86 



AEROPLANE PERFORMANCE CALCULATIONS 



The values of L/D and k imax for the model test are then to 

 be filled in in the next column, and finally the last column is to 

 be worked out by multiplying the five corrections and the model 

 figure together horizontally across the page. 



Cautions in Applying the Corrections. When the model 

 wing whose channel tests are being used is a 6:1 aspect ratio 

 monoplane with square tips (as is usually the case), no special 

 caution is necessary. If, however, the test was carried out on a 

 model of any other specification, the model tests must first be 

 corrected back to standard model by dividing by the appropriate 

 corrections read off the curves. No long explanation of this 

 point is necessary, as it is quite obvious, but it is perhaps as well 

 to mention it. 



Often, nowadays, the designer has at his disposal a model 

 test on a complete set of wings for his machine with correct 

 aspect ratio, gap/chord, stagger, and wing tips. In this case, of 

 course, the only correction to apply to the model tests to get the 

 last column of the above table is the dimension correction. 



Presentation of Model Results. Test results received from 

 a laboratory are usually in the form of tables giving k l , k^ and 

 L/D for a range of values of angle of incidence. These can be 

 converted readily with the aid of plotting so as to give the values 



