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Javron Cub Building for Dummies

Floorboards

Floor boards
The standard Javron kit comes with pre-cut ¼” Baltic birch plywood floor boards. There is a good diagram of these in the Backcountry Super Cub build manual (figure #78). The diagram shows a notch in both the rear baggage panel and the front baggage panel to fit the dogleg tube – you’ll need to make this as discussed below. Also, there is a 6[SUP]th[/SUP] board not shown on the diagram. This is the back of the rear seat. When I was in Brainerd, Jay tossed a few pieces of scrap plywood into my kit. These scraps have been extremely helpful for: testing stain colors and testing out various drill techniques. If you’re ordering a Javron kit, you might ask Jay to do the same for you.

Staining boards
The first thing I did to the boards was to stain them. The Backcountry manual helpfully points out that the untreated boards can easily be marked or stained. I guess the safest approach would be to varnish them as well, but I knew I’d be drilling and sanding them to fit. So I split the difference and just stained them. For the stain, I used Minwax Cherry stain and followed their directions. One of the smaller cans covered the top of all the boards and the backs of the two seat boards. Before staining, I sanded the boards smooth with 220 sandpaper.

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Fitting rear baggage panel: starting in the back, I sanded a slight bevel in the rear edge to better match the angle of the rear end. Throughout, you’ll notice that I hand-sanded the boards to get the proper fit. I could have probably used a different technique and saved a lot of time. But if I’m saving time that means the process is faster which also means that I can screw something up much faster! So I stuck with sanding. So far, I’ve found that these kinds of manual tasks (e.g. sanding or filing) don’t really seem to add a lot of time to the build. And they're nice distractions at the end of a work day. Best yet, they can be safely performed while enjoying a beer. (There’s a saying in the wine country that it takes a lot of beer to make good wine. I’m finding that it’s taking a lot of beer to build a plane.)

The sides of the rear panel were in pretty good shape. I will talk about the aluminum side panels in a later post, but I had them installed for fitting the floorboards to ensure there was good clearance. The front edge required a notch to be cut out for the dogleg tube. Using my trusty calipers, I got an idea of the size of the required hole and marked where it should go on the board. I removed the board and attempted to drill the hole with a hand drill. Guess what? Drilling a partial hole at the edge of the board with a spade bit and a hand drill is darn near impossible. That bit REALLY wants to walk. So, I bought a drill press off Amazon and was able to drill a proper hole.

Front baggage panel: this was fit similar to the back panel with a corresponding notch to fit the other half (approx.) of the dogleg tube. The dogleg tube is farther forward at the base than at the tube. Therefore, the hole in the front board needs further work so that the dogleg tube can “tunnel” under it. Using a round file from the file kit noted above, I angled the hole until the tube fit in nicely.

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Seat panel: The next board forward was the bottom board for the rear seat. Since I will have underseat storage for this seat, the bottom board will be hinged to the front of the front baggage panel. Therefore, when fitting this board, I also needed to make sure there was appropriate clearance on the sides through the range of motion of the seat panel.

Securing baggage panels: Unless I overlooked it, the kit does not come with hardware to secure the rear baggage panels (Keep in mind, Jay is constantly improving the kit. Accordingly, any comment I make about what I got may not be applicable to new kits). However, the kits does come with hardware to secure the front floorboards. So, I just ordered more of the truss head stainless steel 10-32 screws from Aircraft Spruce (Part# AN526-1032R10). By the way, not only does Jay provide a fairly complete hardware kit in neatly arranged plastic cases, he also provides a detailed inventory sheet of exactly which hardware should be in those cases. This makes confirming the inventory helpful (hey, they’re human and might miss packing a screw among the hundreds of pieces of hardware). And if you want to order extras of anything, you know exactly what the parts are.
To locate the proper spot to drill the holes, I measured the width of the “trays” that the boards sit in. If I recall, it was about 2 cm. So, I evenly spaced 3 holes down each side of the rear panel, 2 in front, 2 matching holes on the rear of the front panel and two on the sides of the front panel. I center punched the spots and then drilled out the holes (top down). These holes will get nutplates. I just need to decide between countersinking and dimpling.
Now that the baggage panels were secured, it was time to fabricate the hinge connecting the baggage panel to seat panel. I purchased the 1.5” aluminum hinge from Aircraft Spruce (part MS20257P4-3). Then I shamelessly copied the layout of the model Javron that was at Oshkosh.
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This gave me both the length and the screw pattern. I used a hacksaw to cut the hinge (cutting the wire separately) and then cleaned up the edges. Using the calipers, I located the holes in the middle of the hinge. I center-punched the holes then drilled and deburred them with the hinge out of the aircraft. I also closed the hinge and redrilled to mirror the hole pattern on the other side. Finally, I placed the hinge back in the plane on the floorboards, secured it with clamps, tested the hinge action and then drilled holes in the boards.
Now the dilemma. Underneath the hinge and boards is a crosstube (which is covered by underseat storage if you have it). If you just put screws through the hinge with nuts on the back, I think you will dig into that crosstube over time. Instead, I’m using this marvelous invention known as the t-nut.
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This nut sits flush with the board. I ordered some ¼” 6-32 t-nuts off of Amazon (https://www.amazon.com/gp/product/B07HYPWCQ7/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1) Once they arrived, I measured the size of the “base” (1/2” if I recall) and also the outside diameter of the barrel (using my…say it with me…calipers). I up-drilled the holes to accept the barrels and countersunk them for the bases.

At this point, I think I had messed with the boards enough and it was time to varnish them. First, I used a tack cloth to get the boards as free from any debris as possible. I used Minwax Polycrylic Clear Gloss and brushed three coats on the boards. Between each coat, I sanded with 220 grit sandpaper working on removing any brush marks. I also put one coat on the bottom of the boards to seal them. I also put a couple of coats on the back of the rear seat board.

The last challenge was that the t-nuts were actually slightly longer than ¼” and would be a little proud of the board thickness if I did nothing. So, I filed them down slightly (making sure the threads still worked after modification).
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I installed them by placing scrap floorboard pieces above and below the board and squeezing the t-nut in with pliers.
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And this is what everything looks like in place
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I’ll cover the front floorboards in a separate post.
 

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Floorboards (cont)

Front floor boards
The front floor boards were fit similar to the rear floor boards. They take a little more finesse to get in due to the torque tube saddles, front seat tabs and a generally smaller space. One important point to note is the Javron contruction method for the bottom front tubes of the fuselage. Note in the following photo how you can see daylight between the edge of the floorboard and the side tube of the fuselage? If I understood Jay correctly, this tube (circled on the next picture) is not set in a jig when the fuse is welded rather it is manually placed. Accordingly, while the floorboards are CNC cut, the spot the front floorboards goes into may not perfectly match up.

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When I first installed the front floorboard, it was actually resting on the side tubes. Accordingly, I had quite a bit of sanding before I was happy with the fit. Once I was happy with it, I clamped the floorboard in place and drilled the initial anchoring holes through the rudder pedal supports in the front of the frame. Since I was drilling up through the wood, I also stuck another piece of wood on top of where the drill would surface through the floorboard to minimize splintering as it breached. I continued drilling the other anchoring holes. These are pretty easy because they are all through tabs fixed to the frame. Some of these holes were difficult to get a backing board on. For these, I just started the holes and completed the drilling after I had removed the board from the plane and could better attach a backing board. I also needed to drill holes for brackets that would hold the front floorboard to the bottom tubes. Piper drawing #13380 shows these 11” along the bottom tubes from the front of the fuselage. I located the brackets for these in that general area, got them to look right, started the holes and then redrilled them on the workbench.
I followed a similar process for the rear floorboard. Jay made sure to point out the bend in the fuselage which occurs under this board. If you’re not expecting it, you would think something was off. He also suggested you might want to glue in a couple of pieces of the spare ¼” plywood to lessen the bend.
I varnished these boards similarly to the baggage boards. However, I applied four coats instead of three due to the beating these get. I may add another coat or two before final assembly.

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Finally, I plan on following Jay’s lead and installing nutplates, Monadnock clips (Aircraft Spruce Part# 04-00153) and a couple of inspection covers to allow the floorboards to go in and out after cover. Something like this (not my plane):

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I found a used brake from an HVAC guy who was selling an ancient pan brake. Highly recommended. The harbor freight brake is narrow and you cannot bend a box, which is nice to have. The other took I find helpful is an electronic nibbler to cut large sheets of aluminum. I can't find a shear at a reasonable price. A neighbor has one, but is difficult to haul my aluminum over there every time. I may be a slow study, but I find myself remaking parts. Usually, I have it how I like it on the third try.
 
I found a used brake from an HVAC guy who was selling an ancient pan brake. Highly recommended. The harbor freight brake is narrow and you cannot bend a box, which is nice to have. The other took I find helpful is an electronic nibbler to cut large sheets of aluminum. I can't find a shear at a reasonable price. A neighbor has one, but is difficult to haul my aluminum over there every time. I may be a slow study, but I find myself remaking parts. Usually, I have it how I like it on the third try.
look at it this way, engineers have tried to make a decent vehicle for over a 100 years now, and they still cant get it right, come fairly close once in awhile, then they go back to there old junk ways.
 
Sam, If you want to get an idea on details go to http://geared2survive.com/supercub It is a Backcountry but it was when Jay was doing the kits for them. I am finishing the fourth Supercub and the next one is Javeron's PA-12. If you have any questions just ask.
 

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PIA as you have to drop the oil cooler off. It isn't too bad to get behind it and I can get the mags on and off if need be.
 
I would go with P-mags and the owner is going to have me change it this winter. That's an Aerosport Power O-320 putting out about 190hp.
 
Whoever wrote up the website is not totally informed with information on the original Piper Super Cub. .035" wall engine mount tubes? There was another but I can't remember. I like to install the engine and route controls, hoses and wires like Piper did. Unhook the tach and swing the engine. Takes me a couple of minutes and then I can easily pull a mag off. See many Super Cub rebuilds where this consideration is not made and it makes maintaining more time consuming.
 
Steve. It’s a new airplane. You’ll never have to swing the engine. [emoji849] especially if it has slick mags.


Sent from my iPhone using Tapatalk

I remember that well. ;) Primer lines, oil pressure, engine controls, wiring. PITA
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The Vetterman exhaust doesn't have the heat muff in back of the engine like the stock Cub so it really opens it up.
So does the Sutton. It isn't that hard to route things like Piper did so you can swing it to pull a mag. Pays dividends the first time you have to do it but I mainly work on certified stuff and prefer to do it like the manufacturer did. I figure they built like 10,000 of these things, they kinda figured out what they were doing. Every time I change or modify something I have to think 3 steps ahead and a lot of times it bites me in the ass anyway.
 
So does the Sutton. It isn't that hard to route things like Piper did so you can swing it to pull a mag. Pays dividends the first time you have to do it but I mainly work on certified stuff and prefer to do it like the manufacturer did. I figure they built like 10,000 of these things, they kinda figured out what they were doing. Every time I change or modify something I have to think 3 steps ahead and a lot of times it bites me in the ass anyway.

But it’s a new airplane. You won’t have to swing the engine
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Sent from my iPhone using Tapatalk
 
Metal Headliner

Metal Headliner

Apologies in advance, this post is a little like War and Peace.

I went with the metal headliner when I ordered my kit. This step was fairly intimidating to me since there were a lot of surfaces involved that all needed to work together. It all worked out in the end. But I will say that I would be much better at it a second time through!

In the Javron kit, you will receive 7 pieces that make up the headliner: 1) a large piece that becomes the top/back, 2) two side pieces roughly cut for the D-windows, 3) two window channel pieces that will connect the sides to the D-windows; and 4) two top front pieces.
The first thing I did was go to my local art supply store and buy some poster board to re-create the top/back piece. This is not a necessary step but it allowed me to mess around with things to get a sense of how everything would fit together. It made my subsequent conversation with Jay much more informative.

In talking with Jay, we discussed the basic process as follows (I’ll go into more detail on each item):

  • Bend top/back piece
  • Match drill holes from top/back piece onto side pieces and cleco together
  • Insert D-window channel pieces into channels
  • Position “box” in fuselage and temporarily secure it
  • Mark, on side pieces, where holes in channel pieces hit (those holes you can access), and scribe channel piece edge onto side pieces
  • Remove everything
  • Drill holes that were marked above and, using scribe line, mark and drill remaining holes
  • Remove excess material on side panels so that D-window channels are flush
  • Dimple and flush rivet d-window channels to side pieces

Here’s “the rest of the story”

Bend top/back piece

Here is a picture of the top view of the flat top/back piece. By the way, I know this is the top view because of the notches in the bottom corners which create a “tab”. That tab will be attached to the bottom of a horizontal member that supports the upper baggage shelf. The notches are different sizes because the tubing for the dogleg comes it at different angles – and the larger notch has to be on the right. Look at your fuselage and this should become clear.

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From top to bottom of the picture: there are two “tabs” at the top which are intended to be bent back to give the front some stiffness. Jay mentioned to me that he believed the front was a little long on his CAD drawing for the standard width cub. I found this to be the case and bent them a little farther back…eventually.

The hole is for the shoulder harness for the rear seat to pass through.

Further down you will note that the sides flare out. The point at which the angles of the sides changes is where you will bend this piece to create a top and a back surface. I measured the angle of this bend, based on the side pieces, as 125* but don’t take my word for it!

On the bottom of the piece, you will put in a couple of bends so that the very bottom tab essentially points straight back and attaches to the underside of a c-channel piece that supports the upper baggage compartment floor. I’ll refer to this part as the “tail” below.

You will also need to put in a V-bend which starts at the center of the front piece and extends back to the sides at the point where the top bends to the back. This will help add stiffness to the top. It will also put a peak in the front which will maximize the head space for the rear seat passenger. Based on the front pieces that the top sits in, I estimated that the peak at the front would need to be about 10*. So each side of the “V” would be 5*. When bending later, I thought this looked like too little of a bend. So I bent it more…only to soften those bends later!

Here is a picture of the underside with the top/back bend and “V” bends laid out.

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I got access to a very nice bending brake and was able to make these bends. The only advice I can add is: 1) practice before you bend the good stuff, and 2) plan the bends in advance – seems like you want to go from the middle out (i.e. start with the top/back bend and work out from there). Also, you may want to delay on bending the front tabs up to confirm that the front of the top piece of the headliner terminates where you want it to.

Match drill holes from top/back piece onto side pieces and cleco together

The top/back piece is pre-drilled along the edges. Also, the side pieces came pre-bent along the top and back with little edges that overlap the top/back piece. I turned the top/back piece upside down and took one of the side pieces and matched it up to the top. I secured the two pieces with cleco clamps and match drilled the sides with the top with a 3/32[SUP]nd[/SUP] bit. As I went along, I inserted clecos in the match drilled holes.

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This was a somewhat tricky step because you have two odd-shaped pieces that don’t naturally sit in a state to facilitate the drilling. As such, its important to look at all sides continually to ensure the two pieces are mated properly. What may look fine from the inside may have actually migrated a bit when looking at it from the outside. At any rate, I repeated the process with the other side as well and soon had something resembling a headliner.

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Insert D-window channel pieces into channels
There are two pieces that go into the D-window channels. One already formed to the window is shown below. By making slight bends between each of the segments, they are easily formed into the shape of the window. Clothes pins are a great way to secure them. Now is a good time to make sure that the tabs which will rest against the side pieces are not bent too far inward.
Also, keep in mind that the bottom front of each of the pieces will go under an interior panel piece on each side.

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Position “box” in fuselage and temporarily secure it

Now it’s time to put the big metal box inside the fuselage. Starting from the back, I slid the “tail” in between the top of the dogleg tubes. I then secured the top by tying a clothes pin with a string* to the top stringer and dropping it through the seatbelt hole in the top of the headliner then tightening it to where it was “about right”. (*In a pinch, I have heard that a daughter’s scrunchie can be used for this purpose.)

Key learning for me: a number of times, you will need to get things to be “where they want to be”. I first learned this with fuel lines. We’re dealing with light materials and they can easily be “persuaded” to go just about anywhere we want to put them. But its much better to have a part that is in place in its natural state rather than under force to be there. This takes patience (for me!)

Back to the headliner. It was helpful to me to visualize how the headliner is eventually secured. In the back, as previously mentioned, it is secured to the bottom of the c-channel the supports the upper baggage floor. On each side, it is secured to the D-windows but also secured to three tabs for interior panels (left side) and the channel above the large lower baggage door (right side). On the front, it is connected to the two overlapping front pieces. Those pieces, in turn, will be secured to the peaked channel that sits above the rear spar carry through. I used various clamps to temporarily secure the headliner at these different points.

The other consideration is the fuel line from the rear of the right tank. It will bend around the metal headliner (if installed correctly!) but will be pretty close. Aside from that, once I got the headliner in, it didn’t come close to interfering with anything else. For instance, I wasn’t sure about the flap pulleys but they are not an issue.

Once I had the “box” where I wanted it and temporarily secured, I drilled the holes in the “tail” and cleco’d it into position in the back. I also drilled the three holes on the left side where the headliner will be registered to the side tabs. Next, I marked where I needed to take a little off the right side so that it would rest in the channel above the lower baggage door.

Finally, I marked six evenly spaced holes where the top piece meets the front pieces and drilled and cleco’d these.
I removed the box for this and re-installed after taking some off the right side. It was now beginning to sit in place semi-permanently.

Mark, on side pieces, where holes in channel pieces hit (those holes you can access), and scribe channel piece edge onto side pieces


Now it was time to tackle the window channels. First, I made sure all the tabs on the window channel were sitting flush against the side piece of the headliner. Next, I drew a line to scribe exactly where the side channel piece hit the side of the metal headliner. Finally, for the tab holes that I could reach, I used a scratch awl to mark the position of the holes on the side pieces of the headliner.

Remove everything. Drill holes that were marked above and, using scribe line, mark and drill remaining holes


Then everything came out of the plane. (By the way, I put it in and took it out about 6-8 more times than I describe here). I center punched the holes I had marked, drilled them out with a #40 bit and inserted cleco’s. Then, by positioning the window channel piece using the reference line I drew, I was able to mark the position of the remaining holes and drilled, deburred, cleco’d these as well. Note: The top of the left piece should bend out slightly to match the window channel. Be sure to put a bend in the side piece before marking this hole.

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Remove excess material on side panels so that D-window channels are flush


Once all the holes were marked on the side piece, I removed the window channel piece and removed the excess aluminum material up to the scribe line. I did this with a few passes of the snips followed by lots of hand filing and sanding. Finally, I re-cleco’d the window channels on the side pieces to confirm that I didn’t have a “lip” and that the channel transitioned nicely to the side piece.

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At this time, I also re-installed each of the side pieces (with the window channel cleco’d on) into the fuselage. One reason for doing this was to determine which of the side tabs needed to be cut down so that the now-static window channel piece could fit into the window channel. Once I cut down a few of the tabs, I found the easiest way to install them was to position the front of the bottom of the window piece in its place (next to the “nubs” for the cross tube) and then rock the piece back into place. I also, reinstalled the whole box at this time and marked, punched, drilled, deburred and cleco’d the tops of the front piece to the peaked channel above the rear spar carry through (those top holes are not shown in the picture below)

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Dimple and flush rivet d-window channels to side pieces


We’re almost there…Next, I dimpled the holes in both the side pieces and the window channel in anticipation of flush riveting. Due to the width of the channel piece, I could not use the rivet squeezer and borrowed a rivet gun to drive the flush rivets.

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That’s about where I stand right now. I still need to install nutplates – I know that’s probably overkill but I don’t know enough to be 100% certain I won’t need to take this out again after I *think* its in for the last time. I will be covering this with fabric. Also, I need to work out the transition from the sides to the wing root panels and maybe put some nutplates there. Stay tuned…
 

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Excellent work!!! 1/3 or more of my flying involves stuffing the plane to the max with a lot of pointy and odd shaped stuff, having a metal headliner is well worth the effort if you plan on doing any kind of fun heavy/working flying with the plane. Now on soapbox. Everything in a cub should be made to install or remove with the fabric on!!!! This includes headliner/extended baggage/floor/pedals/brakes/dash/lights/cables/ect. Ya you can cut a hole and patch it then try to match 10 year old faded pant. Do it right the first time and any work after that will be simple.
DENNY
 
A friend brought his headliner over a few months ago and we had to call Jay to clarify where these bends went. Wasn't hard to do but cannot imagine having to figure all this stuff out without a manual. I have sent him numerous Piper drawings, service documents and the pictures from 5 Super Cub rebuilds. Kudos to all Javron builders to building something like this without a builders manual.
 
.....1/3 or more of my flying involves stuffing the plane to the max with a lot of pointy and odd shaped stuff.....
DENNY
First thing I thought of when you said pointy and odd:p
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This is is more than likely what you were referring too...
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I hope that if I put it on it’s nose the aluminum horse shoes and not the steel are what hits me in the head:oops:
 

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This is what happens when the 180 can't make it back to help fly out moose camp.
DENNY
 

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False Boot and Boot Cowl

False Boot

I opted for the false boot for my project. These pieces are depicted in Piper drawing 12818 and are referred to as Panel – Fuselage Trim. The panels from Javron aren’t exactly the same dimensions as the drawing. I had a choice and understand that it’s a popular option to just extend the fabric to the boot cowl. (If you go that route, I believe you need to fabricate aluminum panels so that the fabric holds its shape around the lower edges.)

First, I drilled holes in both piper channels. I covered the channels with masking tape first so I could more easily mark where holes go. I could also just pull off the tape and start over if I was unhappy with where the holes were ending up. Bill Rusk’s thread suggests starting about an inch down and placing the holes every three inches. This is pretty much what I followed.

Next, I made a copy of a panel on poster board. The panels have dogleg in them and playing with the poster board made it clearer how they would bend under the fuselage (I had it backwards originally). Later, the poster board template would also be very helpful when I overcut one of the panels and needed to make a new one.
I also put a couple of layers of masking tape on the rear piper channel to simulate fabric.
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Once I got the general idea with the poster board, I moved on to the aluminum panels. I’m not sure this is necessary, but I also identified where the angle occurred on the panels to make sure it was lined up with where the panel needed to bend.

First, I centered the top of the piece on the piper channels and clamped it in place. Then, I continued down, clamping and making sure to center piece on piper channel. Once I was comfortable it was in the right spot, I back-drilled the top two holes and cleco’d the panel in place.

I continued down the piece, drilling and cleco-ing until I got to where the bend needed to start. I marked on the piece (both front and rear) where the bend needed to occur. Also, note that the bend is sharper on the rear part of the bend than on the front part of the bend as the fuselage begins to transition to the more rounded shape of the firewall.

I then removed the panel from fuselage and placed it over a pipe. I purchased a length of pipe for just this purpose and discovered that pipe sizes are inside diameter not outside diameter! In the end, a ½” pipe has a ¾” outside diameter which worked nicely for this purpose. I carefully bent the piece – tighter on the read part and looser on the front part of the bend.

After bending, I placed the piece back on the fuselage and continued the clamp-drill-cleco process on the bottom of the fuselage. Once complete, I repeated the process for the other side. I was pretty darned overjoyed when the two pieces met almost perfectly on the bottom! Finally, I removed the false boot pieces for now.

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Assemble boot cowl
The boot cowl comes in two pieces. I’ve seen the discussions here on three-piece boot cowls. While it would be nice to have a stationary piece under the windshield and removable sides, I stuck with the basic design.

The firewall came with a plastic wrap that left a residue when removed. I found WD-40 did the best to help remove the residue.
I followed the guidance in the Backcountry supercub youtube video for assembling the pieces with clecos. It’s pretty straight forward. Just keep in mind that, toward the bottom of the boot cowl, the firewall transitions from being “inside” the cowl edge to being “outside” the edge. This is also explained in the video. Additionally, you can look at Piper drawing 12381 (Cowl Assembly – Fuselage).

There are also two sets of stiffeners for the top and bottom of the boot cowl (10795 and 11408-27). While the boot cowl is pre-drilled for these, the stiffeners themselves need to be match drilled. But, you will need a way to make sure the stiffeners are aligned with the holes. To do this, I drew a line on the inside of the boot cowl along the row of holes and extended it beyond the holes. On the stiffeners, I found the centerline of the edge that will be flush against the holes and drew a line along the length of the stiffener on this centerline. Then it was a simple matter to match up the lines and clamp the stiffener in place, drilling and adding clecos. Also, the bottom stiffeners can potentially interfere with piper channel or the false boot pieces (if you are using those). Piper drawing 12381 shows that the lower stiffeners are set back 1 ¼” from the edge of the lower cowl.
Finally, I cleco’d the six instrument panel clips (22471) in place.

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Once the stiffeners and panel clips were in place, it was time to do some riveting. The instrument panel clips could be riveted in with my rivet squeezer (mine has a 3” yoke). I used dome headed (AN470A4-4) rivets for these. The stiffeners, however, weren’t near an edge. So I borrowed my friend’s rivet gun and installed the smaller dome rivets for these holes (AN470A3-3). I did have a concern about using domed rivets for the top stiffeners because I was worried that they would interfere with the window trim strips. But I understand from Jay that the trim strip will go between the rivets.
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I didn’t do any more riveting of the boot cowl (i.e. attached the two sides or the firewall). I will eventually be making a blank of the firewall out of aluminum to use when locating all the engine stuff and I don’t want to mess up my good stuff with misplaced holes.

Fitting Instrument Panel
Before putting the boot cowl on the plane, I needed to drill the 6 edge holes for the instrument panel. In the interest of full disclosure, I did this two times! The first time I “missed” on the first two holes and had to begin again. While my first try was probably workable, it was a spot I was going to be looking at every time I flew.

First, using the calipers, I scribed a line 7/16” from the top edge of the panel. This is a good reference line to make sure that your scribed holes are in the right spot. For me, the tops of the traced holes just touch the scribed line. This step would have saved me from ruin on my first attempt. In the following picture, you should be able to make out the scribed line and the traced holes (as well as the drilled hole).

Next, find centerline of instrument panel. I did this a couple of ways. First, I used a fabric tape measure to find the halfway point over the rounded top of the instrument panel. I backed up this measurement by finding the center point between the two straight edges at the bottom of the panel and then confirmed this was in line with the top halfway point. I then marked two points on the top of the panel that were 2” off the center line.

On the top of the boot cowl, I measured the “gap” where the v-brace will slide into. Subtracting half that measurement from 2”, I measured out from the edge of the gap by the difference and made a mark on either side. Now I had two marks each 2” from the “centerline” of the boot cowl.

Next, I placed the instrument panel on the boot cowl and lined up the 2” marks on both. This is where it gets a bit tricky because the boot cowl is pretty “loosey goosey” as Sammy Sosa would say (that is to say, it doesn’t stay still!). Once in the proper place, I used two cleco clamps to hold the panel in place and rechecked everything.

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Then I took a sharpie and carefully traced the holes of the instrument panel clips onto the back of the instrument panel.

I then removed the instrument panel from the boot cowl and examined my newly drawn “holes” on the back of the panel. As noted above, the tops of these drawn holes just touched the edge of the 7/16” scribe line. I also noted that they were the same distance from the center line. I held my breath and center-punched these holes and drilled them up to a #19 bit (for the #8 panel screws).

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After deburring the holes, I placed the instrument panel back on the boot cowl and attached it by my new two screw holes. The instrument panel clips have a wide channel for the screw to fit in – so it’s important to go through the process of matching all your alignment marks noted above. Then I marked the next two holes out. Removed the panel, marked and drilled the holes. And repeated the process one more time for the last set of holes.

At this point, I removed the instrument panel from the boot cowl and turned to fitting the boot cowl on the fuselage.

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Fitting boot cowl to fuselage


The first thing I did was purchase four bolts, washers and nuts at the hardware store to stand in for the good AN hardware. Next, I filed the powder coating out of the engine mount bolt locations in the fuselage. Once the hardware fit in smoothly, I placed the boot cowl on the fuselage and secured it with the temporary hardware. (The backcountry supercub video suggests covering the v-brace with tape to protect it. And this isn’t a bad idea.)

Next, I attached the instrument panel to the boot cowl. The lower part of the instrument panel rested against the diagonal fuselage tubes. So, I noted the portion of the panel that needed to be filed down, removed it, filed down the sides and re-installed (actually I did this a few times! Those instrument panel screws are kind of a bear to get on).
Once the instrument panel was on, and the boot cowl “looked about right” for now, I reinstalled the false boot pieces by sliding them under the boot cowl and cleco’d them into place on the rear channel only (i.e. the channel that is not shared with the boot cowl).

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I attached a ratchet strap to one of the windshield/wing root loops, ran it under the belly of the boot cowl and up to the loop on the other side as shown below:

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Before back-drilling the boot cowl, you may also want to take a straight edge and confirm that the firewall is straight. (The boot cowl is still a little “swimmy” at this point.)

Starting from the top of the piper channel, I back-drilled through the boot cowl while an assistant (random family member) held a block of wood against the boot cowl. I alternated sides and cleco’d as I went.

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And this is about where I stand right now. I still need to back drill the two fuselage tab holes into the instrument panel. Also, while the Piper drawings don’t appear to call for it, I understand that folks will rivet the boot cowl halves on the bottom. I still need to do this.

I hope this helps someone coming after me!
 

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You may run into an issue with the holes lining up on the ginger bread once you hang a motor on the fuselage. The frame will flex a bit so you might want to try the fit with a motor/weight on the front before you paint the boot cowl. Also don't forget the angles and reinforcement doublers for the cowl rails.
DENNY
 
Wingtip light bases

It's been a while since I posted. I'd like to blame it on the pandemic, but that doesn't really cover the period from December to March! I've slowly been working on little projects and will get updates posted here. In reading through this thread, I was reminded that there is a lot of helpful advice from folks. So, I need to pay back with some updates.

This was a smaller project and is still in process. With my kit, I purchased Aveo Engineering Powerburst Daylight Nav/Position wing tip lights. These lights are shown below and include the rear facing white light that normally goes on the tail. Accordingly, they need to be visible in front and in the rear of the aircraft. I have the rounded wing tips. So, these lights need to go on the apex of the wingtip (versus toward the front for standard cubs without the need for rear facing lights).

To find the apex of the wingtip, I made sure the wings were level (they are leading edge – down on a simple wing rack) then using a large socket on a string (who needs a proper plumb bob?), I identified the outermost edge of the bow in each of the wingtips.

For a base for these lights, I purchased a length of oak cut two pieces about the size of the lights.

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Now, the challenging (fun) part – how to create a channel in the wood so that it would sit on the rounded and circular wingtip? To match the rounded edge of the wingtip, I eventually settled on a 1” router bit.
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This matched the rounded edge of the wing tip nicely. However, the base would not sit squarely on the wingtip because of the bow in the wood. How do you match that?

Luckily, I find myself unencumbered by experience (or, arguably, intelligence). This allows such harebrained ideas as…the swinging router. I used a couple of coat hangar wire to hold the router to the swinging arm and set the swing radius equal to the radius of the wing tip bow (and rechecked with a simple pencil in a string).
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Believe it or not, this worked just about perfectly. After routing out the channel, I shaped the sides of the bases to more closely match the light footprint. I then sanded the sides to the shape of the light.
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Next steps for me will be to epoxy the bases on to the wing tip bows (I may send them down a bit so that they are a bit closer to the wingtip bow), drill holes for the wiring bundle and pilot holes for the fasteners, and wire the lights in the wing.

Hope this helps someone.
 

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Nutplates and Piper channel

Nutplates and Piper channel

As Bill Rusk pointed out, getting nutplates in the Piper channel can be a challenge. Here is one method that is working out pretty well for me that doesn’t involve riveting. It involves 3M 08115 Panel Adhesive which is a two-part adhesive used for auto panels.

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According to the manufacturer info, it has a 30-minute working time (which is about right – it gets thick and difficult to work with eventually), a 4-hour set time and a 24-hour cure time. Here’s how my process worked:

Cut approx. 1” segments of 6-32 allthread and screw into nutplates

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Add adhesive to ears of both sides of nutplate. Be careful not to get the adhesive near the threaded portion of the nutplate.

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Insert nutplate into hole and hold in position with nut.

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Some areas are too difficult to get a nutplate and allthread into position. For those areas, I positioned the nutplate behind the hole and then inserted a 6-32 screw (with a pre-threaded nut) from the front.

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These things are rock solid after curing.

Hope this helps!
 

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If you can move that top fuel line up about 1/2 inch. Some day down the road someone will loose a screw for that hole and the grab whatever is handy it will be longer and hit the line. Been there, done that.
DENNY
 
ELT Installation

I selected the Artex 345 ELT for my project and opted to mount it in the rear of the upper baggage area. The ELT comes with a tray that must be securely mounted to the airframe. The challenge is: how do you do this if you don’t want to drill into the steel tubing?

Here I used the following design. If you think its brilliant, I borrowed the idea from Jon Lee. If you don’t like it, I came up with it myself! Essentially, you create a backing plate for the tray that goes underneath the upper baggage floor and wraps around a fuselage tube. Additionally, I positioned it so that it ties into a point where the upper baggage floor is anchored with the rear bulkhead.

This was a fun project figuring out how to transfer a 3 dimensional piece onto a flat piece of aluminum. The flat outline was not what I would have imagined.

ELT tray -- this is what needs to get secured to the airframe. (the attached buzzer bracket is discussed below)

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Paper mock-up next to piece reading for bending.

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Bending in the brake. Because of the closeness of the bends, I had to just start the bend (i.e. not bend the full 90*) in the brake and then finish by hand. In the first version, I put in the bends exactly backward and couldn't figure out why the diagonal went on the wrong direction! I believe the middle picture below is actually my backward version. I then matched drilled the holes in the tray and drilled for nutplates. I also had the pieces for the upper baggage powder coated.

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I also created a small bracket to hold the ELT buzzer and anchor to the tray/backing plate.

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Here is a view from the underside of the backing plate installed. Plus an action shot of my daughter holding it in place so I can put the screws in (this is why we have kids, right?).

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Once in place, the next step was wiring. Here is a link to some helpful responses to my questions about reading the Artex wiring diagram.

Finished product. I added a small ground tab to make it easier to work with the wires grounded to the airframe if needed.

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One final note, in trawling around the web, I understand that there are a couple of formats for the GPS data (it may just be baud rate): 1) 9600 baud Aviation protocol; and 2) 4800 baud NMEA. The Artex 345 must be configured to the same protocol. I have not yet finalized my avionics choices and may be faced with a mismatch. If so, the unit would need to be reprogrammed to match the format.
 

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