Week 207 - Electrics Cont.

Hours to date: 1933.0

As you will see below I'm getting on with the electrics. 

In fact there is not much more to do other than the fuel flow and a tidy up in some areas.

I'm still trying to figure out the fuel flow set up as things were not clear from the manufacturer of the 'Red Cube' FT60 fuel flow transducer. 

After contacting the factory direct it does seem that I was right all along to install 2 transducers (even though their literature disagreed with this). However I also need to buy a small module that takes the readings from each transducer and works out the difference before sending that information to the Dynon D180. This is because with the UL engine we have a return line and most of the fuel travelling through the system has not been burned up each time it passes the transducers.

Make sure you include a big ground lead from the case of the Dynon to your master ground as the Dynon needs this to work correctly.

After what seemed like hours I finally got the harness sorted through the firewall and fixed the firewall protection plate (I'd previously made up out of stainless steel) in place. Quite a confined space to work in both sides of the firewall but we got there in the end. The white goo is from the other passthrough kit and makes a fireproof airtight seal. As you can see I used a piece of firesleeve to wrap the harness before doing this.

I noted that Pete doesn't do anything here and has a big gap around his wiring harness which means that his firewall is not truly a firewall! No wonder he had smoke coming in the cockpit when his alternator cooling fan failed.

I finally got the top panel in yesterday and have switched a few things on. The Dynon, GPS, Radio and Transponder - which all work okay. The only thing that isn't working at the moment is the Push to Talk for the radio - so I'm trying to trouble shoot that now. The power for the iPad also works fine.

The Dynon is going to take a lot of configuring but I have made a start. All the temp gauges are accurate so far, reading ambient temperature and agreeing with one another. The sensors must be configured as they will almost certainly be set up wrong in the Dynon as default sensors. I noticed my oil pressure was reading 85psi but after I had configured the sensor correctly it dropped to zero.

With the fuel sender electric connection on the wings I've gone for the same set up as Pete, which is an automatic connecting device when the wings go on. The wing part of which needs to exactly align for it to work, so I've made a small plate out of carbon which I will bond to the wing when I put them on next. This way the wing part of the connection will be in the perfect position. A trough needs to be made into the wing root around the area where this plate will bond. All of that I will do when I get the wings on next time.

When I've finished all the electrics and hopefully the weather improves then I will switch back to the flap drive job which I got part way through last year.

Dynon remote compass all wired up.

Headset plug sockets all wired up and installed.

Big ground lead from the case of the Dynon.

Main wiring harness firewall passthrough.

Getting tidier...

Conduit and P-clip added to main harness from cockpit to firewall.

Firesleeve over main harness as it passes through the firewall.

Fuel sender electric auto connect/dis-connect. Carbon plate will be bonded to wing root.

Getting tidier underneath with spiral wrap and zip ties.

All fired up for the first time. Everything works except for the PTT.

Catto props

I'd love to hear this talk by Craig Catto.

Using a GoPro attached to the prop centre he is able to study airflow and refine the fences. An improvement to the prop improves the whole aircraft performance envelope (much as tyres are the most important component on a motorcycle or car).

It will be interesting to see if this catches on and other prop manufactures follow suit/copy.

New engine from Rotax

Announced yesterday at Oshkosh.

It looks like a real challenger to the UL Power 350iS, which is rated at 130hp. And I'm sure the UL would have a higher fuel burn and has a reduction in power with altitude being normally aspirated.

Week 205 - Electrics

Hours to date: 1910.75

Slowly making my way with the wiring. Quite enjoyable work this - no messy resin or carbon splinters.

As you can see below I have redone the hook for the canopy securing cable as I was unhappy with the screw in single post effort I did before. It seemed like it would pull out if the canopy were opened to it's full extent in a hurry. This new hook is rock solid.

With the wiring I started off in connecting mode and have now shifted to tidying mode before doing any more. The below pictures were taken in the connecting stage.

Canopy cable hook redone using unused part from canopy parts board.

First it has to get messy then it gets tidy.

Conduit and p-clips to come here.

Week 203 - Plenums cont.

Hours to date: 1888.5


Good progress this week. 

I'm now taking a day off during the week (when I can) and this seems to help with moving forward. Honestly I've been pretty frustrated with the slow speed of progress over the build of this kit but the end is in sight now and I'm redoubling my efforts to finish it by early next year. Hopefully it will be ready for paint by April/May. Then final fettling and test flying in June/July is the plan.


Onto the plenums.


After sanding the micro I still had to add a little body filler to fill in the pin holes and gaps in the micro. Once that was done I used duct tape as a release.


Then followed a tricky layup which seemed to take forever. 5 layers of carbon were used and laid up on plastic then cut out to a neat shape. My big mistake was not allowing for the fittings close to the edges - which stop the carbon from laying flat against the sides. If I were to do this job again I would remove anything close to the top edge. But it was too late as I didn't have access to the inside of the baffles as the foam plug was there. My mistake for not thinking far enough ahead again. 

I find things stick better when you apply a coat of neat resin to the plug early on in the layup - then by the time you are ready to put the carbon on the resin has cured a tiny bit and become quite sticky.


As it turns out things worked out pretty good anyway and only the back area is not great - although it will still seal air tight with a good application of RTV.


The duct tape release worked well and with a couple of plastic wedges I was able to remove the plenum tops with no trouble.


Slow steady pressure is the idea here - don't force things too much.


As you can see below the plugs came out in one piece from the baffles - so if anyone wants to borrow these to layup their own plenum tops then give me a shout. They will save you at least a days work.

All that was left to do was trim the plenum tops out and then fit them with 4mm nut plates all round. I used 14 on the Starboard one and 13 on the Port one. The odd spacing is due to obstructions on the inside and or access from the outside to drill. There will be quite a lot of air pressure inside here at VNE so it's best to make sure it is properly secured. I read a forum in the USA about building a plenum for an RV8 and the forces measured were very high for the plenum. If I remember it right it was over 200 lbs at 200knots. Just think what it does to the top of your cowl if you only have baffles - no wonder they are so inefficient.

The 5 layers of carbon is just right - very strong but with just a little flexibility so the nut plates pull the edges in tight.

Next job is installing the top instrument panel and finishing all the wiring.

Micro and body filler sanded smooth - all ready for duct tape.

Duct tape added.

5 layers of carbon layup.

Plastic wedges help with releasing from the plug.

Foam plugs released easily and in one piece.

Trimmed out. Now for some nut plates.

Port side done. (RTV not added at this stage).

Starboard side done.

Nice flush profile