weather in the limited area sustained by the ground stations ties the hands 
of the operating units until suitable photo weather occurs. Months of 
waiting can make this procedure exceedingly costly. 
In this paper I will explain a new approach to the problems of aerial 
mapping which has been developed into a new streamlined operational concept 
and by which horizontal and vertical control data can be obtained by the 
aircraft rapidly and efficiently. This concept was first envisioned using 
a highly stable aerial platform which is worthy of explanation. 
The Boeing KC-135 aircraft was conceived and designed as a high speed, 
high altitude stable platform for air refueling missions. To maintain its 
high altitude, high speed stability while rapidly discharging its many 
tons of fuel was solved by retaining its center of gravity throughout the 
refueling operation. The aircraft was also designed to consume its 
internal fuel (including tanker fuel), for maximum range or ferry operations. 
All of its tanker fuel is below the cargo floor. Above this floor an area 
the size of a bowling alley will accommodate multiple cameras, electronic 
survey equipment, etc. 
The skilled engineering of the auto pilot compliments the stability 
characteristics of the aircraft and maintains it rigidly in space as a 
firm stable platform ideal for the aerial mapping mission. 
Before proceeding with our discussion on the aircraft development, I 
would like to relate my views of the task of the photogrammetrist. This 
skilled technician receives the geometrically perfect (less than 10 micron 
distortion) aerial photographs which were taken by the mapping aircraft. 
The camera, if cradled in our present stabilized mount, is pointing almost 
vertically when the aerial photographs are taken. But which way that first 
photo was tilted and how much cannot be determined without the aid of ground 
control. Accurately surveyed ground positions which can be identified or 
plotted on the mapping photograph must be correlated with the aerial 
exposure to correct it to its true vertical. When one photograph has been 
properly oriented to the ground survey control data, then overlapping 
stereo photographs can be leveled and the control extended by aero 
triangulation. Aero triangulation works fine over a short distance, but 
accuracy gradually deteriorates as it is cantilevered from the first 
model or bridged between two separate models. Approximately seven successive 
stereo photographs are generally considered to be the maximum extension 
possible for first order aero triangulation. 
In summary, it would seem reasonable to conclude that it would be a 
very major benefit to the photogrammetrist when he can rapidly determine 
the true vertical axis of the mapping camera in our new aerial mapping 
system. The vertical readout of the inertial platform optically recorded 
and synchronized with the aerial exposure to less than 30 arc seconds will 
greatly enhance the photogrammetric accuracy of extensions by cantilever 
and bridging.