How interchangeable were aircraft spares and consumables? (1 Viewer)

[tyrodtom]

You don't have to have to have Whitworth or British standard sockets or wrenches to work on whitworth bolts or nuts, you can do it with SAE sockets or wrenches.
SAE wrenches are sized by the flats on the heads, Whitworth, or British Standard tools are sized by the outside diameter of the threaded stud.

I've worked on many a early MG , Triumph, and RR cars with standard SAE tools.
You may need some sockets sized in 1/32 increments to have a correct fit on some BS bolts though, so that's quite a sizable socket set, or wrench set.

 

[GrauGeist]

I remember my first socket set (when I was a teenager), it was from Taiwan and the Standard portion was in 1/32 increments and the Metric portion had half millimeter increments in the smaller sockets: 5mm, 5.5mm, 6mm, 6.5mm, etc.

Years later, when I was working as a mechanic and came across an odd bolt, I'd break out that old set and tackle the job.

 

[fastmongrel]

I remember my first socket set (when I was a teenager), it was from Taiwan and the Standard portion was in 1/32 increments and the Metric portion had half millimeter increments in the smaller sockets: 5mm, 5.5mm, 6mm, 6.5mm, etc.

Years later, when I was working as a mechanic and came across an odd bolt, I'd break out that old set and tackle the job.

I have hammered an AF or Whitworth ring spanner or socket onto many a damaged or rusted metric bolt. Sometimes that odd tool that's sat in the bottom drawer of the tool chest for years gets you out of a deep hole.

 

[SaparotRob]

Hammers are so very useful, no matter what it started life as.

 

[Shortround6]

Was there universality in spark plug threads, Schrader valves, tires, etc. across different nations in WW2? How about propeller blades, machine gun or cannon parts?

As has been noted by others, the spark plug threads were often universal (or only a few changes)

However there were often variations in the depth of the threads (how deep was the hole), materials in the insulator, total height of the spark plug and even for plugs that looked pretty close, heat different heat ranges.
If you don't have the correct spark plugs your engine may operate just a little bit off, or a lot off and get worse with time. A plug that runs too cold will foul quicker than the correct plugs. Plugs that run hot will erode the electrodes sooner at the best and possibly just plain fail (crack/break the insulator and/or the electrode)

Tire valves were probably easy.
Tires not so much. Just like a lot of truck tires you can have aircraft tires that came in similar or identical sizes that were made with different layers/plies for different weights.
An eight ply tire may fit the rim and wheel wheel of 4 ply tire of the same nonmodal size but the tires are going to weight more.
In the reverse the 4 ply tire may blow out trying to carry the load of the 8 ply tire.
Tire sizes were a lot less universal even on cars before WWII than after.

Machine gun and cannon parts are pretty much specific to the guns. A German MG 17 has no interchangeable parts with a Browning .30 cal.
The US .30 Browning and the British .303 Browning did have a number of parts that could be interchanged. Also a lot that didn't.

British and the Americans couldn't even get the different 20 mm Hispanos to play well with each other

 

[Jabberwocky]

I wonder if this was the case for Oerlikon's 20 mm cannon and Bofor's 40 mm cannon that seemed to be used by many nations.

Standardisation between nations is HARD. Look at the case of the Hispano-Suiza HS.404.

The UK and US both purchased manufacturing licenses for it (the US for an obscene amount more), so theoretically their guns could have been interchangable. But, both countries modified the original drawings to their own standards and there were issues with the US built versions (chamber too long, weak single recoil spring). As a result, a common production standard was never reached.

From Chin's 'The Machine Gun' pp 556-557:

"... promising reports [about the HS.404] were coming in daily from the British, who had used practically the same procedure as our Army ordnance engineers in getting the gun into production status. The original Birkigt Type 404 gun was used as the model for the Mark I. This was followed shortly by the Mark II.​

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Drawings and a sample of this improved cannon arrived in the United States for purposes of study and test in January 1942. The British strongly suggested that American ordnance officials confer with their representatives in order to accomplish an early standardization. It was further desired that all 20-mm aircraft cannon of this design procured for British use be of the Mark II type, the principal differences between the Mark II and the American M1 being pointed out as follows:​

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"1. The magazine carrier of the Mark II gun had a different latch; the ejector was provided with a buffer, and changes had been made in the magazine holding boss.​

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"2. A heavier rear buffer was provided in the Mark II gun and the back plate was dovetailed into the receiver instead of being fitted with a simple groove as in the M1 gun. Inertia blocks were used in the breechblock slides of the Mark II gun.​

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"3. The sear of the Mark II gun had been modified.​

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"4. Triple wire driving spring and extractor springs were used in the Mark II gun instead of simple single-strand coil springs which were used in the M1 gun.​

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"5. Minor changes had been made in the muzzle brake of the Mark II gun.​

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"6. The receiver of the Mark II gun was substantially different from the one used in the M1 gun; much heavier guide rails were used and the receiver itself was larger, heavier, and designed in accordance with British manufacturing methods.​

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"7. The chamber of the Mark II gun was 2 mm shallower than the chamber of the M1 gun."​

The US basically failed/refused to make most of these modifications. Even with the AN-M3 (the US version of the UK's Mk V), many of these issues persisted.

The end result was that the UK never used US made Hispanos - even those that had been supplied to the UK under Lend Lease. Anthony Williams reports the Royal Air Force modified thousands of US built AN-M2s as ground AA (shortening the chamber and installing triple recoil springs), but none of these guns ever saw service.

I've also read accounts that US manufactured Hispano ammunition didn't play well with the UK built Hispanos. The RAF had a number of issues with US Hispano ammunition, to the point where they had to order inspections of the ammunition to eliminate duff rounds and then abandoned US ammunition for aerial use completely. The RAAF experienced something similar - their Beaufighters seemed to like US ammunition much less than UK/Commonwealth made ammunition.

 

[special ed]

You don't have to have to have Whitworth or British standard sockets or wrenches to work on whitworth bolts or nuts, you can do it with SAE sockets or wrenches.
SAE wrenches are sized by the flats on the heads, Whitworth, or British Standard tools are sized by the outside diameter of the threaded stud.

I've worked on many a early MG , Triumph, and RR cars with standard SAE tools.
You may need some sockets sized in 1/32 increments to have a correct fit on some BS bolts though, so that's quite a sizable socket set, or wrench set.

Way back in the 1960s when I worked on old cars, I found five or so, open end Whitworth (Craftsman brand) wrenches in the clearance bin at Sears. A quick check with SAE wrenches showed they would fit other sizes than marked. Those bargains are still in the tool boxes and allow pranks on the young ones. I have no idea why a US Sears store would have received Whitworth wrenches.

 

[GrauGeist]

Way back in the 1960s when I worked on old cars, I found five or so, open end Whitworth (Craftsman brand) wrenches in the clearance bin at Sears. A quick check with SAE wrenches showed they would fit other sizes than marked. Those bargains are still in the tool boxes and allow pranks on the young ones. I have no idea why a US Sears store would have received Whitworth wrenches.

Figure in the 60's, vintage (for that day) cars would have been 50 years old at best.
In the early days of American automobiles, there were several dozen car makers over the years and there wasn't really much of a manufacturing standard like there was post-war.

So you could encounter just about anything between the teens and thirties as far as hardware was concerned.

 

[RichardSuhkoi]

Germans used a 20x80RB cartridge with a 116g bullet for their Mg FF (the later, high explosive shell weighted only 96g); the Japanese Type 99-I cannon used a 20x72RB cartridge with a heavier bullet of around 130g. Therefore, despite being essentially the same design (Oerlikon FF 20mm), the two weapons used different cartridges and had different performance (muzzle speed, cyclic rate). The Japanese version was also lighter.

When the Germans introduced the lighter 96g HE Minengeschosspatrone, they had to change the recoil spring since the Oerlikon 20mm was an open bolt machine gun that relied entirely on recoil to operate. The lighter shell had lower momentum, so the spring needed to be weaker, otherwise the bolt wouldn't open completely. Therefore, even inside the Luftwaffe, the ammunitions were not interchangeable between the standard Mg FF and the new Mg FF/m that could fire the new high explosive round, despite sharing the same cartridge dimensions and despite being the same weapon in all aspects but the force of the bolt spring!

Most interesting are the German electric primers on 20 mm.

Germans used a 20x80RB cartridge with a 116g bullet for their Mg FF (the later, high explosive shell weighted only 96g); the Japanese Type 99-I cannon used a 20x72RB cartridge with a heavier bullet of around 130g. Therefore, despite being essentially the same design (Oerlikon FF 20mm), the two weapons used different cartridges and had different performance (muzzle speed, cyclic rate). The Japanese version was also lighter.

When the Germans introduced the lighter 96g HE Minengeschosspatrone, they had to change the recoil spring since the Oerlikon 20mm was an open bolt machine gun that relied entirely on recoil to operate. The lighter shell had lower momentum, so the spring needed to be weaker, otherwise the bolt wouldn't open completely. Therefore, even inside the Luftwaffe, the ammunitions were not interchangeable between the standard Mg FF and the new Mg FF/m that could fire the new high explosive round, despite sharing the same cartridge dimensions and despite being the same weapon in all aspects but the force of the bolt spring!

 

[RichardSuhkoi]

Germans used a 20x80RB cartridge with a 116g bullet for their Mg FF (the later, high explosive shell weighted only 96g); the Japanese Type 99-I cannon used a 20x72RB cartridge with a heavier bullet of around 130g. Therefore, despite being essentially the same design (Oerlikon FF 20mm), the two weapons used different cartridges and had different performance (muzzle speed, cyclic rate). The Japanese version was also lighter.

When the Germans introduced the lighter 96g HE Minengeschosspatrone, they had to change the recoil spring since the Oerlikon 20mm was an open bolt machine gun that relied entirely on recoil to operate. The lighter shell had lower momentum, so the spring needed to be weaker, otherwise the bolt wouldn't open completely. Therefore, even inside the Luftwaffe, the ammunitions were not interchangeable between the standard Mg FF and the new Mg FF/m that could fire the new high explosive round, despite sharing the same cartridge dimensions and despite being the same weapon in all aspects but the force of the bolt spring!

Most interesting are the German 12.7 mm electric primed machine guns used on various aircraft like 109. I read that the superior repeatability over wide temperature reduced the probability of a prop strike.

 

[RichardSuhkoi]

A post war comparison. 9 years ago I did some work on a MiG-15 UTI located at Wendover Utah. The hangar I was in had a RR Nene, J33 and a VK-1. Looking at them side-by-side they were identical except for some fittings and electrical connectors. I wanted to take a photo of the three but got wrapped up with work and then forgot about the picture.

Maybe 1996 Mr.Dean Martin in Vt showed me his MIG -15 engine next to a Nene and explained he could even swap spares such as starter. Supposedly when Britain gave the design to Russia they didn't want to make any errors so copied every detail.

 

[MiTasol]

By the 1930's, spark plugs would have had a standardized thread, typically 14mm.
So chances are, a spark plug for a BMW801 would have been able to screw into an R-2800.

However, there was a wide range of temperature ratings for spark plugs to meet an engine's requirements, so just because it would fit, doesn't mean it would work.

You are right about car engines but most aircraft engines use 18mm threads. That said there are always exceptions and one engine I did the annual inspections on in the 80s used 10mm plugs that were a nightmare to obtain. I worked on some weird ones at that time but I think this was the Walter engine in the MetaSokel. Not positive tho. dH Gypsy Major engines use 14 mm plugs. Cant remember what the six and Queen used but I think they were 14mm also.

As you say there are a wide range of heat ranges and also there are both long and short reach plugs. Fitting a short reach plug instead of a long reach gives all sorts of problems apparently but I have never had that problem.

Fitting long reach plugs usually means damage to both the plug and piston when they collide. Again, never been there but I did service one engine one time where a monkey fitted long reach plugs and a big stack of gasket washers. Several of those plugs worked loose which is why I got to fix it. Got to fix other problems as well. I suspect the problem to all those defects was owner maintenance.

 

[MiTasol]

A post war comparison. 9 years ago I did some work on a MiG-15 UTI located at Wendover Utah. The hangar I was in had a RR Nene, J33 and a VK-1. Looking at them side-by-side they were identical except for some fittings and electrical connectors. I wanted to take a photo of the three but got wrapped up with work and then forgot about the picture.

The big differences between the Nene and VK-1 is that the later has greater mass air flow and thrust, metric fittings, and the turbine after 2000 hours looks like it has only run a few hours whereas the Nene turbine shows lots of erosion at 300 hours.

 

[MiTasol]

Maybe 1996 Mr.Dean Martin in Vt showed me his MIG -15 engine next to a Nene and explained he could even swap spares such as starter. Supposedly when Britain gave the design to Russia they didn't want to make any errors so copied every detail.

You are right about the Nene and the Russian RD-45 engines but the VK-1 was extensively redesigned and develops about 20% more thrust. It is also far more reliable with an engine life in Polish Air Force of 2,000 hour, in China a sort of "on condition" meaning just replace what needs replacing and no hard time. The Nene was good for 300 hours.

I have the thrust data somewhere but I cannot see it in my MiG folder so I will need to go hunting

 

[MiTasol]

You don't have to have to have Whitworth or British standard sockets or wrenches to work on whitworth bolts or nuts, you can do it with SAE sockets or wrenches.
SAE wrenches are sized by the flats on the heads, Whitworth, or British Standard tools are sized by the outside diameter of the threaded stud.

I've worked on many a early MG , Triumph, and RR cars with standard SAE tools.
You may need some sockets sized in 1/32 increments to have a correct fit on some BS bolts though, so that's quite a sizable socket set, or wrench set.

The British, being British, have different spanners for course and fine thread bolts. Fortunately they use one size smaller Whitless spanners on the BSF bolts so you only need the one set.

Metric spanners fit BS bolts much better than SAE spanners

 

[GrauGeist]

I'm sure many will find this funny!

 

[MiTasol]

Was there universality in spark plug threads, Schrader valves, tires, etc. across different nations in WW2? How about propeller blades, machine gun or cannon parts?

There is little, if any, interchangeability between Brit 303 Brownings and the US 30 cals they are derived from. Not only are there minor changes to the barrel and feed to accept the different cartridges but many of the internals are changed because the Brits required the gun to stop with the breech open instead of closed and many other minor changes and the Brits used a powder developed about 100 years earlier where as the US used modern powder.

American Hispano cannons, and many parts, are not interchangeable with Brit and early war French ones. Later war Brit ones share many parts with the French but once France fell the Brits made a number of improvements.

This is because when the Brits sent the US the blueprints the US did not realize that the Brits used first angle projection while the US used 3rd angle. As a result the US guns were essentially mirror images of the Brit and French ones.

 

[GrauGeist]

You are right about car engines but most aircraft engines use 18mm threads.

I had actually meant 18mm originally.

Automobiles and aircraft used that as an unwritten standard well into the 60's.

By '73, the automobile industry started switching to the 14mm "peanut plugs" and the 18mm started to fade into obscurity.

The interesting thing about the 18mm plugs, was that it took a 13/16" socket.

 

[MiTasol]

The interesting thing about the 18mm plugs, was that it took a 13/16" socket.

Or 21 mm

 

[MiTasol]

The interesting thing about the 18mm plugs, was that it took a 13/16" socket.

Depends on who made the plug. Some use 13/16, some use 7/8 and some use 21mm. If my rusty memory is correct there were a lot of WW2 US plugs that used 3/4 sockets just to keep the confusion maximised