Stjohn's RV-7

I thought this was going to be a fairly easy exercise.  After all, what’s the big deal, right?  Attach a flange to the baffle, mount the cooler, fab up some fiberglass ducting, slap on a length of SCEET, and presto, done.

Nah.  Slow your roll, dude.

First thing that needed to happen was removing the old cooler mounting flange.   Rather than take the baffles apart, which may have been a poor decision, I figured I’d just unzip all the rivets along the top and left of frame so the baffle can open up, swinging open from the bend right about where the spark plug wires go in.  That hypothesis was borne out.  After some less-than-stellar de-riveting, I have the baffle exposed, but even opening up, it was difficult to get any kind of squeezer or rivet set into the area by the engine mount tubes.  Before anyone freaks out, yes I did clean up the mangled rivet holes, and a couple of them went away entirely when I cut out some excess for the 4″ flange opening, seen in the next shot.

So now there’s a big plate of aluminum doubling up the baffle, to which is attached a beefy 4″ aluminum duct flange from an industrial dust collection system.  Fun fact about that:  Originally, this duct was two pieces, which included a sliding gate to control the amount of air going through the duct.  Cool setup, but it was not to be.  I either had edge-distance issues or conflicts with other parts of the structure, and it didn’t look like I would be able to set up the control cable and mount it.  Bummer, but that’s the way it goes.   I want to return to flight ASAP, I don’t want to be back to project status for any longer than necessary to make this a safe, effective modification.

The final configuration looks a little different from the above.  The flange is flipped over to provide material to rivet along the top where the baffle parts connect, and I cut one of the tabs off to allow for clearance of something else.   But it looks like I have enough room for a 90 bend of SCEET (or one of those boy-racer intercooler inlet elbows) and a diffuser.

This is where I plan to put the oil cooler.  I’ve checked for clearance to mount tubes, wires, and my fuel line (important, that), and it also clears the lower cowl.  I think I can connect to the engine mount with Adel clamps in at least 4 places, both from above and below.  It also looks like there are no immediate obstacles to exit air, but I’m not sure how airflow will be affected by the proximity of the engine mount tubes, but there is nothing directly up against the fins on the bottom.

So I guess my New Year’s resolution for 2018 is to solve all my cooling issues.  Among the things that keep me awake at night is the possibility that the 4″ duct will now steal too much cooling air from the cylinder heads.  Also on the list is to rework the baffle seals to be fewer, more continuous pieces, made of silicone instead of the black rubber baffle material.

Today is New Year’s Eve.  It’s unlikely I’ll be making more headway on this until after I go back to work, but if I keep it chill on tonight’s festivities, I might be able to put in some work tomorrow.

Happy New Year, everyone!

Finding a spot for the new oil cooler was just part of the adventure.  I needed to make room by disconnecting the plug wires and temperature probes from the left side so I could work.  I also needed to find a new spot for the fuel pressure sensor.  Fortunately, that’s easy. I can clamp it to the top strut of the engine mount, pretty much where you see it resting now, top middle of the frame.

Ordinarily, I hate working with steel.  it’s sharp, unyielding, and awkward to work with.   This all changes when you have the proper tools. EAA 96 has a plump machine shop, with a shear, two sheet metal bending brakes, numerous drill presses, grinding wheels, table saws, a massive lathe, and two Bridgeport mills, one of which is working, but neither of which I know how to use.  There are also a number of projects in the hangar that utilize the tube-and-fabric method, so there’s a scrap can full of 4130 steel tubing and sheet cut-offs.  So that’s where I went to get the brackets I needed.   I’m sure there’s some fancy engineer-y math I could have used to bend a bracket so it works in one piece like papercraft, but I was able to get this together with two pieces.  This connects to an angle brace on the cooler and suspends it from the engine mount at the angle and distance I’ll need to get a fiberglass plenum on it, which will connect to the baffle via 4″ SCEET tube.

I chose steel because it was available, I have the tools to work it, and I can get away with less material.  I don’t have the right circumstances to do a solid aluminum webbing, so steel it is.

There will also be a support member on the bottom of the cooler, where I have to battle the mechanics of attaching to the engine mount without blocking the airflow from the cooler.  I paid for 10 rows of cooling, I want all 10 rows cooling.

New oil hoses will also be a necessity.  The top one barely made it to the cooler with an acceptable bend in the line.  There’s no way it makes it now.   I may be able to repurpose the from-cooler line as the to-cooler line, but that’s doubtful, given the fittings necessary.