the Air Force had never been in favor of a
separate type of aircraft for reconnais-
sance and mapping purposes prior to World
War II, two types of aircraft were then
procured for use for photographic pur-
poses. These were the F-1 and F-2 air-
craft: (The Fairchild 70D and Beachcraft
18-S with certain modifications for carry-
ing photographic equipment.)
With the advent of World War II in
1941 it was necessary to provide installa-
tions in aircraft that could be readily used
for carrying photographic equipment and
the following airplanes were modified for
reconnaissance purposes:
P-38 modified to the F-5
B-24 4 F-7
British Mosquito s F-8
B-17 & F-9
B-29 « F-13
Late in 1944 the F-11 aircraft, which was
designed primarily for reconnaissance pur-
pose, was produced by the Hughes Air-
craft Company.
' In 1946 the Republic Aircraft Company
built the F-12 which was also a basic pho-
tographic airplane. However, neither of
these two airplanes to date has been ac-
cepted by the Air Force as reconnaissance
aircraft.
'The Shoran Straight Line Indicator was
standardized and placed in use in the US
Air Force in 1948; fifty-five of these in-
struments were in use in 1952. Conceived
originally and developed by this Labora-
tory, an application for a patent for the
device was made in 1947. The indicator
24 HISTORY OF PHOTOGRAMMETRY IN THE UNITED STATES
is capable of handling flight lines up to 400
miles in length and represents the first use
of a precision flight line navigation aid
based on electronic means, or Shoran,
keyed in with two ground stations.
Later, in 1949, an entirely new system
was developed for the navigation of straight
and parallel flight lines. This method in-
volved the use of a modified Land-Polaroid
hand-held camera. It was first used in
flight between Dayton, Ohio and Pitts-
burgh, Pa. when two mapping flight lines
300 miles long were flown, with continu-
ous side lap of 30%, and with no variation
of more than 500 feet. The technique in-
volved in this system is astonishingly sim-
ple and effective and is planned for stand-
ardization by US Air Force.
During the development of cameras,
processing equipment and sensitized ma-
terials it was also necessary to produce
auxiliary equipment, such as stereoscopes,
magnifying stereoscopes, height finders,
stereocomparators and other accessories
which were required to make the best use
of aerial photographs in the production of
maps and charts.
Commercial mapping agencies have
been benefited considerably by the devel-
opments that were initiated and carried to
successful conclusion by the Air Force.
This is evidenced by the great amount of
surplus war photographic equipment which
has been purchased by commercial map-
ping agencies for use in conducting aerial
surveys and in the production of photog-
raphy for use by Federal and commercial
mapping agencies.
AERONAUTICAL CHART AND INFORMATION SERVICE
The global aspect of World War II
made apparent that extensive coverage of
aeronautical charts for the planning and
execution of air operations would be re-
quired. For this material to be made avail-
able, it was necessary that terrain infor-
mation be procured for the large areas of
the world over which American aircraft
might be expected to operate. To meet
this, the Map Section of the Information
Division of Headquarters, Army Air Corps
was redesignated in 1942 as the Map-Chart
Division of Air Traffic Service, Army Air
Corps, and assigned the responsibility for
providing the required aeronautical charts
* See report of the U, S. Geological Survey, p. 857
for operations of the Army Air Corps.
From a nucleus of some 20 personnel there
grew the current organization, the US Air
Force Aeronautical Chart and Informa-
tion Service, with responsibility for provid-
ing all US Air Force map and chart re-
quirements.
The need for reliable terrain information
resulted in the development of the trimet-
rogon system of aeronautical charting by
the Alaskan Branch* of the U. S. Geo-
logical Survey. This work was done in
1940 under the leadership of Gerald Fitz-
Gerald. The primary objective of the sys-
tem was securing photographic coverage
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