LockheedL-188

 The Aeroproducts military propeller also was adapted to commercial service, with many additional safety features and improved maintenance, such as providing a single point spinner attachment, readily removable governor and improved oil filling procedures. This propeller had a hydraulic blade angle changing mechanism that used a rifle-bore helical splined sleeve and piston arrangement, all of the propeller oil being self-contained and completely separate from the engine. Operating power for blade angle changes was generated by propeller rotation and employed higher hydraulic pressures than most other propellersw. The hole in the spinner provided cooling air that was directed through an annular space in the propeller hub. The only electrical signals used for control purposes were for rpm synchronizing, phase synchronizing and auto-feathering; all other basic control functions such as governing, feathering, reverse pitch, negative torque signal (NTS), and taxi operation were mechanically operated from the flight station or the engine

The spinner and blade cuffs were electrically de-iced, a feature important for avoiding ice buildup that would seriously affect engine inlet air flows. The Napier Spraymat system was used and was the first application of its kind on American aircraft. No de-icing was provided on the propeller blades themselves apart from the cuffs. The blades were forged  hollow steel construction with a brazed-on camber sheet.

The 13.5-foot propeller diameter was small by reciprocating-engine propeller standards although the thrust was very high, approximately 8,000 lb for takeoff. Surprisingly enough the 18.5" wide blades had a high cruise efficiency of approximately 90%, due mainly to the blade thinness, coupled with good blade twist distribution. The cuff design and the cuff-to-spinner intersection also contributed to the high efficiency. The propeller weight complete with all control components was 1,017 lb and was thus roughly equivalent to those then used on high-powered reciprocating engines. On the other hand, the saving represented by the engine dry weight of only 1,714 lb meant a 2,731 lb total power plant weight; when compared to the Model 1049G Constellation, the total weight saving per airplane was about 6,400 lb.

An alternative propeller, the Hamilton-Standard type 54H60-47 with solid dural blades , was available, and had a CAA-certified performance that was substantially similar to the Aeroproducts propeller. Cooling air entered through circumferential slots just aft of the blade cuffs and an externally applied electrical boot was used for ice protection. The hydraulic blade angle changing mechanism was similar to previous Hamilton-Standard designs.