Section 45: Cowling Mod Skybolt and Carbon Fiber

RV14 Build December/January

Cowling

After reading about the top cowling hinge being hard to install and remove especially when the engine is hot I decided to look at Skybolt. I reached out to another builder about his experience with using it and he said he didn't reinforce the cowling as was getting some illowing between the fasteners. After reading dan Horton say 100lb/ft of pressure could be on the cowling and that he would definitely use quarter turns and reinforce with carbon I decided that was the path for me.

First thing to do is figure out the spacing. The directions are for some of the older RV models and start back with trimming the cowling, but the 14 design makes these steps not necessary. 

I found that if I went to the 3" spacing from 3.5" I could fit 18 brackets across the top firewall

Next I had to find a center and work out towards the edges each way, measuring hole center to hole center as I went. Then clamping the brackets in place for match drilling.

I also measured from the forward skin edge to the end of the bracket hole center.

and per the instructions the flange overlap area I set a .250. Once everything was clamped and set I drilled.

I kept measuring and tweeking as I drilled. First i used a 3/32 drill and then final drilled with #40.

I wanted to carry the brackets down the edge, but the engine mount was too close and this is as far as the piano hinges go so Im hoping with the carbon fiber the cowling will be stiff enough.

All final drilled.

Then I countersunk the holes.

Some of the hols ended up in strange places on the flange overlap. I did my best to counter sink these so that the brackets would all be even.

I didn't get a photo after counter sinking but before this was the spacing for the cowling.

How thick the cowling is before reinforement.

My measurements after countersining gave me a gab of .078" from the top of the skybolt to the top of the forward skin. The Cowling was .050, the 8.8oz unidirectional carbon is .012x2 (layer top and bottom) = .024, and the  2.1oz fiberglass to cover the carbon is .002". This all adds up to .078, which would be perfect if I had a vacuum bag system. In the end the cowling ended up being .094" do to the extra resin from a hand layup.

The unidirectional carbon is extra strong, but the threads holding it together I should have trimmed off the leading edge. It proved troublesome for the fiberglass to lay down on smoothly.

Cutting the fiberglass to length.

After the carbon and the fiberglass I put on the peel ply.

Next day I did the bottom. This time I did trim the white strands form the forward edge, made for a much better layup of the fiberglass overtop.

Top of the cowling after removing the peel ply before sanding.

Bottom after removing peel ply before sanding.

After a few rounds of sanding and micro. I most concerned with the profile since it will be painted.

Final, for now, layer of epoxy.

Final layer of epoxy on the inside. Here I'm most concerned that the carbon is isolated from the aluminum with the fiberglass and anywhere that I might have sanded through with a layer of epoxy, this should stop galvanic corrosion. The bottom of the cowling will eventually get a medium to thick layer of white dyed epoxy to seal the cowling and help find any leaks, so this is good for now.

Final Layer on the top

Since the final cowling thickness was .094" and the gap was only .078" I made extra shims from .020" and plan on ordering an extra set of the shims that came with the kit to ensure the cowling is set as close to flush as possible, or rather the skybolt are adjusted so the cowling is flush in the end.

Shims and brackets ready for primer.

Etched and cleaned ready to prime.

Time to dry.

Looking good! Just need the FWF so i can hang the engine and get back to work!

Section 45 Cowling Skybolt Mod 16.5 Hours

E-Magair EICAD

RV14 Build December 

EICAD

Right when I was going to order my engine Vans announced the new YIO-390-EXP119 motor for the RV14! Yeah less weight, more power, reduced drag on the cowling re-design! Booo more cost. Well I went for it, but I decided not to go for the thunderbolt version because of cost. Since it was a standard motor Lycoming would only ship it with 1 Emag and a standard Impulse Mag.

I called Emag and ordered the other Pmag, plus the lycoming gear, harness, and spark plug adaptors. I spent a ton of time on the forums trying to find the best settings for the IO-390 and Bill at EICommander was super helpful! Bill@repucci.com. Even though I wasn't installing his unit he emailed me back and forth to help me get the harness connections correct and recommend settings.

This is the wiring guide from EICAD program that I help use to understand how to wire my DB9. This drawing I found a little confusing because of the location of the numbers on the DB9. But the pin numbers are correct and just go with those.

This is how I ended up wiring mine, except I went with a 4C shielded cable and used a dedicated ground wire and not the shielding as a ground, but the pins are the same.

My wire color and pin out on the DB9

Pin 1 = N/A

Pin 2 = Blue

Pin 3 = Green

Pin 4 = N/A

Pin 5 = Orange

Pin 6 = White

Pin 7 = N/A

Pin 8 = N/A

Pin 9 = N/A

I made one for each Pmag and plan on installing them through the firewall and behind the subpanel to make changing setting or checking settings easier, or if I want to upgrade to an EICommander.

These are instructions I found on Vans Airforce

Bills recommended way of setting up the Emad for a IO-390.

I had some trouble getting V3 from Emag. THey wouldn't come out and say it but I think they only want to send out version 4. The problem with version 4 is that you can't put in negative values for Advance shift and know that it took it correctly. It will never read a negative value when you restart to check, V3 will.

Version 3 to check the changes are hard to find unless you know someone with it. I found it web.archive.org and searching around, but this might help.

I make the changes with V4 then check them with V3, take a screen shot so I know for the future.

EICAD 1.5 Man Hours

Section 46B: Wheel Fairings - Rework and bodywork

RV14 Build December 

Wheel Fairings

I had drilled the outboard main wheel fairing brackets because the called for AN3H3A Bolts wouldn't fit in easily. Turns out this was a mistake, after all the work on the wheel fairing there was a relatively easy enough rotation where the fail end would move up and down about 2-3".

So  I decided since I had the time waiting on the FWF kit to order new brackets are redo the work. I did these 1 side at a time, because I wasn't sure how much it would make a difference. Spoiler it removed almost all the movement and I ended up re-working both sides.

New Brackets. About to be deburred and primed.

The fit is very tight, I would say the bolts tap there way through.

After installing the brackets it was just a matter of going through the process again.  I used a dremel sanding wheel to sand out the Flux that was on the inside of the 2 halves of the wheel fairing. Before sanding.

This allowed the new bracket to to float on it while I reset the front and back wheel fairing height. What was helpful was the forward top screw hole on both inboard and outboard of the fairing location was set with the holes already drilled and I could use this to keep the "toe in" angle matched then I leveled the airplane and measure the distance the rear bracket hole is off from level and transfer that to the wheel fairing.

What ending up being level was about and even 8" off the ground for me after adjusting for the bracket hole location.

I did drop a plumb bob off a fuselage rivet line to the ground and transfer that line to the wheel to make sure the longitudinal axis was still aligned with the fuselage and thus the airflow. This one was more of a check than setting it. Since I used the top forward hole on both the inboard and outboard of first fairing mounting attempt this orientation should not have/didn't change. Also at this stage I located and drilled the other mounting holes. I don't know if this is what they are for but the kit comes with round magnets that work perfect for locating holes in opaque panels. 

I then put tape over the bracket and added flux to the inside of the fairing to set the bracket into.

i used pan head screws to hold the fairing while the flux was setting up.

After It set up I countersunk the holes and put in the correct screws. Since I still had time to kill before my next kit I decided I didn't really like the way the halves matted after being secured to the gear. There was a unevenness between all the screws.

I had been working with the chop cotton flux so much I just went with it for the "filler" I should have used micro-balloons and did on the other side....it would have been way easier to sand. I taped off the front half to prevent flux from sticking to it, scuffed up the gel coat and laid on the flux.

After sanding forever I realized I needed more filler to transition smoother and this time I used micro. Much easier to sand.

Repeated for the other side.

Finally 2 wheel fairing that I am happy with and hopefully will be easy for the painters to finish and make perfect.

Section 46B: Wheel Fairings 18.5 Hours