1940s (both during the war and right after) than they were in the 1950-60s or even later.


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## ppopsie (Jun 10, 2010)

Material; I once saw a TV documentary in which an ex-automobile engineer saying that when Toyota or Nissan started to manufacture automobiles after the war, they found themself even couldn't copy just a piece of leaf spring taken out from a US made jeep, which actually had been shot peened. The material composition could have been analysed or purchased, but it is evident that type of material treatment wasn't known to us then.


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## FLYBOYJ (Jun 10, 2010)

Shortround6 said:


> did the British "spec" 7075 aluminium or did they "spec" something like "B.B. 111" As in Bermabright 111?
> 
> See: iii | flight advertisements | ill birmabright | 1944 | 1049 | Flight Archive
> 
> or: flight advertisements | hiduminium applications | aluminium alloys | 1944 | 2487 | Flight Archive


I believe that is correct


Shortround6 said:


> The British were into proprietary alloys. Now another supplier might be able to supply the same thing or maybe not unless they paid royalties to the first company?


Again it depends what was being ordered and what was being produced. Usually machine shops were given the material to machine and also given limited detail of what they were 'cutting.' If the material was eating up (for example) routers, then manufacturing engineers would talk to the machinists about speeds, feed times and cooling.



Shortround6 said:


> Remember Bristol tried over 40 alloys and hundreds of heat treatments and manufacturing processes to get the sleeve of the sleeve valve to stay round. It took a bit of high level coercion to get them to share this knowledge with Napier when Napier ran into trouble with their sleeves.
> Many British companies had small engineering staffs and sometimes relied upon suppliers to suggest or recommend special alloys for specific applications.
> Sometimes they didn't know why something worked, they only knew that it did and if they tried substituting something else it failed.
> * Most, if not all Bristol Hercules engines used imported Swedish roller bearings on their crankshafts. No British supplier could meet Bristols standards? or there was something about the Swedish bearings that was different but not readily identifiable*?


Hard to say but also consider costs



Shortround6 said:


> There is a story about one of the Shadow factories tooling up to produce aero engines. The Car manufacturer who ran this plant wanted to "Buy British" when it came to the machine tools but the parent plant insisted on Swiss gear cutters for the reduction gears. Finially it was decided to try the British gear cutter on a trial bases before buying the majority of machines. The trail set of gears failed about 70-80 hours into the standard British type test. The way the two different gear cutters worked stressed the gear teeth differently as they were being cut.
> 
> *BTW, I didn't dream this up on my own. I believe the proprietary alloys thing was mentioned by Herschel Smith in his book "A History of Aircraft Piston Engines" but perhaps he was wrong and I am seeing things that were not there*.


I'd like to hear about more substantiation of this - I do know in the US, before the AF allowed a pilot to strap himself into a new aircraft, there are AF engineers who want to know how the thing was put together and what it was made from. 


Shortround6 said:


> The British aero industry and it's suppliers may have been very different in the 1940s (both during the war and right after) than they were in the 1950-60s or even later.


Perhaps - the war years produced things out of necessity and need. In the later years processes were refined to mitigate risk, today that risk mitigation is pounded into design teams with risk assessment requirements.

With all this said, it goes back to my original point about the Soviets reverse engineering Nene engines. Not an easy undertaking and actually in a sense an engineering marvel, even though they weren't the original designers.


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## FLYBOYJ (Jun 10, 2010)

ppopsie said:


> Material; I once saw a TV documentary in which an ex-automobile engineer saying that when Toyota or Nissan started to manufacture automobiles after the war, they found themself even couldn't copy just a piece of leaf spring taken out from a US made jeep, which actually had been shot peened. The material composition could have been analysed or purchased, but it is evident that type of material treatment wasn't known to us then.



Actually not so much the material, its properties. they probably didn't know what shot peening did to mild steel.


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## Shortround6 (Jun 11, 2010)

FLYBOYJ said:


> Hard to say but also consider costs



The Bearings were either flown in by Mosquitos or brought in by blockade running converted motor torpedo boats. At least that's how the story goes but such transport couldn't help but run up the cost. 


FLYBOYJ said:


> I'd like to hear about more substantiation of this - I do know in the US, before the AF allowed a pilot to strap himself into a new aircraft, there are AF engineers who want to know how the thing was put together and what it was made from.
> Perhaps - the war years produced things out of necessity and need. In the later years processes were refined to mitigate risk, today that risk mitigation is pounded into design teams with risk assessment requirements.


The mechanical properties would be listed in the manufactures data sheets. For special duties (connecting rods, piston rings, valve seats or even turbine blades or discs it is probably a question of the engine maker asking one or more suppliers what they have or would recommend for the job specified. After trying one or more samples/suggestions from each supplier one alloy is selected for use. Subject to further testing or service use. 
I think that samples would be supplied for testing, to confirm manufacturers specifications. as in "super alloy XXX" has a tensile strength of "YYY" when heat treated so and so. Other properties would also be given in the metal manufacturer's specification data and testing done to confirm these properties. What they might not tell people is the EXACT alloy percentages.
As long as the production stock meets the original specs and passes quality control checks why should the government care if Alloy "XXX" has .25% more of one element than Alloy "ZZZ" from another company? 
If alloy "XXX" is doing the job needed and there is enough of it the British might not have cared that much about a second source except in the case of bomb damage to the supplier. The government may have been controlling the flow of raw materials in any case. 
These materials are not total unknowns and the government is not allowing engines/aircraft to be built with materials that are untested., as in "trust us, you don't need to know the yield strength, or bending strength or wear characteristics of our alloy, we say it will do the job and that should be good enough for you"



> With all this said, it goes back to my original point about the Soviets reverse engineering Nene engines. Not an easy undertaking and actually in a sense an engineering marvel, even though they weren't the original designers.



No disagreement on this point. While the Soviets can certainly order any alloy they decide on (from analyzing the sample engines or shavings) without having to pay royalties, getting the heat treatment and other manufacturing processes correct is going to be quite a trick.
Some wartime contractors couldn't do even with help from the parent factory.


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## ppopsie (Jun 11, 2010)

Thanks.>its properties. 

In my opinion the Tupolev 4 is the only example of "copying" in history for its scale and significance. As for license manufacturing I am interested in what were the differences between the Merlin engines built in Britain and America. I know some of the important component in the Packard Merlin were of American made. Also I would like to know can the British build Merlin be fitted into the Mustang or not, in terms of airworthiness.


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## FLYBOYJ (Jun 11, 2010)

Shortround6 said:


> The mechanical properties would be listed in the manufactures data sheets. For special duties (connecting rods, piston rings, valve seats or even turbine blades or discs *it is probably a question of the engine maker asking one or more suppliers what they have or would recommend for the job specified*. After trying one or more samples/suggestions from each supplier one alloy is selected for use. Subject to further testing or service use.


That's more the exception than the rule. Having seen this as a prime contractor and from a sub-tier I can tell you that most of the time the prime contractor has those issues worked out, however I have seen items manufactured where the subcontractor presented evidence that the part could be made better or was even impossible to make and the prime made the necessary changes.



Shortround6 said:


> I think that samples would be supplied for testing, to confirm manufacturers specifications. as in "super alloy XXX" has a tensile strength of "YYY" when heat treated so and so. Other properties would also be given in the metal manufacturer's specification data and testing done to confirm these properties. What they might not tell people is the EXACT alloy percentages.


Actually when raw material is purchased by say an engine manufacturer for critical applications, not only does the material supplier supply material certifications, but must also supply "coupon" testing and results for the material and sometimes the prime may do their own analysis for verification.



Shortround6 said:


> As long as the production stock meets the original specs and passes quality control checks why should the government care if Alloy "XXX" has .25% more of one element than Alloy "ZZZ" from another company?


Because depending on the applications, some "allowed" impurities can cause problems down the line. For example, in wrought 7075 ingots, you would not want a high silicon content for something that going to be continually exposed to a salt environment.



Shortround6 said:


> If alloy "XXX" is doing the job needed and there is enough of it the British might not have cared that much about a second source except in the case of bomb damage to the supplier. The government may have been controlling the flow of raw materials in any case.


They did then and in some cases they do in today's world


Shortround6 said:


> These materials are not total unknowns and the government is not allowing engines/aircraft to be built with materials that are untested., as in "trust us, you don't need to know the yield strength, or bending strength or wear characteristics of our alloy, we say it will do the job and that should be good enough for you"


No but the argument lies in some proprietary processing that a manufacturer may be reluctant in sharing with the government. During my years at lockheed I seen this on several occasions. 



Shortround6 said:


> No disagreement on this point. While the Soviets can certainly order any alloy they decide on (from analyzing the sample engines or shavings) without having to pay royalties, getting the heat treatment and other manufacturing processes correct is going to be quite a trick.
> Some wartime contractors couldn't do even with help from the parent factory.


True


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## evangilder (Jun 11, 2010)

I don't think there is a great difference between the 2 Merlins. Keep in mind that it was the British who first put the Merlin in the Mustang. The Mustang originally came with a Allison.


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## FLYBOYJ (Jun 11, 2010)

ppopsie said:


> Thanks.>its properties.
> 
> In my opinion the Tupolev 4 is the only example of "copying" in history for its scale and significance. As for license manufacturing I am interested in what were the differences between the Merlin engines built in Britain and America. I know some of the important component in the Packard Merlin were of American made. Also I would like to know can the British build Merlin be fitted into the Mustang or not, in terms of airworthiness.



Agree to a point - The TU-4 was a huge undertaking and refined the Soviet's ability to reverse engineer captured technology, however the B-29 was built from materials the Soviets more than likely already seen in other American planes. Be rest assured that from the hordes or lend lease aircraft sent to the Soviet Union, I'd bet dollars to donuts that they took at least one example of each aircraft they got their hands on in mass quantity and took it apart, analyzing each nut and bolt. In the case of the Nene, they not only have to figure out material and their properties, the the processing that went into them. (ex - your comment about the Japanese and the leaf spring/ shot peening.

I'll address your other questions when I get to work!


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## ppopsie (Jun 11, 2010)

Thanks. I read in the past some of the key parts in the original RR Merlin required hand processing by skilled workers' and that was a potential hazard to mass produce the engine in Britain. The Packard's however didn't require such treatment but had performed equally with the original. 

Also I think the British had been wise in having contracted an American company for manufacturing the Merlin in early 1940 and prior to sign contract with North American for a new fighter. It must've been easy for everyone in that year, to foresee an occurence of bottleneck in the near future by the reason that most of the fighter types existed in 1940 relied sorely on the Allison engine.

PS mine is not a copy of anybody's


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