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Altitude Wind Tunnel Investigation of Performance of Several Propellers on YP-47M Airplane at High Blade Loadings - IV - Curtiss 732-1C2-0 Four Blade Propeller

An altitude-wind-tunnel investigation has been made to determine
the performance of a Curtise 752-102-0 four-blade propeller on a
YP-47M airplane at high blade loadings and engine powers. Propeller
characteristics were obtained for a range of pewter coefficients from
0.30 to 1.00 at free—stream Mach numbers of O.40 and 0.50. The
results of the force measuremants indicate primarily the trend of
propeller efficiency for changes in power coefficient or advance-
diameter ratio because corrections for the effects of tunnel-wall
constriction have not been applied. Slipstream surveys are presented
to illustrate the blade thrust load distribution for certain operating
conditions.

At a free-stream Mach number of 0.40 the highest efficiencies
were obtained at a power coefficient of 0.50 in the low range of
advance-diameter ratios and at a power coefficient of 0.90 in the
high range of advance-disaster ratios. The envelope of efficiency
curves for power coefficients from 0.30 to 0.90 decreased. about 8 per-
cent between advance-diameter ratios of 2.10 and 4.00.

The thrustloading increased more rapidly on the outboard blade sections
than on the inboard sections as the power coefficient was increased or as
the advanced diameter ratio was decreased. Within the range of power coef-
ficients and advance—diarheter ratios investigated at a free-stream
Mach number of 0.40, there was no evidence of blade stall or compress-
ibility effects. At a free-stream Mach number of 0.50 maximum effi-
ciencies were obtained at power coefficients from 0.50 to 0.70 at
advance-diameter ratios between 2.10 and 2.50. The envelope of effi-
ciency curves for power coefficients from 0.50 to 1.00 decreased by
about 17 percent between advance-diameter ratios of 2.10 and 4.00.

An investigation of the performance of several propellers on the
YP-47M airplane at high blade loadings has been conducted in the
Cleveland altitude wind tunnel at the request of the Air Materiel
Command, Army Air Forces. As part of the program, a study was made
of a Curtiss 752-102-0 four-blade prepeller. The results of the
investigation and a brief discussion of the characteristics of this
propeller are presented.