Twisted: Week 63 - Oil cooler and ducts

Hours to date: 606.0

Well the oil cooler install is coming along nicely. Lots of work this - I just hope it works as planned when I'm done!

This week I've installed the nut plates and also closed up the gap around the edges of the air scoop (where it sits on the flange).

I filled the gap using slightly runny micro and used our old friend duct tape on the flange to seal it and provide a release while doing that.

Fits spot on now with only a tape width of gap all around. I still plan to tape this gap when the plane is finally finished and painted - same procedure as done on gliders - to make it air tight.

After that I made up some brackets for the oil cooler and bonded them on the safety cell with flock plus 2 layers of glass.

With the brackets I drilled another couple of holes in them where they were to be bonded as Pete showed me some brackets made for composite bonding once and they were just metal brackets with a few holes in them to allow the flock to come through and make the bond air bubble free. (I also put some more brackets on the other side but haven't taken a photo for some reason).

The oil cooler must be rubber mounted as the interior of radiators are delicate things that don't like too much vibration. As a consequence of this install location there will be nothing like the vibration that it would normally be subjected to if attached to the engine. So that's another positive in favour of this location - that and the fact it helps bring the C of G rearwards too. I know Pete struggled with the C of G in his install, and ended up putting some components behind the firewall rather than forward of it.

The safety cell will need a very minor mod around the area of one of the hose connectors as space is too tight there. I've looked at the location on the inside and it is in an area where Pete has installed a 'glove box' type bag. It will be behind that and shouldn't present too much of a problem as my right hand will be on the stick whilst flying and won't be affected by a loss of space in this area. It's a pretty small mod in any case.

So having established the placement of the oil cooler it was time to begin making up the foam plugs for the inlet and outlet ducts.

Again a bit of a mess in the workshop with that green foam but I found that I got to the right shape much quicker than when I was doing the air scoop. I put that down to a simpler shape and feeling more comfortable working with the foam.

I've also bought some gel coat - in flame orange! - and will be using that on the inside of the ducts so it leaves a perfect smooth finish when the part is released. This is important as we want the air flow to be as smooth and turbulent free as possible.

I've never worked with gel coat before but I think I understand the procedure and if it works it will certainly cut down on the workload of smoothing up and painting the inside of the ducts afterwards - which would be a hassle (if not impossible).

This means quite a bit more work on the plugs to make sure they are perfectly smooth before applying the gel coat as any imperfections will show on the surface of that gel coat.

After finalising the shape in foam I will apply body filler and sand until smooth then spay with a primer paint. After that some more sanding with progressively finer grades and then a polish should produce the right finish. Then the plug will only need PVA release adding and it will be good to go.