Fig. 12 
Installation of the Static Probe 
The Doppler navigator computer determines continuously the true air speed, the 
drift angle, and the distance along the track. 
To provide an accurate source of static pressure for the 
statoscope, a special swivel probe was installed (Fig. 12) near the tip of the 
wing, approximately two chord lengths forward of the leading edge of the wing. 
The probe consists of a set of concentric cylinders expanding rearward, always 
with a diameter less than one-tenth the distance from the tip. Holes are 
drilled at right angles to the surface. The swivel probe is supported at the 
center of gravity and carries a ring behind the centroid so that it will 
weathercock and keep a constant attitude to the air flow. 
The statoscope is connected to the static probe. We employed both 
the Wild and Zeiss Statoscope and the Litton Pressure Altimeter. 
4. AERIAL TRIANGULATION TECHNIQUES 
4.1 General 
The auxiliary instruments described above provide the following 
orientation elements of the aerial camera at the moment of exposure: 
Horizon Camera 
and for each of the aerial 
photographs