Experiments on the Gyroscopic Recording of the 
Nadir Point according to the Nistri Method 
by 
Dr. GINO PARENTI 
PAPER FOR THE VIII CONGRESS OF PHOTOGRAMMETRY - STOCKHOLM 1956 
I COMMISSION 
In the experimental laboratories of the Ottico Meccanica Italiana in Rome there has 
been conducted some series of experiments on the gyroscopic units of the type of those 
used in the Nistri method for the recording of the carthesian components of the nadir 
point. As is known the unit consists of a gyroscope of which only the oscillations of 
the primary axis are recorded, while those of the secondary axis are not utilized. 
The object of these experiments is that of submitting the gyroscope to the solicita- 
tions and to the dynamic, thermic and electric variations that it can undergo a flight 
and to study separately the effects for cach of them. 
So as to be sure to be able to examine the behaviour of the gyroscope for the entire 
duration of each test there has been instituted a system of continuous recording of the 
inovements of the primary axis and it has also been made in such manner so that 
said recording can have a duration at least equal to that of a normal flight. 
To do this the continuous recording, obtained by means of a lens having an ade- 
quate focal length, has been imposed upon a rotating drum that also has uniform 
longitudinal translation, the dimensions and the speed of translation are such that it is 
possible to record on cach sheet the results of tests lasting more than three hours. 
The periferical rotation speed of the cylinder corresponds to I mm per second so 
that it is possible to examine the behaviour of the gyroscope in its most minute parti- 
culars, thereby revealing eventual irregularities even of short duration. 
In Fig. 1 there is schematically shown the recording apparatus employed in actual size. 
The tests were performed on two instruments of standard construction for a total 
period of time about 110 hours for each gyroscope, the tests in which there was 
encountered some working anomaly were repeated on two other gyroscopes, these also 
of standard construction, so as to ascertain and study the nature and the origin of the 
anomalies themselves. 
The tests made and recorded belong to the follewing groups. 
  
  
   
   
    
    
  
      
  
        
  
  
  
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