View Full Version : VC-118 (DC-6 variant) with Curtiss Electric Propellors

4th Feb 2012, 03:07
Back in latter part of 1950's, when I was at Lockheed Air Service at then KIDL in New Yor, we converted a C-118 (may have been a VC-118) from Hamilton Standard props to Curtiss Electric props. Memory is dim but I seem to recall reason was aircraft was to fly to Soviet Russia and it was believed Curtiss Electric props were to be preferred in cold weather. Why that should be so I do not know as Ham Standard props were in use worldwide. LASI as it was called, had the contract for maintaining the SAMFLEET VIP aircraft and the Green Valley Presidential aircraft in those days.
I know there were some original DC-6 with Curtiss props but believe they were removed after an in-flight reversal incident, I think at KEWR.
I worked and saw a lot of DC-6 models over the years but never another with Curtiss props. Saw and worked many L749 and L1049 Constellations with Curtiss Electrics but not any DC6 or DC-7.
As a point of interest, LASI converted the ex-United Airline B377 Stratocruisers from Curtiss props to Hamilton Standards prior to their use at BOAC. We also refitted the cockpit with the standard Flight Engineer's station. That was done to make them uniform with the rest of BOAC's fleet.
Does anyone remember anything about this aircraft? Was it ever converted back to Ham Standards? Does anyone remember any other DC-6 models with Curtiss props? Why, in spite of their popularity on Connies, particularly foreign ones, they were not used on DC-6?

4th Feb 2012, 08:04
Can someone give a little summary of what were the advantages/disadvantages of each type. I've seen a number of articles which implied the Curtiss Electrics were unreliable.

Spooky 2
4th Feb 2012, 14:31
Doing the FE station/panel conversion must have been quite a task. Were you directly involved in that project and if so, can you shed a little light on it?

4th Feb 2012, 14:36
I wonder if this was anything to do with the Stratocruiser's problems with hollow-bladed propellors? Can't remember if it was the Hamilton Standard ones or the Curtiss Electric that were so and caused the problems.

4th Feb 2012, 15:36
Putting "VC-118 Curtiss" into Google will bring back a range of comments about the whole DC6 range's experience with Curtiss props. There seem to have been quite a few of them built, including multiple mentions that while the military versions for the USAF went for Hamilton Standard hydraulics, the Navy went for Curtiss electrics.

7th Feb 2012, 00:21
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.

7th Feb 2012, 05:45
Thanks for that Tonytales-very interesting.

7th Feb 2012, 18:08
Spooky 2
Doing the FE station/panel conversion must have been quite a task. Were you directly involved in that project and if so, can you shed a little light on it?
The “BOAC Project” as it was known at LASI in the mid 1950’s was one of the biggest mod programs of its day. All the work was done in Hangar 7 (still there but now a cargo facility) at the then Idlewild. The vertical fins had to be folded to get the aircraft in. It involved six (I think) ex-UAL and then a number of BOAC aircraft as well for lesser mods. The UAL B.377 Stratocruisers had a strange cockpit layout presumably to make their Flight Engineers feel they were in a DC-6. Instead of the FE having his own panel and sitting sideways as on other B377, the FE was seated just behind the throttle pedestal facing forward. All the instrumentation normally on the FE panel was in front of the pilots necessitating some very small diameter units to fit them all in. How the FE could read them at night in turbulence was a wonder. I would love to hear from some ex-UAL FE that flew them.
This necessitated stripping the entire cockpit and so I saw electricians using bolt cutters on wire bundles to remove them. The B.377 was an electric airplane, only rudder oost, brakes and nose steering (I think I have it right) were hydraulically operated. All that Curtiss prop wiring had to be removed so the wings were stripped too. Essentially, all the wiring was removed and new wire looms fitted throughout.
For access, the turbo-superchargers and their ducting had to be removed. The nose cases of all the engines were removed and sent to Pratt and Whitney for installation of prop control oil passages as these were not installed or were blanked off on the UAL engines.
If this was not enough, BOAC wanted additional seating. This required the addition of another overwing exit on each side. This was no small task ond on one aircraft the cutting of the hole was done without the radius at each corner. BOAC, with its memory of the Comet wanted no sharp corners or repairs and LASI had to replace the skin panel which Boeing was able to supply. In a project that size, there were inevitable cockups. On Day shift one crew started stringing prop and engine wire looms fro the E and E going aft and then outboard. On the afternoon shift another crew started laying engine wire looms from the engines inward. They met at the wing root and were disconcerted to find a similiarly number wire loom coming in while they were going out. One had to be removed of course.
Replacing the instrument panels and installing an FE panel also required replumbing the piot static system as well. I believe our now familiar seat tracks were installed in the cabin as well to allow flexible seating arrangements. A new interior was installed.
I wonder how the aircraft were received at BOAC considering the mods were outsourced? Were they more troublesome than their own original aircraft?

7th Feb 2012, 18:18
Incredibly interesting TT!

Your powers of recall are amazing....keep going!!!


Spooky 2
7th Feb 2012, 23:08
Unbelieveable... Thanks for the history lesson!

8th Feb 2012, 18:27
In my years jumpseating Navy C118's (R6D),14 to be exact,I heard of an experimental type C118 with Curtiss Elec props but that's it,never found out the outcome.It's good to see things written by guys like you about the 6-er and we need more along with the C54 and C117D.:)

13th Feb 2012, 02:34
Going through my files, I found a picture of an American Overseas B.377 Stratocruiser. Lo and behold, it too had Curtiss Electric props. So both UAL and American Overseas had the Curtiss on ther B.377. Pan American bought them out (to the later regret of American) and must have converted them to their standard of Ham Standards.

13th Feb 2012, 18:20
Wonderful stories, as usual, Tony. Thanks for posting. :ok:

17th Feb 2012, 23:09
I found this on the web, about the Stratocruiser rather than the DC6, but comparing Ham Stan hydraulics to Curtiss Electrics on that aircraft, so may be interesting to some. Note that aircraft with Curtiss were allowed a lesser MTOW than Ham Stan fitted aircraft.

CalClassic Forum - Boeing 367 & 377 Contextual History (http://calclassic.proboards.com/index.cgi?board=fsaviator&action=display&thread=3155)

a few of the other comments are opposed to what I have read elsewhere.

18th Feb 2012, 23:06
Thanks WHBM for that Link -
Very interesting read and one of the best overviews of the whole B-50/B376/B377 family I have seen. Very informative.
Explains why the Ham Standards were preferred to the Curtiss props. The increased MTOW went right to payload if not to safety. Author calls it right, no one ever made a profit flying Stratocruisers. Notably however, in examining pictures, I notice that most of the B-50 had the Curtiss props though at least one had the square tips of a Ham Standrd.

Monograph contains what I believe are a few errors. The B-50 was not operated by the RAF to my knowledge and it was not named the Washington. However the B-29s operated by the RAF were called Washingtons. In US service the B-29 and B-50 were both the Superfortress. I also found the repetitious use of the phrase :New World Order" annoying.

19th Feb 2012, 19:35
There is a pdf publication called Washington Times which has much material on the B-29 (and not just in the RAF)...e.g.#8 has an account of the only B-29 in Europe in WWII, the 'Hobo Queen' The history of the Washington (http://www.rafwatton.info/History/TheWashington/tabid/90/Default.aspx)