The US Navy initially preferred ex-airline Douglas DC-8s as test-beds (EC-24 163050 illustrated), but took NKC-135s as well.

In addition to working as a tanker test-bed, NKC-135E 55-3135 also provided tanker support for other programmes.

NKC-135A 55-3122 soon after entering storage at Davis-Monthan in late 1993. It had previously been flown by the 4950th TW.

Close-up of the ALL NKC-135A 55-3123 on the museum ramp at 'Wright-Patt'.

In company with several J/NKC-135As used for recording high-altitude events, 55-3124 had a number of large optically flat windows along its fuselage.

Eleven optical windows and a large fairing were installed on NKC-135A 55-3127 initially for Project 'Skyscraper'. Tlte upper surface of the port wing was painted black to reduce glare.

While it is best known as an icing tanker NKC-135A 55-3128 was also used to test the AN/APQ-140 radar in an enlarged nose radome.

Этот JKC-135A входил в число трех самолетов «Vomit Comet», использовавшихся для подготовки астронавтов, а с 1979 года испытывал винглеты.
NASA flew 55-3129 as a research aircraft from mid-1979 to assess the benefits of winglets.

'Big Crow’ NKC-135E 55-3132 flew missions during Operation ‘Iraqi Freedom', deploying to Souda Bay on Crete from March 17, 2002.

Several C-135s associated with nuclear readiness testing had large numbers of windows on one side, including NKC-135A 55-3135.

After being assigned as a tanker test-bed, many of the smaller windows on the starboard side of 55-3135 were filled in. Pictured at Edwards AFB as an NKC-135E, 1997.

Impressive line-up at Edwards, 1997.

NKC-135E 55-3135 at Edwards, 1997.

'Navy King Crow I' was the second NKC-135A flown on behalf of the US Navy.

Possibly the most famous NKC-135A test-bed was the Airborne Laser Laboratory, the first to destroy a missile in flight.

KC-135A 55-3129 is seen painted in Wright Air Development Center, Air Research and Development Command markings prior to being delivered by Boeing, before becoming a JKC-135A.

top to bottom: NKC-135A 55-3121; NKC-135A 55-3123 HEL; NKC-135A 55-3123 ALL; NKC-135A 55-3128; NKC-135A 55-3129 NASA winglets; NKC-135A 55-3132 SLAR test-bed; NKC-135A 55-3132 'Big Crow'; NKC-135A 55-3124 celestial navigation research; NKC-135A US Navy FEWSG; NC-135A 60-0370 nuclear; NC-135A 60-0376 'Piccolo Tube'; NC-135B 61-2669 SATCOM test-bed.

NKC-135s have been involved in extensive flight testing for the 747-based YAL-1A ABL.

EC-135E 60-0374 at Tinker in 1995.

For the ARIA mission the EC-135Ns and 'Es had a high-frequency antenna on the tip of the starboard wing.

The most distinctive feature of the ARIAs was the large nose radome, within which was one of the largest dishes ever installed on an aircraft.

AFMC EC-135E 61-0326 at Edwards, April 1997.

Moody image of EC-135E 61-0326 at Edwards in 1997.

EC-135N (top) and EC-135N ALOTS.