Editing Lockheed U-2 (section)

===Sensors===
[[File:U2withExperiments.jpg|thumb|upright=1.4|U-2 with range of possible payloads (2009)]]

Existing cameras had ground resolution down to {{convert|7|m|ft|order=flip}} from an altitude of {{convert|33000|ft|m}}, and were inadequate for the {{convert|70000|ft|m}} altitude. Ground resolution of {{convert|3|m|ft|order=flip}} was required, at a maximum payload weight of {{convert|200|kg|lb|order=flip}}. The U-2's camera was specially designed by [[James G. Baker]] of Harvard and [[Richard Scott Perkin]] of the [[Perkin-Elmer]] Company, initially in collaboration and later separately.{{sfn|Pedlow|Welzenbach|1992|loc=Chapter 2: Developing the U-2}}

Initial missions were flown with the [[trimetrogon]] "A" camera, consisting of three {{convert|24|in|mm|adj=mid|-focal-length}} cameras, with F/8 resolving 60 lines per mm, and the ground resolution can be inferred by calculation to be {{convert|60|cm|in|order=flip}}. This was followed by the "B" camera with a {{convert|36|in|mm|adj=mid|-focal-length}} lens with F/10 and image motion compensation, resolving 100 lines per mm, and the ground resolution can be inferred by calculation to be {{convert|23|cm|in|order=flip}}. It was a panoramic camera which took pictures of an extremely large area of the earth's surface. The lens design consisted of a single [[aspheric]] [[singlet lens]]. {{convert|6000|ft|spell=In|adj=on}} reels of film were used, with the [[Photographic emulsion|emulsion]] being coated on a polyester ([[Polyethylene terephthalate|PET]]) base that offered significantly improved dimensional stability over extremes of temperature and humidity compared to conventional [[cellulose acetate]].{{sfn|Brugioni|2010|p=115}}<ref>{{cite journal |last1=Calhoun |first1=J. M. |last2=Adelstein |first2=P. Z. |last3=Parker |first3=J. T |title=Physical Properties of Estar Polyester Base Aerial Films for Topographic Mapping |journal=Photogrammetric Engineering |issue=June 1961 |pages=461–470 |url=https://www.asprs.org/wp-content/uploads/pers/1961journal/jun/1961_jun_461-470.pdf |publisher=American Society of Photogrammetry |access-date=5 July 2022 |archive-date=5 July 2022 |archive-url=https://web.archive.org/web/20220705192007/https://www.asprs.org/wp-content/uploads/pers/1961journal/jun/1961_jun_461-470.pdf |url-status=live }}</ref>

In addition, the U-2 also carried a low-resolution Perkin-Elmer tracking camera using a 3-inch lens, which made continuous horizon-to-horizon photographs. This is common practice in high resolution cameras in later systems also, where the large image helps localize the small high-resolution images.

The aircraft carries a variety of sensors in the nose, Q-bay (behind the cockpit, also known as the camera bay), and wing pods. The U-2 is capable of simultaneously collecting [[signals intelligence|signals]], imagery intelligence and air samples. Imagery intelligence sensors include either wet film photography, electro-optic, or radar imagery—the latter from the [[Raytheon]] [[ASARS-2]] system. It can use both line-of-sight and over-horizon data links.
{{clear}}