Wednesday, 27 May 2015

Week 198 - Upholstery, Spinner, EGT probes

Hours to date: 1822.25

Another slack week as I was away in Poland for a wedding.

Still, some progress has been made.

The upholstery is back and I'm very pleased with the way it looks. Orange stitching has been added and the zip on the side pocket now goes the right way. Also there is a toggle and drawstring on the stick gaiter.

I've stuck the headrest pad to the headrest itself with contact cement and fitted the side pocket with those composite spiky fasteners embedded into the safety cell side and then countersunk washers with Allen head screws - looks pretty neat and gives a large area to grip the leather with. The other two cushions are fixed with Velcro so they can be removed easily.

Onto the EGT probes.

These should be fitted 3 inches down from the exhaust exit point and point away from the engine itself - this is in case if one were to fail a hot stream of exhaust gas would not burn into the engine itself. If I could do the job again then I would most likely run the cylinder number 4 probe the same as Cylinder number 3 - ie: backwards. Brand new cobalt drill bits of 3.5mm did the trick nicely to drill the holes - as you are drilling into stainless steel here, go slow so it doesn't get too hot and use a new bit that is sharp. I cut off the excess hose clamp with the Dremel. I'll figure out exact routing and fixing of the thermocouple wires later. Note that you must not shorten the wires at all as this would give a different reading per cylinder.

Onto the spinner.

Going slow, slow, slow here. I really am going like a snail on this job as you can't really fix things easily if you cut too much off. I used the usual method of a cardboard template to get a rough shape. Cut well within the line and then go slowly backwards and forwards fitting and trimming it until things are as they should be.

I'm fixing the spinner to the back plate with the standard Vans method of countersunk Tinnerman washers and coarse thread screws. They give a nearly flush final effect and I'll get them painted to match the spinner too.

My method for centering the spinner (see video below) was to use a turntable I had that is normally used to display a model motorbike. I centered the prop and back plate on it then hung a plum bob from the roof and watched it from two opposing angles to see where it was out of center. A small adjustment here and there and I've got it tracking pretty much spot on now.

EGT probe

Fixed to the left bank

And the right

Template for spinner cutout.

Tinnerman washer and countersunk screw with sprung fastener

Gives a nearly flush final effect.

Turntable method of centering spinner.

Video below - this is one stage before it was centered so it is still a bit out of center in this video.

Monday, 18 May 2015

Cowling visualisation

Just having a play here but this gives you some idea of the final cowl shape.

Week 197 - Engine and prop flange

Hours to date: 1813.5

Not much progress I'm afraid as last weekend I was away in Paris.

I've made the pass-through protection plates for the electrical wires out of stainless. Not the finest bit of metal work you'll ever see but it will work. I trolled the internet for hours to find a ready made one but couldn't find such a thing. I think there is a gap in the market for large diameter hole firewall protection plates.

Good news is that I got around to doing the dreaded prop flange swap over.

I had to put all my weight on and then bounce up and down on it to get the bolt to undo. Same deal when I was doing it up to get the holes to line up.

I may as well stop writing and let the pics do the talking.

Next job is to fit the spinner.

Firesleeve all done on oil hoses.

Stainless steel firewall pass through protection for the electrical wires.

Prop flange holder on so engine does not move when undoing the bolt.

Ali sleeve goes over bolt to stop it moving.

Holes must line up for grub screw

Grub screw in place with Loctite and punch marks so it can't come out.

Other baffle rough cut and in place. Starting to visualise the cowling shape now.

Inlet rings in rough position.


Got to build carbon ducts from inlet ring to baffle - plus a top for the baffles so they become a sealed plenum.

Making up the Ignition wires. Crimp and solder then click and screw slightly into place.

Ignition cables all done.

Reasonably neat routing of the ignition wires - they will be tied off with zip ties eventually.

Rectifier/Regulator cooling hose all done.

May as well get the prop on then!

Crush plate is solid lump of ali.

Tuesday, 5 May 2015

Week 195 - Engine install cont. Oil hoses and muffler

Hours to date: 1799.75

All but there to 1,800 hours. One of my initial estimates for completion ha!

The muffler is finally back. They screwed it up the first time round - got the angle of the end pipe all wrong. All sorted now, I'm happier with the quality of the welding here as it was TIG rather than MIG and done by another company.

After a bit of swearing and frustration I found that I needed to take the ECU cover off to get the engine cable attached. Just not enough room for my fat fingers when the cover is on to get in there and do it up.

Onto the oil hoses.

There are 9 to do in total. I did 5 on the Saturday and then the remaining 4 on Sunday. I ran out of firesleeve so I've ordered some more and a set of aviation snips to cut out the baffles for the cylinder cooling.

With the firesleeve - I follow Pete's practice of putting heatshrink on each end to seal the interior of the sleeve. If you don't do this the interior will suck up any oil or dirt and get contaminated.

Luckily my oil cooler mod has not presented any problems with the hoses coming form the firewall to the oil filter - they all fit okay and clear the muffler by miles.

I've made a start on one of the cylinder cooling baffles. Going very slow here to the get the right shape. Will wait till the snips arrive before completing this job. 

I will be making a sealed plenum, with a carbon top to these, rather than using the useless sealing baffles that is the traditional way. I have read a NASA study that found that sealing baffles are hopelessly inefficient - even on a brand new certified Piper they found losses of 55%. A proper sealed plenum increases efficiency and keeps a big difference in pressures which is how a pressure cowl works in the first place. High pressure above the cylinders and low pressure everywhere else. You have to be fussy about making the two areas completely air tight from one another otherwise the air will take the easy route and raise the pressure in the lower part destroying efficiency.

Muffler back from the welders. They got the angle spot on.

ECU all sorted now with both plugs in. P-clip to secure and protect them.

These two oil hoses were a fiddle. Access is very limited so I took off the air filter while I did this job.

As you can see things get intimate here with the alternator gear close by.

Oil lines on starboard side.


Port side - didn't like the 90 degree hose fitting at right so...

I changed it to a 120 degrees. Much better now with good clearance to the muffler. Firesleeve to come on those 2 hoses and we're done.

Oil cooler lines coming off the firewall.

Another view of clearance over the muffler.

Front view.

Side view.

And finally the mod oil line from the oil/air separator to the exhaust (to be burnt up).

Trying out the port cooling baffle.

Rough cut to size.