tkatc

tkatc

Well Known Member
Ok, I just started doing loops and rolls. I even tried momentary inverted flight but I am probably pretty sloppy. I do not have inverted fuel or oil. IO-360.

I land and my hangar mate says "Holy oil leak!" I said yeah, it seaps some but I haven't been able to find it. (Thinking he was talking about my pesky seep down the nose gear fairing) Seconds later I see what he meant. The pilot's side of the fuse and belly had very healthy streaks of oil going towards the tail. I mean it looked bad!! A little rain probably didn't help it.

I didn't have time to uncowl but I did check the oil which was a quart lower than when I started my 2 hour flight. I checked it just after landing so some of the oil could have been hiding up in the top of the engine but I am very alarmed. Any experiences?
 
Without an inverted oil system, negative (or even zero) g will pump a lot of oil out of the breather tube.
 
Any negative g's will throw mass amounts of oil out of your breather if you do not have inverted oil.
 
Yup - you can tell how good you are at avoiding "negative-G" by how little oil you have on the belly (unless you have an inverted system). That's why I installed the "Half Raven" system on the new RV-3 - so I can avoid dumping all that oil!
 
You mentioned flying the rain as well. Even without going negative, flying through the rain will make your airplane look dirty in places. I get in the rain about every 200 hours and when I do I have long black streaks in places around the cowling.
 
Whew! Makes sense! Definately pulled 0 to -1 G. Now my heart will stop palpitating a little less than it was while performing the maneuvers. Today was my first loop!

I am dreading pulling the cowl to see the mess I have to clean. Oh well, I'm due for an oil change anyway.
 
Also, if you have topped off the oil to full before you do some aerobatics you will lose a lot over the side, as much as a quart if you have been sloppy and gone 0 or negative. Ask me how I know.
 
I wanted my loop to be "round" vs pointed so I deliberately eased off the back pressure to hold the top of the loop before starting the increasingly stronger pull after cresting over the top. I also remember pushing a little during an aileron roll to hold the inverted position for just a second or two. I suspect the 2 loops coupled with an attempt at inverted flight was enough to let the oil dump all over the place. (I have had some light instruction but it was in a Pitts designed to do ANYTHING)

This was a learning experience as far as not being set-up for inverted flight. I knew I could be inverted for BRIEF periods but I did not know I'd be dumping oil all over the place. Now I know I have to avoid neg Gs. It will be a lesson I wont soon forget!! I will be regretting my mistake as I am cleaning the belly in near freezing temps!
 
Finally uncowled today expecting to find a huge mess. I was surprised at how little oil was in the FWF area.
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Judging for the amout of oil on the belly I was expecting MUCH worse.
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This is about 3/4 of a quart.
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Most of the oil exited the breather tube through the bottom of the cowl but some came out the anti-ice/pressure relief hole in the breather tube. I am very relieved to discover this is normal for my configuration but would like to avoid this in the future. No more neg Gs?

On a side note, filling the engine with 7 quarts of cold oil after an oil change takes a LONG time.
 
tkatc said:
Most of the oil exited the breather tube through the bottom of the cowl but some came out the anti-ice/pressure relief hole in the breather tube. I am very relieved to discover this is normal for my configuration but would like to avoid this in the future. No more neg Gs?
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No more negative G's or put in a "half-Raven" tank and sump fitting. Not teribly expensive (in Aircraft dollars), and effective.

Paul
 
Hmm, looks like an attractive option. What kind of weight does the half raven system add? And I'm wondering off the top of my head where I could retrofit the can....
 
tkatc said:
Hmm, looks like an attractive option. What kind of weight does the half raven system add? And I'm wondering off the top of my head where I could retrofit the can....
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The can mounts pretty easily on to the engine mount (next to the dipstick) in most cases. I would guess the weight at less than 5 pounds - depends on the hose material you use. Raven was GREAT to work with!
 
inverted

A Pitts with full inverted oil can dump as much as half a quart an hour, maybe more depending on the maneuvers flown. A rolling turn dumps a lot of oil. The good news is it goes out the breather-the breather exits the tail-no oil on the belly.
 
tkatc said:
I am dreading pulling the cowl to see the mess I have to clean. Oh well, I'm due for an oil change anyway.
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The insides of the cowl will likely be just fine. All the oil dumped out the breather tube primarily ends up along the belly, the tail end, and sometimes up the side of the vertical stab/rudder :eek:
 
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