Of course a dolphin is a very different thing from a dauphin. 
They sound similar though.
M stands for “Mark” or “Model”, doesn’t it ? So M1911 is “that one pistol we designed in 1911”, while M2 is “the second type of X we designed and validated”. M1 was the first semi-auto rifle for the US Amry, and its first submachine gun, and its first turbine-powered tank.
Where it gets tricky is when you get to designations like M1A1 : Model 1, first variation on the first variation ? But it gets sillier, with the M1A1AIM v.2 ! 
That’s not too ridiculous, when you consider they have to separate major revisions, minor revisions, and variants in a name that’s easy to remember, and, more importantly, hard to mess up in communication (e.g. “did he order an a1.1 or an a11?”)
It was worse before WWII, when you could have a Medium Tank M2 and a Light Tank M2 that had absolutely no relation to each other aside from both happening to be tanks.
Also, as I think I mentioned upthread, the Army, Air Force, and Navy/Marines once used their own naming systems. For example, the F4H Phantom II (F for Fighter, 4 for 4th design from this manufacturer, and H for McDonnell) which was the F-110A Spectre (technically the last of the “Century Fighter” series that started with the North American F-100 Super Saber).
Another example is the SBD: SB for Scout Bomber (in practice, this meant a Dive Bomber), D for Douglas. The same aircraft saw service with the Army Air Forces as the A-24 Banshee (I haven’t looked into it, but I’d be willing to bet money that the name derived from the sound the air going through the dive brakes made as the plane dropped from 5,000 feet to 1,000 feet directly on top of some poor soul’s helmet)
The Air Force, being spun off from the Army, had a very similar system, with some customizations (F for Photorecon became R for Recon, P for Persuit became F for Fighter, A for Attack became F if single engine and B if twin engine, C for Cargo and B for Bomber stayed the same). It got weird whenever the two services would share kit in later decades, like the Air Force’s GAU-5, which was an automatic rifle based on the CAR-15 (in other words, it was an M-16 in all but name with a few minor differences).
Where it got really weird with the Air Force was with missiles. For a while, a missile designed to shoot down fighters was given an F designation, with the reasoning evidently being that it was an aircraft that engaged other aircraft. Similarly, early cruise missiles were given B designations. They only did that for a few years before they stopped.
EDIT: Also mentioned up thread I’m pretty sure, all three services were told to use one unified system because Congress was tired of every branch of the military using their own designation for identical hardware. This was in the days when the US Air Force joked that the Russians were merely their opponents, while their enemy was the US Navy.
Pedantic unrelated point: The larger turret-and-radio version was the Grant, and the smaller turret, no-radio version was the Lee.
D’oh, got 'em mixed up.
Talk about getting things mixed up take the example of the M2 listed above and add in an M2 (ma deuce) machine gun.
You need a new barrel for your machine gun. Supply sends you a barrel for first one tank then another.
I think Mitch Hedberg used to do that.
‘That machine, thats the people killer. I’m going on break’.
No. Years ago on the AOL SDMB I got involved in this debate to the point of sending an email to the US Army Transportation Corps Museum asking about the original nomenclature of what we know as the Jeep. I said it was GP (General Purpose) and someone else said WC (Weapons Carrier).
I received an email and two attached PDF files. The original Jeep was a “Truck, 1/4 ton, 4x4, CR” (Command Reconnaissance*). The WC was a “Truck, 3/4 ton, 4x4, WC**”
The best I could find out about the name “Jeep” IIRC, was something like this. The word “Jeep” first entered the national consciousness with the character “Eugene the Magical Jeep” from the Popeye cartoon series. Eugene was able to walk (4 legged) up walls and across ceilings. And in those days (the late 1930s, if you went to a movie theatre, you sat through some cartoons and a newsreel before the main feature started. Then, the Transportation Corps put out a request for bids on a 1/4 ton, 4x4, 40 hp vehicle. 6 to 8 companies responded with proposals. The TC reviewed them and contracted with Willys, Ford, and Bantam to provide something like 6 prototypes each for testing. They put them in sets of three (one of each brand) and sent them to various climates/terrains with automotive engineers, mechanics, and test drivers for evaluation. In one of the test groups, the test driver who was just about to put a Ford prototype though it’s paces, commented “Let’s see what this jeep will do.” and the name stuck.
- The first jeeps issued had a big 2 way radio mounted on them that ran off the jeeps electrical system, which radiomen who previously had to carry them on their backs everywhere really appreciated. So commanders and recon parties could report back their findings to higher echelons.
** In the movie “Patton”, after the Kassarine Pass when Patton arrives to take over command, he’s in a small motorcade of a jeep, himself riding in a WC, and followed by another jeep. They look a lot like jeeps, but it’s a bit larger.
No. Because that is one of several theories, including mine, for the origin of the word.
FWIW…
The Lockheed S-3 was officially the Viking, but was most often called the Hoover in real life (i.e., on the flight deck) because of its huge TF-34 turbofan engines. [The A-10 uses the TF-34, too.] The S-3 was supposed to be a carrier bases ASW platform and was late in its life uses as an electronic intelligence aircraft, but had the flying characteistics of a dairy cow. Someone may be able to correct me, but I remember hearing that during the frst Gulf War, an S-3 dive bombed an Iraqi patrol boat and nailed it by mistake with its inflight refuelng store (D-704). Good hit, though.
I always heard of the Grumman F-14 as the Turkey, which seemed very appropriate as with the engines it had (except in the few F-14Ds produced), it was notoriously prone to sudden engine failures/explosions and could not be manuvered as hard as it might otherwise have been. It seems to have been intended as a long range missile platform (truck) for fleet defense, and not at all the dogfighter you see in Top Gun.
The new, improved F-18 Hornet is (IIRC) ~65% different from the old version with significantly upgraded preformance and so in real life they call it the Super Hornet. The easiest way to tell it from its predecessor is by its large, rectangular engine air intakes. It really should be designated the F-something else (other than -18) because it is really a different airplane, but it apparently takes an act of Congress (literally) to allow NAVAIR to establish a new PMA (Program Manager Air), which they’d need to manage a new aircraft type.
The Douglas A-4 remains one of the best aircraft ever to grace a flight deck. Officially the Skyhawk, it was unofficially the Scooter (and a few other names that I no longer remember).
The Douglas A-3 was the Skywarrior but in real life was called the Whale.
The immense North American A-5 Vigilante I think was more often called the Elephant. They say it was quite fast, but in then end it ended up being pretty much useless.
The McDonnell-Douglas F-4 Phantom was actually most often called by its given name, although in its later days, they called it the Lead Sled sometimes.
The Vought A-7 preceeded the S-3 in service by quite some time, and I think sometimes they called it the Hoover as well, because its low intake sucked up a lot of FOD and the occasional deck ape.
The Grumman A-6 Intruder seemed to have had a lot of weird nicknames, but none of them seems to have really stuck.
All of the above mentioned aircraft (with the exception of the F-18) are out of service now.
Which reminds me : the P-39 Airacobra was often called the “Iron Dog” or “Iron Coffin” in WW2, because it had a nasty habit of going into irrecoverable spins and its design made bailing out more difficult than in other planes (i.e. instead of a removable/sliding canopy, you had to open a side door and walk on the wing. Which is kind of troublesome to do in a frakking spin).
The Russians loved it though, and called it the Little Shaver (“shaving” being Russian airman slang for low-altitude strafing). Then again, anything must have flown *awesome *to them compared to the Polikarpov I-16 :). King of the flying anvils, that one.
Maybe semantically, but the helicopters were for all intents and purposes identical.
(I used to work for American Eurocopter’s IT dept on their ERP system; parts was parts, and the HH-65 and Dauphin parts were exactly the same, except for some numbering that the Govt. required, and that we sold them some parts for gearboxes and the like that we typically reserved for depot level servicing on civil aircraft)
Oh… and Army helicopters were named after native American tribes long before the AH-1 Cobra; it’s the exception to the rule. Even the famous “Huey” of Vietnam fame is more properly called the UH-1 Iroquois, and that ancient ugly sort from MASH fame is the Bell H-13 Sioux.
Navy/USMC helicopters don’t really conform to that naming scheme with names like Seasprite, Seahawk, Super Stallion, etc…
Dauphin is French for Dolphin, incidentally.
Regarding the F/A-18D Hornet vs the F/A-18E Super Hornet, that kind of thing has happened before. The F-86D Saber (the "Dog Saber, for it’s unusual rounded nose with chin intake instead of a more typical open nose jet intake) only shared a few parts in common with other F-86 models, and filled a different mission (the normal F-86 was your typical gun-slinging fighter plane, the F-86D was a night-time Interceptor armed with radar-triggered rockets).
Then again, North American’s jet fighters were in a rapid state of evolution at the time (along with Republic’s own Thunderjets, which evolved in a number of interesting and absurd ways, to include a rightfully maligned turboprop version known as the Thunderscreech), one that seemed to outpace the Defense Department’s ability to produce new designations, as evidenced by the Navy’s Fury program. The FJ was basically as close to a jet-powered Mustang as one could get (and was goofy looking as all get-out). It evolved to become the F-86, which was adapted to become the FJ-2 and FJ-3, and the FJ-4 was a complete rebuild that shared few parts in common with the -2 or -3.
Meanwhile, Boeing had finally ironed out the wrinkles in the problematic B-29, presenting the B-29D, which was promptly shot down (metaphorically) because Congress didn’t want more WWII airplanes, they wanted something new! So Boeing took the exact same design and presented Congress with the B-50A Superfortress! This brand new design was put into production and would see various derivatives of it’s own such as the expanded-body C-97 family.
Right. I keep forgetting that to many Anglophones it only means a French prince.