View source for K-class blimp

{{More citations needed|date=January 2010}}
{{short description|Class of non-rigid airships built by the Goodyear Aircraft Company for the U.S. Navy (1938-59)}}
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{{Infobox aircraft
|name=''K''-class
|image=K class blimp.jpg
|caption= NAVY K-110
|type=Patrol airship
|manufacturer=[[Goodyear Aerospace|Goodyear-Zeppelin and Goodyear Aircraft Corporation]]
|designer=
|first_flight=6 December 1938
|introduction=
|retired=1959
|status=
|primary_user=[[United States Navy]]
|more_users=
|produced=
|number_built=134
|variants=
}}

The '''''K''-class blimp''' was a class of [[blimp]]s (non-rigid airship) built by the [[Goodyear Aircraft Company]] of [[Akron, Ohio]], for the [[United States Navy]]. These blimps were powered by two [[Pratt & Whitney R-1340|Pratt & Whitney ''Wasp'']] nine-cylinder [[Radial engine|radial]] air-cooled engines, each mounted on twin-strut [[outriggers]], one per side of the control car that hung under the [[Airship#Envelope|envelope]]. Before and during [[World War II]], 134 ''K''-class blimps were built and configured for patrol and [[anti-submarine warfare]] operations, and were extensively used in the Navy’s anti-submarine efforts in the Atlantic and Pacific Ocean areas.

==Development==
[[File:K-Type-Blimp WW2 k13953.jpg|thumbnail|A color photo of an unidentified Navy K blimp]]

In 1937, ''K-2'' was ordered from [[Goodyear Aerospace|Goodyear]] as part of a contract that also bought the ''L-1'', (Goodyear’s standard advertising and passenger blimp). ''K-2'' was the production [[prototype]] for future ''K''-class airship purchases. ''K-2'' flew for the first time at Akron, Ohio on December 6, 1938<ref>{{cite book |editor1-last=Grossnick |editor1-first=Roy A. |title=Kite Balloons to Airships: The Navy's Lighter-than-Air Experience |date=1987 |publisher=Deputy Chief of Naval Operations (Air Warfare) and the Commander, Naval Air Systems Command |location=Washington, D.C. |page=35 |chapter=Pre-WW II Blilmps and the Evolution of the K-class and WW II Airships |chapter-url=https://www.history.navy.mil/research/histories/naval-aviation-history/navys-lighter-than-air-experience-monograph/pre-ww-ii-blilmps-and-the-evolution-of-the-k-class-and-ww-ii-airships-and-their-operations-pages-34-46.html}}</ref> and was delivered to the Navy at [[NAS Lakehurst]], New Jersey on December 16. The envelope capacity of the ''K-2''—404,000&nbsp;ft³ (11,440&nbsp;m³)—was the largest for any USN blimp up to that time. ''K-2'' was flown extensively as a prototype, and continued to operate testing new equipment, techniques, and performing whatever tasks were needed, including combat patrols in World War II.

On October 24, 1940, the Navy awarded a contract to Goodyear for six airships (''K-3'' through ''K-8'') that were assigned the designation '''Goodyear ZNP-K'''. These blimps were designed for patrol and escort duties and were delivered to the Navy in late 1941 and early 1942. ''K-3'' through ''K-8'' had only minor modifications to ''K-2''{{'}}s design, the only major change was in engines from Pratt & Whitney R-1340-16s to [[Wright R-975|Wright R-975-28s]]. The Wright engine/propeller combination proved excessively noisy and was replaced in later K-ships with slightly modified Pratt & Whitney engines. The K-3 cost $325,000.<ref>Crestview, Florida, "U. S. Navy Gets World's Largest Blimp", ''Okaloosa News-Journal'', Friday 31 October 1941, Volume 27, Number 42, page 3.</ref> A series of orders for more K-class blimps followed. Twenty-one additional blimps (''K-9'' through ''K-30'') were ordered on 14 October 1942. On 9 January 1943, 21 more blimps (''K-31'' through ''K-50'') were ordered. The envelope size of ''K-9'' through ''K-13'' was increased to 416,000&nbsp;ft³ (11,780&nbsp;m³) and those delivered thereafter used an envelope of 425,000&nbsp;ft³ (12,035&nbsp;m³). The final contract for the ''K''-class blimp were awarded in mid-1943 for 89 airships. Four blimps from this order were later canceled. The remaining deliveries were assigned numbers ''K-51'' through ''K-136''. But, the number ''K-136'' was not assigned to a specific airship as the control car assigned for ''K-136'' was used to replace the car for ''K-113''. The original car for ''K-113'' was destroyed in a fire.

The US Navy's experiences with K-ships in tropical regions showed a need for a blimp with greater volume than the K-class to offset the loss of lift due to high ambient temperatures. Goodyear addressed these concerns with a follow-on design, the [[M-class blimp]], which was 50% larger.

==Variants==
After World War II a number of ''K''-class blimps were modified with more advanced electronics, radar, sonar systems and larger envelopes. These modified blimps were designated:
;ZNP-K
:The original designation of the ''K''-class blimps. Individual blimps were identified by a sequential suffix number, e.g. ZNP-K-2, ZNPK-8 etc. In everyday use only the K and numerical suffixes were used. Batches of blimps were built with sometimes major differences, but the designations remained in the ZNP-K range, until the later versions, listed below, emerged.
;ZPK
:Revised designation of the ZNP-K series.
;ZP2K
:A larger envelope with the volume increased to {{cvt|527000|cuft}}, sensors and other improvements re-designated '''ZSG-2'''.
;ZP3K
:A larger envelope with the volume increased to {{cvt|527000|cuft}}, with systems and controls even more advanced than the ZP2Ks, re-designated '''ZSG-3'''.
;ZP4K
:Delivered in 1953, retaining the {{cvt|527000|cuft}} envelope volume and length of {{cvt|266|ft|m|2}}, re-designated '''ZSG-4''' in 1954.

==Operational history==
[[File:Mk47aerialdepthcharges.jpg|thumb|right|US Navy sailors attach Mk 47 aerial depth charges to the underside of a K-class blimp at NAS Weeksville, North Carolina in 1944]]

The ''K''-ships were used for [[anti-submarine warfare]] (ASW) duties in the Atlantic and Pacific Oceans as well as the Mediterranean Sea.<ref>{{Cite book|url=https://archive.org/details/warcooperationco0000bapt/page/161|title=War, cooperation, and conflict : the European possessions in the Caribbean, 1939–1945|last=André.|first=Baptiste, Fitzroy|date=1988|publisher=Greenwood Press|isbn=9780313254727|location=New York|pages=[https://archive.org/details/warcooperationco0000bapt/page/161 161]|oclc=650310469}}</ref> All equipment was carried in a forty foot long control car. The installed communications and instrumentation equipment allowed night flying. The blimps were equipped with the [[Radar in World War II#S-Band Navy Search|ASG radar]], that had a detection range of {{convert|90|mi|km|abbr=on}}, [[sonobuoy]]s, and [[magnetic anomaly detection]] (MAD) equipment. The ''K''-ships carried four {{convert|350|lb|kg|abbr=on}} [[depth bomb]]s, two in a bomb bay and two externally, and were equipped with a machine gun in the forward part of the control car. An aircrew of 10 normally operated the ''K''-ships, consisting of a command pilot, two co-pilots, a navigator/pilot, airship rigger, an ordnanceman, two mechanics, and two radiomen.

On 1 June 1944, two K-class blimps of United States Navy (USN) Airship Patrol Squadron 14 (ZP-14)<ref>{{Cite web |url=http://www.warwingsart.com/LTA/zp-14.html |title=Blimp Squadron 14 |access-date=2010-02-07 |archive-url=https://web.archive.org/web/20091113084811/http://www.warwingsart.com/LTA/zp-14.html |archive-date=2009-11-13 |url-status=dead }}</ref> completed the first transatlantic crossing by non-rigid airships.<ref>{{Cite web |url=http://www.naval-airships.org/resources/documents/NAN_vol93_no2_KShips_feature.pdf |title=Kaiser, Don, K-Ships Across the Atlantic, Naval Aviation News, Vol. 93(2), 2011. |access-date=2012-07-31 |archive-url=https://web.archive.org/web/20150217071129/http://naval-airships.org/resources/documents/NAN_vol93_no2_KShips_feature.pdf |archive-date=2015-02-17 |url-status=dead }}</ref> ''K-123'' and ''K-130'' left [[South Weymouth Naval Air Station|South Weymouth, MA]] on 28 May 1944 and flew approximately 16 hours to [[Naval Station Argentia]], Newfoundland. From Argentia, the blimps flew approximately 22 hours to [[Lajes Field]] on Terceira Island in the Azores. The final leg of the first transatlantic crossing was about a 20-hour flight from the Azores to [[Kenitra Airport|Craw Field]] in Port Lyautey (Kenitra), French Morocco. The first pair of K-ships were followed by ''K-109'' & ''K-134'' and ''K-112'' & ''K-101'' which left South Weymouth on 11 and 27 June 1944, respectively. These six blimps initially conducted nighttime anti-submarine warfare operations to complement the daytime missions flown by FAW-15 aircraft ([[PBY]]s and [[B-24]]s) using magnetic anomaly detection to locate U-boats in the relatively shallow waters around the [[Straits of Gibraltar]]. Later, ZP-14 K-ships conducted minespotting and [[minesweeping]] operations in key Mediterranean ports and various escort missions including that of the convoy carrying Franklin Roosevelt and Winston Churchill to the [[Yalta Conference]] in early 1945. In late April 1945, ''K-89'' and ''K-114'' left Weeksville NAS in North Carolina and flew a southern transatlantic route to [[Naval Air Station Bermuda|NAS Bermuda]], the Azores, and Port Lyautey where they arrived on 1 May 1945 as replacements for Blimp Squadron ZP-14.<ref>Kline, R. C. and Kubarych, S. J., Blimpron 14 Overseas, 1944, Naval Historical Center, Navy Yard, Washington, D. C.</ref>

The ability of the ''K''-ships to hover and operate at low altitudes and slow speeds resulted in detection of numerous enemy submarines as well as assisting in search and rescue missions. The ''K''-ships had an endurance capability of over 24 hours which was an important factor in the employment of ASW tactics.

The mooring system for the ''K''-ship was a {{convert|42|ft|m|1|abbr=on}} high triangular [[mooring mast]] that was capable of being towed by a tractor. For advance bases where moving the mooring mast was not needed, a conventional stick mast was used. A large ground crew was needed to land the blimps and moor them to the mast.

During the war, only one ''K'' ship was lost to enemy action. On 18 July 1943, ''K-74'' was shot down by {{GS|U-134|1941|2}} in the [[Straits of Florida]]. The crew was rescued eight hours later, except for one man who was attacked by a shark and drowned only minutes before the rescue. Five weeks later, ''U-134'' was sunk by a British frigate in the [[Bay of Biscay]] on its return voyage to Germany.<ref>{{cite journal 
| last = Vaeth | first = J. Gordon | title = "Incident in the Florida Straits" 
| url = https://www.usni.org/magazines/proceedings/1979/august/incident-florida-straits
| journal  = United States Naval Institute Proceedings | date = August 1979 | pages = 84–86}}</ref><ref>[https://www.defensemedianetwork.com/stories/blimp-vs-u-boat/ defensemedianetwork.com, Blimp vs. U-boat, By Robert F. Dorr	- October 11, 2017]</ref>

In 1947, Goodyear acquired the former Navy ''K-28'' and operated it as part of its [[Goodyear Blimp|commercial advertising blimp fleet]]. The ''K'' ship was named ''Puritan'' and was the largest ever Goodyear blimp. The airship was purchased from the Navy primarily to experiment with [[Trans-Lux]] illuminated running copy advertising signs attached to the envelope. Costly to operate and maintain, ''Puritan'' was retired from the Goodyear fleet in April, 1948 after only one year of operation. The blimp was deflated and placed in storage at Goodyear's base at Wingfoot Lake in [[Suffield, Ohio]] and was later sold back to the Navy. 

''K-43'', the last operational Navy "''K'' Ship", was retired from service in March, 1959.

===Nuclear weapon effects tests===
[[File:NTS - Plumbob - Stokes test with Goodyear ZSG-3 blimp.jpg|thumb|Aftermath of the Plumbbob-Stokes test]]
Several ''K''-class blimps were used for nuclear weapon effects tests at the [[Nevada Test Site]] (NTS) during the [[Operation Plumbbob]] series of tests in 1957. K-40, K-46, K-77 and K-92 were destroyed in Project 5.2, events Franklin (Fissile) and Stokes (19 kt, XW-30 device).<ref>Defense Nuclear Agency, Plumbob Series 1957 DNA 6005F, Washington D.C., pages 6–7, 41–42, 45, 82</ref> The tests were to "determine the response characteristics of the model ZSG-3 airship when subject to a nuclear detonation in order to establish criteria for safe escape distances after airship delivery of antisubmarine warfare special weapons."<ref>Defense Nuclear Agency, Plumbob Series 1957 DNA 6005F, Washington D.C., page 133</ref> According to the Navy, the "airship operations were conducted with extreme difficulty."<ref>Defense Nuclear Agency, Plumbob Series 1957 DNA 6005F, Washington D.C., page 133</ref> The Navy was trying to determine whether the airship could be among the aircraft to deliver its planned [[Mk_101_Lulu|Lulu (W-34)]] nuclear depth charge.<ref>Hansen, Chuck, The Swords of Armageddon, 1995, Chuckelea Publications, Sunnyvale, California, Volume VII, page 456</ref>

==Airship designations==
During the life of the ''K''-class airship, the U.S. Navy used three different designation systems. From 1922 through World War II, the Navy used a four character designator. The ''K''-class blimps were designated ZNP-K where the "Z" signified lighter-than-air; "N" denoted non-rigid; "P" denoted a patrol mission; and "K" denoted the type or class of airship.

In April 1947, the General Board of the U.S. Navy modified the designation system for airships. The second character of the designator was dropped as the Board dropped the code for rigid airships so that the "N" for non-rigid was no longer needed. The designation for the ''K''-class blimps then became '''ZPK'''.

In April 1954, the designation system for lighter-than-air airships was further modified so that it conformed to the designation system for [[heavier-than-air]] aircraft. By this time the ZPK blimps had been retired from service and only the later version K-Class blimps were in service. Under the 1954 system the ZP2K blimp became the ZSG-2, the ZP3K became the ZSG-3, the ZP4K became the ZSG-4, and the ZP5K became the '''ZS2G-1'''. In new designation system, the "Z" signified lighter-than-air; the "S" was the type denoting an anti-submarine warfare mission; the numeral (i.e., "2") was the model; and the "G" was for Goodyear, the manufacturer's letter in the Navy's designation system. The final numeral denoted the series of the vehicle within the type/model. The US Navy ordered a new type of airship in 1951 for the [[Korean War]]. The new air ship was designated '''ZP4K''' (later called ZSG-4), which had a different design than WW2 K-type. The first ZP4K was delivered in June 1954. A total of 15 were built. In 1955 an update version a called the '''ZP5K''' (later called ZS2G-1) was delivered, a total of 15 were built. The ZP5K has an inverted “Y” tail.<ref>[https://www.globalsecurity.org/wmd/systems/lta.htm globalsecurity.org  Airship]</ref><ref>history.navy.mil, XV. Airship Types in the Postwar Period </ref>

==Surviving aircraft==
[[File:Goodyear ZNP-K Control Car.jpg|thumb|Goodyear ZNP-K Control Car on display at the New England Air Museum]]

* ''K-22'' Control car currently under restoration at the Moffett Field Museum on Moffett Federal Airfield in Santa Clara County, California. 
* ''K-27'' and several other K class blimps were seen in the [[Metro-Goldwyn-Mayer]] film ''[[This Man's Navy]]'' (1945), one of the few motion pictures to depict U.S. Navy blimp operations. The film starred [[Wallace Beery]] who actually served as a Navy blimp commander during World War II.
* ''K-28'' - Goodyear ''Puritan'' – Control car on static display at the [[New England Air Museum]] in [[Windsor Locks, Connecticut]].<ref>{{cite web|title=Goodyear ZNPK-28 Blimp Control Car|url=http://neam.org/ac-goodyear-znpk28.php|website=New England Air Museum|access-date=18 February 2018}}</ref>
* ''K-47'' - Control car on static display at the [[National Naval Aviation Museum]] in [[Pensacola, Florida]].<ref>{{cite web|title=K-47 CONTROL CAR|url=http://www.navalaviationmuseum.org/attractions/aircraft-exhibits/item/?item=k-47|website=National Naval Aviation Museum|publisher=Naval Aviation Museum Foundation|access-date=18 February 2018}}</ref> The K-47 was upgraded to the ZP3K configuration before it was retired in 1956.<ref>Shock, James R., U.S. Navy Airships 1915–1962, 2001, Atlantis Productions, Edgewater Florida, {{ISBN|978-0963974389}}, page 113</ref>

==Specifications (''K-14'')==
[[File:Goodyear ZSG-2 3-view line drawing.png|300px|right|3-view line drawing of the Goodyear ZSG-2]]

{{Aircraft specs
|prime units? = imp
|crew=9–10
|length m=76.73
|length ft=251
|length in=8
|dia m=17.63
|dia ft=57
|dia in=10
|volume m3=12,043
|volume ft3=425,000
|lift kg=3,524
|lift lb=7,770
|eng1 number=2
|eng1 name=Pratt & Whitney R-1340-AN-2 radials
|eng1 kw=317
|eng1 hp=425
|max speed kmh=125
|max speed mph=78
|cruise speed kmh=93
|cruise speed mph=58
|range km=3,537
|range miles=2,205
|endurance=38 hours 12 minutes
|armament = *1 × {{convert|.50|in|mm|1|abbr=on}} [[M2 Browning machine gun]]
*4 × {{convert|350|lb|kg|abbr=on}} [[Mark 47 depth charge|AN-Mk 47]] depth charges
}}

==See also==
*[[Aircraft Warning Service]]
*[[Naval Air Station Hitchcock]], [[Texas]]
*[[US Navy airships during World War II]]
{{aircontent
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|related=
|similar aircraft=
|lists=
*[[List of airships of the United States Navy]]
|see also=
}}

==References==

===Notes===
{{Reflist}}

===Bibliography===
{{Refbegin}}
*{{cite book |last= Althoff|first= William F. |title=Sky Ships |year=1990 |publisher=Orion Books |location=New York |isbn=0-517-56904-3 }}
*{{cite book |last= Althoff|first= William F. |title=Forgotten weapon: U.S. Navy airships and the U-boat war |year=2009 |publisher=Naval Institute Press |location=Annapolis, MD |pages=419 |isbn=978-1-59114-010-8 }}
*{{cite book |last= Shock |first= James R. |title=U.S. Navy Airships 1915–1962 |year=2001 |publisher=Atlantis Productions |location=Edgewater, Florida |isbn=0-9639743-8-6 }}
*{{cite book |title=United States Navy K-Type Airships Pilot's Manual |date=September 1943 |publisher=Goodyear Aircraft Corporation |location=Akron, Ohio |url=http://www.faa.gov/regulations_policies/handbooks_manuals/aviation/media/airship_pilot_manual.pdf |access-date=22 April 2021}}
*{{cite book |last= Vaeth |first= J. Gordon |title=Blimps & U-Boats |year=1992 |publisher=US Naval Institute Press |location=Annapolis, Maryland |isbn=1-55750-876-3 }}
{{Refend}}

==External links==
{{external media
| float  = right
| width  = 300px
| video1 = [https://archive.org/details/84484-the-story-of-goodyear-aircraft-part-one-building-airplanes-vwr The Story of Goodyear Aircraft] The manufacture of K-class blimps is shown starting at 10:30.
}}
{{commonscat|K-class blimps}}
*[https://www.faa.gov/sites/faa.gov/files/regulations_policies/handbooks_manuals/aviation/airship_pilot_manual.pdf United States Navy K-Type Airships Pilot’s Manual]

{{Goodyear aircraft}}
{{USN non-rigid airships 1954}}
{{USN non-rigid airships 1947}}
{{USN non-rigid airships 1940}}
{{USN non-rigid airship classes}}

{{DEFAULTSORT:K Class Blimp}}
[[Category:1930s United States patrol aircraft]]
[[Category:1940s United States patrol aircraft]]
[[Category:Airships of the United States Navy]]
[[Category:Goodyear aircraft]]