other words, into areas with equal flight line 
spacings. These, as well as the theoretical 
spacings for 30°/'o overlap, are then plotted 
on flight maps. 
The guide point for the first run als well as 
other conspicuous landmarks along the different 
lines of flight, such as lakes, indented coast 
lines, river bends, highway crossings, settle 
ments etc. are also marked. Thus, every run 
is previously “flown“ mentally on the map. 
The weather forecast for the territory to be 
photographed permits to study the probable 
wind conditions, which may be fairly con 
stant in some areas according to the seasons. 
This permits to select the navigational plot 
ting sheets which have been prepared for the 
different possibilities, such as turns with head 
or tail wind, with “intermediate run“ or ad 
ditional “S“ turn. According to the annual 
change the isogones are reduced to the date 
of the flight and recorded at V2-degree inter 
vals along the plotted flight paths. Diagrams, 
compass correction tables etc. should be pre 
pared and pasted on cardboard of convenient 
size for use on board the airplane. A careful 
briefing of the entire crew on the intended 
mission will substantially contribute to its 
success. On the other hand, a discussion of 
the results obtained after the completion of the 
mission will prove a valuable incentive for fu 
ture flights. 
The crew of a two-engine photographic 
airplane should consist of 4 persons: naviga 
tor, pilot, photographer and radio operator. 
The duties will be assigned in such manner 
that they can be performed dependably and 
accurately despite the physical strain of ex 
tensive flights at high altitudes. The naviga 
tor as captain of the aircraft is responsible 
for the control and observation of all naviga 
tion instruments; he computes the settings of 
the automatic pilot system, flies the turns with 
the aid of direction indicator lever and stop 
watch, issues instructions to the photographer 
and checks all phases of the run. The pilot is 
in charge of the engines and the controls of 
the airplane, trims the aircraft, sets the auto 
matic pilot on the course according to the 
data computed by the navigator and con 
tinuously checks the statoscope readings so as 
to maintain the ship constantly at the same 
level. The photographer operates the aerial 
camera at a signal from the navigator, cor 
rects the drift, the correct intervals of the 
consecutive photographs and the vertical po 
sition of the camera, and changes the maga 
zines according to the readings of the meter 
ing mechanism. The radio operator maintains 
contact with the ground station, obtains the 
bearings for the return trip as soon as the 
photoflight is over, acts as steward and is 
responsible for the safety of the flight. One 
of the most important means for maintain 
ing the proper coordination during the entire 
trip is the intercommunication telephone. 
In particular, the following suggestions 
should be observed on photoflights: 
Immediately before the start, the wind con 
ditions in the higher levels of the target area 
should be obtained from the weather station. 
This permits to make a preliminary naviga 
tional computation during the climb and pro 
vides a certain check on the own determination 
of wind, which, however, is much more ac 
curate. After the correct photographic alti 
tude has been reached, the pilot sets the en 
gines for optimal r.p.m. so as to ensure a well 
balanced flight altitude. This engine speed 
remains constant during the entire photogra 
phic flight. Measuring and computation of wind 
and navigation data will take between 10 
and 12 minutes. The filling in of the plotting 
sheets will practically eliminate the occuren 
ce of errors. Magazines are changed always 
at the end of a run. The aircraft continues on 
its course beyond the target area until the 
photographer has changed the magazines. On 
ly then will the ship go into the turn. During 
the run, the navigator picks up distant targets 
on the line of flight through the prism of the 
Lotfe and simultaneously marks those points 
on the flight map which have been crossed 
and unequivocally identified. Immediately 
after the end of the photoflight a record of 
the actual flight path is therefore available on 
the map, which will greatly facilitate the 
matching of the individual photographs at a 
later date. 
Resalts : 
The above described methods have been 
employed on photoflights covering a total 
area of approximately 300 000 km 2 . On sec 
tions covering a total area of approximately 
80 000 km 2 , the statistical data on the results 
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