A Contribution to the Navigation of Photoflights 
Covering Large Areas * 
By Walter A. Bruck lâcher, Heiden heim, Germany. 
Introduction: 
Electric radar processes such as Decca, 
Shoran, GEE now provide the facilities for 
carrying out with comparative ease an accurate 
navigation that is required for systematic 
photoflights. However, a rather extensive 
ground organization in the form of trans 
mitting stations is needed for this purpose. 
Where such installations are not yet available 
for the control of civilian and military air 
traffic, their acquisition for the navigation of 
occasional photoflights alone would be ex 
tremely expensive. For this reason, naviga 
tional methods which do not use the radiation 
of electric waves will have to be employed 
also in future. On the basis of experiences 
made on extensive photoflights covering large 
areas, methods will be discussed which permit 
to undertake the systematic flying of photo 
graphic strips in scantily charted territory with 
the use of the conventional navigational aids. 
Emphasis is placed on photoflights covering 
large areas. As a matter of fact, these principles 
may also be employed to advantage for photo 
graphic flights at low levels for local large- 
scale surveys, even in cases where adequate 
map material would permit to fly such missions 
by the “contact flying“ or pilotage method. 
Tasks: 
Photoflights covering large areas generally 
involve the production of small-scale photo 
graphs, that is flying at high levels (above 
4000 m). To reduce the number of photo 
graphs, wide-angle cameras are usually em 
ployed. The direction of the lines of flight is 
generally north-south or east-west, for in the 
delineation of extensive projects of this nature, 
the direction of local features, valleys, moun 
tain ranges etc. plays only a minor role. 
To obtain complete coverage of the entire 
territory to be photographed by means of 
parallel photographic strips, navigation is sub 
divided into the following duties: 
1. Maintenance of straight-course lines of 
flight of 100 to 300 km in certain definite 
geographical directions; 
2. Flying the turns at the ends of the strips 
in such a manner that the prescribed 
flight line spacing is maintained; 
3. Maintainance of absolutely equal flight 
altitudes for all strips. 
To obviate the occurence of gaps in the 
photographic strips, the tolerance of flight line 
spacing must be kept at a low figure. As shown 
by the following table, it is between 0.7°/o and 
3°/o of the length of the strips. 
f (cm) 
Type of Camera 
Format (cm 2 ) 
Objective 
h 4 000 
6 000 
8 000 (m) 
10 
18X18 
Topogon 
5 (2) 
7.5 (3.5) 
10 (4) (km) 
7 
12 
18X18 \ 
30X30 / 
Pleon 
7 (3) 
11 (4) 
14 (6) (km) 
15 
23X23 
Metrogon 
10 (4) 
15 (6) 
19 (9) (km) 
(trimetrogon a 
useful picture 
rrangement; 
angle 120°) 
Flight line spacing in km at 30% strip overlap for different types of cameras and flying heights. 
The figures given in parantheses indicate the range of tolerance for the line of flight. 
* The German version of this report will be published in the Dezember 1952 issue of „Bildmessung 
und Luftbildwesen“ 
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