Editing Boeing RC-135 (section)

==Variants==

===KC-135A Reconnaissance Platforms===
At least four KC-135A tankers were converted into makeshift reconnaissance platforms with no change of Mission Design Series (MDS) designation. KC-135As 55–3121, 55–3127, 59–1465, and 59-1514 were modified beginning in 1961. That year the Soviet Union announced its intention to detonate a 100 megaton [[Thermonuclear weapon|thermonuclear device]] on [[Novaya Zemlya]], the so-called [[Tsar Bomba]]. A testbed KC-135A (55–3127) was modified under the [[Big Safari]] program to the SPEED LIGHT BRAVO configuration in order to obtain intelligence information on the test. The success of the mission prompted conversion of additional aircraft for intelligence gathering duties.

===KC-135R Rivet Stand / Rivet Quick===

Not to be confused with the CFM F108-powered KC-135R tanker, the KC-135R MDS was applied in 1963 to the three KC-135A reconnaissance aircraft under the '''Rivet Stand''' program. The three aircraft were 55–3121, 59–1465, and 59–1514. A fourth, serial no. 58–0126, was converted in 1969 to replace 1465, which crashed in 1967. Externally the aircraft had varied configurations throughout their careers, but generally they were distinguished by five "towel bar" antennas along the spine of the upper fuselage and a radome below the forward fuselage.

The first three aircraft retained the standard tanker nose radome, while 58-0126 was fitted with the 'hog nose' radome commonly associated with an RC-135. A trapeze-like structure in place of the refueling boom which was used to trail an aerodynamic shape housing a specialized receiver array, colloquially known as a "blivet", on a wire was installed. This was reported to be used for "Briar Patch" and "Combat Lion" missions. There were four small optically flat windows on each side of the forward fuselage.

On some missions, a small wing-like structure housing sensors was fitted to each side of the forward fuselage, with a diagonal brace below it. With the loss of 59–1465, KC-135A 58-0126 was modified to this standard under the '''Rivet Quick''' operational name. All four aircraft were lost in accidents or converted to KC-135R tanker configurations. They are among the few KC-135 tankers equipped with an aerial refueling receptacle above the cockpit, a remnant of their service as intelligence gathering platforms.

===KC-135T Cobra Jaw===

In 1969, KC-135R 55-3121 was modified by Lockheed Air Services to the unique KC-135T configuration, under the Cobra Jaw program name. Externally distinguished by the 'hog nose' radome, the aircraft featured spinning "fang" receiver antennas below the nose radome, a large blade antenna above the forward fuselage, a single 'towel bar' antenna on the spine, teardrop antennas forward of the horizontal stabilizers on each side, and the trapeze-like structure in place of the refueling boom. The aircraft briefly carried nose art consisting of the Ford Cobra Jet cartoon cobra. It was later modified into an RC-135T Rivet Dandy.

===RC-135A===
Four RC-135As (63-8058 to 8061) were photo mapping platforms used briefly by the Air Photographic & Charting Service, based at [[Turner Air Force Base]], [[Georgia (U.S. state)|Georgia]] and later at [[Forbes Air Force Base]], [[Kansas]] as part of the 1370th Photographic Mapping Wing. The mission was soon assumed by satellites, and the RC-135As were de-modified and used in various other roles, such as staff transport and crew training.<ref name="USW" />

In the early 1980s they were converted to tankers, with the designation KC-135D, of the same basic configuration as the KC-135A and later E, plus some remaining special mission equipment. Due to delays in reinstalling their original equipment, the RC-135As were the last of the entire C-135 series delivered to the USAF. The Boeing model number for the RC-135A is 739-700.<ref name="USW" />

===RC-135B===
The as-delivered version of the RC-135. The RC-135B was never used operationally, as it had no mission equipment installed by Boeing. The entire RC-135B production run of ten aircraft was delivered directly to [[Martin Aircraft]] in Baltimore, Maryland for modification and installation of mission equipment under the [[Big Safari]] program. Upon completion, the RC-135Bs were re-designated RC-135C. The Boeing model number for the RC-135B is 739-445B.<ref name="USW" />

===RC-135C Big Team===
Modified and re-designated RC-135B aircraft used for strategic reconnaissance duties, equipped with the AN/ASD-1 electronic intelligence ([[ELINT]]) system. This system was characterized by the large 'cheek' pods on the forward fuselage containing the Automated ELINT Emitter Locating System (AEELS&nbsp;– not Side Looking Airborne Radar&nbsp;– SLAR, as often quoted), as well as numerous other antennae and a camera position in the refuelling pod area of the aft fuselage. The aircraft was crewed by two pilots, two navigators, numerous intelligence gathering specialists, inflight maintenance technicians and airborne linguists. When the RC-135C was fully deployed, SAC was able to retire its fleet of RB-47H Stratojets from active reconnaissance duties. All ten continue in active service as either RC-135V Rivet Joint or RC-135U Combat Sent platforms.

===RC-135D Office Boy / Rivet Brass===

The RC-135Ds, originally designated KC-135A-II, were the first reconnaissance configured C-135s given the "R" MDS prefix designation, although they were not the first reconnaissance-tasked members of the C-135 family. In 1962, they were delivered to [[Eielson Air Force Base]], Alaska as part of the Office Boy Project. Serial numbers were 60–0356, 60–0357, and 60–0362. In 1963, the aircraft began operational missions. These three aircraft were ordered as KC-135A tankers, but delivered without refueling booms, and known as "falsie C-135As" pending the delivery of the first actual C-135A cargo aircraft in 1961.<ref name="clubhyper.com">{{Cite web |last=Heilig |first=Jennings |title=C-135 Variants - Part Two |url=http://www.clubhyper.com/reference/c135jh_2.htm |url-status=live |archive-url=https://web.archive.org/web/20230528092107/http://www.clubhyper.com/reference/c135jh_2.htm |archive-date=28 May 2023 |access-date=2 February 2019 |website=clubhyper.com}}</ref>

The primary Rivet Brass mission flew along the northern border of the Soviet Union, often as a shuttle mission between Eielson and [[RAF Upper Heyford]], Oxfordshire, and later [[RAF Mildenhall]], Suffolk, UK. The RC-135D was also used in Southeast Asia during periods when the RC-135M (see below) was unavailable. In the late 1970s, with the expansion of the RC-135 fleet powered by TF33 turbofan engines, the RC-135Ds were converted into tankers, and remain in service as receiver-capable KC-135Rs.<ref name="clubhyper.com" />

===RC-135E Lisa Ann / Rivet Amber===
Originally designated C-135B-II, project name Lisa Ann, the RC-135E Rivet Amber was a one-of-a-kind aircraft, equipped with a large 7 MW [[Hughes Aircraft]] phased-array radar system.<ref name="rc135dotcom">{{cite web|url=http://www.rc135.com/0000/INDEX.HTM|title=Raven-1|website=www.rc135.com|access-date=2 February 2019|archive-date=5 February 2019|archive-url=https://web.archive.org/web/20190205174859/http://www.rc135.com/0000/INDEX.HTM|url-status=live}}</ref> Originally delivered as a C-135B, 62-4137 operated from [[Shemya Air Force Station]], [[Alaska]] from 1966 to 1969. Its operations were performed in concert with the RC-135S Rivet Ball aircraft (see below). The radar system alone weighed over 35,000 pounds and cost over US$35 million (1960 dollars), making Rivet Amber both the heaviest C-135 derivative aircraft flying and the most expensive Air Force aircraft for its time. This prevented the forward and aft crew areas from having direct contact after boarding the aircraft.<ref name=DrBob/>

The system could track an object the size of a soccer ball from a distance of {{convert|300|mi|km}}. Its mission was to monitor Soviet [[ballistic missile]] testing in the reentry phase. The power requirement for the phased array radar was enormous, necessitating an additional power supply. This took the form of a podded [[Honeywell T55|Lycoming T55-L5]] turboshaft engine in a pod under the left inboard wing section, driving a 350&nbsp;kVA generator, dedicated to powering mission equipment.<ref name=DrBob>{{cite book|title=The KC-135 Stratotanker; More Than Just a Tanker |last=Hopkins III |first=Robert S. |year=1997 |publisher=Midland Publishing Limited |isbn=978-1-85780-069-2}}</ref>

On the opposite wing, in the same location, was a podded heat exchanger to permit cooling of the massive electronic components on board the aircraft. This configuration has led to the mistaken impression that the aircraft had six engines. On 5 June 1969, Rivet Amber was lost at sea on a [[ferry flying|ferry flight]] from Shemya to Eielson AFB for maintenance. No trace of the aircraft or its crew was ever found.<ref name="aviation-safety.net">{{cite web|url=http://aviation-safety.net/database/record.php?id=19690605-0|title=ASN Aircraft accident Boeing RC-135E Rivet Amber 62-4137 Shemya, AK, USA [Bering Sea]|first=Harro|last=Ranter|website=aviation-safety.net|access-date=2 February 2019|archive-date=5 November 2013|archive-url=https://web.archive.org/web/20131105143859/http://aviation-safety.net/database/record.php?id=19690605-0|url-status=live}}</ref>

===RC-135M Rivet Card===
The RC-135M was an interim type, with more limited ELINT capability than the RC-135C, but with extensive additional COMINT capability. They were converted from [[Military Airlift Command]] C-135B transports, and operated by the [[82d Reconnaissance Squadron]] during the [[Vietnam War]] from [[Kadena AB]], gathering [[signals intelligence]] over the [[Gulf of Tonkin]] and Laos with the program name Combat Apple, originally Burning Candy.<ref name="82d">{{Cite web|url=http://www.55srwa.org/gallery/55_glr_pic36.html|archive-url=https://web.archive.org/web/20051023141128/http://www.55srwa.org/gallery/55_glr_pic36.html|url-status=dead|title=82d Recon Page|archivedate=23 October 2005}}</ref> There were six RC-135M aircraft, 62–4131, 62–4132, 62–4134, 62–4135, 62–4138 and 62–4139. All were later modified to and continue in active service as RC-135W Rivet Joints by the early 1980s.<ref>Don Logan, ''C-135 Series'', Schiffer Publishing</ref>

===RC-135S Nancy Rae / Wanda Belle / Rivet Ball===
Rivet Ball was the predecessor program to Cobra Ball and was initiated with a single RC-135S (serial 59–1491, formerly a JKC-135A) on 31 December 1961. The aircraft first operated under the Nancy Rae project as an asset of [[Air Force Systems Command]], and later as an RC-135S reconnaissance platform with Strategic Air Command under project Wanda Belle. The name Rivet Ball was assigned in January 1967. The aircraft operated from Shemya AFB, Alaska. Along with most other RC-135 variants, the RC-135S had an elongated nose radome, housing an [[S band]] receiving antenna.<ref name="rc135dotcom"/><ref name="C-135 Variants by Jennings Heilig ">{{cite web|url=http://www.clubhyper.com/reference/c135jh_1.htm|title=C-135 Variants by Jennings Heilig (Artwork, No Scale)|website=www.clubhyper.com|access-date=2 February 2019|archive-date=3 March 2016|archive-url=https://web.archive.org/web/20160303234406/http://www.clubhyper.com/reference/c135jh_1.htm|url-status=live}}</ref>

The aircraft had ten large optically flat quartz windows for tracking cameras on the right side of the fuselage. Unlike any other RC-135S, Rivet Ball had a plexiglass dome mounted top-center on its fuselage for the Manual Tracker position. It obtained the first photographic documentation of Soviet [[Multiple Reentry vehicle]] (MRV) testing on 4 October 1968. On 13 January 1969, Rivet Ball was destroyed when it overran the runway when landing at Shemya, with no fatalities.<ref name="rc135dotcom"/><ref name="C-135 Variants by Jennings Heilig "/>

===RC-135S Cobra Ball===
[[File:RC-135 Cobra Ball aircraft parked at Offutt.jpg|thumb|Two Cobra Ball aircraft on the flightline at [[Offutt Air Force Base]], Nebraska, 2001.]]
The '''RC-135S Cobra Ball''' is a [[measurement and signature intelligence]] (MASINT) collector equipped with special electro-optical instruments such an All Weather Tracking Radar and Medium Wave Infrared Array (MIRA) designed to observe [[ballistic missile]] flights at long range.<ref>{{Cite web |title=RC-135S Cobra Ball – Missile Defense Advocacy Alliance |url=https://missiledefenseadvocacy.org/defense-systems/rc-135s-cobra-ball/ |access-date=2023-07-21 |language=en-US}}</ref> The Cobra Ball monitors missile-associated signals and tracks missiles during boost and re-entry phases to provide reconnaissance for treaty verification and [[theater ballistic missile]] proliferation. The aircraft are extensively modified C-135Bs.<ref name="alm08"/> The right wing and engines are traditionally painted black to reduce sun glare for tracking cameras.<ref>{{cite web |url= http://www.airforcemag.com/MagazineArchive/Magazine%20Documents/2008/October%202008/1008warriors.pdf |title= Air Force Magazine, October 2008 |access-date= 4 June 2014 |archive-date= 4 March 2016 |archive-url= https://web.archive.org/web/20160304043046/http://www.airforcemag.com/MagazineArchive/Magazine%20Documents/2008/October%202008/1008warriors.pdf |url-status= live }}</ref>

There are three aircraft in service, assigned to the [[55th Wing]], [[45th Reconnaissance Squadron]] based at [[Offutt Air Force Base]], Nebraska. Cobra Ball aircraft were originally assigned to Shemya and used to observe ballistic missile tests on the [[Kamchatka peninsula]] in conjunction with [[Cobra Dane]] and [[Cobra Judy]]. In 1969, two aircraft were converted for Cobra Ball. Following the loss of an aircraft in 1981, another aircraft was converted in 1983. In 1995, the sole RC-135X was converted into an RC-135S to supplement the other aircraft.

===RC-135T Rivet Dandy===

In 1971, KC-135T 55-3121 was modified to a RC-135T Rivet Dandy configuration. It was used to supplement the RC-135C/D/M fleet, then in short supply due to ongoing upgrades requiring airframes to be out of service. It operated under the Burning Candy operational order. In 1973, the aircraft's SIGINT gear was removed and transferred to KC-135R 58–0126, resulting in 55-3121 assuming the role of trainer, a role which it fulfilled for the remainder of its operational existence. Externally the aircraft retained the 'hog nose' radome and some other external modifications. The aerial refueling boom and trapeze below the tail were removed, and it had no operational reconnaissance role.<ref name="ReferenceA"/>

In this configuration, it operated variously with the 376th Strategic Wing at [[Kadena AB]], Okinawa, the 305th AREFW at [[Grissom AFB]], Indiana, and the 6th Strategic Wing at Eielson AFB, Alaska. In 1982, the aircraft was modified with Pratt & Whitney [[TF33]]-PW102 engines and other modifications common to the KC-135E tanker program, and returned to Eielson AFB. It crashed while on approach to [[Valdez Airport]], Alaska on 25 February 1985 with the loss of three crew members. The wreckage was found in August 1985, six months after the accident.<ref name="ReferenceA">{{cite web|url=https://aviation-safety.net/database/record.php?id=19850225-3|title=ASN Aircraft accident Boeing RC-135T Rivet Dandy 55-3121 Valdez Municipal Airport, AK (VDZ)|first=Harro|last=Ranter|website=aviation-safety.net|access-date=2 February 2019|archive-date=3 February 2019|archive-url=https://web.archive.org/web/20190203030403/https://aviation-safety.net/database/record.php?id=19850225-3|url-status=live}}</ref>

===RC-135U Combat Sent===
[[File:USAF Combat Sent.jpg|thumb|A Combat Sent aircraft in flight with its unique nose cone, wingtips, and tail]]
The RC-135U Combat Sent is designed to collect technical intelligence on adversary radar emitter systems. Combat Sent data is collected to develop new or upgraded [[radar warning receiver]]s, [[radar jammer]]s, decoys, [[anti-radiation missile]]s, and training simulators.<ref name="alm08"/>

Distinctly identified by the antenna arrays on the fuselage chin, tailcone, and wing tips, three RC-135C aircraft were converted to RC-135U (63-9792, 64–14847, & 64–14849) in the early 1970s. In 1978, 63-9792 was converted into a Rivet Joint. All aircraft remain in service based at [[Offutt Air Force Base]], Nebraska. Minimum crew requirements are 2 pilots, 2 navigators, 3 systems engineers, 10 [[electronic warfare]] officers, and 6 area specialists.<ref name="cs-factsheet">{{cite web |title=RC-135U Combat Sent factsheet |url=https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104495/rc-135u-combat-sent/ |publisher=United States Air Force |date=28 September 2007 |access-date=10 July 2011 |archive-date=16 February 2016 |archive-url=https://web.archive.org/web/20160216060055/http://www.af.mil/AboutUs/FactSheets/Display/tabid/224/Article/104495/rc-135u-combat-sent.aspx |url-status=live }}</ref>

===RC-135V/W Rivet Joint===
[[File:20200311 RC-135 Rivet Joint Tail 62-4139 Kadena AB-75.jpg|thumb|An RC-135V Rivet Joint on final approach at [[Kadena AB]]]]

The RC-135V/W is the USAF's standard airborne [[Signals intelligence|SIGINT]] platform. Missions flown by the RC-135s are designated either '''Burning Wind''' or '''Misty Wind'''.<ref>{{Cite book|url=https://books.google.com/books?id=IiedBAAAQBAJ&pg=PA235|title=The U.S. Intelligence Community|last=Richelson|first=Jeffrey T.|date=14 July 2015|publisher=Avalon Publishing|isbn=978-0-8133-4919-0|page=235|access-date=30 August 2017|archive-date=13 March 2023|archive-url=https://web.archive.org/web/20230313152430/https://books.google.com/books?id=IiedBAAAQBAJ&pg=PA235|url-status=live}}</ref> Its sensor suite allows the mission crew to detect, identify and [[Geopositioning|geolocate]] signals throughout the [[electromagnetic spectrum]].<ref name="rj-factsheet" /> The mission crew can then forward gathered information in a variety of formats to a wide range of consumers via Rivet Joint's extensive communications suite. The crew consists of the cockpit crew, [[electronic warfare]] officers, intelligence operators, and airborne systems maintenance personnel. All Rivet Joint [[airframe]] and mission systems modifications are performed by [[L-3 Communications]] in [[Greenville, Texas]], under the oversight of the [[Air Force Materiel Command]].<ref name="alm08"/><ref name="rj-factsheet" />

All RC-135s are assigned to the 55th Wing, Air Combat Command at Offutt Air Force Base, Nebraska. The wing uses various forward deployment locations worldwide.<ref name="rj-factsheet">{{cite web |title=RC-135V/W Rivet Joint factsheet |url=https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104608/rc-135vw-rivet-joint/ |publisher=United States Air Force |access-date=5 March 2024}}</ref> They have flown from [[Eielson AFB]], [[Alaska]]; [[Howard AB]], [[Panama]]; [[Hellenikon Air Base]], [[Greece]]; [[Kadena Air Base]], [[Okinawa Island|Okinawa]], [[Japan]]; and [[RAF Mildenhall]], Suffolk, and [[RAF Upper Heyford]], Oxfordshire, in the [[United Kingdom]].

For many years, the RC-135V/W could be identified by the four large disc-capped Multiple Communications Emitter Location System (MUCELS) antennas forward, four somewhat smaller blade antennae aft and myriad of smaller underside antennas. Baseline 8 Rivet Joints, in the 2000s, introduced the first major change to the external RC-135V/W configuration, replacing the MUCELS antennas with plain blade antennas. The configuration of smaller underside antennas was also changed significantly.

====RC-135W Rivet Joint (Project Airseeker)====
[[File:RAF100 Flypast -13 ‘GOOSE’ formation. 10-7-2018 (43920147152).jpg|thumb|A British RC-135W, 2018]]
<!-- Although Air Seeker is often seen in third-party sources, the MoD use Airseeker to refer to the RIVET JOINT project (and originally used it as the UK name for the aircraft themselves) -->
The United Kingdom bought three KC-135R aircraft for conversion to RC-135W Rivet Joint standard<ref name="fg201003" /> under the Airseeker project.<ref name=FG20131112>{{cite web | url=http://www.flightglobal.com/news/articles/pictures-first-raf-rivet-joint-aircraft-arrives-in-uk-392875/ | title=PICTURES: First RAF Rivet Joint aircraft arrives in UK | first=Dominic | last=Perry | date=12 November 2013 | work=FlightGlobal | access-date=18 December 2013 | archive-date=22 January 2016 | archive-url=https://web.archive.org/web/20160122031208/http://www.flightglobal.com/news/articles/pictures-first-raf-rivet-joint-aircraft-arrives-in-uk-392875/ | url-status=live }}</ref> Acquisition of the three aircraft was budgeted at £634m, with entry into service in October 2014.<ref>{{cite web | url=http://www.official-documents.gov.uk/document/hc1213/hc06/0684/0684_i.pdf | title=Ministry of Defence – The Major Projects Report 2012 Appendix 3 | page=32 | publisher=National Audit Office | date=8 January 2013 | url-status=dead | archive-url=https://web.archive.org/web/20131219073623/http://www.official-documents.gov.uk/document/hc1213/hc06/0684/0684_i.pdf | archive-date=19 December 2013 }}</ref> The aircraft formed [[No. 51 Squadron RAF]], based at [[RAF Waddington]] along with the RAF's other ISTAR assets. They are expected to remain in service until 2045.

Previously, the Royal Air Force had gathered signals intelligence with three [[Hawker Siddeley Nimrod R1|Nimrod R1]] aircraft.<ref name="uk08" /> When the time came to upgrade the maritime Nimrods to [[Nimrod MRA4|MRA4 standard]], Project Helix was launched in August 2003 to study options for extending the life of the R1 to 2025.<ref name=MPR2010>{{cite web | url=http://www.official-documents.gov.uk/document/hc1011/hc04/0489/0489_i.pdf | title=Ministry of Defence – The Major Projects Report 2010 Appendix 2 | page=24 | publisher=National Audit Office | date=15 October 2010 | url-status=dead | archive-url=https://web.archive.org/web/20131105223335/http://www.official-documents.gov.uk/document/hc1011/hc04/0489/0489_i.pdf | archive-date=5 November 2013 }}</ref> In 2008, the option of switching to Rivet Joint was added to Helix,<ref name=MPR2010 /> and the retirement of the R1 became inevitable when the MRA4 was cancelled under the UK's [[Strategic Defence and Security Review 2010|2010 defence review]]. The R1's involvement over Libya in [[Operation Ellamy]] delayed its retirement until June 2011.

Helix became Project Airseeker, under which three KC-135R airframes were converted to the RC-135W standard by [[L-3 Communications]]. L-3 provides ongoing maintenance and upgrades under a long-term agreement. The three airframes are former [[United States Air Force]] [[Boeing KC-135|KC-135R]]s, all of which first flew in 1964 and were modified to the latest RC-135W standard before delivery. These three airframes were the youngest KC-135s in the USAF fleet.<ref>{{Cite web |date=20 August 2009 |title=UK Yet To Confirm Nimrod SIGINT Replacement |url=https://www.ainonline.com/aviation-news/defense/2009-08-20/uk-yet-confirm-nimrod-sigint-replacement |url-status=live |archive-url=https://web.archive.org/web/20231011032125/https://www.ainonline.com/aviation-news/defense/2009-08-20/uk-yet-confirm-nimrod-sigint-replacement |archive-date=11 October 2023 |website=Aviation International News}}</ref> As of September 2010 the aircraft had approximately 23,200 flying hours, 22,200 hours and 23,200 hours.<ref>{{cite web|url=https://publications.parliament.uk/pa/cm201011/cmhansrd/cm110118/text/110118w0004.htm|title=House of Commons Hansard Written Answers for 18 Jan 2011 (pt 0004)|website=publications.parliament.uk|access-date=2 February 2019|archive-date=30 November 2018|archive-url=https://web.archive.org/web/20181130121932/https://publications.parliament.uk/pa/cm201011/cmhansrd/cm110118/text/110118w0004.htm|url-status=live}}</ref>

In January 2011, 51 Sqn personnel began training at Offutt for conversion to the RC-135.<ref name="fg201101">{{cite web |last=Hoyle |first=Craig |date=14 January 2011 |title=RAF personnel start Rivet Joint training |url=http://www.flightglobal.com/articles/2011/01/14/351887/raf-personnel-start-rivet-joint-training.html |url-status=dead |archive-url=https://web.archive.org/web/20110119141337/http://www.flightglobal.com/articles/2011/01/14/351887/raf-personnel-start-rivet-joint-training.html |archive-date=19 January 2011 |access-date=21 January 2011 |publisher=Flight International}}</ref> The first RC-135W (ZZ664) was delivered ahead of schedule to the Royal Air Force on 12 November 2013, for final approval and testing by the Defence Equipment and Support team prior to its release to service from the [[UK MAA]]. The second (ZZ665) was delivered in September 2015 and the third (ZZ666) in June 2017. The latter entered operational service in December 2017.<ref>{{cite web |last=Chuter |first=Andrew |date=22 April 2016 |title=Type 26 Frigate Production Approval Date Revealed in Letters Release |url=http://www.defensenews.com/story/defense/international/europe/2016/04/22/letter-release-reveals-type-26-production-approval-date/83381446/ |url-status=live |archive-url=https://archive.today/20240108000452/https://www.defensenews.com/global/europe/2016/04/22/type-26-frigate-production-approval-date-revealed-in-letters-release/ |archive-date=8 January 2024 |access-date=23 April 2016 |website=Defense News}}</ref><ref>{{cite web|last1=Allison|first1=George|title=UK takes delivery of third and final RC-135 Rivet Joint surveillance aircraft|url=https://ukdefencejournal.org.uk/uk-takes-delivery-third-final-rc-135-rivet-joint/|website=UK Defence Journal|access-date=12 June 2017|archive-url=https://archive.today/20170612150832/https://ukdefencejournal.org.uk/uk-takes-delivery-third-final-rc-135-rivet-joint/|archive-date=12 June 2017|date=8 June 2017|url-status=dead}}</ref>

===RC-135X Cobra Eye===
The sole '''RC-135X''' Cobra Eye was converted during the mid-to-late-1980s from a C-135B Telemetry/Range Instrumented Aircraft, serial number 62–4128, with the mission of tracking ICBM [[Multiple independently targetable reentry vehicle|reentry vehicles]].<ref>{{cite web|url=https://fas.org/spp/military/program/lexicon.htm|title=Lexicon<!-- Bot generated title -->|website=fas.org|access-date=2 February 2019|archive-date=14 September 2016|archive-url=https://web.archive.org/web/20160914060502/http://fas.org/spp/military/program/lexicon.htm|url-status=dead}}</ref><ref>Rendall, David. ''Jane's Aircraft Recognition Guide'', 2000.</ref> In 1993, it was converted into an additional RC-135S Cobra Ball.<ref name="82d"/><ref>{{cite web|url=http://www.clubhyper.com/reference/c135jh_3.htm|title=C-135 Variants Part Three by Jennings Heilig (Artwork, No Scale)|website=www.clubhyper.com|access-date=2 February 2019|archive-date=4 March 2016|archive-url=https://web.archive.org/web/20160304064650/http://www.clubhyper.com/reference/c135jh_3.htm|url-status=live}}</ref>

===TC-135===
Three aircraft are in service for crew training, and lack fully functional mission equipment. One TC-135S (62–4133) provides training capability for the Cobra Ball mission, and is distinguishable from combat-ready aircraft by the lack of cheeks on the forward fuselage. It was converted from an EC-135B in 1985 following the crash of the former RC-135T 55–3121, which had been used as a trainer up to that point. Two TC-135Ws (62-4127 and 4129) serve as training aircraft, primarily for the Rivet Joint mission, but can provide some training capability for RC-135U Combat Sent crews. They carry considerably fewer antennas than the fully equipped aircraft, but are otherwise similar in appearance to other Rivet Joint aircraft.