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Dave, As a point of reference I have a 1” breather tube connected between the stock oil filler neck location “T pipe” and an aircraft blow-by can. The blow-by can has a 1” exit that is routed to the cowl exit and a small ¼” tube that should return to the oil pan for self-draining. I have the small tube plumbed to small glass jar to see how much oil gets past the vent system. I do see some oil in the collection jar. Not sure if all the oil venting happens under boost or also in cruise. I’m not sure a 1” vent is adequate for a boosted rotary. My PSRU oil drains to the bases of the #2 rotor housing well above the oil pan. Two -6 hoses. Bobby Hughes Super Charged Renesis 265 hrs. From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
Sent: Thursday, January 14, 2016 2:04 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Oil Scavenge Pump vs Custom Oil Pan Steve, Thanks for the great input. Maybe the things you mention could work for me. I had been thinking about crankcase pressure because all I use is the rather small stock outlet on the fill tube and I run that through a long length of -4 aluminum tube to "keep the engine compartment dry" (my original plan). Step 1 should be to get rid of that length of AN-4 tube and drain the RD-1B back to the housing leg like you do. I love your turbo installation! I sure wish I had the room to to mine like that. Very professional!!!! On Thu, Jan 14, 2016 at 11:21 AM, Steven W. Boese <flyrotary@lancaironline.net> wrote: Dave, I have attached a photo of the drain from the turbo on my Renesis test stand. The orange fire sleeve covers a section of 1986 13B stock oil cooler hose that connects the turbo drain flange to an oil level sensor port (also 1986 13B) which is installed below the oil level in a custom oil pan that I built. There is a steel tube brazed to the bottom of the turbo oil drain as close as possible to the drain flange. There is a hose connected to this steel tube which is leads to a crankcase vent port near the oil filler location. This makes the fire sleeved hose essentially an extension of the oil pan where the turbo drains into it above the oil level in the pan. No air lock should occur due to the connection to the crankcase vent. This has worked for me so far. I initially had a scavenge pump to return the turbo drain oil to the crankcase, but I decided to try the vented drain to simplify things. I have had no oil coming from the RD1B input shaft seal in about 500 flight hours on my NA 13B installation. The drain is a -6 aluminum tube with a slight downhill slope from the RD drain to the side of a rotor housing leg. A 5/8" id crankcase vent is installed in the center iron where the stock oil filler standpipe was originally located. I haven't measured the crankcase pressure under WOT throttle conditions. Is there any possibility that crankcase pressure is contributing to the oil leaking by your RD seal? RV6A, 1986 13B NA, RD1A, EC2
I have decided to install an oil scavenge system to return the oil from Tracy's gear box and perhaps from my turbo as well. I am really getting tired of all the oil getting all over everything. It clearly seems to be coming from the area between the RD1B and engine, which means that it is probably coming past the RD1B oil seal. Tracy calls for a nice big line and downhill only run of the oil to a point that is higher than the oil level in the sump. However, there is precious little elevation drop and I have not been able to achieve those requirements with a gravity only system. If I run the oil level very low in the sump the problem is improved, but I think it is time for a better solution. I am considering either a custom oil pan that allows for a deeper drop of the oil, or a scavenge pump. The benefit of the custom oil pan is that it can be an improvement in weight over the stock pan, and requires no moving parts or power and is unlikely to fail. The scavenge pump is nice because it would be an easier installation and will probably be more effective at fixing my solution, though I do worry about adding another possible failure point. 1) Soliciting pinions on the decision between Scavenge pump and custom oil pan. 2) Recommendations on someone who makes custom oil pans and pickups? 3) If I choose a pump, does that solution require a tank or can the drain lines be connected directly to the pump? This would create a suction on the outlets of the RD1B and or the Turbo, does anyone see a problem with that? Drain oil from the RD1B too fast? Bad for turbo bearings? 4) Would I need 2 pumps for redundancy? I am leaning that way, which means I am leaning more toward custom oil pan. 5) Turbo drain back seem adequate, which means I could use the pump to isolate the Gear Box oil, allowing for different oil there. Thoughts on this option?
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