7.0 



5.0 



3.0 



O 



ID 7 



in 



0.5 



> 



2 3 



HI 



3 



o 



uj 0.2 



K 



Li. 



Z 



o 



H 



< 0. I 



I- 

 o 



(E 



0.07 



05 



0.03 



002 — 



01 



1 1 I I I I 



i r 



i i i 



NOTES: 



SOLID CURVE IS LINEAR IN RANGE OF 

 0.15 TO 10 KNOTS. 



2. DASHED LINES ARE EXTENSIONS OF 

 LINEAR SEGMENT. 



3. STANDARD DEVIATION IS 0.0031 KNOTS 

 IN RANGE OF 05 TO 15 KNOTS; 0.01 

 KNOTS IN RANGE OF 0.15 TO 0.5 KNOTS; 

 AND 08 IN RANGE OF 0.5 TO 1.0 KNOTS. 



DATA TAKEN JULY 1962, HYTECH TOW 

 TANK 



J I I I I I I 



J I I I I 1 I 



0.02 



0.05 07 0.1 



0.2 0.3 0.5 0.7 1.0 



TOWED SPEED (KNOTS) 



5.0 



Fig. 7- Calibration for rotor unit CS-2. 



started or its speed changed. Steady state 

 calibration results derived from 60 runs are 

 shown in Fig. 7- Standard deviations of rota- 

 tional frequency relative to the estimated best 

 fit smooth curve have been calculated for vari- 

 ous speed ranges and are noted in Fig. 7- 



COMPARATIVE PERFORMANCE OF ROTOR MODELS 



Steady state calibration results for each of 

 the rotor models are shown in Fig. 8. Not shown 

 are data for ST-1 (standard size) which, within 



limits of experimental error, corresponded to 

 the reference curve of CS-2. On this basis it 

 is assumed that the remaining models may be 

 validly compared to CS-2 for performance features 

 associated with rotor geometry. 



The following observations seem pertinent con- 

 cerning the curves in Fig. 8. The half scale 

 model (ST-2) rotates about 60$ faster over the 

 range from 0.1 to 3-5 knots. Visual observance 

 of ST-2 indicated that the threshold speed was 

 much lower than for CS-2 which qualitatively 

 supports an extrapolation of the curve with the 



119 



