More cooling issues

Looks like I did the victory dance a little early with my cooling issues. When I went out to fly my plane in 74 degree temps, the oil temperature went straight past redline. I landed as quickly as I could to prevent any damage. I’m convinced that the oil cooler isn’t doing much at all. I’m thinking the only reason it worked last year when it was mounted on the top of the case is that cool air blew through the cooler and cooled the case itself.

Before I started on more drastic measures, I decided to bypass my new thermostat to make sure it wasn’t causing my cooling issues. In this picture and the last picture, I’ve capped off the thermostat and joined the hoses with AN couplers. No change. Still ran right to 225 degrees and was headed higher when I landed after 3 laps overhead the airfield.

I dug through all the junk that came with my airplane when I purchased it 7 years ago and found the original baffles. There’s no way I’m putting this junk back on my shiny new airplane, but maybe it’ll be good for a pattern. Or not. In the end I decided I like the plenum over the cylinders and how it fits… I just need to extend it over the top of the case to (hopefully) provide better cooling.

I used my contour tool and some foam core board to make a few patterns. I have previously used poster board in these situations, but find that it gives too much for an accurate pattern. My plan is to seal off the case from just behind the spinner to just in front of the engine mount bolts.

Here’s the aft piece fabricated from .032″ aluminum. It fits the contours of the case well enough that it shouldn’t be a problem sealing it up airtight with some RTV. If the combination of the RTV and the plenum isn’t enough to hold the piece in place, I could always attach a few brackets to mechanically hold it in place.

Here’s the nose piece just setting in place for a preliminary test fitting. There are two attach holes on either side of the crank flange that will allow me to attach this piece to the case. I think the holes were used as part of the stock baffling installation. In any case, a quick trip to the aviation aisle at Ace Hardware and I’m all set with the proper 1/4″ coarse threaded bolts.

With the fore and aft partitions in place, it was time to plug up the irregular-shaped holes on either side of the front of the case. Again, I used foam core board and my contour tool to come up with the shape. After I took this picture, I marked the patterns to be trimmed so they’ll just meet up with the forward partition.

I needed a flange along the top of the forward and aft flanges so I broke out my stock of Van’s-supplied stiffener material. Van’s fabricates this stuff for use as control surface stiffeners. It’s the greatest thing since sliced bread as far as I’m concerned. I ordered a bundle of it and have found many uses for it during the Midget Mustang project. Here I’ve cut notches along one side so it can follow the gentle contour of my new baffle.

Here’s a shot of the baffles after priming and after the flange has been cleco’d in place. I always get excited when things start to come together like this.

With the flanges in place it was time to fit the pieces at the front of the case to the left and right of the crank flange.

I’m pretty happy with the way these fit. After a few tweaks I separated all these parts, primed the remaining pieces and riveted everything together. The next day I painted everything black to match the existing pieces at the valve covers. I don’t have a picture of the freshly painted pieces because they were still tacky when I left the hangar on Saturday afternoon.

While waiting for the paint to dry, I decided to tackle another little squawk that’s been bugging me for almost a year. I just don’t have enough elevator trim authority. At different phases of flight I find myself trimming to the full up and full down positions and wishing I had more. The painted piece to the right side of this picture is my existing trim tab. The one on the left is the replacement.

Here’s a better shot to see the difference in size between the old and the new. Believe it or not, the new tab is more than 50% larger in surface area. I’ll start with this and if it’s too much I can always trim it down a bit. I can’t believe I put this project off for almost a year. Once I got started on it, the project probably only took me 30 minutes to complete.
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I was really busy at work during the months of April and May, but I’ve vowed to be less busy during the month of June. I’ve already missed some fantastic flying days so I’m highly motivated to return my Midget Mustang to flying status as soon as possible. I’m off work for 5 days in a row starting next Thursday. I’m hoping for some serious progress during that time.

Gotta show a picture of my new beater truck. I bought this in anticipation of my next project… finishing my basement! 4 x 8 sheets of drywall will certainly fit better in this truck than they’ll fit in my VW Passat! It’s not much to look at and it doesn’t get very good gas mileage, but it’ll serve a purpose. I’m finding it really fun to not have to worry about where I park for fear of door dings, too!


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