Back to the Firewall

Getting back to the firewall, I installed both the Dynon ammeter shunt and the ANL current Limiter.  These guys are in line between the alternator and the battery relay.  Basically, it works as a breaker to protect the Alternator, and allows for measurement of the current being produced by the Alternator.   Eventually, this will be visible on the VP-X screen on my Skyview.   Looking forward to that day..

These aren't the best pics so I will most likely update eventually.. but you can see where I installed them and as well where I placed the doubler on the inside of the firewall.   Next step is to connect these units all together with thin copper bar.

Antenna Doublers

I don't know why, but today I decided to attach the Comm Antennas (temporarily so I could get the doublers figured out.)..  Not much information about how to mount these, but basically they go through the skin; need to be about 3 feet apart; and since they are out in the wind will need to have doublers so that they don't consistently flex the skin and eventually start to pull and or tear at the skin.  Also, they need to have a metal ground plane, which is no problem here since the airplane is all metal.  ;-)

A lot of people, just add a second layer of .032 or .040 where the antenna penetrates and move on.  For me I was still concerned about the amount of flex in the skin, at least with these bent whip antennas.  So I decided to tie the doubler into one of the seat ribs.  According to the aircraft handbook, this is the way you are supposed to do it anyway.  I decided to mount them under the seat pans, on each outside bay.  The actual center post is exactly 9 inches aft of the main spar web, which is as far back as I could get them.  Since the skin at this point in the fuse has a slight fore/aft curve, I decided to cut the angle so that I did't have a straight edge the length of the doubler.  This allows for the slight curve with no problems.  Happy the way this turned out, now I just need to prime or alodine these parts and get Bekah to help me rivet them in..  

Gear Leg egress, Flap Sensor

While the engine mount was on, I measured out the bit of firewall flange that needed to be cut back to allow for the gear legs.   You can see in this pics what I mean by this.  Basically I used a die grinder with cut off wheels and various and other bits to trim back the flange.  Turned out OK, but in the process I sure breathed in a lot of metal..  Probably should have been wearing a mask for this one..

After that I started working back inside the fuse again, on the flap sensor.  This is a cool unit as it will tell my EFIS where the flaps are and I will get a readout on the panel if they are up/down, or in the middle.  It also will allow my flaps to be set so that one flip of the switch will either raise them all the way then stop, or will raise them to a preset point.   Without this sensor, I would have to hold the switch and count or look at the flaps to know exactly where they are.  I didn't take any shortcuts on installing this sensor.  I created a fully serviceable mount, and took the time to make sure it was in line and was a straight shot at the sensor.  Hopefully a long useful live out of this one.  Those who are familiar might recognize some of the parts I  used on this.  Lets say they aren't TSO'd but are fully functional.  ;-)

Fuel Line Penetration, Engine Mount

Lots of Progress over the last couple days on big stuff and little stuff.  I mounted a few firewall nut plates that are used to hold the oil pressure line, but won't even show pics of this..  The stuff I am proud of is the Fuel line penetration of the firewall, and the engine mount.  First I used a step-drill and after careful measuring installed the doubler for the fuel line per the plans.  This turned out pretty well except I riveted it too quickly after painting and bunged it up a bit..  Touched up though and its now looking good.

What I am really excited about is how well the engine mount drilling went.  I was nervous because drilling through the stainless firewall is always a risk.  The drill bit sticks, pulls chips in under the stainless, tries to lodge them where you can get them out, and deforms it etc.. In general it is just tough to drill through the firewall, and with these holes, they go through a lot of metal layers, first stainless firewall, then some aluminum doublers, then finally into a doubled over metal web that connects to the rest of the forward fuse structure..  Lots of metal for sure, but for good reason since it holds the entire engine on the front of the plane...

The mount was secured to the fuse by bungees and clamps..  Then I used two bits, first 1/4 inch bit inside some scrap tubing.  This worked great as the tubing fit snug in the engine mount hole, and the 1/4 inch bit didn't wander at all.  I drilled the top two holes, then used a AN4 bolt to hold the mount in place.  Then I pulled the tubing and used my 3/8 inch bit, and with some BOE Lube, went to town.  Pressing firmly on the mount to try to keep the stainless from pealing up underneath.. Turned out Great..  I am really excited how clean my holes are, and how accurate they are..    here are some pics, you can see the one with the bolts in place sticking through the firewall, the holes are clean !

After I did the 4 holes around the outside, I made some small spacers, and drilled the two lower central holes the same way. These were a bit easier, because once through stainless all you had to drill through was aluminum.

All in all, great progress  !

Fuel line plumbing, Wing Nutplates, Battery, Starter Relay Bar

I got lots accomplished this weekend and don't know where to start logging it..  First off I finished all misc items needed while the wings were mounted, namely the fuel line tubing is now complete.  I will pull these apart and save them for the next year or so until the wings are finally mounted for good.  These complex bends in 3/8 inch tubing are a pain and I am just really glad they are done.

 After the plumbing was complete I pulled the wings and finished up all the nutplates and misc items to get the wings ready for final assembly.  This piece alone took about 3-4 hours, much longer than I expected..  Drilling all those nutplates is crazy...  Some of them were countersunk, some dimpled, different nutplates were needed for each scenario..  It wasn't trivial, but doable.


After the wings were complete I put them back in the cradle reorganized the entire garage and started do to some minor work on the firewall.   From here forward it is pretty much going to be all firewall, and electrical work.  In fact, pretty soon the plane will be on its own gear..  For now I mounted the battery, and also connected the Battery and Starter relays with the Copper Bar as indicated in the plans..  There are many amps that go through this connection when starting the engine, so it needs to be solid.

Flap Hinge Pin Secure

I am just about wrapping up the wings but wanted to get a few more items out of the way now so I don’t have to worry about them later.  Here you can see how I decided to secure the flap piano hinge pin.  It goes on easy and is very secure.

Wing Root Fairing, Tank Attach, and Vent Tube work

This weekend I put about 6 hours into the RV.  Got lots done and am now almost ready to remove the wings and get them up to the airport.

I started with a test fit of the root fairings, they are pre punched and can cleco into the back part of the wing, but where they wrap over the tank there are no pre-drilled holes.  I measured out a line 3/8 inch from the edge of the tank and after aligning the holes from the fairing I started drilling into the edge of the tank skin.  Once I reached the leading edge of the wing, I wrapped the fairing around and anchored the underneath to the aft most point on the tank and finished drilling.  Took some time, but it came out straight and looks good.

After that I started working on the tank attach points and vent tube.  for the attach point, i bent it per the plans until it mated well with the tank flange.  To drill the hole I just used my 1/4 inch angle drill here and leveraged the steel attach point to help keep the bit centered as I let her rip.   I did find that it was easier with the fuse attach point bolted down..  Made it solid and drilled straight and clean.  I used a sharpie and marked 1/4 seam away from the fuseloge.  Then removed them, cut them along the seam and cleaned them up.   Now ready to dimple and prime.

The vent tube was pretty easy, just some short runs here to connect the vent out from the tank into the fuse vent pick up.  Easy..   

We have Flaps

Over the last couple days I worked on the flap egress holes..  The egress holes are holes right through the bottom of the fuse where the flap pushrods go.  I started by just mounting the flap bolt/bearing without the pushrod, then found where it contacted the fuse and trimmed to fit.   Basically this takes you up the side of the fuse a bit and underneath.  Vans marks places where this hole starts too which helps.  Once the bearing was clear, I lowered the flaps all the way to see where the rod ended up.  Cut the hole to that location using my dremel and a small sanding drum... Then wouldn't you know it after about 2 hours on the first side, and a third hour on the second side I have flaps.  They work great, up, down, up, down..  Bekah even likes them.  ;-)

Wing Incidence Complete

After you set the incidence and sweep on the wings, you lock it in by drilling a bolt hole in the rear spar of each wing.  To set the wings I used 4 plumb bobs and string along the leading edge to ensure tip to tip they were straight.  With only one mount and removal of the wings I was able to trim the rear spar up enough to get the sweep what seemed perfect to me.  I confirmed by measuring and getting the exact same measurement on each side from a common point on the tail.   I don't think I can do anything more to ensure the wings are straight.

Then I used a bubble level and measured the incidence on each wing  from tip to tail with a 3 inch riser off the rear spar.  I don't have any pics, but the fuse had already been leveled, so with the spacer on the rear spar and the level on the front spar, I moved the aft part of the wing up and down until the wing was level.  So basically the rear of the wing is 3 inches lower than the main spar, when the fuselage is level.  Its most important that both wings are even and level, so I measured this several times.  With both wings leveled out I was finally set to drill the rear spar retaining holes.

These holes are arguably the most important holes to drill correctly on the entire build.  Edge distance is critical as well as a straight clean hole.   I used an undersized reamer and stepped up to it with various drill sizes, and took about 2 hours to get the hole thing done.   I am pretty darn confident that I nailed it.. At least I am happy with the outcome and will trust this to hold on the aft portion of my wings.  ;-)

Also, before I did this I installed the flaps to ensure they were even on the fuse, they looked good at this incidence, also I noticed that with the hardware bolts in the main spar attach holes, there was about 1/4 inch slop out at the wingtip.  Something no builders have talked about.   However, the slop was even and consistent on both sides and only in the up/down direction, not for/aft or longitudinally..   I am good here, but just something for other builders to note.

Mated the Wings ! - Kinda like building a ship in a bottle...

I spent the last couple days rearranging the garage so that I could get the wings mounted for the first time.  In building, you need to mate the wings a couple times about midway in the build to set the sweep and incidence, drill the fairings, drill the flap holes, drill the fuel tank bracket, and finish the plumbing for the fuel line and vent..    So all in all I will have the wings on for a couple weeks.  This is the first time in the build that Bekah will need to park her car outside for a while and I am bummed that it is December, but the time of year can’t be planned.

Anyway, I organized the garage and measured everything out, looks like it will fit..   I lubed up the spar and drift pins with Boe Lube, filed an ever so slight bevel in the spar per the directions.  Got the wings prepped by removing the flaps and anchoring the ailerons..  Then had a fellow builder and Bekah help slowly slide the wings  into the fuse.  It went really well and faster than I thought.   The whole process after the prep was done only took about 30 mins I assume.

Looks awesome !  I can’t  believe how exciting this moment was to see the plane coming together in my garage..  Kind of like a ship in a bottle, but very cool just the same.  Once the wings were mounted I put some plumb bobs over the leading edge at the root and tip and used them to get an idea of the “sweep” of the wings..  Its only about 1/8 inch forward sweep, and will need to trim a small amount off the rear spar attach point to correct this.  All builders have to do this, but to see how much needed to be trimmed, I had to mount the wings first.   Its the forward bar on the fuselage spar where it interferes with the wing rib flange.   Quite common..  Tomorrow they will come off and I will trim it all up then get them back on to set the incidence..   Looking good ! !