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IO-390 Inverted oil system

iamtheari

Well Known Member
I am trying hard to talk myself into ordering an engine on the Oshkosh special. I plan to have an inverted oil system in my RV-14 so that I don't have to worry about the engine every time I get bored and fly a half Cuban 8.

Has anyone already done this to an IO-390? What is required beyond having the parts? Will I be removing and drilling holes in my brand new engine's brand new sump?
 
Technically true. But not workable for all maneuvers. Slow rolls are a good example where you are going to have some period of time with negative G at the engine and where an inverted oil system is probably a valuable investment. :)
 
Oil Accumulator

Often used by race car drivers who corner hard, the oil accumulator is there to provide momentary oil pressure while the pickup accesses air.

Also nice to have oil pressure before you crank the engine, and when the valve is closed in flight you know you have a squirt in reserve.
 
oil accumulator is there to provide momentary oil pressure while the pickup accesses air.

The main concern with gentlemen's aerobatics is cleaning up the mess on the belly, not starvation.

I'm planning on a half-Raven with the OP's setup but don't have my engine yet.
 
Inverted oil system

The Doll is equipped with inverted fuel, and Christen inverted oil. I put it on because I owned a Christen Eagle II. I knew I would be selling the Eagle when I started flying the 8. I didn't want my new 8 to limit me to positive G flight since I had been putting the Eagle through everything for the previous 12 years.

Fast forward 18 years....... If I had it to do over again, I would saved the cost and the weight. The Christen Eagle is equipped with an aerobatic propeller. If oil pressure is momentarily lost during zero G, the prop will move to a higher pitch, thus decreasing RPM until pressure returns. The props we fly are spring loaded to move to a lower pitch when zero G causes an oil pressure interruption!

During hammer head turns in the Doll, I had the RPM runway twice even equipped with Christen inverted oil. When the oil feed shuttle valve stalls in-between positive or negative G position, the oil flow will be cut to the pump. I installed a small oil pressure accumulator that prevented all future runways.

Save your money and the weight. Install an oil pressure accumulator, and plan on positive G aerobatics. The accumulator will take care of momentary negative or zero G flight.
 
Technically true. But not workable for all maneuvers. Slow rolls are a good example where you are going to have some period of time with negative G at the engine and where an inverted oil system is probably a valuable investment. :)

"Slow rolls" even at RV roll rates are fast enough that an inverted oil ball valve has insufficient time to properly reseat and redirect oil pressure under negative G before the roll is finished, so you really don't need to worry about that. Inverted oil is primarily for sustained negative G oil pressure, not negative G transitions. Preventing a little oil from pumping out the breather during brief negative G transitions is another matter. I agree w/ Danny's post above, however a full inverted oil system does allow you to expand your flying should you eventually want to do more. Acro can be addicting. ;)
 
Thanks for the oil accumulator tip.

Is an aerobatic prop basically a twin-engine prop on a single-engine plane, so that loss of pressure feathers it rather than flattening it out?
 
"Slow rolls" even at RV roll rates are fast enough that an inverted oil ball valve has insufficient time to properly reseat and redirect oil pressure under negative G before the roll is finished, so you really don't need to worry about that. Inverted oil is primarily for sustained negative G oil pressure, not negative G transitions. Preventing a little oil from pumping out the breather during brief negative G transitions is another matter. I agree w/ Danny's post above, however a full inverted oil system does allow you to expand your flying should you eventually want to do more. Acro can be addicting. ;)
Any tips on the breather issue? I noticed that the "slobber tubes" on the Great Lakes planes that I got to fly for my introductory aerobatics lessons last winter made a lot of "slobber" after the inverted lessons, so I inferred that the inverted system kept oil going to the engine but didn't keep it off of the belly of the plane (without help from the tube to the tail, that is).

Talk about addiction...I had 10 hours of aerobatic lessons in December and I'm still twitching for more. But until the RV is flying, the only plane I have that is remotely capable of aerobatics is a J-3 Cub and...well, the advice I am getting on that is that, if you have to ask the entry speeds for loops and such, you shouldn't do them, and I have to ask. So I have been constrained to the boring old Normal Category for months now. I will say that I didn't get addicted to sustained inverted flight or inverted spins, but I would really enjoy a hammerhead right about now!

I'm now torn on the inverted oil system. Probably the right thing to do is finish the 14 and fly it a thousand hours without sustained inverted flight and, if I need more, build an RV-8 or buy something already set up for such foolishness.

For now, I'm shopping for oil accumulators and information on how to get them hooked up to an IO-390. :)
 
I installed a small oil pressure accumulator that prevented all future runways.

Save your money and the weight. Install an oil pressure accumulator, and plan on positive G aerobatics. The accumulator will take care of momentary negative or zero G flight.

Danny, is your oil accumulator plumbed in addition to the inverted scavenging, or did you remove the inverted system entirely?

From the apparent size of the oil accumulators google brings up it seems that they would provide a fairly short burst on a Lycoming before they run out?
 
Any tips on the breather issue? I noticed that the "slobber tubes" on the Great Lakes planes that I got to fly for my introductory aerobatics lessons last winter made a lot of "slobber" after the inverted lessons, so I inferred that the inverted system kept oil going to the engine but didn't keep it off of the belly of the plane (without help from the tube to the tail, that is).

Aerobatic planes route the breather all the way to the tail so that any dribble will not end up on the belly. Even with a full inverted system, the "slobber pot" will still allow a small amount of oil to dribble out during and for a short time after a flight with a significant amount of positive/negative G transitions. But without it, you'd pump a lot out. There's a lot of info on this site. Search 'half raven' if you only want to contain oil.

the advice I am getting on that is that, if you have to ask the entry speeds for loops and such, you shouldn't do them

Agree there!

I will say that I didn't get addicted to sustained inverted flight or inverted spins, but I would really enjoy a hammerhead right about now!

It's not about getting addicted to 'sustained inverted' or inverted spins - that is simply incidental to more advanced aerobatics, should you become interested. 99.9% of RV pilots who do aerobatics just fly the basic loop, roll, Cuban, hammer, spin figures, and you don't need any inverted systems at all for the usual RV acro. If you want to compete, and maximize you potential, there are other considerations. Unfortunately, only more aerobatic experience will tell you how far you want to take things, and exactly what style of flying you want the airplane capable of.
 
Ari--we havent done any inverted oil systems for the 14 yet, but similar systems on the 6, 7 & 8 as well as several other experimental models. Plumbing it is no issue.

I would suggest getting mockups or really good dimensions of the tank and ball valve before you buy anything. The location of the oil cooler might hinder the right (co pilots side) install location.

You might also talk with Allan Barrett on the sump situation.

Tom
 
Danny, is your oil accumulator plumbed in addition to the inverted scavenging, or did you remove the inverted system entirely?

From the apparent size of the oil accumulators google brings up it seems that they would provide a fairly short burst on a Lycoming before they run out?

The Christen inverted oil system is still installed, so the Doll can fly continuous inverted flight. Still, with a Hartzel prop that is spring loaded to low pitch, I still need the accumulator for protection against zero G when the Christen oil flop valve stops between positive and negative positions. A good example is when doing a Hammer head turn when on the up line the aircraft is at zero G.

The accumulator is plumbed to a #6 AN fitting given to me by Bart at Aero Sport engines. It replaced the cap fitting at the top of the accessory case oil passage way.

Consider this when making your decision. The oil/air separator function of the Christen system also switches the breather between positive and negative G flight. The oil/air separator tank returns most (but not all) of the oil back to the sump.

Unless you plan continuous negative G flight, the accumulator should handle momentary pressure loss.
 
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Find a parts book for the new extream decathlon. It uses an IO390 if you duplicate that setup and propeller you should be good.
Dave
 
Watch Jim's hammerheads.......

https://www.youtube.com/watch?v=I4MFxXrih_M

I learned that 80? is fine for an upline and it keeps the belly dry. I can get 2,000' upline at 190kts, 2g pull to 80? and a dry belly.

Hesitations, slow rolls, cubans, all OK, provided as earlier correspondents have said, just keep a gnats of positive on. Adds to the technique discipline... ;)
 
I wanted to resurrect this thread to see if someone has installed either a full or half Raven on a 14 with the IO-390, and if you installed after construction. I am tired of oil on the belly, but there isn't a whole lot of room under the hood for more installation and wanted some pictures of a completed project.
 
I wanted to resurrect this thread to see if someone has installed either a full or half Raven on a 14 with the IO-390, and if you installed after construction. I am tired of oil on the belly, but there isn't a whole lot of room under the hood for more installation and wanted some pictures of a completed project.
I was going to resurrect this thread sometime this week, anyhow. I have mostly decided on a half Raven and an Accusump oil accumulator. However, I am having a really hard time pulling the trigger ordering those because, until I mount the engine, I have no idea where or even if they will fit.

I also want to put on a 90-degree oil filter adapter. My Arrow oil changes already frustrate me and it has a lot more space between the oil filter and the firewall than the RV-14 engine mount looks to afford. But again, I don't know if it will fit.

I hope someone has pictures of these various items on an RV-14 to share.
 
... I hope someone has pictures of these various items on an RV-14 to share.
This the only picture I could find of the Half Raven installed in my -14. The tank is installed where the battery should be; the battery has been moved between the subpanel and the firewall. You can see I added an access panel. The tank needs to be high and on the opposite side of the engine from the return line; therefore, you will likely need to move the pressure sensor manifold and firewall penetrations or the battery. Another option is to attach it to the engine mount, but that makes it harder to mount it high. I seriously doubt you will have room for all the other stuff you are considering.

The Half Raven has served me well, I have never put oil on the belly.
awez2g.jpg
 
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Looking at the parts for the half Raven system, it appears just to be the tank and the adapter for the oil return.

Trying to understand what size fittings and hoses will have to be ordered to complete the install. On the Raven directions, it gives the tank openings as "larger ¾” NPT fitting is up and the smaller ½” NPT is down", and would need male fittings into the tank. Then a female is needed for the attachment to the included sump adapter. I would assume it is a 1/2" female.

Did you use 3/4" hose or ? (guessing I.D.) or different sizes needed, and what lengths would be needed?
 
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Looking at the parts for the half Raven system, it appears just to be the tank and the adapter for the oil return.

Trying to understand what size fittings and hoses will have to be ordered to complete the install. On the Raven directions, it gives the tank openings as "larger ¾” NPT fitting is up and the smaller ½” NPT is down", and would need male fittings into the tank. Then a female is needed for the attachment to the included sump adapter. I would assume it is a 1/2" female.

Did you use 3/4" hose or ? (guessing I.D.) or different sizes needed, and what lengths would be needed?

Sorry, I can’t remember the fittings and hoses and I won’t have my cowling off anytime soon. Tom at TsFlightlines made the hoses for me, he may have kept records. Raven has two tank sizes you May not be able to fit the larger tank in the -14.
 
Marvin, How and where did you plumb the return line from the Half Ravin? I was under the engine today and could not see any fittings. I hope I don't have to get welding done.......:confused:
 
Marvin, How and where did you plumb the return line from the Half Ravin? I was under the engine today and could not see any fittings. I hope I don't have to get welding done.......:confused:
You should have two of these oil plugs. Choose the one on the opposite side of the engine from your Raven tank.
1qfzq1.jpg
 
Marvin, Thanks for the reply and the picture!

I believe the picture you have shown is the main oil drain on the front left (pilot side) of the engine. I have a quick oil drain there. I could always add in an adapter there. Do you know where the second one is? Is it on the front, opposite side? Not at the airport now, and I just put my cowling back together last night.
 
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Marvin, Thanks for the reply and the picture!

I believe the picture you have shown is the main oil drain on the front left (pilot side) of the engine. I have a quick oil drain there. I could always add in an adapter there. Do you know where the second one is? Is it on the front, opposite side? Not at the airport now, and I just put my cowling back together last night.

My oil drain is on the rear of the engine. I don?t have a picture, but there is a post (somewhere) where RVBuilder2002 explains it.
 
This one? I believe this is the rear oil port that RVbuilder2002 is referring to as a preferred oil drain and/or secondary port. I have sent him a PM with this picture to confirm.

jjta6v6.jpg
 
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Thank you very much Marvin. I will probably move my oil drain to the rear also, and use the other port for the return line.
 
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