Twister meeting at Paderborn Haxterberg

A selection of pages from Ingo's excellent write up of our Twister meeting in July of this year.

As always, click on the images for a larger view.

STOP PRESS

More information has come to light since my last post. 

I've been busy visualising all the possible flight conditions to better understand what's going on. 

As you can see the 'kick' for the ball valve should be at the bottom not the top as I currently have it. It's not a 'biggie' to change this as I can re-use the mount, just flip it up the other way and drill and pot three new holes is all. The hoses and fittings will remain the same. Something to do in the New Year. While I'm at it I think I may change the oil air separator mount so that it kicks slightly out at the bottom too as this seems to be a more optimal solution. 

Click on the image for a much larger view.

Oil Air separator and more

Way back in early 2015 when I was installing the engine and its accessories I was told by Pete to just copy what he did. 

Since then I've realised it was rather naive of me not to question the placement of certain items a bit more and do my own research.

There has always been some oil loss when doing aeros but since competing at Intermediate grade I've noticed a massive increase in oil loss. Sometimes to the point of returning with the mark on the bottom of the dipstick...

Obviously this is unacceptable. Not only thrashing the engine with low oil but the subsequent mess down the belly of the fuselage and the cost of having to top up the oil all the time.

Time to do some research and figure out what is wrong!

I read up on the Christian Inverted oil installation guide. Also UL Power now give advice for placement of the oil air separator - see below, BTW this information was not available when I was installing my engine.

It turns out the placement of the Oil Air Separator was completely wrong.

It should be on the other side of the engine (opposite side to the sump return connection) and as high as possible so that the path for the oil return line from the bottom is a steady descent (when flying upright and level) with no 'buckets' for the oil to collect.

So the plan was to relocate the oil air separator to the Starboard side of the engine and place it as high as possible.

Of course "when you change one thing you change everything" and so it was that now the ball valve was in the way! So that would have to be relocated inboard.

This also was a blessing in disguise as I'd been meaning to remake my ball valve mount for some time. I found out that even though UL Power say to mount this perfectly vertically on the firewall - if done so then in a vertical climb (something I do a lot in Intermediate aeros) the ball will not know which way to go as it is not subject to gravity when in this state. The solution is a small 'kick' out at either the top or bottom of the mount so that the ball positively stays put or moves to inverted position when on a vertical upline. I prefered that it stay down so put the kick at the top.

Potentially I was looking at 2 new mounts, and up to 8 new hoses and 16 fittings.

As it turns out I was able to reuse most of the hoses and some of the fittings but both mounts had to be fabricated.

Everything was a fight with this job as the access behind the engine to the firewall is extremely limited and a lot of what was installed was done prior to the engine going on back in the day, so certain fasteners took a lot of time and swearing to get to and undo and then redo later on. This meant I was out of the air for nearly 2 months.

I finally got everything finished two weeks ago and gave it a ground run with the cowlings off to check everything was ok. All was well with the work I'd done but a fuel fitting that I didn't even touch decided to fail and was leaking fuel badly. I had hoped to fly it that day but that was out of the question now. Another weeks delay while I waited for a new fitting. 

Last week I was finally able to get the cowlings back on and take it up for a test flight. All seems well and I even did a few aeros pulling a few vertical lines. No oil smoke so far. I'll have to give it another longer test to be sure but so far it looks like this fix has worked.

Now it's time to clean all that old oil off the belly!

UL Power current information recommending placement of the Oil Air Separator - wish I'd had this information when I was doing my engine install.

How my oil air separator was installed

Ditto

Red line shows where the drain line was and how much of a 'bucket' was in it.

How things were before I started the fix.

Idea was to put move the Oil Air Separator to this location but as you can see the ball valve will be in the way so it had to move too!

Early thoughts with new placement and angle of the ball valve. keeping this forward facing option was out of the question as the hoses and fittings would conflict with the engine mount so I ended up flipping it 90 degrees sideways which is a Christian option BTW.

New Ball valve. Made from 12 plys of Carbon with a foam core and solid carbon sides. Very strong yet only 100 grams in weight.

'Kick' out from the Vertical is clear here. This makes sure the ball valve stays down when pulling a vertical line.

Finalising the position of the Oil Air separator - better check the top cowling clears it first!

Almost there. Ball valve has had to move inboard and flip on its side.

All done. Time for a ground run.

Red line shows new path of drain line from Oil Air Separator. Downhill and no buckets!

Same as above pic but without the red line.