|Quoting SLCPilot (Reply 17):|
My Uncle has been very impressed with your memories. He is a docent at the Air Force Museum and had this to share after your first post. Thank you very much for sharing with us! Cheers!
The engine was quite reliable. I have about 1000 hours and only shut down 3 engines. One was a precautionary shutdown which could have been run if necessary.
Thanks for the info,
2 years ago I went to the Air Force Museum, and it was fascinating, I did spend some time looking at the KC
-97 on display and it looked like it was ready for flight.
3 engine shutdowns in a 1000 hours of flying, that sounds about right for the R-4360.
When the KC
-97 was the frontline air tanker in the SAC
fleet, they would have to use max power to keep up with the B-47’s when air refueling, so they were only getting around 800 hours or so on their engines, but once the KC
-135’s took over as the frontline SAC
air tanker, then the KC
-97’s could then be operated at reduced power settings and engine times increased.
I do have to admit that our air crews were very cautious and would shut an engine down if possible to keep any damage to a minimum. By shutting the engine down quickly as soon as the FE
discovered a problem, we could sometimes get it back in service by changing a cylinder, where if they kept the engine running and it swallowed a valve or a piston ring lets go, then the damage was done and the engine had to be changed.
If you uncle has 1000 hours in a KC
-97, then he has probably been through times when it was not the amount of fuel left on board, but the engine oil consumption that required watching very closely. The R-4360, like all radial engines was a dry sump engine, the engine oil was held in a 27 gallon tank mounted on the QEC. Mounted in the forward bulkhead of the lower cargo compartment was about a 55 gallon oil tank that the FE
could pump oil to replenish the individual engine oil tanks. I heard that some units even jury rigged a 55 gallon oil drum with a electric pump that could be used to transfer oil from the oil drum into the belly oil tank.
I believe normal oil consumption was about a gallon per hour per engine, but as the engine times increased, so did the oil consumption, so it was not unusual for an airplane with high time engines to use up all the oil in the belly tank to keep the engine oil tanks topped off on a long flight. To service the oil, our base had a 500 gallon oil truck, like the fuel trucks at small airports use to service airplanes with avgas, and it towed the trailer that had the ADI water used for takeoff. The engine oil was straight 50 weight, and they gravity filled the oil truck from 55 gallon drums lifted above the truck with a fork lift, and in the winter the oil was as thick as molasses, so it took a while to top off the oil truck.
Because of the 50 weight oil, engine preheating was needed in the colder temperatures, at home base we had ground engine heaters, but they could also preheat by ducting heat from the avgas fueled wing deice/cabin heaters to the engine nacelles, if I remember correctly there was one heater in the rear of each outboard engine nacelle, a third unit was in the lower section of the vertical fin for tail deicing.
Going back into my memory mode again, the basic engine out of the can weighed 4800 pounds, the QEC weighed 1500 pounds and the prop assembly weighed 1200 pounds, so the entire power package weighed about 7500 pounds. In SAC
service, to keep the airplanes on ready status, the engines were designed to be changed out in less than 2 hours. If the engine required more than 2 hours unscheduled maintenance, they would take the entire power package off and install it on a flat bed trailer where they could bolt the QEC on to a special frame. The trailer was also capable of test running the engine because it had all the necessary electrical and fuel hookups, so after maintenance like a cylinder change, the engine could be run up and checked out and then if everything was okay, transferred to a rolling engine dolly and stored there for when needed.
We would also keep an engine in a special engine cradle on wheels, the cradle held the engine and QEC, but not the prop, once the engine/QEC was mounted in the cradle, it was rotated 90 degrees so the engine sat on its side to reduce the height because the QEC was taller than wider. The cradle then could be hoisted up by a fork lift or winched up the rear ramp of an airplane like a C-130 for air transportation. If one of our airplanes had an engine problem within the US, we had to supply the engine, and if needed we would send the crew to change the engine if the base where the airplane was did not have experience on the KC
I know there was a larger experimental piston engine made, but it never made it past the prototype stage, so the R-4360 will probably remain as the largest production aircraft piston engine. The R-3350 put out basically the same power as the R-4360, using 1000 less cubic inches, 10 less cylinders and weighing much less, but after my Air Force time I worked at an engine teardown/ buildup company that smaller passenger and cargo airlines used and I can still remember today an airline maintenance rep yelling at the Curtis Wright tech rep that their engines are the biggest piece of $hit and their engines are going to bankrupt them.
One interesting thing, the oil screen on the R-4360 was made up of multiple elements, it would be hard to describe but basically it was multiple discs, one disc had grooves on the outside letting oil under pressure to flow to and through a mesh and then to another disc that had the grooves on the inside to let the oil flow out. There was probably 50 or so discs stacked up and held together by a large threaded cap which had a relief valve built into nut in case the oil screen got clogged to let the oil continue to flow. Part of the 200 hour inspection we had to disassemble the filter to check for metal, clean and then reassemble the filter. P&W used the same exact filter, with not as many discs on the P&W JT
-12 engines on the JetStar, I would not be surprised if they were the same part numbers, good enough for the R-4350, good enough for the JetStar.
Thanks for the comments about my postings on the R-4360, it’s my pleasure to share my experiences, and I must admit it brings back a lot of memories, the more I post, the more I remember about the R-4360.