KC-135 Stratotanker

infobox Aircraft
name = KC-135 Stratotanker
type = Aerial refuelling and transport
manufacturer = Boeing



caption = KC-135R refuels an F-22A Raptor
designer =
first flight = 31 August 1956
introduction = June 1957
retired =
status = Active service
primary user = United States Air Force
more users = French Air Force Republic of Singapore Air Force Turkish Air Force
produced = 1954-1965
number built = 803
unit cost = US$39.6 million (FY98 constant dollars)
developed from = Boeing 367-80
variants with their own articles = C-135 Stratolifter

The Boeing KC-135 Stratotanker is a United States aerial refueling tanker aircraft. It has been in service with the United States Air Force since 1957.

Development

The KC-135 is derived from the original Boeing jet transport "proof of concept" demonstrator, the Boeing 367-80 (commonly called the "Dash-80"). As such, it has a narrower fuselage and is shorter than the Boeing 707 jetliner. Boeing gave the tanker the designation of Model 717. [ [http://www.boeing.com/news/frontiers/archive/2006/july/i_history.pdf "Historical Perspective, Start of a PROUD MISSION"] , "Boeing Frontiers", July 2006.]

Developed in the late 1950s, the basic airframe is characterized by swept wings and tail, four underwing mounted engine pods, a horizontal stabilizer mounted on the fuselage near the bottom of the vertical stabilizer with positive dihedral on the two horizontal planes and a hi-frequency radio antenna which protrudes forward from the top of the vertical fin or stabilizer. These basic features make it strongly resemble the commercial Boeing 707 and 720 aircraft, although it is actually a different aircraft.

The Strategic Air Command had the KC-135 Stratotankers in service from 1957 through 1991 and with the Air National Guard and the Air Force Reserve from 1975 through 1991, when most were re-assigned to the newly-created Air Mobility Command (AMC). As AMC gained the preponderance of the aerial refueling mission, a small number of KC-135s were also assigned to directly United States Air Forces in Europe (USAFE) and Pacific Air Forces (PACAF). Reconnaissance and command post variants, including EC-135 Looking Glass, Post Attack Command & Control Systems were operated by SAC from 1963 through 1991, when they were re-assigned to the Air Combat Command.

Boeing's 367-80 was the basic design for the commercial Boeing 707 passenger aircraft as well as the KC-135A Stratotanker. In 1954 the USAF's Strategic Air Command ordered the first 29 of its future fleet of 732. The first aircraft flew in August 1956 and the initial production Stratotanker was delivered to Castle Air Force Base, California, in June 1957. The last KC-135 was delivered to the Air Force in 1965.

Four turbojet engines, mounted under 35-degree swept wings, power the KC-135 to takeoffs at gross weights up to 322,500 pounds (146,300 kg). Nearly all internal fuel can be pumped through the tanker's flying boom, the KC-135's primary fuel transfer method. A special shuttlecock-shaped drogue, attached to and trailing behind the flying boom, may be used to refuel aircraft fitted with probes. A boom operator stationed in the rear of the aircraft controls the boom while lying prone. A cargo deck above the refueling system can hold a mixed load of passengers and cargo. Depending on fuel storage configuration, the KC-135 can carry up to 83,000 pounds (37,600 kg) of cargo.

Design

General upgrades

The KC-135Q was the variant modified to carry the JP-7 fuel necessary for the SR-71 Blackbird, segregating the JP-7 from the KC-135's own fuel supply (the body tanks carrying JP-7, and the wing tanks carrying JP-4). When the KC-135Q model received the CFM-56 engines, it was redesignated the KC-135T model, which was capable of separating the main body tanks from the wing tanks where the KC-135 draws its engine fuel. The only external difference between a KC-135R and a KC-135T is the presence of a clear window on the underside of the empennage of the KC-135T where a remote controlled searchlight is mounted.

Eight KC-135R aircraft are receiver-capable tankers, commonly referred to as KC-135R(RT). All eight aircraft are with the 22nd Air Refueling Wing at McConnell AFB, KS as of 1994. [Hopkins, pp. 71-72.] They are primarily used for force extension and Special Operations missions, and are crewed by highly qualified receiver capable crews. If not used for the receiver mission, these aircraft can be flown just like any other KC-135R.

In order to expand the KC-135's capabilities and improve its reliability, the aircraft has undergone a number of upgrades. Among these was the Pacer-CRAG program (CRAG="Compass, Radar And GPS") which ran from 1999 to 2002 and modified all the aircraft in the inventory to eliminate the Navigator position from the flight crew. The modifications were performed by BAE Systems at the Mojave Airport in California. ["BAE SYSTEMS delivers final Pacer CRAG KC-135", "Aerotech News and Review", 2002-09-20] The latest block upgrade to the KC-135 is Block 40.3 which allows the KC-135 to comply with CNS/ATM.

Re-engining

All KC-135s were originally equipped with Pratt & Whitney J-57-P-59W turbojet engines which produced 10,000 lb of thrust dry, and approximately 13,000 pounds of thrust wet. Wet thrust was achieved through the use of water injection on takeoff. 670 gallons of water were injected into the engines over the course of two and a half minutes. This water allowed a second set of fuel injectors to activate without melting the turbine buckets. The water turned to steam, was ejected out the rear of the engine, and increased thrust. The water and the extra fuel increased the mass through the engine, increasing thrust. The engine ran a little hotter, increasing thrust as well as engine noise. The A-model on takeoff was a loud jet. In the 1980s the first modification program re-engined 157 Air Force Reserve (AFRES) and Air National Guard (ANG) tankers with the Pratt & Whitney TF-33-PW-102 engines from 707 airliners retired in the late 1970s and early 1980s. The re-engined tanker, designated the KC-135E, (now retired) was 14% more fuel efficient than the KC-135A and could offload 20% more fuel on long duration flights. (The difference is that the A-model weighed only 104,000 lb empty, while the E-model weighed 115,000 lb empty. But the maximum takeoff weight was not increased for the E-model. Therefore, the A-model could takeoff with 200,000 lb of fuel, while the E-model could only takeoff with 190,000 lb of fuel.) Only the KC-135E aircraft were equipped with thrust-reversers for takeoff aborts and shorter landing roll-outs.

The second modification program re-engined 500 with new CFM International CFM56 (F-108 for the military designation) engines produced by General Electric and Snecma. The re-engined tanker, designated either the KC-135R or KC-135T, can offload up to 50% more fuel (on a long duration sortie), is 25% more fuel efficient, costs 25% less to operate and is 96% quieter than the KC-135A.

The KC-135R's operational range is 60% greater than the KC-135E for comparable fuel offloads, providing a wider range of basing options. [http://www.globalsecurity.org/military/systems/aircraft/kc-135e.htm KC-135E] , Globalsecurity.org]

No longer in consideration, upgrading the remaining KC-135E into KC-135R would have cost about three billion dollars, about 24 million dollars per aircraft. According to Air Force data, the KC-135 fleet had a total operation and support cost in fiscal year 2001 of about $2.2 billion. The older E modelaircraft averaged total costs of about $4.6 million per aircraft, while the R models averaged about $3.7 million per aircraft. Those costs include personnel, fuel, maintenance, modifications, and spare parts. [http://www.gao.gov/new.items/d03938t.pdf]

Multi-Point Refueling System program

This program adds refueling pods to the KC-135's wings. The pods allow refueling of U.S. Navy, U.S. Marine Corps and NATO tactical jet aircraft while keeping the tail-mounted refueling boom. [http://www.globalsecurity.org/military/systems/aircraft/kc-135r-mprsp.htm]

Research and development

Besides its primary role as an inflight aircraft refueler, the KC-135, designated NKC-135, has assisted in several research projects at the NASA Dryden Flight Research Center at Edwards Air Force Base, California. One such project occurred between 1979 and 1980 when special wingtip "winglets", developed by Richard Whitcomb of the Langley Research Center, were tested at Dryden, using an NKC-135A tanker loaned to NASA by the Air Force. Winglets are small, nearly vertical fins installed on an aircraft's wing tips. The results of the research showed that drag was reduced and range could be increased by as much as 7 percent at cruise speeds. [ [http://www1.dfrc.nasa.gov/Gallery/photo/KC-135/HTML/index.html KC-135 Aircraft Photo Gallery Contact Sheet] ] [ [http://www.clubhyper.com/reference/c135jh_2.htm C-135 Variants - Part 2, by Jennings Heilig] ] Winglets are now being incorporated into most new commercial and military transport jets, as well as business aviation jets.

NASA also has operated several KC-135 aircraft (without the tanker equipment installed) as their infamous Vomit Comet zero-gravity simulator aircraft. The longest-serving (1973 to 1995) version was KC-135A 59-1481, named "Weightless Wonder IV" registered N930NA. [http://www.clubhyper.com/reference/c135jh_6.htm "C-135 Variants, Part 6" by Jennings Heilig] ]

Electronic warfare

A number of KC-135A and KC-135B aircraft have been modified to EC-135 configuration for use in several different roles.

Operational history

In Southeast Asia, the KC-135 Stratotankers ability as a force multiplier truly came to the fore. Midair refueling brought far-flung bombing targets within reach, and allowed fighter missions to spend hours at the front, rather than just a few minutes, due to their limited fuel reserves.

Air Mobility Command (AMC) manages more than 481 Stratotankers, of which the Air Force Reserve and Air National Guard fly 292 in support of AMC's mission as on April 2008.

Replacing the KC-135

As of 2006, the KC-135E fleet is flying an annual average of 350 hours per aircraft and the KC-135R fleet is flying an annual average of 710 hours per aircraft. The KC-135 fleet is currently flying double its planned yearly flying hour program to meet airborne refueling requirements, and has resulted in higher than forecast usage and sustainment costs. [http://www.globalsecurity.org/military/library/congress/2006_hr/060228-bartlett.pdf]

The Air Force projects that E and R models have lifetime flying hour limits of 36,000 and 39,000 hours, respectively. According to the Air Force, only a few KC-135s would reach these limits before 2040, but at that time some of the aircraft would be about 80 years old. The Air Force estimates that their current fleet of KC-135s have between 12,000 to 14,000 flying hours on them-only 33 percent of the lifetime flying hour limit. [ [http://www.globalsecurity.org/military/systems/aircraft/kc-135e.htm KC-135E ] ] Nevertheless these aircraft are over 40 years old and maintenance costs are increasing, with airframe corrosion being the worst problem.

Between 1993 and 2003, the amount of KC-135 depot maintenance work doubled, and the overhaul cost per aircraft tripled. [ [http://www.afa.org/magazine/jan2003/0103aircraft.asp When Aircraft Get Old ] ] In 1996 it cost $8,400 per flight hour for the KC-135, and in 2002 this had grown to $11,000. The Air Force’s 15-year cost estimates project further significant growth through fiscal year 2017. For example, operations and support costs for the KC-135 fleet are estimated to grow from about $2.2 billion in fiscal year 2003 to $5.1 billion (2003 dollars) in fiscal year 2017, an increase of $2.9 billion, or over 130 percent, which represents an annual growth rate of about 6.2 percent. [ [http://www.iwar.org.uk/news-archive/gao/dod-aerial-refueling/d04349.pdf GAO-04-349, MILITARY AIRCRAFT: DOD Needs to Determine Its Aerial Refueling Aircraft Requirements ] ]

The USAF has decided to replace the KC-135 fleet. However, since there are over 500 KC-135 these planes will be replaced gradually, with the first batch of about 100 aircraft to be replaced in the current buy. The effort to replace the KC-135 has been marked by intense controversy.

Initially the first batch of replacement planes was to be an air tanker version of the Boeing 767, leased from Boeing. In 2003, this was changed to contract where the Air Force would purchase 80 KC-767 aircraft and lease 20 more. [ [http://www.afa.org/magazine/feb2004/0204tanker.asp Tanker Twilight Zone] , Air Force magazine, February 2004, Vol. 87, No. 2.] In December 2003, the Pentagon froze the contract and in January 2006, the KC-767 contract was canceled. This followed public revelations of corruption in how the contract was awarded, as well as controversy regarding the original leasing rather than outright purchase agreement. This was also designed to be a cost-cutting measure and is part of a larger reorganization and redefinition of the Air Force's mission that includes the retirement of the E-4B fleet, the cancellation of the Boeing 767-based E-10 MC2A program, as well as the elimination of all but 58 B-52 Stratofortresses. Former Secretary of Defense Rumsfeld stated that this move will in no way impair the Air Force's ability to deliver the mission of the KC-767, which will be accomplished by continuing upgrades to the KC-135 and KC-10 Extender fleet.

In January 2007, the U.S. Air Force formally launched the KC-X program with a request for proposal (RFP). KC-X is first phase of three acquisition programs to replace the KC-135 fleet. [ [http://www.defenselink.mil/Releases/Release.aspx?ReleaseID=10463 "Air Force Posts Request for Proposals for Tankers"] , US DoD, January 30, 2007.] On 29 February 2008, the US Defense Department announced that it had selected the EADS/Northrop Grumman "KC-30" (to be designated the KC-45A) over the Boeing KC-767. [ [http://www.af.mil/news/story.asp?id=123088392 "Tanker contract award announced"] , US Air Force, February 29, 2008.] On June 18, 2008, the US Government Accountability Office sustained Boeing's protest of the selection of the Northrop Grumman/EADS's tanker.cite web |url=http://www.king5.com/sharedcontent/northwest/pdf/gao_boeing.pdf |title=Statement Regarding the Bid Protest Decision Resolving the Aerial Refueling Tanker Protest by the Boeing Company |publisher=Government Accountability Office |date=2008-06-18 |accessdate=2008-06-18] The status of the KC-45A is in doubt and the Air Force may have to rebid the contract, potentially reversing their earlier decision.cite web |url=http://www.king5.com/topstories/stories/NW_061808BUB_boeing_gao_air_tanker_contract_JM.161e241b.html |title=GAO backs Boeing tanker protest |publisher=King 5 News |date=2008-06-18 |accessdate=2008-06-18]

Operators

;FRA
* French Air Force;SIN
* Republic of Singapore Air Force;PAK
* Pakistan Air Force - 4 US surplus stocks to be acquired.whenFact|date=August 2008;TUR
* Turkish Air Force;USA
* NASA
* United States Air Force operated 505 KC-135 aircraft as of September 2007 (199 active duty, 80 reserve, and 226 guard). Mehuron, Tamar A., Assoc. Editor. [http://www.airforce-magazine.com/MagazineArchive/Magazine%20Documents/2008/May%202008/0508facts_figs.pdf 2008 USAF Almanac, Fact and Figures] , Air Force Magazine, May 2008.]
** Air Education and Training Command
*** 97th Air Mobility Wing - Altus AFB, Oklahoma
**** 54th Air Refueling Squadron
**** 55th Air Refueling Squadron
** Air Mobility Command
*** 6th Air Mobility Wing - MacDill AFB, Florida
**** 91st Air Refueling Squadron
**** 911th Air Refueling Squadron
*** 22d Air Refueling Wing - McConnell AFB, Kansas
**** 344th Air Refueling Squadron
**** 349th Air Refueling Squadron
**** 350th Air Refueling Squadron
**** 384th Air Refueling Squadron
*** 92d Air Refueling Wing - Fairchild AFB, Washington
**** 92d Air Refueling Squadron
**** 93d Air Refueling Squadron
*** 319th Air Refueling Wing- Grand Forks AFB, North Dakota
**** 905th Air Refueling Squadron
**** 906th Air Refueling Squadron
**** 912th Air Refueling Squadron
*** 19th Air Refueling Group - Little Rock AFB, Arkansas
**** 99th Air Refueling Squadron
** Pacific Air Forces
*** 18th Wing - Kadena AB, Japan
**** 909th Air Refueling Squadron
** United States Air Forces in Europe
*** 100th Air Refueling Wing - RAF Mildenhall, England
**** 351st Air Refueling Squadron
** Air Force Reserve Command
*** 434th Air Refueling Wing - Grissom JARB, Indiana
**** 72d Air Refueling Squadron
**** 74th Air Refueling Squadron
*** 452d Air Mobility Wing - March JARB, California
**** 336th Air Refueling Squadron
*** 459th Air Refueling Wing - Andrews AFB, Maryland
**** 756th Air Refueling Squadron
*** 507th Air Refueling Wing - Tinker AFB, Oklahoma
**** 18th Air Refueling Squadron - McConnell AFB, Kansas
**** 465th Air Refueling Squadron
*** 916th Air Refueling Wing - Seymour Johnson AFB, North Carolina
**** 77th Air Refueling Squadron
*** 927th Air Refueling Wing - MacDill AFB, Florida
**** 63d Air Refueling Squadron
*** 940th Air Refueling Wing - Beale AFB, California
**** 314th Air Refueling Squadron
** Air National Guard
*** Alabama Air National Guard
**** 117th Air Refueling Wing - Birmingham IAP
***** 106th Air Refueling Squadron
*** Alaska Air National Guard
**** 168th Air Refueling Wing - Eielson AFB
***** 168th Air Refueling Squadron
*** Arizona Air National Guard
**** 161st Air Refueling Wing - Sky Harbor IAP
***** 197th Air Refueling Squadron
*** Hawaii Air National Guard
**** 154th Wing - Hickam AFB
***** 203d Air Refueling Squadron
*** Illinois Air National Guard
**** 126th Air Refueling Wing - Scott AFB
***** 108th Air Refueling Squadron
***Kansas Air National Guard
**** 190th Air Refueling Wing - Forbes Field
***** 117th Air Refueling Squadron
*** Maine Air National Guard
**** 101st Air Refueling Wing - Bangor IAP
***** 132d Air Refueilng Squadron
*** Michigan Air National Guard
**** 127th Wing - Selfridge ANGB
***** 171st Air Refueling Squadron
*** Mississippi Air National Guard
**** 186th Air Refueling Wing - Key Field
***** 153d Air Refueling Squadron
*** Nebraska Air National Guard
**** 155th Air Refueling Wing - Lincoln ANGB
***** 173rd Air Refueling Squadron
*** New Hampshire Air National Guard
**** 157th Air Refueling Wing - Pease ANGB
***** 133d Air Refueling Squadron
*** New Jersey Air National Guard
**** 108th Air Refueling Wing - McGuire AFB
***** 141st Air Refueling Squadron
***** 150th Air Refueling Squadron
***Ohio Air National Guard
**** 121st Air Refueling Wing - Rickenbacker ANGB
***** 145th Air Refueling Squadron
***** 166th Air Refueling Squadron
***Pennsylvania Air National Guard
**** 171st Air Refueling Wing- Pittsburgh International Airport
***** 146th Air Refueling Squadron
***** 147th Air Refueling Squadron
*** Tennessee Air National Guard
**** 134th Air Refueling Wing - McGhee Tyson Airport
***** 151st Air Refueling Squadron
*** Washington Air National Guard
**** 141st Air Refueling Wing - Fairchild AFB
***** 116th Air Refueling Squadron
*** Wisconsin Air National Guard
**** 128th Air Refueling Wing

Note Italy has been reported in some sources as operating several KC-135s, [ [http://seattlepi.nwsource.com/business/30685_tanker10.shtml "Boeing wins Italian bid military 767s"] , Italy operates 4 KC-135s, SeattlePi.com, 2001-07-10] ] however these are actually Boeing 707-300s converted to tanker configuration. [ [http://www.aeroflight.co.uk/waf/italy/italaf4.htm Aeroflight's listing of Italian Air Force aircraft] ] [ [http://www.airlinerlist.com Airframe tracking information from Airlinerlist.com] ]

Variants

;KC-135A:Original production version powered by four Pratt & Whitney J57s, 732 built.;NKC-135A:Test-configured KC-135A;KC-135B:Airborne command post version with 17 built equipped with turbofan engines. Provided with in-flight refueling capability and redesignated EC-135C.Donald, David. "Boeing Model 717 (C/KC-135 Stratoliner/Stratotanker." "The Complete Encyclopedia of World Aircraft". Barnes & Nobel Books, 1997. ISBN 0-7607-0592-5.] ;KC-135D:All four RC-135As were modified to partial KC-135A configuration in 1979. [DoD 4120.14L, "Model Designation of Military Aerospace Vehicles", May 12, 2004] Hopkins, p.144] They were given a unique designation as they differed from the KC-135A in that they were built with a flight engineers position on the flight deck. [Pither, Page 73] The flight engineer's position was removed when the aircraft were modified to KC-135 standards but they retained their electrically-powered wing flap secondary (emergency) drive mechanism and second air conditioning pack which had been used to cool the RC-135As on-board photo-mapping systems. [Hopkins, pp. 142-144.] Later re-engined with Pratt & Whitney TF33 engines and a cockpit update to KC-135E standards in 1990. [Pither, p. 73.] ;KC-135E:Air National Guard and Air Force Reserve KC-135As re-engined with Pratt & Whitney TF-33-PW-102 engines from retired 707 airliners (161 modified). These aircraft are being retired to Davis-Monthan Air Force Base and replaced with R models. [Baker, MSgt Burke. [http://www.af.mil/news/story.asp?id=123099872 "48-year-old KC-135 retires"] , Air Force news, May 22, 2008.] ;NKC-135E:Test-configured KC-135E;C-135F:Variant with J57 engines for the French Air Force, 12 built, 11 re-engined with CFM-56 as C-135RF.;KC-135Q:KC-135As modified to carry JP-7 fuel necessary for the SR-71 Blackbird, 56 modified, survivors to KC-135T.;KC-135R:KC-135As re-engined with CFM-56 engines.;KC-135R(RT):Receiver-capable KC-135R Stratotanker, 8 modified with either a Boeing or LTV receiver system and a secure voice SATCOM radio.;KC-135T:KC-135Q re-engined with CFM-56 engines, 54 modified.;EC-135Y:An airborne command post modified in 1984 to support CINCCENT. Aircraft 55-3125 was the only EC-135Y. Unlike it's sister EC-135N, it was a true tanker that could also receive in-flight refueling. Pratt & Whitney TF-33-PW-102. Currently retired at AMARC.

pecifications (KC-135R)

aircraft specifications
plane or copter?=plane
jet or prop?=jet
ref=USAF Fact Sheet [http://www.af.mil/factsheets/factsheet.asp?fsID=110 KC-135 fact sheet] , USAF, April 2008.]
crew=3: pilot, copilot, boom operator
capacity=57 passengers
payload main=83,000 lb
payload alt=37,600 kg
length main=136 ft 3 in
length alt=41.53 m
span main=130 ft 10 in
span alt=39.88 m
height main=41 ft 8 in
height alt=12.70 m
area main=2,433 ft²
area alt=226 m²
airfoil=
empty weight main=98,466 lb
empty weight alt=44,663 kg
operating empty main=124,000 lb
operating empty alt=56,200 kg
loaded weight main=297,000 lb
loaded weight alt=135,000 kg
useful load main=
useful load alt=
max takeoff weight main=322,500 lb
max takeoff weight alt=146,000 kg
more general= Maximum Fuel Load: 200,000 lb (90,719 kg) or 31,275 US gal (118 kL)
engine (jet)=(R/T) CFM International CFM56 (F108-CF-100)
type of jet=turbofan
number of jets=4
thrust main=21,634 lbf
thrust alt=96 kN
thrust original=
afterburning thrust main=
afterburning thrust alt=
engine (prop)=
type of prop=
number of props=
power main=
power alt=
power original=
max speed main=580 mph
max speed alt=933 km/h
cruise speed main=
cruise speed alt=
stall speed main=
stall speed alt=
never exceed speed main= 373 Knots at 26,500 ft
never exceed speed alt= mach 0.90
range main=3,450 mi
range alt=5,550 km
ceiling main=50,000 ft
ceiling alt=15,200 m
climb rate main=4,900 ft/min
climb rate alt=1,490 m/min
loading main=
loading alt=
thrust/weight=
power/mass main=
power/mass alt=
more performance=
armament=
avionics=

ee also

aircontent
related=
* Boeing 367-80
* C-135 Stratolifter
* C-137 Stratoliner
* Boeing 707
similar aircraft=
* Boeing KC-767
* KC-10 Extender
* Airbus A310 MRTT
* Airbus A330 MRTT (KC-30)
* Northrop Grumman KC-45
see also=
* Vomit Comet
* Palomares hydrogen bombs incident

References

* Tony Pither, "The Boeing 707 720 and C-135", Air-Britain (Historians) Ltd, England, 1998, ISBN 0 85130 236 X.
*cite book |last= Hopkins, III |first= Robert S. |title= Boeing KC-135 Stratotanker: More Than Just a Tanker |year= 1997 |publisher= Midland Publishing Limited |location= Leicester, England |isbn= 1 85780 069 9

External links

* [http://www.boeing.com/defense-space/military/kc135-strat/index.html KC-135 page on Boeing.com]
* [http://www.boeing.com/defense-space/military/kc135-strat/kc135photos.html KC-135 image gallery on Boeing.com]
* [http://www.af.mil/factsheets/factsheet.asp?fsID=110 Official USAF KC-135 fact sheet]
* [http://www.af.mil/photos/index.asp?galleryID=38 Public domain KC-135 photo gallery at official USAF website]
* [http://www.awacs-spotter.nl/index.htm KC-135 page on awacs-spotter.nl]
* [http://www1.dfrc.nasa.gov/Gallery/photo/KC-135/index.html Public domain photo gallery of NASA's KC-135A tanker]
* [http://www.globalsecurity.org/military/systems/aircraft/kc-135.htm KC-135 page at globalsecurity.org]
* [http://www.fas.org/nuke/guide/usa/bomber/kc-135r.htm KC-135 page at fas.org] - (not updated since late 1999, but still perhaps useful)
* [http://www.aero-web.org/locator/manufact/boeing/c-135.htm C-135 page at aero-web.org] - Includes specs for many variants
* [http://www.ausairpower.net/DT-Smart-AAR-0705.pdf Smart Tankers (Defence Today)]