Mk.13-6 Case (2,216 lb)

Description

Side view of an Mk.13-6 Case (2,216 lb) torpedo.

Data for Mk.13-6 Case (2,216 lb) torpedo
	Metric	Imperial
Overall Length	4 m	161 in
Body Diameter	570 mm	22.5 in
Filling Weight	272 kg	600 lb
Total Weight	1,005 kg	2,216 lb
Explosive Filling	Torpex
Bomb Type	High Explosive

The Mk.13-6 Case (2,216 lb) torpedo was a guinea pig of a torpedo having been the subject of testing and modification since 1925. Used early in World War II, this torpedo failed to operate properly approximately 70% of the time with problems of running cold (propeller mechanism failed to start), sinking, not running true (deviating path), improper depth, running on the surface or porposing (continuous jumping out of the water) due to improper water contact. Aircraft were required to fly extremely slow and low when dropping the torpedo as to not damage it on impact with the water and to provide the most stable drop possible, unfortunately, this put the torpedo bomber in a bad position of being an easy target for anti-aircraft guns mounted on enemy ships.

Extensive testing in 1942 determined that the low and slow approach to the Mk.13 launch was actually counterproductive as it caused the torpedo to “belly-flop” on the water resulting in damage sustained to its internal components. New modifications were tested which replaced fragile parts and components which were susceptible to damage upon impact with the water. A new study also implemented the addition of frangible “drag rings” and box-shaped tail stabilizers. These devices served to stabilize the torpedo during higher drops, lower the nose for the initial impact and reduce the depth at which the torpedo dove after impact. The wood drag rings and stabilizers were obliterated on impact with the water which absorbed some of the impact, protecting the torpedo. By 1944 the Mk.13 was essentially a brand new torpedo and was accepted as the best aircraft torpedo in the U.S. inventory at that time and was credited with the sinking of the Japanese battleship Yamato.

Later after World War II, there came a need for river patrol boats to be outfitted with torpedo launchers. The Mk.13 was the ideal torpedo to fulfil this need due to its short stature (compared to other torpedoes) and excelled in a shallow launch and run which afforded it to operate in shallow waters without hitting the bottom. Opportunities for sea use on smaller vessels were available in shallow areas where larger ships and torpedoes could not operate.

General info

General Data for Mk.13-6 Case (2,216 lb) torpedo
	Nautical	Metric	Imperial
Average Drop Altitude		0 - 250 m	0 - 820 ft
Average Drop Speed	0 - 2680 kts	0 - 144 m/s	0 - 322 mph
Speed in Water	33.5 kts	17.2 m/s	38.5 mph
Run Depth	0.54 fathom	1 m	3.2 ft
Max Distance	3.0 nm	5,720 m	3.5 mi
Optimal Drop Angle	22° - 32°

Frangible add-on parts for aerial drop

• Drag ring: Outfitted over the nose of the torpedo, this wooden device worked in combination to both slow the torpedo's descent and to also stabilize it, ensuring it impacted with the water at the proper angle. The drag ring would shed off of the torpedo upon impact with the water acting as a shock absorber, protecting the internal mechanics of the torpedo.

• Box stabilizer: A plywood, box-shaped stabilizer has been built around the shroud ring of the torpedo and is held together with wooden pegs which sheer during impact with the water. The wooden stabilizer acts to guide the torpedo to drop in a smooth curve and help the drag ring in pointing the torpedo nose-first into the water.

Effective damage

The Mk.13 torpedo had a large high-explosive warhead compared to the Mk.VII which was frequently used at the time. The Mk.13 had a 600 lb (270 kg) Torpex (Torpedo Explosive) warhead compared the Mk.VII’s 466 lb (211 kg) warhead. Torpex was an explosive which was about 50% more powerful than TNT by mass alone as this mixture contained 40% TNT, 42% RDX and 18% powdered aluminium. While not as fast nor had as long of range as other torpedoes, the Mk.13 was used effectively at night when stealthy operations from PT boats which took place requiring torpedoes to reach the target with the least amount of warning. Aerial operations took advantage of the slower torpedo by dropping it from a higher altitude, increasing its time in the air and getting it closer to the target before it entered the water.

Comparison with analogues

Give a comparative description of torpedoes that have firepower equal to this weapon.

Usage in battles

The upgraded Mk.13 torpedo can be utilised against any target which is in the water which can include ships, boats, tanks (at the water's edge), boat-planes or even structures. Due to the higher altitude in which it can be dropped from, the delivering bomber can make a safer approach, release and get-away avoiding ship-board anti-aircraft fire and fighters patrolling around ships.

Pros and cons

Summarise and briefly evaluate the weaponry in terms of its characteristics and combat effectiveness. Mark pros and cons as a list.

Pros:

• Can be dropped from higher altitudes (800 - 2,000 ft)
• Can be dropped at higher speeds (maximum 470 mph (756 kph))
• Higher release increases glide distance, decreases time in the water to the target

Cons:

• Aircraft typically only carry one or two at a time
• Slow, given enough distance a ship can avoid the torpedo

History

Describe the history of the creation and combat usage of the weapon in more detail than in the introduction. If the historical reference turns out to be too long, take it to a separate article, taking a link to the article about the weapon and adding a block "/ History" (example: https://wiki.warthunder.com/(Weapon-name)/History) and add a link to it here using the main template. Be sure to reference text and sources by using <ref></ref>, as well as adding them at the end of the article with <references />.

Media

Technical operations of U.S. Mk.13 Torpedoes [Historical]

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  Mk.13-6 Case (2,216 lb) torpedo being dropped from a TBF-1C.
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  Successful drop of a Mk.13-6 Case (2,216 lb) torpedo from a TBF-1C naval bomber.

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 weapon;
• references to approximate analogues by other nations and research trees.

External links

• NavWeaps Website [World War II Torpedoes of the United States]
• Flight Journal Website [Iconic Firepower: The Outstandingly Bad Mark 13 Torpedo]
• Ordnance Pamphlet No. 629(A) [U.S. Navy Torpedoes Mark 13, B-1 & 2 July 1942]
• NAVPERS 10826 [Naval Airborne Ordnance], p. 153-166