‚5: 
elements, or to stabilize the aerial camera, the final accuracies m a 
will be slightly lower than those listed above. The overall sys- 
tem performance is described as^a circular error of position (CEP) 
expressed in nautical miles per hour. Typical results experienced 
by some users range from .36 NM/hour to .76 NM/hour. The maximum 
CEP is approximately 2 NM/hour. The on-track distance from which 
the distances between individual exposures can be derived have an 
accuracy in the order of + 200 meters. The purchase price of 
LTN-51 is approximately $110,000.00, maintenance cost approximately 
$10,000.00 per year. Systems for determination of the angular 
orientation elements V and i2 , would be more reliable in aerial 
triangulation, if they would yield accuracies approaching those 
of relative orientation. Gyroscopes and intertial guidance in- 
struments, which can produce data with these-dccuracies, are 
extremely expensive and beyond teach of private and governmental E 
organizations engaged in civilian mapping. The high cost of e eo 
such instrumentation nullifies any possible advantage they may 
have. 
Among the instruments which provide useful auxiliary data 
in vertical aerial triangulation, the statoscope is the most 
reliable and least expensive. There are several differential 
height sensing devices on the market which can be used as stato- 
scopes. A very important component of the statoscope system is 
a reliable. source of static pressure, (8), which requires a ‘spe- 
cial, but relotively simple, installation of a ‘static probe in 
the aircraft. The accuracy of the differences in elevation be- 
tween each exposure station, determined by statoscope, is the 
same as that of a comparable height corrector in APR. It can be 
  
an 
ma 
st 
an 
ga