Now that the cowls have been fitted (or at least we have a working configuration which may have to be tweaked when we get the prop) I went back to the baffles and started looking at the trimming needed.
The first thing was to set the inward set on the foreward side baffles. NOTE: This is wrong - the baffle should be outside the cowl inlet.
A bending brake and a rough idea of the angle was useful. The 'tricky' bit is the bottom left edge (in this photo) where it is very thin and difficult to get a good even bend.
The after photo - again note wrong position of the baffle front edge vs. cowl inlet. Then a small trim at the front and got both sides to fit. Only rough stuff at this point, lots more trimming to go.
Then I started looking at the trimming of the top line to allow the cowl to sit correctly. After trying to estimate distances, I gave up and mocked up the main side baffles on some card. I just traced the parts out onto the card and then trimmed until they fitted.
The results - the black is the line for trimming - it looks huge - it is huge amounts of trimming. I started slightly outside the line (being cautious) but ended up back at or even slightly inside the black line. And this is just to get flush with the cowl, another 3/8" needs to be removed to provide clearance for the cowl / engine comparative movement.
The RHS requires even more trimming as the #1 cylinder is further forward.
The resulting rear LHS side baffle (the one the oil cooler attaches to). Remember the outboard flange also needs radiusing to match the cowl curves.
Then onto the forward side baffles.
Initial trims give you some idea of the amount being cut off - this is for cowl touching - another chunk to come off yet.
The final rough cut for the day was the forward folded tabs that go into the inlet. More trimming will be needed. I also removed the spinner to ease access for the top cowl.
I'm still debating on whether to make a full plenum for the engine - I'm very tempted and it would be another small unique for our plane. My only conerns are: a) Additional time - not a real biggy but needs to be considered, b) Impacting the cooling and then having to chase gremlins / squarks due to poor cooling. I may try and put off the decision and wait until I've completed an order with Aircraft Spruce and get some reading material on the subject.
If I was doing it again, I would order the Sam James cowl / plenum kit rather than the VANs cowl - it looks cool and should provide better cooling and more speed.
