I had posted this on Nostalgia
On the B377, the Ham Standard props originally fitted had square-tipped hollow steel blades. Gave tremendous problems finally leading to a Airworthiness Directive requiring for frequent magnetic inspections of blades. They changed over to solid dural blades and these had the rounded tips. United Airlines, uniquely I believe, had Curtiss Electric props fitted. On the sale of the UAL B377 fleet to BOAC the aircraft were converted to Ham Standards requiring, in addition to major wiring changes, removal of the engine nose cases for rework and installation of oil passages.
United also, I think alone of the B377 operators, did not have a proper flight engineer's station but seated the FE just behind the throttle pedestals facing forward. All the engine instruments, etc that were normally on the FE panel were up front. BOAC required installation of an FE station plus conversion to HS props and this required almost complete gutting of electrical looms in wings and fuselage and their replacement. The B377 was almost all electric in operation so this was a major project.
These aircraft also went to higher density seating and this mandated installation of an additional overwing exit on each side. UAL aircraft had the square windows.
All this work was done at Lockheed Air Service International (LASI) at Idlewild International Airport (KIDL) in New York. Was said to be one of the biggest conversion projects done at that time. DeHavilland props were license built modified Ham Standards. The Bristol Britannia had these fitted. Like the Stratocruiser, they went from the steel to the solid dural blades and that is when the tips went from square to rounded.
Prop configurations were quite variable and dependent on customers preference. Many L-749 Constellations, expecially those of non-US companies utilized Curtiss Electrics which had quite a broad butter-paddle shape for their steel blades. USAF C-121A (L749 types) Connies had them too. Later military Connies (L-1049 types), USAF and US Navy all had Ham Standards. Seaboard and Western Airlines had Curtiss Electrics (square tips) on their L-1049 D and H models. Their single L-1049E-01 passenger aircraft had Ham Standards.
Northwest Orient sold their four L-1049G Connies to LAV of Venezuala. These had Ham Standard props but they were squarish-tipped dural blades (rouned corners) and, unlike any other Connies I ever worked, had electric prop deicing boots on the blades. These required alternators to be fitted on the inboard engines for power. All other Connies I saw had alcohol slinger rings and rubber distribution boots on the blades.
Only DC-6 I worked with Curtiss Electrics was a VC-118 that LASI converted from HS to the Curtiss for USAF for a cold-weather mission. I know there were other civil DC-6 with Curtiss props but I never saw any by 1954 when I started work.
Most Electras had Aeroproduct props with square tipped steel blades. American Flyers and KLM had Hamilton Standards. Customer's choice again.