| Mark 31 torpedo | |
| Origin: | United States |
| Type: | Acoustic torpedo[1] |
| Is Ranged: | yes |
| Is Explosive: | yes |
| Is Missile: | yes |
| Service: | never in service |
| Designer: | Underwater Sound Laboratory, Harvard University Ordnance Research Laboratory, Pennsylvania State University |
| Manufacturer: | Naval Torpedo Station Newport |
| Design Date: | 1944 |
| Weight: | 2800 pounds |
| Length: | 246 inches |
| Diameter: | 21 inches |
| Range: | 4000 yards |
| Filling: | Mk 31, HBX |
| Filling Weight: | 500 pounds |
| Engine: | Electric |
| Speed: | 29 knots |
| Guidance: | Gyroscope |
| Launch Platform: | Destroyers |
The Mark 31 torpedo was a destroyer-launched acoustic torpedo developed by the Harvard and Pennsylvania State universities during World War II. A modification of the Mark 18 electric torpedo, it was conceived as an interim weapon to be used in the Pacific War until a new high-speed acoustic torpedo could be developed for the United States Navy.[1]
Further development of the torpedo was terminated due to the status of other more promising programs, notably the Mark 16 torpedo and the Mark 35 torpedo.