Identify that Tank/Ship/Plane/Artillery etc

[Spitfire -WONDERBOLT!]

it's a submarine.

[Sar1n]

it's a submarine.

Obviously, but which one?

[Spear Dog]

actually, (technically) it's a midget or mini-submarine.

[paleologos]

I think it is the Welman Midget Submarine, but I am not entirely sure.
Image below from a Norwegian museum:

[Sar1n]

Correct. Developed at Station IX for British SOE, it was rather poor design, and its only operational use ended in fiasco.

[paleologos]

Another airplane from me but this time it is a bit unusual it that I don't know the answer (though I think the insignia are Iranian).
I will give 2*rep to the first who will provide a documented answer.

[Abdülmecid I]

Yes, the aircraft is definitely Iranian, although the flag's emblem is not clear due to low resolution (still, it's almost certainly the five pillars of Islam and not the Imperial Lion). It looks like an Iranian F14a (the improved versions were never delivered to Iran because of the Revolution and the subsequent blockade). Many of them are still operational, as Iran lacks broad access to the international weapons market, although that's probably not true for the specific warplane depicted in the image.

[Sar1n]

Cheeky one, aren't you...

The aircraft is JF-17 Thunder, developed jointly by China and Pakistan.

Joke here is, the Iranian colours here are photoshopped, lifted from this article:
http://military-photoshops.blogspot....7-thunder.html
Iran is, or was, rumored to attempt to acquire JF-17, however there is nothing specific yet. By the way, the first air-to-air victory of JF-17 was a Pakistani fighter shooting down Iranian drone.

Looking forward to your 2 rep.

[paleologos]

...
Joke here is, the Iranian colours here are photoshopped...

That's why I couldn't find a match for it in the asset list of the Iranian air force.
Some people have no shame, insignia falsification is usually dealt with in a court marshal.
Your first point comes now, expect the as soon as I can commandeer some favors.

[Sar1n]

The +rep has been taken care of with a little extra, thanks to Lifthrasir and Abdülmecid I.

Sorry for a bit bit messed up tail due to removal of markings, but it should be clear nevertheless.

[Owlparrot3]

I just loveeeeeeeeeeeeeeeee pre 1926 planes. So i will make a wild guess.

Looks like a Curtis NC3 flying boat.

[Sar1n]

Nope.

[Spear Dog]

Boeing XPB 2, the re-designated 1925 XPB 1 after a 1928 engine change to Pratt and Whitney R-1690 radials.

[Sar1n]

Correct, down to the engine configuration. There was only one airframe of Boeing XPB ever built, but it flown with two different engine configuration, first with inline engines under XPB-1 designation, and then with radial engines as XPB-2.

Your turn.

[Spear Dog]

[General Brewster]

Hillberg carbine

[Spear Dog]

Correct, a WW2 concept (light) rifle; and the big brother of the Whitney Wolverine pistol.

*spread some rep around so I could rep Gen.Brewster twice in the same day and went over the 24 hour limit. Could someone please rep the General for me? Thanks.

[General Brewster]

Shouldn't be too hard

[Sar1n]

Heckler & Koch XM8 carbine version. It was designed for US Army as replacement for M16, but the program was eventually terminated.

[General Brewster]

Correct!