GV—64 PHOTOGRAMMETRIC ENGINEERING 
in a plane established by the base line 
and the line of sight rays AP and BD. 
It can be seen by the shading that ex- 
tending this plane until it cuts the 
vertical plane OCDE will result in a 
horizontal trace in that plane (paral- 
lel to AM). 
If one then takes any image on the 
trajectory trace OG (for which the 
time history is known), and extends a 
horizontal line until it cuts the other 
trajectory trace OF, this intersection 
will establish the place on OF where 
the missile would have been at the 
same instant. From here on it isap- 
parent that the horizontal displace- 
ment of the two curves OF and OG is 
Fıc. 9. a measure of the distance which the 
missile is offset from the reference 
plane. To compute this offset M one can use the simple geometric relation of 
similar triangles PFG and PAB; M:L=FG:AB, or M=(LXFG)/R. But, since 
offset = M + L or L —offset — M, the final relation is: 
FG 
R + FG 
Once L is known, the scale for either Analyzer record is established, and all 
three coordinates in space may be found. 
One variant of this second method covers the case where the path is hori- 
zontal, and as a result both trajectory traces are horizontal. In this situation it 
is impossible to work with the horizontal displacement of the two curves and 
it is necessary to use two Analyzers set up on a base line perpendicular to the 
reference plane. This case then becomes very similar to the situation presented 
in the first method, and is in reality a variant of it. 
  
  
M = offset X 
DETERMINATION OF DEVIATION FROM FLIGHT PATH 
The third method is more applicable to flight trajectories where the devi- 
ation from a planned reference plane is slight, such as would be the case in an 
ILS approach, a high speed pass, take-off, or in landing tests. Although the 
other methods may be used, this method does not require the use of two or 
more Analyzers. In this method a pulse-actuated 35 mm. camera provided with 
a reticle plate which superimposes a cross hair on each frame is used. This camera 
is located either facing down-range or up-range and boresighted along the 
planned flight path. Its site must be accurately established with respect to the 
Flight Analyzer position. A radio interlink beams a pulse each time the Analyzer 
records to a receiver which in turn pulses the down-range camera taking one 
frame for each image on the Analyzer record. The position of the aircraft from 
the down-range camera is established by each image on the Analyzer record 
so the range of the pulsed camera is known for each frame, and deviations from 
the cross hairs may thus be translated into feet and the offset value of the 
Analyzer record established. Generally, in this method, only four or five points 
are necessary to establish the deviation from true course, so it is not as laborious 
as it might appear to be. If the flight course is at a slight angle instead of parallel,