by Tony Vasko
The Curtiss Electric Props were relatively rare in American commercial service although fairly common on some models of the Constellation used by foreign airlines. Oddly, for I believe they were the only ones so fitted, United used them on their Boeing B.377 Stratocruisers. BOAC procured them from United in the mid-50's and among their immediate modifications was removal of the Curtiss Electric props and substitution of the more familiar oil operated Hamilton Standards. However, the Stratocruiser's props seemed to be snakebit no matter what type and I will drop that issue.
Seaboard and Western Airlines had selected the Curtiss props for their Super Constellations for reasons I never learned. The Curtiss props were more fun to operate than the Hamilton props as you had very direct control of blade pitch. A prop control switch located on the flight engineers panel was fitted for each engine. The switch could be toggled to: INCREASE (increase pitch), DECREASE (decrease pitch), OFF (essentially fixed pitch), and AUTOMATIC (where it responded to the master motors commands). There was a guarded FEATHER switch, which activated one of two voltage boosters under the cockpit. This motor-generator raised the propeller operating power to 65 Volts instead of the normal 28 Volts. This higher voltage speeded the prop's motion toward feather or reverse as selected. There was a device carried in the engineer's desk that looked like a set of brass knuckles. Four hollow pegs protruded that slipped over the four prop control switches. It gave the flight engineer the ability to move all four switches at once.
To complete the system there was a master motor with four prop contactors fitted. The master motor was electrically driven and its RPM was controlled by a master prop control lever. A tach indicator on the FE panel indicated the RPM of the master motor. The FE set the master motor RPM to its desired point, threw all four prop switches to AUTO and listened to a lot of clicking and clacking of contactors. Each contactor was synchronously driven by a prop alternator on its respective engine. If contactor and master motor RPM did not coincide, the contactors were displaced to activate the prop motor and the pitch (and thereby the RPM) was adjusted. It was a mechanical system operating electrical contacts. It was noisy but it worked.
One minor item might be noted. The prop control switches on BOTH the Curtiss and Hamilton Standard props had an INCREASE and a DECREASE position. Curtiss however referred to the pitch, Hamilton to the RPM. In other words, the two systems had markings that said the same thing but were directly opposite in effect.
We ran a Seaboard Connie one midnight shift after a maintenance check. I rode the brakes in the Captain's seat. Down below on the ramp, acting as fire guard was Lex Kutter. He had injured his knee and so could only hobble. He leaned on the big CO2 extinguisher and watched the engines crank. The fuel injected R-3350's were less likely to catch fire than the carbureted types so he stood at ease. The run commenced.
Riding brakes on a Connie during runup is dull and boring. All the controls and most of the engine indicators are located on the FE panel. The airplane rocks and the sound of the engines is soporific. The run ground on for several hours as we had to pressurize, a slow and tedious process on the Connie. Finally the high moments were reached with the mag and prop checks. My numbed brain (midnight shift) only registered the highlights. The Seaboard Airlines maintenance rep was in the cramped cockpit behind the Lead mechanic who was at the FE panel. The rep was reading the steps to follow from the runup form and we launched into exercising the Curtiss props. We ran at high power and the knuckle buster was used to toggle all four props to INCREASE. The airplane bucked as the prop pitch increased and the engines loaded up under the increased strain. Now DECREASE and things lightened up. Down below I could dimly see Lex Kutter still leaning on the fire extinguisher nursing his sore knee.
Now came the command, "feather four". This is somewhat ambiguous as the "four" may be defined in two ways: "four" referring to the engine position OR "four" referring to the number of engines installed. It is not truly ambiguous however as the intent was to feather check the four engines BUT, one at a time. This was midnight shift however and the lead mechanic, brain in slow gear, reached out and raised the guards on all four feather switches and indeed "feathered four!"*
The voltage boosters did their work. The 65 volts drove the props toward feather. I dully realized the airplane was lurching and bouncing in a most peculiar way. I looked out the window and saw the entire ramp was brilliantly lit. I vaguely wondered what could be lighting up the ramp? It was easy! It was us!
Under the load of the feathered props the four engines slowed to 200 RPM and lumped over, protesting under the abuse and spouting raw fuel out the exhaust hoods and every exhaust joint. It burned very brightly. In the light I could see Lex Kutter with the fire extinguisher. His mouth was agape and he futilely moved the wheeled bottle back and forth trying to decide which fire to attack. The Seaboard rep was screaming at the Lead who now was thoroughly flustered. In desperation he threw the four prop switches to AUTOMATIC but the master motor wasn't running so the props stayed in feather.
The engine fire bell began to ring and soon all four engine Zone 1 fire lights were brightly lit. The noise further addled the lead mechanic's wits. He grabbed the knuckle-buster and toggled all four prop switches to INCREASE. The rep began to pound on the lead mechanic's back driving him down on top of the prop controls. It was getting serious as the engines continued to lump over spouting fuel and flame. The FAA control tower saw the fire and dispatched the crash trucks. The fourth person in the cockpit was Old Jim Lerwick. He was an Inspector who accompanied us on the run to verify its proper completion. He had been dozing on the 260 step and now came to life (The Constellation cockpit's floor is lower than the cabin floor. The cockpit door is at aircraft station 260 and the step-down was known as the 260 step)
He pushed the frenzied rep off the lead mechanic, pulled the lead off the controls and calmly toggled the four props to DECREASE while he added power. The engines responded as the prop pitch decreased, the RPM went up and the fires were blown out. Just then the crash trucks arrived having broken through the taxi gates to get onto the Lockheed property.
We were the perfect picture of a Connie on runup as they pulled up. The four engines were at power and the PRT exhausts spouted long blue flames just like normal. The trucks stood poised but puzzled and then left after Lex assured them there was no problem. Their Lieutenant stayed till the run was complete.
"No problem!" the lead mechanic explained. "The tower must have panicked over a little torching".
We thoroughly inspected the engines and aircraft. No damage. No problem. Feather "four" indeed!
*The correct procedure during a "feather" check was to feather one engine at a time. You toggled the guarded feather switch and watched to see that the RPM decreased rapidly indicating the prop was indeed feathering. You then returned the feather switch to normal long before it actually reached feather and toggled the control switch to "decrease" pitch and went back to normal operation. You didn't actually allow the engine to reach full feather. You could, and I have seen the engine run in feather, throttle open quite a bit and mixture leaned back to prevent flooding. If you didn't add power the engine could stall and if you didn't lean there was excess fuel with the results given above.
Hal Davey replies:
"I love that story; I had a similar experience in 1966. I was at that time a 707 simulator operator at LAX for American Airlines. I was working the late shift and bored to tears. The check captain, Stan Clark, a crusty old ex-B-26 Marauder veteran, was in the right seat giving a captain training before a check ride the next day. We had a lousy intercom system in the old simulator. The captain was struggling but doing OK. We were executing an ILS to 100 feet. On the missed approach at 100 feet, Stan calls back and says "Kill two" Half asleep, I killed numbers one AND two! The poor captain jams the rudder to the stop and is sweating bullets, but manages somehow to make it to clean up OK. Stan just turns around and looks at me with a smirk and waves his stoggie at me. The captain passed."
What Are These Funny Red Buttons For?
by Tony Vasko
Seaboard and Western, later Seaboard World Airlines, operated four L-1049D Constellation aircraft. These Connies were the only "D" models made and were also were nearly unique among American operated L-1049 in that they had Curtiss Electric propellers rather than the almost universal Hamilton Standard Hydromatic propellers (although their later "H" models also had Curtiss). The Curtiss electric props had good and bad points. Good in that you could change pitch without running the engine or using the Hamilton's required feathering pump. They were certainly cleaner to maintain as they did not use the engine oil to activate the pitch change mechanism and never, but never required desludging of the dome. Grease for the bull and bevel gears, brush blocks for transferring the electric power from a fixed engine nose case to a rotating propeller and checking and replacing the prop brakes were the main worry but the hollow steel blades and the composition blade cuffs made them expensive to overhaul.
British Overseas Airways Corporation (BOAC) contracted with Seaboard to operate the New York to Bermuda passenger flights for them. BOAC was short of equipment as the Comets and Britannias were in trouble. The Bermuda run, being short and well travelled used an all-coach airplane. Seaboard, with nice new Super Constellations was contacted. The L-1049D's, while primarily cargo planes, were indeed passenger capable as seats could be installed in floor mounted tracks. Two lavatories in the rear were marginal for long flights but not for the Bermuda run. One minor problem was that the curtains that stretched down the sides covered mostly bare wall for there were only had four windows on each side.
The passengers were vocal for they did not like staring at a blank wall. They tore the curtains down as if they could find windows under them. BOAC was upset. No one had lied or misrepresented anything. They simply hadn't asked. Nevertheless the word came out. No windows, no contract. Seaboard was faced with a dilemma. They searched for a Super Connie but they were in demand. They finally found that CUBANA had an L-1049E-01 available. A slightly higher gross weight version of the E model it was perfect except for having a standard first class and tourist configuration instead of the desired all-coach set-up.
Not to worry. The maintenance company I worked for, Lockheed Aircraft Service International at Idlewild Airport in New York (Now JFK Airport) would do an interior conversion to all coach and do it in stages with no interruption to the schedule. The airplane was duly delivered and registered as N505C. After a maintenance check it was ready for its initial flight as a Seaboard aircraft.. The crew conducted an extended preflight which seemed to entail a lot of discussion about the props but finally boarded. The Connie had a crew door on the right forward fuselage just aft of the Flight Engineer's (FE) panel. When starting engines, the mechanic would position himself down below it and signal up to the FE. I stood there waiting to give the engine start signals but instead got a call from above.
"Could you come up here please?" said the FE.
I retrieved the crew ladder and mounted. The FE looked very confused. Nowadays, the FAA would require an airline conduct extensive "difference" training when an "E" model of anything was integrated into a fleet of "D" models. In the 50's nothing much was apparently required.
"What are these red things?" asked the FE pointing at the feathering buttons. "Why don't the props work when I move the control switches, I can't hear the master motor and I don't see a master prop tachometer?"
I rose to the occasion. "This aircraft has Ham Standards, not Curtiss Electric props. Those are the feather buttons. Push to feather and the light comes on inside to tell you the button is pushed. The feather pump runs and feathers the prop and when the pressure builds up enough the button pops out to tell you it is fully feathered. To unfeather, pull the button until you get RPM on the engine. There is no voltage booster for feathering or reverse, the feather pump does the job instead".
"The last airplane I flew with feather buttons was the DC-4 but it didn't have prop control switches", yawned the Captain.
"No", I responded. "The DC-4 used cables to control the prop governors and had manual synchronizing. This one is electrically controlled and will synchronize automatically".
The FE nodded. The Captain looked bored. I continued, "The prop control switches on this airplane signal the synchronizer box which doesn't make grinding and clicking noises like a master motor. To set RPM you have to be in governing range. The props will all follow the prop control lever if each switch is in the middle position. There is no "off" or fixed pitch position like the electric props. You can control individual props with their switch".
"That should do it", said the Captain. "Lets get this thing on the gate. I don't want to blow the first departure".
I left the cockpit and descended the ladder. Pulling it I made twirling motions to the FE. The big R-3350-DA-3s belched smoke and we waved them out to taxi the terminal.
NOTE: N505C, after its flying career, ended being placed on top of a diner in Pennsylvania
by Tony Vasko
I have on theory on why Curtiss props were unpopular. I think it was mainly because you had to "operate" them. Ham Standard control was much simpler and unless you reversed it or feathered it you were between the governors high and low RPM settings and couldn't escape. Basically, a Ham was always in AUTO. You couldn't overspeed it as the governor prevented that.
Ahh, but with the Curtiss you could! Once out of AUTO, you had an adjustable prop that stayed where it was put. On the old systems with the governors on the engine, if you went to AUTO you went to where the governor was set. On aircraft like the Connies and DC-6 with synchronizing, the Master Motor had to be running. If it wasn't, you went to AUTO and it stayed where it was. No signals to change RPM.
In short, the Curtiss gave you too much control. A pal of mine here at Piedmont Triad International airport, Ronnie Macklin was the Director of Quality for Piedmont Airlines. He was, very briefly, Jimmy Dolittle’s crew chief in North Africa on B-25s. But more to this point, he was in Martin B-26s before that when they were very new. He recounted the run-down battery theory to me years ago before I saw it anywhere else. He swears that the main trouble was an undernourished generator system and people starting and checking the aircraft out on battery power and running it down. On takeoff, props in AUTO and full DECREASE (pitch), the aircraft would accelerate and the prop revs would start to increase due to airspeed picking up. The governor would signal overspeed, contacts closed and the electric power went two places, to the brake release and to the motor to increase the pitch. With a weak battery, the brake would release but the motor wasn't getting juice enough to overcome centrifugal twisting moment. The prop would go flatter and RPMs would wind off the clock. "One a day in Tampa Bay". Actually, I don't think Ronnie was in Tampa, it was before that but the result was still the same. That was weakness that the Ham Standard never had.
I seem to recall that late in the use of Ham Standard props on Connies they added a pitch lock in the distributor valve. That would lock the prop at some increment of overspeed which would occur only if the dome seal blew or the nose case had a reduction gear failure. No oil pressure and maybe the oil passages were kaput so no feather either. There were flyweights inside that extend out and locked things up. You were stuck with the pitch the prop was at but that was far better than it going flat, which it otherwise would.
Berge Jermakian replies:
I read Tony Vasko's mussing on the Curtiss Electric Prop. It brought back memories of my time working line maintenance at KLM (Idlewild International).
KLM had Curtiss props on all their Connies from the O49 thought the 1049G. KLM liked the Curtiss for the additional control, plus the props required less maintenance and were cleaner to work on. The Hamilton Standards needed to be regularly de-sludgged by removing and dismantling the dome, then scraping out the built-up hard sludge in the dome. With the Curtiss props, occasional line problems were usually fixed by adjustment of the motor brake.
Removing the dome from the engine while on the airplane sometimes got a bit exciting. That was when the small expansion plug (looked much like a miniature of the critter you find on engine water jackets) that kept the hundred or so tiny ball bearings the dome nut rode on. If you were unaware of this plug, or were weren't paying attention, or it was loose and fell out while you were unscrewing the nut, then quick as a flash all the bearings poured out like water and bounced all over the floor. You couldn't see the plug till you had backed out the nut a ways. By then your attention was on supporting the loosened dome. Fortunately our floor was kept clean as the several mechanics working on the prop, plus anyone else in the vicinity were on all fours hunting up the errant ball bearings. We did manage to find them all.
Another Missing Bearing Story
On the Berlin Airlift Boeing C-97G I'm helping restore, I noticed the crew was having a problem getting the propeller lifting fixture on the prop that had to be removed. I also noticed a trail of small ball bearings on the ground leading to the engine from which they were to remove the propeller. Having seen this story before, I went over to see what was going on. The retaining nut, which is the same as on a prop dome, was cocked and would not engage the threads. I had the men remove the tool and upon checking, it was found to be missing most of its ball bearings due to a lost plug. We found enough dropped bearings to place in the ring and made a plug with tape so remain correctly orientated. After the prop was removed I set about to repair the lifting fixture. The bearings (144) were easy to find, but the plug was another issue. The plug is small, about 3/8 " diameter and I couldn't find any vendors that sold Welsh plus that small. In my search I learned how the plug got its name. There was an early 1900s car manufacturer called Welsh Bros. Motor Co. In early engines, the holes left in casting water jackets of engine blocks were closed with a threaded plug. The Welsh Brothers devised a concave plug that we are all familiar with today that could be installed in the place of the threaded plug. This reduced the cost of making blocks. The company, H D Hubbard Spring Co. who made the plugs for the brothers makes plugs of all sizes and materials to this day and still calls them Welsh Plugs. Thank you to Hubbard sales, who were kind enough to send me a few as samples so I could fix our prop lifting fixture dome retaining nut.
More Thoughts on Props
by Tony Vasko
I read Berge Jermakian’s recollections regarding the Hamilton Standard props with great amusement. Exactly the same thing happened to me. As he says, the prop dome is attached to the hub by means of a retaining nut which is retained on the dome by means of lots of ball bearings riding in internal grooves machined in the dome and the retaining nut. They were fed in there through a hole on the nut which was sealed, as Berge says, with an expansion plug, I think they were called Welch plugs. Boy would those ball bearings pour out if the plug came loose. Then there was Hell to pay.
Not so bad if it was a prop change as overhaul could take care of it but usually it wasn’t. If it was only being pulled for a dome desludge or an engine change with the old prop being reused, you had to find all of the little bitty balls that came out. Usually too, there were always a few that remained jammed in the nut by the weight of the dome which was quite heavy. They had to come out too so you could count them. You could find the required number of balls in the Illustrated Parts Catalog (IPC) so it was a matter of finding all the spilled ones and getting the rest out of the dome nut and then counting them up. I know we couldn’t and ended up robbing an unserviceable removed prop dome to make up the shortfall. Finding ball bearings out on an asphalt ramp at night was not easy.
Desludging domes was a nasty task. Aside from having to remove the prop dome thereby releasing several quarts of thick, blackened oil you had to carry it down the stand and then hump it into the cleaning shop. You took the dome shell off the stationary cam and revealed a thick, oil covered mass of sludge. The prop, of course, spins and nicely centrifuges the sludge from the oil. Some engines were notorious sludge makers, like the BA version of the R-3350 used on the Lockheed 049 Connies, but they all made plenty of it. The sludge was like thickened modeling clay but was composed of decomposed oil, combustion products and lead ends from the fuel. It had to be chiseled out by the handful and all the surfaces scraped clean and then the whole assembly washed with mineral spirits (Varsol). It was a filthy job and you could tell how you stood with the Lead Mechanic if you got assigned to it a lot.
Berge is right about the Curtiss Electrics being cleaner. Their hub was filled with grease but since it never mixed with the engine oil it was relatively clean. It was a regular thing to measure the brake pad on the end of the motor. I replaced a lot of them as it was a critical element. The brushes transferred the electric power from the stationary nose case to the slip rings on the prop. They were mounted in a brush block that was easily, but very carefully removed. Brushes were very brittle, wore down, sometimes stuck and the carbon bits that wore off had to be washed away regularly. It was not nearly as bad as desludging a dome though.
The steel blades usually found on Curtiss props stood up pretty well from a line maintenance standpoint. They didn’t nick as easily as aluminum blades but also were not as tolerant of damage. Aluminum props were more easily damaged but you could dress damage out with files and emery paper as the limits were quite large. The Ham Standard steel blades originally used on the Boeing 377 Stratocruisers were a disaster and were replaced by aluminum blades.
The Aeroproducts props used on the Lockheed Electras had steel blades. When I came to Eastern as a mechanic in 1964 I worked phase checks on them at JFK. I was put on the job of cutting inspection windows in the blade cuffs. Using a template to accurately locate the position and shape, I marked the location on the backside of the cuff. I then cut through the outer covering into the foam filling. I then carefully chiseled a tapered square hole down to the blade shank. It had to be cleaned of paint and primer. This allowed inspection for a crack in the shank. I had to coat the foam and seal it to keep the elements out.
I always wondered why Curtiss and Aeroproducts went away. Curtiss apparently was just a prime example of beancounters triumphing over engineering. They certainly had a good product that seemed to be made to order for the turboprop engine. Aeroproducts had the advantage of being associated with the company that made the engine they were fitted to. Yet both faded away. It seemed though that Hamilton Standard was in it for the long haul and still goes on.
One final word, the Hamilton Standard governors fitted on the piston engines were actually Woodward governors. You could see their nameplate on the units. Woodward is an old line company, still very much in business but one that started life building governing devices for waterwheels back when only birds, bats and a few fish were flying.