This weapon was manufactured by Rheinmetal-Borsig and was essentially a longer barrel version of the Army 3.7 cm Flak 36. This new gun was a great improvement over the older 3.7 cm/83 SK C/30 and had a much higher rate of fire. Recoil operated, air cooled and used five-round ammunition strips.
These were the first Kriegsmarine light anti-aircraft guns to have shields, a surprising shortcoming of earlier weapons.
The design of this gun emphasized ease of manufacturing. Constructed of a monobloc barrel which was connected to the breech ring by a bayonet joint to allow easy replacement. Used a vertical sliding breech block, hydraulic brake and spring recuperator.
| Designation | 3.7 cm/69 (1.5") Flak M42 |
|---|---|
| Ship Class Used On | U-boats, Emden, destroyers and minesweepers |
| Date Of Design | 1942 |
| Date In Service | 1944 |
| Gun Weight | 240 lbs. (109 kg) |
| Gun Length oa | N/A |
| Barrel Length | 100.79 in (2.560 m) |
| Rifling Length | 90.1 in (2.289 m) |
| Grooves | (20) 0.0217 in deep x 0.150 in (0.55 mm x 3.81 mm) |
| Lands | 0.087 in (2.2 mm) |
| Twist | Uniform RH 1 in 25.6 |
| Chamber Volume | 16.5 in3 (0.270 dm3) |
| Rate Of Fire | 160-180 rpm rounds per minute cyclic
60 rpm practical |
| Type | Fixed |
|---|---|
| Weight of Complete Round | HE tracer: 3.0 lbs. (1.36 kg
HE incendiary: 3.02 lbs. (1.37 kg) AP tracer: 3.31 lbs. (1.50 kg) |
| Projectile Types and Weights 1 | HE tracer: 1.40 lbs. (0.635 kg)
HE incendiary: 1.42 lbs. (0.644 kg) AP tracer: 1.54 lbs. (0.700 kg) |
| Bursting Charge 2 | HE tracer: (0.026 kg)
HE incendiary: (0.048 kg) AP tracer: (0.013 kg) |
| Projectile Length | N/A
HE incendiary, complete round: 14 in (355 mm) |
| Propellant Charge | 0.386 lbs. (0.175 kg) RPC/38N |
| Cartridge Case Type, Size and Empty Weight | Brass, 37 x 248R, N/A [1.0 lbs. (0.51 kg) loaded] |
| Muzzle Velocity | HE tracer: 2,838 fps (865 mps)
HE incendiary: 2,772 fps (845 mps) AP tracer: 2,674 fps (815 mps) |
| Working Pressure | 18.7 tons/in2 (2,950 kg/cm2) |
| Approximate Barrel Life | 7,000 rounds |
| Ammunition stowage per gun | 2,000 rounds 3 |
- ^
Actual German designations AP 3,7 cm Psgr. 42 Lh 1 HE tracer 3,7 cm Br Spgr. 42 Lh 3 HE Incendiary 3,7 cm Br Spgr. 42 Lh 13 - ^Burster weights (reiner Sprengstoff) from M.Dv. Nr. 198.
- ^Minesweeper outfits were half AP tracer and half HE tracer. Outfits on other ships was intended to be two-thirds HE incendiary and one-third AP tracer.
- The sources below differ in many areas for this weapon. The figures given in this table come mainly from "Naval Weapons of Word War Two."
| Elevation | Distance |
|---|---|
| 45 degrees | 7,000 yards (6,400 m) |
| AA Ceiling @ 85 degrees | 17,750 feet (4,800 m) |
Tracer range was 5,250 yards (4,800 m).
| Designation | Single Mount for U-boats: Ubts. LC/39
Single Mount for Surface Ships: Flak LM/42 Twin Mount for U-boats: Ubts. Dop. LM/42 Twin Mount for surface ships: Dop. LM/42 |
|---|---|
| Weight | Ubts. LC/39: N/A
Flak LM/42 with shield: 2,980 lbs. (1,350 kg) Twin: 3,860 lbs. (1,750 kg) |
| Elevation | -10 / +90 degrees |
| Elevation Rate | Manual operation, only |
| Train | 360 degrees |
| Train Rate | Manual operation, only |
| Gun recoil | N/A |
- Shields on U-boat mounts were fitted with hinge points such that they could be folded back against the barrels in order to reduce water drag. Surface ship mounts had more complex shapes and did not fold.
"Naval Weapons of World War Two" by John Campbell
"German Warships 1815-1945" by Erich Gröner
"Das Buch der Deutschen Kriegsmarine" by Jak P. Mallmann Showell
"German Naval Guns: 1939 - 1945" by Miroslaw Skwiot
"German Destroyers of World War Two (2nd Edition)" and "German Cruisers of World War Two" both by M.J. Whitley
---
Special help by Dave Krakow and Anthony G. Williams
15 May 2006 - Benchmark
20 May 2012 - Updated to latest template
23 March 2013 - Redid photograph of Z39
23 April 2020 - Converted to HTML 5 format, reorganized notes, added data and photograph of U-190
17 August 2024 - Added burster information