We have that problem with part numbers today on light aircraft. An identical vendor part can have a different part number for the same item, with different pricing even. Wheel bearings come to mind. The same Timken bearing can have different numbers assigned by the airframe manufacturer as well as different numbers for the same bearing by the wheel manufacturer. About 15 years ago, I checked pricing on a particular bearing under a whole bunch of airframe & wheel manufactuers' numbers & it ranged from about $5 to nearly $50!
I sort of liked the USN system, (same for IJN a/c system). Without taking up a lot of space, you knew the mission &/or secondary mission(s), design, manufacturer & variation in one little chunk. Just look at all of the mislabeled a/c today (all the F/A junk & F-35) under McNamara's system. Even back in the '60s after he "improved" it. (A-37 & AV-8 & FB-111 come to mind). Really doesn't matter, does it?
TBF/TBM examples would be the instrument panel and it's mounting brackets and one cowling panel...off the top of my head. Not sure on the Corsairs what was vendor specific.
Not so much different with aircraft but the Navy system for drawings and their part numbering system. They really didn't care who made the firing pin in that 40mm Bofors as long as it was to Navy drawing XXXXX-XXXXXXXXX and was identified by that drawing number, pretty much the same across all Navy hardware at the time.
Again it goes to the Navy numbering system, everything made for the Navy had to follow it.
Their "finished" aircraft designation system and their drawing numbering system for parts are two distinct critters and the latter was actually designed to provide part number commonality across different manufacturers.
Way back when Fairchild Space was still a company we found the NSN for the original AR-10 rifle and ordered half a dozen.....our material control geek was way pissed when he got a phone call about why we needed them for a Hubbel upgrade.
Well, no it's not. EA, as in EA-6 Prowler. It's a primary attack a/c with a secondary electronics. F/A, OTOH, is not correct. The F-18 is a fighter. F/A-18 indicates it's the Attack-18 with a Fighter secondary mission. If they want to show an F-18 has a secondary attack mission, it should be AF-18, or at least according to McNamara's system. But it's just like there was no B-111 converted to a fighter, the A-37 should've been AT-37 the Harrier wasn't an attack version of the V-8. What's the diff? The system isn't working any better now than prior to '62!
You miss my point. With the M4, it was as if the receiver for an ALCO 40mm gun was Ordnance drawing & P/N D12345, one for a PSC gun was Ordnance drawing & P/N E7890, and one for a PS gun was Ordnance drawing & P/N D45678. Although at arm's length they all looked the same, they were subtly different, enough to impact interchageability. This was dismissed because the receivers (or tank hulls, or left ailerons, I imagine) were "vendor specific parts". The parts were all made to Ordnance drawings, each had it's own Ordnance stock number, but the drawings were prepared under contract by the various suppliers to meet their own interpretation of what a
40mm receiver should be.
I can imagine that multi-site aircraft production was pretty much the same: Three companies were given a BuAer data package and the three companies made their own detail and assembly drawings. Thus, the firewall on a FG was probably different from the firewall on a F4U or a F3B. So, spare firewalls (or other parts not specified as GFI or mandated to be used by contract) would need to be stocked individually per part number, i.e., by aircraft manufacturer
The solution would be like the Army's: Have Ordnance (or ONE contractor) prepare the drawings for the whole end item and make all the associate contractors use those drawings rather than creating their own. (*)
Well, once you have an item that is interchangeable in detail regardless of who made it, why should an end item made at Vought carry a different designation at all from the end item made at Goodyear? Or, as McNamara pointed out, why should an aircraft made for the Navy carry a completely different designation than a virtually identical aircraft made for the Air Force or Army?
Nevertheless, the Navy should've been forced to change their system 15 years earlier. If I had my druthers we'd have privates pulling up anchors in BDUs on the right side of the ship too, but that's me. Ceterum censeo Carthaginem esse delendam, y'know.
(*) Heck, it's still a problem today. The reactor parts to the OHIO class subs were built by three vendors, more or less in accordance with design drawings prepared by Knolls Atomic Power Lab. However, each vendor made their own drawings of the parts they made, and individual interpretations of tolerances and dimensioning crept in. KAPL - in their infinite wisdom - did not make their design drawings the contract drawings, but rather each vendor's. Thus, parts that look the same are ever so slightly different such that some combinations will always fit together while others might not. Real havoc when you are trying to fit spares . . .
That's not true - each aircraft now has one basic designation, albeit a misapplied one. If it was as bad as before the Navy would have F8Ds (?) while the Marines (might) have the identical F/A-18s flying off the same carrier.
Kurt, From what I've heard from some of the old timers when I first started work - it was even worse than that. Aircraft made at the same site sometimes had different size subassemblies in some cases because of the way tooling was set up in different plants. So an aircraft coming off one line had wings a little different from one in another. The Navy had a training movie on why things have to be calibrated that mentioned this. (many years back)
Actually, it WAS transgendered, and that was/is the whole point.
...and considering that it started life as the USAF YF-17, got Navalized, and grew to carry a wider variety of ornance than any Naval carrier jet to that date, yes - I'd have to say the operation was a complete success.
The worst part of the Navy's system for me was the helicopter designations. I recall one that was 'HSS'. I know who built it (and they shall remain nameless) but it looks silly.
Sometimes for fun I sit down and re-designate planes out of Macnamara's into the old style. How about the F12F for the F-111B? Would they skip the F13F for the Tomcat?
Eh, I think the AAF system was the best. (IMO, only place it gets confusing is with the reece P-38s and P-51s) When the deisignation is written out fully (like P-51B-5-NA), you get the type, the number, the variant, production block, and maker. You knew you were talking about the same aircraft regardless of who built it. The only thing that made it less than perfect was having P pursuit and F for photo, instead of F for fighter and P for photo.
That's probably due to the fact that the aerodynamic pieces weren't built from dimensioned drawings but from undimensioned "lofts" that had airfoils and fuselage sections drawn full size that were used to make templates and jigs and fixtures. (This was pre-CADD, when things were faired in with splines and french curves. The exact profile was never really defined along the full length, just blended between the important points.) The parts came out to be what the tool was made at, not to any drawing. Obviously if the subcontractors used different tools, the resulting parts would be different.
As I recall the B-2 was the first plane to be fully defined dimensionally. As a result the wingspan plane-to-plane varied only +/-.25 inch (or so) whereas previous bombers varied +/- 2-1/2 inches.
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