3 : - ' '■ Castagneto and Maioli 



(a) Lift coefficient due to incidence. 



' '^ ' Mean line NASA 65 c^^ = 6.10 (1 - 0.15 /:„/c) a 



Mean lines I ^ ~ Q g c^^ = 5.80(1 + 0.25 ^„/c)a 



As can be seen, the thickness effect on the mean line NASA 65 leads in the 

 opposite direction to that on the mean lines a = l and a = 0.8. 



When the thickness ratio ranges between 3% and 10% of the chord, it can be 

 more easily assumed in both cases that 



C^^ = 6.00 a = 0. 105 a° 



where a and a° , expressed respectively in radians and degrees, represent the 

 angle of attack with reference to the chord. 



(b) Lift coefficient due to ca?nber. Designating the lift produced by cam- 

 ber by the symbol \Cif\^ [as can be deduced from relation (6) for operation in 

 ideal flow], the same coefficient Ic^/I^, for operation in actual flow, can be cal- 

 culated as follows: •-• ■'■'•' 



« r,r , , . ,. [a = 0.8 



\CLf\, =0.75 \CLf\. for mean lines I ^^g^ gg 



I^L/I^ = 0.675 \Ci^f\. for mean line a = l. 



(c) Zero lift angle of attack. It can be assumed with sufficient accuracy 

 that 



I^LfL 



in radians. 



(d) Pressure distribution along the surfaces of the foils. An experimental 

 result obtained with a NASA-16 section foil, a = l, t^/c = 0.06, and 4,/c = 0.011, 

 at shock-free entry, is shown in Fig. 11. The values of the pressure distribution 

 on the surface, as they resulted from experiments, are compared with the theo- 

 retical values which were calculated on the basis of the methodology previously 

 discussed, by employing the velocity increments tabulated in NASA Report 824 

 for several stations along the chord. 



The experimental data were measured in a cavitation tunnel, with a test 

 section of 60cm x 60cm, by means of thirty pressure holes drilled at appropri- 

 ate intervals on the surface of a profile (with a chord of 20cm and a span of 

 60cm), connected with the same number of mercury manometers. In order to 

 avoid difficulties arising from the effect of finite span and correction for sup- 

 port interference, the span of the foil was made equal to the width of the test 

 section. 



1034 



