These results, especially in the best case, are very encouraging, indicating an 

 observed test accuracy similar to the expected accuracy of the gages. The only 

 discrepancy in the overall result is the Reynolds number effect, which when corrected 

 for, produces test accuracy similar to the expected accuracy of the instrumentation. 



The runs conducted with Propeller 4718 in inclined flow produced noticeably 

 larger error bands than the uniform flow runs. Some of the increase was due to the 

 inclusion of one or two questionable runs in the inclined flow case. The general 

 policy was to remove bad runs from results if justifying errors where found. If 

 errors were concluded to be random for given gages, then the result was not removed. 

 This type of error can be seen in Figure 13. Another possible error in the inclined 

 flow runs was the use of speed corrections generated from the uniform flow runs. 

 Any difference in the speed dependence between inclined and uniform flow runs would 

 show up as an error in the inclined flow result. It appeared that on some gages with 

 large speed corrections, for example, Gage 25, the C values in inclined flow did not 

 collapse onto the fitted curve as well as in uniform flow. Another possible source 

 of error in inclined flow could have resulted from instrumentation problems asso- 

 ciated with maintaining and measuring carriage speed that occurred at the beginning 

 of the inclined-flow measurements with Propeller 4718. 



The average error bands generated from runs of Propeller 4679 in inclined flow 



and uniform flow are both noticeably larger than the best case. Table 8b indicates 



many gages having numerous bad runs that were not removed from the error analysis, 



implying no obvious gage malfunction. It was generally felt that the gages on 



Propeller 4679 were less reliable due to previous use on two other tests. These 



gages were more prone to zero shifts during a given run, which would cause random 



errors in the pressure measurements. Fortunately, most gages performed properly 



in both uniform and inclined flow so that C versus J measurements were available. 



P 

 Speed correction problems did not occur in the error analysis due to the small 



speed dependence of most of the gages. 



Generally, error bands were reduced on both propellers when the second-order 



curve fit was used. From Figure 17 it is obvious that certain gages displayed a 



nonlinear behavior that was better fitted by the second-order curves. Where no 



improvement occurred using a higher order fit, then the C versus J relationship 



could be assumed linear. 



30 



