18-inch Mk.7 (450 mm)
Contents
[hide]Description
18-inch Mk.7 was an American lightweight torpedo developed by Bliss-Leavitt in 1911 as the first American torpedo used on submarines and surface vessels alike. By 1917 an airborne Mk.7 Type D variant was developed, but it has never seen serial production. Mk. 7 remained in service until the end of the World War 2, primarily on the O-type submarines.
Currently, the only vessel using the torpedo is the PT-3 torpedo boat. Due to the short range and relatively low speed, it's best used against barges rather than more mobile targets.
Vehicles equipped with this weapon
General info
| Torpedo characteristics | ||||||||
|---|---|---|---|---|---|---|---|---|
| Torpedo Mode | Mass (kg) | Maximum speed in water (km/h) | Travel distance (km) | Depth stroke (m) | Arming distance (m) | Explosive type | Explosive mass (kg) | TNT equivalent (kg) |
| No | 720 | 59 | 3.65 | 1 | 50 | TNT | 93 | 93 |
Effective damage
With a 93 kg warhead the Mk. 7 can destroy any coastal vessel and a majority of a low-BR destroyers, larger vessels will require a hit directly on the magazines to achieve a kill, though ships equipped with a torpedo bulges might be completely immune to the weapon.
Comparison with analogues
The closest peer among US torpedoes is the Mk.8-3 C/D, a torpedo with nearly double the explosive mass, 15% slower speed (50 km/h instead of 59 km/h) and over triple the range, making it overall by far more versatile weapon.
The closest foreign equivalent would be the Japanese Type 44 No.2 which has a similar mass and same calibre, but a better speed, higher explosive mass and a slightly longer travel distance.
Usage in battles
Much like all lightweight torpedoes, it's best used against large, slow targets with no torpedo defense. When using it, one must remember about the minimum arming distance, which is 50 m, or triple the full length of the PT-3. When faced with multiple fast coastal vessels and no alternative targets, it's worth to just launch torpedoes in a general direction of the enemy vessels - sometimes lucky hits are the best one can hope for.
Pros and cons
Pros:
- Low mass
Cons:
- Low maximum range
- Relatively low speed
- Small explosive filler
History
The Mk. 7 was the first American steam-driven torpedo that could be used by both submarines and surface vessels alike. Designed in 1911, it was also the first American wet heater torpedo.
The exact calibre of the torpedo was 17.7 inch, or 450 mm, though in the US it was typically rounded to "18 inch". It carried the Mk 7 Mod 5 warhead with 326 pounds of either TNT or TPX and a Mk 3 Mod 1 contact fuse. Torpedo had two modes, a low-pressure for 3,500 yards (3.2 km) travel distance and a high-pressure for 6,000 yards (5.5 km).
During the WW1 it has seen use primarily on the American K, L, M, N and O class submarines. With the retiring of the last of the O-class in 1946, the Mk. 7 ended its 34 years of career in the US Navy.
Media
Excellent additions to the article would be video guides, screenshots from the game, and photos.
See also
Links to the articles on the War Thunder Wiki that you think will be useful for the reader, for example:
- reference to the article about the variant of the cannon/machine gun;
- references to approximate analogues by other nations and research trees.
External links
- [Wikipedia] Bliss-Leavitt Mark 7 torpedo
- [NavWeaps] Bliss-Leavitt 18" (45 cm) Mark 7
- [San Francisco Maritime National Park Association] E.W. Jolie, A Brief History of U.S. Navy Torpedo Development - Part 2: Detailed Description Of Torpedoes - Bliss-Leavitt Torpedo Mk7
- [Naval History and Heritage Command] Navy’s Use of Torpedoes
| [Expand]Torpedoes |
|---|
