Well, thanks for the responses and inquiries.
What were advantages and disadvantages of the two major American prop suppliers? Curtiss was early with reverse. The Consolidated B-32 Dominator had reversing Curtiss Electrics. I knew a mechanic at Lockheed who worked them in WW II. They used to show them off by backing the aircraft.Once, he said, the pilot was backing into parking space and built up some speed. He hit the brakes, a big No-No when backing. The B-32 main gears were stressed to take aft drag loads caused by braking/landing impact but not forward loading and they collapsed causing heavy damage.
Little noted is that Col. Tibbets had his A-Bomb toting B-29’s fitted with Curtiss Electrics off the B-32. You can see them on the Enola Gay at the museum. In the event of an aborted takeoff he wanted every adbvantage for stopping and he had the priority to get them fitted.
Curtiss props were very popular with non-American carriers. KLM and BOAC L-749, Qantas, Trans Canada and others had them on their Connies. Seaboard and Western used them on their L1049D and H models. They lost one on takeoff at JFK when an internal bull gear sheared allowing the blades to go to negative pitch.
Curtiss props required some maintenance, keeping the hub cavity grease and checking prop brake wear and replacing it if necessary. The brush blocks bringing power from the fixed nose section of the engine to the commutators on the rotating prop needed frequent cleaning to remove carbon dust buildups which could bring on a cross-short. They transmitted a lot of amps to operated the pitch change motor. On feather or reverse a voltage booster came pumped in 65 volts DC. The carbon brushes had to be checked for wear and the commutators cleaned of any pitting.
The Ham Standards also had electrical brushes but were low amperage as they connected to blade switches. The Ham Standards built up sludge in the dome as they acted like a centrifuge. On some engines like the BA model of the 3350 it was a lot and domes had to be taken off, the dome shell removed and sludge scraped out and the workings parts cleaned up. It was very messy and the prop domes for four bladed props was particularly heavy. There were some problems with the Hydramatics evidenced by the mods installing feather locks, spring loaded fingers that locked the blade pitch in feather. Also a pitch lock was introduced to handle runaway operations.
Curtiss used hollow steel which caused line maintenance little trouble. I understand overhaul however was expensive. The solid dural blades on the Hydromatics were more easily dinged by rocks but you could file away quite a bit to remove stress risers. The Ham Standard hollow steel blades as used on Stratocruisers were another matter and eventually were replaced by solid dural blades. Ham Standard actually made hollow dural blades for the L-1649 which I saw split along the seam at the leading edge and the foam stuffing hanging out. They were replaced by solid dural blades.
When I wrote a column for Airways Magazine about Curtiss props I received quite a few messages from flight engineers who had operated them and liked them. But the same was true for the Ham Standards. Curtiss was earlier than Ham Standard in producing “butter paddle” blades.
IMHO Curtiss lost out due to stodgy management. Had they developed a successful turboprop engine they might be around today. They were advertising Turbo-Electric props and I thing the early C-130 had them fitted.
I noticed that there were some references to the R6D model of the DC-6A which claimed they had Curtiss Electrics. LASI got an IRAN (Insect, Repair as Necessary) contract for the Navy R6D. All the ones I saw had Ham Standards. We were also doing a throttle pedestal mod in the cockpit adding additional interlocks to prevent inadvertent reversal. I was a Lead Mechanic for a while on that line. I looked through on-line pictures of R6D’s and they all seemed to have Ham Standards.
I would love to see the picture of a four bladed prop on a DC-6.