Thursday, 5 March 2015

Week 186 - Engine Mount, ECU cover, RR Cooling Flange and Oil Air separator mod

Hours to date: 1680.0


As you'll see below the engine mount needs modifying.


This is because UL Power changed the Alternator fan securing method (6 months after I bought the mount from Pete). This was due to the previous attaching method failing in flight. Pete was over the Swiss Alps when this happened and was lucky that an airfield was directly below him. A bit scary as he said the cockpit was filling with smoke and he was contemplating 'hitting the silk'.

The fan is now bolted in place with a series of Allen head cap screws.
 
After about 3 hours work I had the offending cross brace cut off and the other two tubes cut down and shaped to fit.


After fitting to the back of the engine and tightening up the mount rubbers to the specified 45mm distance the clearance was just 3mm. This is too small for me so I will do some more work to make it 5mm.

When I was at Pete's the other weekend he showed me the Oil Air separator mod that the does. I'm going to copy him here. Replacing the push on fitting with a weld on -10 male end. It is probably overkill at the push on end but it's the other end of that breather hose that is important. Pete says that he used to run that hose all the way to exit at the back of the aircraft (the same setup as most other aerobatic aircraft) but this long tube resulted in a lot of oil building up in the hose and that caused a pressure build up in the crankcase resulting in an engine stoppage. The solution is to plumb this line into the exhaust pipe. Any oil therefore gets burnt up. The pipe is very short and no pressure build up results. So I'll need to get a male -10 steel fitting welded to my exhaust pipe.

Onto the ECU cover - which is now done and ready to install back in. I made a mould out of modelling foam, put that on the ECU and covered the lot in duct tape. 4 layers of carbon - with an extra layer where the bolt holes go did the trick. I strengthened the back by putting a 'strap' of 4 layers of carbon over the end. (see pic). It weighs just 120 grams and is plenty strong enough to protect the ECU cables from a kick by the pilot's feet.

I've also made up a cooling flange for the Rectifier/Regulator. I did this with a block of plywood shaped to fit the top of the R/R, covered the whole lot in duct tape and laid up 4 layers of fiberglass over this. After that was set I cut a 25mm hole in the middle and bonded a PVC pipe to that with flock and 2 layers of glass. I will finish this piece with body filler and paint to make it look less scuzzy.


I've just heard my parachute is on it's way so it should be delivered by early next week.


Mount before cutting cross brace off completely.

3 hours later

Gap is only 3mm - too small - so I will make it out to 5mm.
Mount on back of engine

Oil Air separator mod - weld on male AN fitting

Pete's set up with breather plumbed into the exhaust pipe

Moulds ready for lay up for the ECU cover and Rectifier/Regulator cooling flange.

RR Flange part way through. PVC pipe just about to be bonded to the base.


All done - except for paint for the RR cooling flange.


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