Difference between revisions of "18-inch Mk.7 (450 mm)"

Revision as of 15:49, 25 January 2024

18-inch Mk.7 deployed by the PT-3

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

PT-3

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 kilogram 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.

Name	Diameter (mm)	Mass (kg)	Explosive type	TNT equivalent (kg)	Max speed (km/h)	Max range (km)
12.75 inch Mark 44	324	235	HBX	54.4	56	5.49
12.75 inch Mark 46	324	235	TNT	44.5	91	7.30
18 inch Mark XII	450	702	TNT	176	74	1.37
18 inch Mark XV	450	817	Torpex	395.2	61	3.20
18 inch Type 38 No.2 B	450	663	Shimose	104.5	59	2.00
18-inch Mk.7	450	720	TNT	93	59	3.65
21 in Mk.8	533	1,252	TNT	146	50	9.14
21 inch Mark I	533	1,270	TNT	102	56	11.00
21 inch Mk.20 Bidder	533	821	TNT	89	37	11.00
21 inch Type 43 (1910)	533	1,187	Shimose	143	50	8.00
45-36NU	450	951	TNT	200	76	4.00
53-38	533	1,615	TNT	300	82	4.00
53-39	533	1,780	TNT	317	94	4.00
53-56	533	2,000	TNT	400	93	8.00
53-57	533	2,000	TNT	306	83	18.00
53-65	533	2,070	TNT	300	126	12.00
Bliss-Leavitt Mk.1	533	680	TNT	91	50	3.66
C/06D	450	810	TNT	122.6	50	5.90
G6c	533	1,008	TNT	160	50	5.00
G7	500	1,365	TNT	249.6	69	4.00
G7a	533	1,528	SW39a	358.4	81	6.00
H/8	600	2,160	SW39a	268.8	67	6.00
LT 1A/1	450	812	TNT	250	74	2.00
Mark 35	533	803	Torpex	196	50	13.71
Mk.8-3 C/D	533	1,373	TNT	174.2	50	12.35
Mk.13	569	884	TNT	178	56	5.21
Mk.15	533	1,559	TNT	224	83	5.50
Mk.16	533	1,766	Torpex	915.2	85	6.40
Mk.IV	533	1,454	TNT	234	65	7.30
Mk.IX	533	1,693	TNT	340	67	9.60
Mk.IX**	533	1,693	Torpex	587.2	76	10.00
Mk.V	533	1,736	TNT	305	74	4.57
Mk.VIII	533	1,566	TNT	327	84	4.57
1909R	450	716	TNT	144	61	2.00
Model 1919V	550	1,358	Picric acid	261.8	80	2.00
Model 1923DT	550	2,100	TNT	308	72	9.00
1926V	400	674	TNT	144	81	2.00
L3	550	910	TNT	200	46	5.00
Pattern 1910	450	665	TNT	100	54	3.00
Pattern 1912	450	810	TNT	100	80	2.00
R.G.F. Mark VI**	450	700	TNT	134	56	5.49
S.I.170/450X5,25	450	860	TNT	170	76	4.00
S.I.270	533	1,715	TNT	270	74	4.00
S.I. 250/533,4X7,5 Tipo A	533	1,781	TNT	250	76	4.00
S.I. 270/533,4X7,2 Tipo I	533	1,700	TNT	270	89	4.00
S.I. 270/533,4X7,2 Tipo M	533	1,715	TNT	270	93	4.00
S.I. 270/533X6.84 Tipo L	533	1,700	TNT	270	93	4.00
Seal DM2A1	533	1,370	TNT	250	61	20.00
SET-40	400	550	TNT	80	54	8.00
SET-53M	533	1,480	TNT	100	54	14.00
SET-65	533	1,740	TNT	205	74	16.00
SET-72	400	730	TNT	80	74	8.00
Type 2	450	1,000	Type 97	448	72	3.00
Type 6	533	1,432	Shimose	223.3	65	7.00
Type 8 No.2	610	2,362	Shimose	380.6	70	10.00
Type 43	450	663	Shimose	104.5	48	5.00
Type 44 No.2	450	750	Shimose	121	65	4.00
Type 54 model 3	533	1,600	TNT	100	44	6.00
Type 72 mod.1	533	1,760	TNT	300	120	10.00
Type 89	533	1,660	Type 97	384	83	5.50
Type 90	610	2,540	Type 97	480	85	7.00
Type 93 Model 1, Mod 2	610	2,700	Type 97	627.2	91	20.00
Type 93 Model 3	610	2,800	Type 97	998.4	91	15.00
W.200/450X5,75	450	930	TNT	200	81	3.00
Whitehead A 110/450	450	936	TNT	110	56	4.00

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 meters, 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. Being 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 3500 yards (3.2 km) travel distance and a high-pressure for 6000 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.

External links

Torpedoes
USA
450 mm	Mk.7
533 mm	Bliss-Leavitt Mk.1 · Mark 35 · Mk.8 · Mk.8-3 C/D · Mk.15 · Mk.16
569 mm	Mk.13 · Mk.13-6^† · Mk.13-6 Case^†
Germany
324 mm	Mark 44
450 mm	C/06D · LT 1A/1 · F5W^† · F5b^†
500 mm	G7 · G6c
533 mm	G7a · Seal DM2A1
600 mm	H/8
USSR
400 mm	SET-40 · SET-72
450 mm	Pattern 1910 · Pattern 1912 · 45-36NU^‡ · 45-36AN^† · 45-36MAN^†
533 mm	53-38 · 53-39 · 53-56 · 53-57 · 53-65 · SET-53M · SET-65
Britain
450 mm	R.G.F. Mark VI** · Mark XII^‡ · Mark XV^‡
533 mm	Mark I · Mk.IV · Mk.V · Mk.VIII · Mk.IX · Mk.IX** · 21 inch Mk.20 Bidder
Japan
324 mm	Mark 46
450 mm	Type 2 · Type 38 No.2 B · Type 43 · Type 44 No.2 · Type 91 Model 2^† · Type 91 Model 3^†
533 mm	Type 6 · Type 43 (1910) · Type 54 Model 3 · Type 72 Model 1 · Type 89
610 mm	Type 8 No.2 · Type 90 · Type 93 Model 1, Mod 2 · Type 93 Model 3
Italy
450 mm	F200/450^† · S.I.170/450X5,25 · W.200/450X5,75 · Whitehead A 110/450
533 mm	S.I.270 · S.I. 250/533,4X7,5 Tipo A · S.I. 270/533,4X7,2 Tipo I · S.I. 270/533X6.84 Tipo L · S.I. 270/533,4X7,2 Tipo M
France
400 mm	1926DA^†
450 mm	1909R
550 mm	L3 · Model 1919V · Model 1923DT
Sweden
450 mm	m/38^† · m/41^†
	† = Aerial torpedo ‡ = Aerial and ship-launched torpedo

@@ Line 1: / Line 1: @@
+[[File:18-inch Mk.7.jpg|thumb|x250px|18-inch Mk.7 deployed by the [[PT-3]]]]
 == Description ==
-''Write an introduction to the article in 2-3 small paragraphs. Briefly tell us about the history of the development and combat using the weaponry and also about its features. Compile a list of air, ground, or naval vehicles that feature this weapon system in the game.''
+<!-- ''Write an introduction to the article in 2-3 small paragraphs. Briefly tell us about the history of the development and combat using the weaponry and also about its features. Compile a list of air, ground, or naval vehicles that feature this weapon system in the game.'' -->
+'''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 [[:Category:Barges|barges]] rather than more mobile targets.
 === Vehicles equipped with this weapon ===
@@ Line 9: / Line 13: @@
 == General info ==
-''Tell us about the tactical and technical characteristics of the bomb.''
+<!-- ''Tell us about the tactical and technical characteristics of the bomb.'' -->
+{| class="wikitable" style="text-align:center" width="100%"
+! colspan="9" | 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)
+|-
+| {{Annotation|No|'Torpedo Mode' modification uninstalled}} || 720 || 59 || 3.65 || 1 || 50 || TNT|| 93 || 93
+|}
 === Effective damage ===
-''Describe the type of damage produced by this type of bomb (high explosive, splash damage, etc)''
+<!-- ''Describe the type of damage produced by this type of bomb (high explosive, splash damage, etc)'' -->
+With a 93 kilogram 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 ===
-''Give a comparative description of cannons/machine guns that have firepower equal to this weapon.''
+<!-- ''Give a comparative description of cannons/machine guns that have firepower equal to this weapon.'' -->
+The closest peer among US torpedoes is the [[Mk.8-3 C/D (533 mm)|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 (450 mm)|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.
+{{Naval special armament table|torpedoes}}
 == Usage in battles ==
-''Describe situations when you would utilize this bomb in game (vehicle, pillbox, base, etc)''
+<!-- ''Describe situations when you would utilize this bomb in game (vehicle, pillbox, base, etc)'' -->
+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 meters, 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 ===
-''Summarise and briefly evaluate the weaponry in terms of its characteristics and combat effectiveness. Mark pros and cons as a list.''
+<!-- ''Summarise and briefly evaluate the weaponry in terms of its characteristics and combat effectiveness. Mark pros and cons as a list.''-->
 '''Pros:'''
-*
+* Low mass
 '''Cons:'''
-*
+* Low maximum range
+* Relatively low speed
+* Small explosive filler
 == History ==
-''Examine 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: <nowiki>https://wiki.warthunder.com/(Weapon-name)/History</nowiki>) and add a link to it here using the <code>main</code> template. Be sure to reference text and sources by using <code><nowiki><ref></ref></nowiki></code>, as well as adding them at the end of the article with <code><nowiki><references /></nowiki></code>.''
+<!-- ''Examine 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: <nowiki>https://wiki.warthunder.com/(Weapon-name)/History</nowiki>) and add a link to it here using the <code>main</code> template. Be sure to reference text and sources by using <code><nowiki><ref></ref></nowiki></code>, as well as adding them at the end of the article with <code><nowiki><references /></nowiki></code>.'' -->
+The Mk. 7 was the first American steam-driven torpedo that could be used by both: submarines and surface vessels alike. Being 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 3500 yards (3.2 km) travel distance and a high-pressure for 6000 yards (5.5 km).
+During the WW1 it has seen use primarily on the American [[wikipedia:United States K-class submarine|K]], [[wikipedia:United States L-class submarine|L]], [[wikipedia:United States M-class submarine|M]], [[wikipedia:United States N-class submarine|N]] and [[wikipedia:United States O-class submarine|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 ==
@@ Line 41: / Line 67: @@
 == External links ==
-''Paste links to sources and external resources, such as:''
+<!-- ''Paste links to sources and external resources, such as:''
 * ''topic on the official game forum;''
-* ''other literature.''
+* ''other literature.'' -->
+* [[wikipedia:Bliss-Leavitt Mark 7 torpedo|<nowiki>[Wikipedia]</nowiki> Bliss-Leavitt Mark 7 torpedo]]
+* [http://www.navweaps.com/Weapons/WTUS_PreWWII.php#Bliss-Leavitt_18%22_%2845_cm%29_Mark_7 <nowiki>[NavWeaps]</nowiki> Bliss-Leavitt 18" (45 cm) Mark 7]
+* [https://maritime.org/doc/jolie/part2.php#page073 <nowiki>[San Francisco Maritime National Park Association]</nowiki> E.W. Jolie, A Brief History of U.S. Navy Torpedo Development - Part 2: Detailed Description Of Torpedoes - Bliss-Leavitt Torpedo Mk7]
+* [https://www.history.navy.mil/browse-by-topic/exploration-and-innovation/navy-torpedoes.html <nowiki>[Naval History and Heritage Command]</nowiki> Navy’s Use of Torpedoes]
 {{Torpedoes}}
 [[Category:Naval special armaments]]

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