Paint Protection

I've had most painted surfaces covered with a "low tack" vinyl for the last 6 months to protect from scratching while I climb all over doing the wiring. I noticed that the vinyl was getting a little brittle and more and more difficult to remove lately, so I decided I'd better just remove it before it became a permanent fixture.  I still want long-term protection on the canopy deck since I've seen that those tend to get really beat up on flying planes.  I purchased some 3M paint protection film (the stuff used as rock chip protection on the bumpers of cars) which I'll wrap the canopy deck with.  There's definitely a learning curve for applying the stuff.  I made the recommended "slip/tack solution" out of water, dish soap and isopropyl alcohol and sprayed the surfaces with it as well as the PPF.  That allows you to slide the film around before using a squeegee to tack it down.  I got the left side done.  It's fiddly, and I made some goofy cuts to trim it around the pieces that are attached to the canopy deck, but I'd say it's good enough.  It should keep the paint from getting beat up and chipping.  The PPF is supposed to last about 10 years, at which point you can peel it off and redo it.  I did end up with some bubbles due to technique, but for the most part it's an invisible cover and the paint looks great through it.  I'll put the PPF on both sides for the canopy to rest on, and I think I'll also do the lower half of the walls of the baggage area.

That's when things went South.  I'm not sure what the story is with the paint on the baggage floor, but it's a wreck.  The vinyl was really stuck to it.  I used a tiny bit of heat to ease pulling it up, but by the time I was done I had pulled up a few patches of paint and in other areas I had created paint bubbles where it didn't pull off but had obviously pulled away from the metal.  Very disheartening, although I'm not surprised.  This paint has been problematic since the get go.  Thankfully it's just the baggage floor.  I'm not sure if I'll cover it with the same clear PPF or just leave it.  The problem with the PPF is it doesn't stretch as well as the thinner "car wrap" vinyl (very different than the cheap vinyl I had on up to this point), so I don't think it would lay down very well over the pop rivet heads on the baggage floor.  Regular car wrap would be able to conform to the rivets with the addition of heat.  The car wrap is really just made to change the color of a car, so doesn't provide nearly the same level of protection as PPF, but it would still help to keep the paint from pealing away any more.

I'm not too worried about the aesthetics of the baggage area, just protection from long-term damage.  I grabbed the carpet I bought from Classic Aero to see what the fit is like.  It's a perfect match to the baggage floor, so at least my perfectionist side won't have to stare at bad paint forever.  If I put some better quality vinyl down under the carpet, I think it'll all be fine.  They make the car wrap vinyl in every color imaginable, so I can probably even find some dark grey to compliment the paint.  If I had it to do all over again I'd skip painting the entire interior and just use the car wrap vinyl over the primer.  Next plane.

Misc Wiring

I haven't updated the blog in a few days, although I have done some work.  I wouldn't say I've made any tremendous progress, just a few minutes here or there.  Small bites will eventually get this thing done though!

While Van's sells a physical flap position setup that acts as a position sensor to help control flap deployment, I opted to use the functionality of the ACM instead.  Van's setup basically uses a bar with detents and a physical switch to turn the motor off when a detent is reached.  Simple and old school, but way too expensive for what it is.  I sold that and instead purchased the small Ray Allen position sensor that the ACM can use the signal from to control the flap motor.  The sensor needs to be mounted in a way that it can connect with the flap weldment and move in/out along the arc of movement.  I eyeballed a location on the back frame of the flap housing and made an angled bracket to attach to it with screws.  The sensor will be bolted to the bracket, and the angle allows the arm from the bracket to be connected to the weldment at a position that enables about 1" of travel of the sensor from flaps fully down to fully retracted.  I am just using a piece of threaded rod from RC plane days to connect the sensor to the weldment.  It'll be dialed in to the exact location and connection point once the wings and flaps are test fit.

I bit the bullet and ordered the autopilot servos this week, so in preparation for those I made the wiring harness for the roll servo.

Pulling wires through the conduit in the center tunnel has become a real pain.  I decided there's no compelling reason to have the conduit under the tunnel itself, so I decided to pull it out.  I will still use a small run of conduit for when the wires pop out of the tunnel and run vertically up the firewall stiffeners though(just for aesthetics more than anything).  This will be a short run and much easier to manage.  I also decided to take the fuel boost pump out for now.  It was getting hard to manage the wires with it in the way.  I only had to undo two lines to get it out.  With that out, I glued down a bunch of cable mounts that will be used for the wire bundles and the fuel line.



I'm not quite sure yet where I'll route the wire bundles to get them up to the subpanel.  The outer ribs are often used - one bundle clamped under the bottom side of each rib to run them up to the subpanel.  That approach really restricts where the bundles pop out at the subpanel though.  For flexibility, I think I may put a piece of angle between those two outer ribs.  This will create an attach point for wire bundles anywhere between the ribs.  It's a little hard to see, but in the picture you can see the angle I'm holding.  I would use adel clamps on it to route wires.

It was painful to write the check, but I ordered my first round of electronic equipment a few days ago, and it's already here!  For now I primarily just ordered the behind-the-scenes items that are necessary to figure out the remainder of wiring, subpanel layouts, etc.  I decided not to order any panel mounted items (like glass screens, radios, audio panels, etc) until much later in the build.  While I don't anticipate any big changes in that equipment between now and the next year or so, they are basically computers, so I may as well wait as long as possible just in case something new comes out.  The beauty of the ACM system is that I don't have to have all of hose end devices in-hand to be able to wire up the plane.  I just need to wire up the ACM, then when I'm ready, the devices will go into the panel and simply plug into the ACM.

So for now I've got the ACM, transponder, ADSB, ELT, EMS (engine data), ADAHRS, and one GPS antenna (I still need to order a second GPS antenna for my backup EFIS, but I have the dimensions for it and can make the mount and run the coax without having it in hand).  That will keep me busy for a while.

Heated Seats Finished

With the power out for a few days, I haven't been spending much time on the plane.  I finished up the wiring for the heated seats though.  The seat bottoms and backs came wired with connections that I cut off, then spliced onto power plugs.

I mounted the female jacks on the edges of the center tunnel.  I drilled clearance holes in the flanges of the side panels of the flap motor housing so I can still take the panels off without having to remove the jacks.  Once the housing is in place and the seats are in, the jacks will be out of the way.  Just the act of turning the jacks to tighten them down caused chipping of the paint.  As much as I like the Stewart primer I've used, I really wish I had gone with a different paint for the interior.  Their Ekocrylic just can't take much abuse.  I think I'm going to have to cover the main interior panels with some paint protection film (the clear film used on car bumpers) to protect it from chipping.

Heated Seats, Control Stick Wiring

Continuing on with the wiring for the heated seats.  The switches have 3 square notches for indexing them in the holes.  Those were a royal pain to file since none of my files are really small enough to be able to get a full stroke.  I chipped away at them with a half inch of the tip of my smallest file, followed by the Dremel and some sandpaper until the switches just barely fit.

The relays and all of the associated wiring will mostly live in the spar carry through gap.  I made a couple of brackets to hang the relays from some existing bolts.

Of course the wires that could be short are long and the wires that should be long are short.  I briefly thought about cutting down the long wires just so there was less to stuff into the spar opening, but I don't have any matching pins to replace in the connectors.  So I just coiled everything up and moved on.

Here you can see where it all lives - one relay for each seat (at least I think they may be relays...I haven't actually bothered looking up the parts to see what they are).

The wires for the switches will connect in the spar gap and the power wires will exit forward in the new holes from yesterday and go to a fuse panel on the subpanel (the ACM doesn't have allowances for the heated seats.  I am putting in a simple fuse block for blade fuses to handle some of these random needs.).  The last couple of wires are for the power to the seats themselves and will exit out the aft side and down the center tunnel.  I want to be able to easily take out the seats without having to fish the connectors out of the tunnel, so I ordered a couple of barrel jack connectors.  I'll install these next to the flap housing (between the seats near the back) so they are out of the way but can easily be unplugged when necessary.

This small addition of heated seats doesn't seem like it should be a big deal, but it took  quite a bit of time to sort out!  I figure a warm wife is a much happier passenger though.

I still haven't decided on which control sticks to get, but I figured I may as well put wiring together for the functions I'm going to put on them.  At least as of this moment, I don't plan on putting any functions on the co-pilot stick.  The only thing that I think might be used once in a while is the push to talk, and that would be rare.  I may put a PTT button on the panel for the copilot, just in case it's ever needed.  Leaving it off of the copilot grip means I don't have to deal with wiring that side (and figuring out a way to easily connect/disconnect the wiring, since the copilot stick is removable).  On the pilot side I've wired up a harness that has PTT, roll/pitch trim, and autopilot CWS/Disconnect (control wheel steering - basically a function that allows you to hold the button down and temporarily override the autopilot, then have the autopilot take back over as soon as the button is released).  I went ahead and did the pin out for the ACM dsub since that is the same regardless of the grip I choose.

As I was working on the wire bundle for the sticks, I had a head slapper moment.  I looked at my notes and realized that I didn't twist the data wires for the two autopilot servos.  Oops.  If there's one thing I'm good at, it's doing something twice!  So I pulled out the 4 data wires for each servo and twisted the correct pairs together.  You'd think getting the wires pulled back through the same holes would be easy, but nope!  In between pulling them out and putting them back in, the holes apparently shrunk in size.  I did finally get them through though.  I'm interested to see what I get to redo tomorrow.

Spar Wire Holes, Flap Motor & Heated Seats

I've been spending gobs of time trying to figure out how in the world I will route all of the bulky coax up to the panel.  For a bare bones plane, the existing holes would be enough for all of the wiring, but the original plans are decades old and avionics have changed!  The issue is the spar carry through area.  The stock setup has four 5/8" holes drilled through it for wiring.  The center two holes are going to pretty much be filled up with data/power wire from the wings and rear of the plane.  That leaves the two outboard holes for the antenna coax and the pitot tubing (the pitot tubing will split at a T after it enters the fuselage from the wing - one tube going back to the ADAHRS box behind the baggage bulkhead and the other tube going forward to the subpanel for the Garmin G5 I'll be using as a backup system).  I think each hole can fit 2 coax cables.  I need room for the coax coming from comm 1 & 2 (I only need one comm for VFR, but I'd like a second comm once I upgrade to IFR, and it would be far easier to just run the wire and install a second antenna now), ADSB, transponder, and IFR GPS for eventual IFR navigator.  The GPS antenna that the AFS system uses is actually built differently, so it doesn't require a coax run, just data wires.  So that means I need holes in the spar area for 5 runs of coax plus pitot tubing.  At most I think I could manage 4 of the 6 with existing holes.

Van's realized this was becoming an issue over the years as systems got more complex, so they have a tech document that shows additional locations for drilling holes through the spar carry through.  You can drill a shocking number of holes.  Had I known I'd need more space, I would have drilled a few more holes way back when the parts were setting on the bench.  Now it's a lot more difficult.

I printed out the templates Van's has that shows the allowed hole locations for the different bays.  You can drill from a 5/8" hole up to a 1" hole.  The allowable location of the hole just changes based on the size (the template basically shows a box for each size hole - the center of the hole has to land within the box).  Access was easier said than done, but I did the gymnastics to get everything centered.

The horizontal center of the spar carry through is the least stressed, so it's best to drill the holes as close to that center line as possible.  I moved the holes up from that line about a half inch so I could use the unibit without fear of hitting the fuel lines.  The last thing I wanted to do was nick a line and have to redo it.

The aft side is pretty much the same story, but the hole is moved outboard a little because of the seat rib locations, creating a little jog from the aft to forward holes.  I had much better access here, so the holes were far easier to do.  I think the addition of those two holes should give me plenty of room for all of the wiring now. 

I'm at the point where finishing wiring means I need to also start installing the actual devices.  I grabbed the flap motor and reattached it to the housing and flap control arm.  The housing structure doesn't really fit well without having the seat cross brace in place, but it's okay for the time being.  I've been putting off riveting the top skin for a long time, but that day is coming.  I can't put the cross brace in until the skin is riveted at the front sides.  I think I just have to accept the fact that I'll need to crawl back into the tailcone to finish wiring no matter what, so I may as well put the top skin on so I can move forward with other things.  I won't be able to rivet the skin completely until I have help, but I can rivet the front part that keeps me from installing the cross brace.  Installing that cross brace has a trickle down effect.  After that's in, I can finish the flap housing and the canopy latch system can be fine tuned and finalized.

Anyway, until then it's a piecemeal approach to tasks.  I need to figure out a mounting system for the flap position sensor, but to do that I need to know what the throw of the flap arm is.  This only runs on 12v, so I'll have to grab the car battery to run the motor in and out and determine the up and down limits.  I didn't feel like pulling a battery out of the car today though.

One of the other big chunks of wiring yet to do is for the heated seats.  I need to locate where the switches will go, where to fit the relays (one for each seat), and how to route power to the seat cushions themselves.  I saw that someone with similar seats actually put the relays in the spar gap, which I think is a great idea to save space.  I'll make a bracket for each relay that will attach using one of the existing bolts in the spar carry through and hang the relay down in the spar gap below the seat pan.  This means that the most convenient place for the switches is in the center of the seat pan, right over the spar gap.  I hate that I'm having to drill in painted metal, so here's hoping nothing chips too bad.  I laid out the location of the switch holes in the right seat pan (the right pan extends past center, whereas the left pan does not).

Thankfully the hole cut pretty cleanly and the paint will be fine.  I still need to file a little square anti-rotation notch in each hole to keep the switches clocked in the right position.  Another day.

Wing Wire Terminal Blocks

I spent most of my afternoon tracking down parts to fix the latest problem with a vehicle, so I didn't spend much time with the plane.  I started out by organizing and tightening down all of the terminal block screws.  It's definitely a lot bulkier than it would be if I just used one of those circular connectors to tie the wing and fuselage wiring together, but the terminal blocks are simple and inexpensive and future modifications will be easy.

One thing I don't love is how thick the clear heat shrink tubing over the labels is.  It looks good, but when you have a bunch of wires together and the labels are all in about the same place, the diameter of the bundle really changes and makes for a messy look.  I'll get over it though.  I glued a small cable mount to the floor to hold the wires down and forward before they go up and through the first rib hole.  The aileron pushrod will come through this area, so it needs to be able to keep clear of anything that could bind on it.

The design of where the wire holes go in the ribs isn't well thought out.  Right in the middle of two of the holes is the control column mount.  A lot of people drill brand new holes at the bottom of the ribs a few inches back from the spar, but I decided to keep the original holes and bend the wires around the mount.  It obviously wouldn't take long for the sharp edges of the mount to chew through the wires, so 3D printing to the rescue again!

In 5 minutes I had designed a couple of plastic pieces to slip over the edge of the mount (just glued in place with Goop - basically contact cement on steroids.  It's amazingly strong once it cures for a few days).  I love that 5 minutes of CAD work and an hour of printing gave me a solution that kept me from having to drill a bunch of new holes in the ribs.  I didn't get any pictures of these in place, but I think they'll work fine.  I wrapped a little silicone tape over the wires where they cross the plastic as well.  I designed a little lip in the top and bottom to make sure the wires didn't migrate over the plastic and onto the aluminum mount.

Flap & Trim Wiring

I hope I'll never have to replace them, but I want parts like the flap motor and sensors to be easily swapped out without ripping out wiring.  I put molex connectors on the flap motor and flap position sensor and put together the wire bundles to run to the panel. 

I did the same for the aileron trim servo.  The wires on the servo are really small, so I had to double up the wire to get the molex pins to crimp well.  I think the crimps on the insulation probably would have been okay, but it didn't look like the crimps were all that tight because of the size of the wire.  I put a little shrink tubing on and crimped over that.

I pulled the flap, sensor and trim wires through the center right spar bulkhead hole.  The thought of wiring was pretty intimidating at first, but it's really not that bad when you take it bit by bit.  The most nerve wracking part at first was just the unknown and not knowing what went where.  I spent hours and hours in front of the computer researching all of the device requirements and the ACM functions.  AFS (makers of the ACM) have fantastic documentation as well, which was a huge help in figuring everything out.  Having a spreadsheet done with every device, wire needs, and termination points listed has made the actual act of wiring a non-event so far.

Next up I'll drill the holes in the seat ribs and run the wing wires to the terminal blocks.  The fuselage devices I still need to figure out requirements for and wire:

• Seat heaters - have to figure out where the switches will live
• ADAHRS - lives behind the baggage bulkhead. Pitot tubes go to it from the wings, data wiring comes from it to the subpanel
• ELT - can't wire this until I order the actual unit.  It will go on the side skin bracket directly behind the baggage bulkhead
• Transponder antenna - behind baggage bulkhead on the floor
• ADSB antenna - behind baggage bulkhead on the floor
• Comm antenna (x2 - probably just use one comm for a while, but may as well install the 2nd for future IFR) - outer bay under the seats
• GPS antenna (x2 - one for AFS system, 2nd for future IFR GPS) - top of the tailcone

I think I can get most of the data wiring done without having the devices in hand.  I'll have to buy coax for the TX, ADSB and comm antennas.  The coax is going to be tougher to route, purely because of its size.  I may have to drill a few new holes in the spar bulkhead to accommodate all of the antennas.

More Wiring

More wire harnesses in the works today.  I finished the right wing terminal harness (includes the lighting and roll servo) and the pitch servo.  The pitch servo was my first experience with D-Sub connectors and shells.  The pins are easy to deal with since I ponied up the cash for a professional crimper that sets all of the stops and crimp amounts automatically.  I found the crimper on Craigslist in Colorado for pennies on the dollar.

I pulled both the left wing wires and pitch servo wires through the left center hole in the spar bulkhead.  So far, the only bundle going through the right center bulkhead hole is the right wing wiring (I'll probably pull the flap motor wires through there as well).  I still need to drill the new holes in the seat ribs to run the wing bundles through to the terminal blocks.

At this point I'm just hanging the wires over the subpanel to keep them out of the way.  I'm going to have to do some research and planning to figure out where all of the devices will go on the subpanel so I know where I can drill the holes to bring the wire bundles through.  Van's has virtually zero guidance on the wiring, so I'm very thankful for the 30 years of info by other builders on the internet!  The downside is that a lot of the info on the internet is from guys who built their planes before glass panels were a thing, so the approach tends to be a lot different.  I do think that by going with the ACM I'm simplifying things quite a bit.  For the most part I just have to figure out how to route wires from the peripheral devices to the ACM, then the ACM handles all of the circuit breakers and middle-man interfaces between devices.  Many of the wiring harnesses that are needed for between the ACM and devices in the panel will come with the ACM.

Left Wing Terminal Block

No exciting photos, but after hours and hours of planning I'm ready to get going on some more wiring.  I don't have a perfect plan for how everything will be routed yet, mostly because the size of the eventual wire bundles will dictate that to a certain degree.  The wiring from the wings will come in through the side skins and end at a terminal block under the seats (the outside rib bays will be where the comm antennas are).  Some people run continuous wiring from the wings to the panel, but doing that would mean I'd be stuck not being able to finish wiring until the wings are on for good.  Putting in terminal blocks means I can run all of the fuselage wiring and be done with it, then just connect the wire from the wings once they are attached.

I'm probably going to have to drill some new wire holes through the seat ribs.  The holes that I drilled in the front of the ribs per the plans won't really work because the brackets for the control sticks are right in that path.  I have no idea why the plans have you drill in that location.

I measured the route from the terminal block, up through the center tunnel and up to the subpanel.  About 9' of wire should give me plenty of length for the left side.  I labeled all of the left wing wiring and crimped on ring terminals for the terminal block.  I'm going to wait on attaching the dsub and labels on the other end until I have most of the other fuselage wiring routed so I can cut it all to the final length.  I need to lay out where the ACM module will go on the subpanel so I can figure out how much of a loop to leave in the wire bundles.

Starting Wire Runs

I have actually been doing a little work on the canopy over the past week, but it's been so incremental that it really wasn't worth photos.  I think I have the front bubble fitting pretty well at this point.  The next step is to use the Sika adhesive to permanently attach it to the frame.  As I was reading up on Sika, I found out that it's activated by humidity, and on a normal day it has about a 1 hour time before it begins to skin over.  With it being 80-90% humidity at this point in the year, I'm afraid that I'd be in a serious rush to get nice filets made before it all started to firm up.  I decided to just put a pin in the canopy for now and move on.  I'll attach the bubble next summer when conditions are a little better.  To give myself more shop space, I went ahead and took the canopy and frame back upstairs to store them.  I also took the aft top skin off to make wiring a little easier.  As usual, it feels like two steps forward, one step back, but that's the name of the game!

The center tunnel between the seats was going to be really awkward to get wires run through while the elevator pushrod was in, so I bit the bullet and took the pushrod out.  I also did my once a month vacuuming of the fuselage.  I'll fill it up with more shavings soon enough though.

The last thing I need to do in the left wing before I can close it up is figure out how to run the wire from the pitot regulator to the pitot itself.  I didn't really want to drill more holes in this rib, so I decided to make a wire support that just attaches under two of the existing mounting screws.  I fabricated a little bracket and pop riveted a wire mount to it.  For now the wire is just looped and zip tied loosely.  Once I attach the wing skin and the pitot is in permanently I can attach the wire and tighten the zip tie.  I drilled the remaining hole at the base of the rib for the other pitot tube.  Because the blue pitot tube was more off of the center line than I wanted it to be in order to mate up with the aluminum tubes from the pitot, I took the heat gun to it and reformed it so it landed in a better spot.

There are only a couple of wires that run all of the way to the very back - the wires for the elevator trim servo and tail light.  I crawled into the fuselage and zip tied those to the cable tie mounts I had glued in a long time ago.  I only zip tied them about half of the way forward, because I think I'll also end up putting the ELT antenna near the tail, so that wire will also need to be captured by the zip ties.  I ran the wires up through the left side of the center tunnel.

I'm not 100% sure yet how I want to route the wires from the seating area through the forward center tunnel and up to the subpanel.  I think using some of the corrugated tubing will help keep it organized, so that's what I'm trying first.  I ran tubing underneath the fuel pump base.  It will run underneath the tunnel cover until it gets to the firewall, then it will exit and run up the sides of the firewall stiffeners.  It's probably hard to picture right now, but it can't go up the center because the cabin heat valve will be there.