Raven/Christen Inverted oil / ASA Separator

I am thinking about installing either a “Half Raven System” or ASA Separator to keep oil off the belly. I really dislike getting on a creeper to scrub grime off the belly of an airplane. At a minimum I am going with a separator but looking at a full inverted oil/fuel system.

Raven Half System VS ASA Separator
1. Does anyone with experience with both of these know if the Raven Half System is worth the extra costs in $ and weight over the ASA Separator as it seems they would both accomplish the same thing? Does the Raven Half System out perform the ASA solution?

Raven VS Christen Full System
2. If I opt for the Raven Half System route, I am halfway to having inverted oil. What are the pros/cons of a Full Raven VS a Full Christen inverted oil system for a YIO-360-M1B RV-8? It looks like the Raven breather may be a little smaller in size than the Christen?

Adding flop tube to QB Tank
3. My QB wings get here in a few months and others report that you can fly inverted for a bit on a non flop tube tank before the engine coughs but I prefer not to go that route. It is a significant operation to “upgrade” the standard pickup to relocate the fuel pickup to the inner bay on a finished QB tank and attaching it to the tank baffle? Also how much service for a flop tube down the road? I imagine this is a bit hard to access once the tank is sealed (back) up.

https://vansairforce.net/community/showthread.php?t=150534&referrerid=25044

I guess which system depends on whether or not you intend to do aerobatics, specifically sustained inverted, or zero G flight.

I have a full Raven system on my -8. I fly a lot of aerobatics, and I still get some oil on my belly. Some of that may be unburnt smoke oil. I try and keep my engine oil at about 5 qts to minimize oil loss from the slobber pot. Also, I just installed the saddle mount from ASA. I have the slobber pot drain hooked directly into the exhaust now. I think that’s about the best I can hope for as far as minimizing oil on my belly.

https://antisplataero.com/products/saddle-mount-clamps

Might be difficult to do on a completed RV but could you run the breather tube the length of the fuselage and exit in the rear like done on Pitts? Wouldn’t save any oil. Would keep it off the belly.

I have an RV-10 time machine that handles the the mail runs so this RV-8 is being built strictly as a fun machine.

I intend to fly acro and would like to do some inverted flight but not sure if inverted flight is just a novelty that quickly wears off while the monetary cost, weight penalty of the equipment, and time to install is spent already. I am at a point right now where it is the easiest it will ever be to add (or not) and looking for others experience.

The -10 has an ASA separator on it that vents about 1” above the exhaust pipe and still gets some oil on the belly with 9 qts in the sump. Maybe the ASA saddle would help with that.

For the -8 I am wondering if its worth the effort to go full inverted oil, but then that brings up how much re-work is involved on the wing tank to add a flop tube and its associated maintenance.

AV8ER said:

I have an RV-10 time machine that handles the the mail runs so this RV-8 is being built strictly as a fun machine.

I intend to fly acro and would like to do some inverted flight but not sure if inverted flight is just a novelty that quickly wears off while the monetary cost, weight penalty of the equipment, and time to install is spent already. I am at a point right now where it is the easiest it will ever be to add (or not) and looking for others experience.

The -10 has an ASA separator on it that vents about 1” above the exhaust pipe and still gets some oil on the belly with 9 qts in the sump. Maybe the ASA saddle would help with that.

For the -8 I am wondering if its worth the effort to go full inverted oil, but then that brings up how much re-work is involved on the wing tank to add a flop tube and its associated maintenance.

Click to expand...

IMO, Sustained inverted flight is challenging in the -8 because of the seat belt and shoulder harnesses. It would be easier with a ratcheting set up like Ron Shreck put in his -8. There is a thread about it on VAF.

That being said, if I had it to do over, I would still install the full Raven.

I had the same set up as you describe in your -10. I had oil dripping directly on my exhaust. With the ASA saddle mount, now it drips inside the exhaust. I’m hoping that cleans things up. It seems to be working thus far.

To me the flop tube is a no brainer. In my opinion it’s a necessity. I have them in both tanks.

You can put the flop tubes in QB wings. It requires a great deal of patience.
You have to move the fuel sender to the back of the tank which has its own set of challenges and compromises.

An inverted system is useful for more than just inverted flight. On a vertical upline oil pools in the accessory case and gets pumped out the breather. Even accelerating on a vertical downline will push oil into the accessory case.

If you want to keep the belly clean without an inverted system of some sort you are limited to loops (with enough positive g while vertical and inverted to keep oil out of the accessory case) and barrel rolls.