With the right wing now in storage, time to clean off the bench, confirm it's level (again) and start fresh on the left wing. I already think things are going to go faster this time as I've already sorted out the order of operations and know any gotcha this time around- as long as I remember this one points left! Most all the parts for the wing are already made as I made a matching part when I made them for the right wing where I could.
Parts roughly laid out. I had already drilled the rib mounting holes in the spar when I made the spar.
After positioning the main ribs, next up was assembly of the rear channel. Clamped the inner rear channel doubler to the rear channel to establish the layout of the mid join point:
Rear mid channel joining doubler:
Rear strut pick-up, laid out for drilling:
I drilled out everything in the rear channel to A3. In preparation for attaching the rear channel, the spar is squared up vertical to the bench using upright posts screwed to the bench. The orange string line confirms the spar is perfectly straight and a level.
Rear channel is attached. Straight, level and held in place with blocking screwed to the table top. A long board under the rear end of the main ribs supports the wing skeleton and keeps the spar vertical and square:
0.125 root doubler in place (another part made at the same time as the right wing one):
Blocking at the inboard and outboard ends of the rear channel keeps it perfect lateral position relative to the spar which also squares the wing ribs. The wing skeleton is now perfectly square and level.
Nose ribs are added to the front of the spar:
When I did my right wing, I took the skeleton apart before fitting the skins and riveted anything I could ahead of time. It meant squaring everything up again before adding the skins. This time, I'm going to fit up the upper skins while the skeleton is secured as square and level. Once the skins are drilled out to A3, then everything will come apart for debur, prime and final rivet.
Here is the outboard upper skin laid out in rough position:
Once completely square to the skeleton, I'll begin drilling the skin to spar and rear channel out to A3. The the rib rivet lines will be laid out. The skin will come off the skeleton to pilot drill the rib lines on the skin and place the upper skin stiffeners. That process worked perfectly on the right wing, so I'm repeating that here.
Next up will be the upper inboard skin which is the piece that goes over the fuel tank bay. I'll need to fabricate the inboard root angle first.
For my regular readers, I'm sorry the blog has been lacking. I'll try and get more regular updates posted, but to be honest there isn't a lot of content here that wasn't already described during the right wing build-up. I do have some extras in the left wing including the pitot and static lines, but that comes towards the end when I run the plumbing for the fuel and wiring for the lights.
As always, thanks for following along.
I haven't been getting to the shop as much as I would like (or need) lately. Work has been so busy that by the end of the day I have little energy left for shop. When I've made it there, I've been slowly plugging away at all the little detail items in hopes of getting the wing off the build table and into storage.
I mentioned in a previous blog post that I wasn't happy with the pulled A5 rivet on the front strut pick-up that the plans call for. A standard A5 wasn't long enough to pass through the strut attach plate and support angle - once pulled the rivet tail won't expand enough to be acceptable in my opinion. So instead I drove a bucked rivet here instead.
It was a bit of a trick to buck the rivet in the tight space, but it turned out very well.
Continued working on the nose root skin using a card-stock template. I also spent some time lightly sanding out some minor surface scratches on the skins caused by moving the wing back and forth on the bench.
I've temporarily fastened the top wing root skin to the new curved angle on top of the spar root (see previous blog for further information). This additional angle works nicely to round out the upper root skin.
The cardstock template is a bunch easier to round out and shape the nose root skin. The nose root skin is only 016 aluminum, but is the most complex curve of the entire build and a tight fitting bend. I've got it started, but it doesn't get final fit until the wings are attached to the fuselage - it meets the cabin roof and windshield here so it's important to have them mated up before final trimming and install. This will be done later.
The weather has also been really wet during June, so although the wing is technically ready to be moved to storage I've been waiting for a nice day to do so and have enough hands to help. Ron is nursing a hand injury, his spouse Donna is recovering from a broken wrist and Brenda and the girls are busy too.
In the meantime, I got started on the ribs for the second wing. After doing the first set for the left wing using a combination of boards and cardstock templates (which worked well), I decided to try a different method (both work equally well, this second method seems to have gone faster).
Set up the bench edge as my template. The edge of the bench represents the lower wing skin, the board fastened to the bench represents the wing spar. I made sure the board is 90 degrees to the horizontal. They are kinda faint in the picture, but the blue vertical lines to the left of the nose ribs are my keypoint lines - where the slat support lines up/attaches to the rib:
With the slat attachment clecoed in place to the bench and the rib clamped down, backdrill through the rib the required 6 rivet holes. Then add the nose skin support L (I did these the same way as the first wing). Repear the process for nose ribs 3, 4 and 6 (four in total):
Next up was the flapperon arms. I used the same principal for these. It starts with matching holes at the trailing end of the arm for all four:
Obviously, the main wing ribs are longer and the flapperon arm protrudes below the lower skin horizontal plane. As a result, I have to extend the "bench edge" upwards with a spacer board. Like the right wing, the flanges on the first rib face opposite than the others, making room for the fuel tank bay:
The spacer I chose left me just enough room at the table edge to fasten the flapperon arm. Clamping it down and the rib:
To make the rivet holes consistent, I laid out a piece of card-stock and placed it inside the rib directly over where the flapperon arm gets attached:
Repeat the process for main ribs 3, 4 and 6:
Add the skin support Ls:
Rib assemblies for wing number 2 complete!
That's it for this blog entry. More to come, thanks for sticking with me.
Got some time in the shop this past week. Here is the latest on the right wing.
Upper main skins, upper nose skins and top side trailing edges are sealed up for storage. This means two temporary rivets in each bay to hold everything together until I re-open it for inspection at a later date.
Also created and installed the curved attach angle for the upper root rib. You may recall from a previous post that the design changed in this area since my plans were issued, however I hadn't seen any update from Zenith. This meant creating a work-around with a curved L bracket, I pleased this will create a much better curved surface for attaching the root skins.
Flipped the wing over to access the lower skins and final rivet them:
The bottom of the wing is almost all final riveted closed, very happy how it looks, but still needs some cleaning and light wet sanding to remove some light scratches:
Jury strut attachment brackets are now firmly in place on the spars/ribs:
Here is the rear strut pickup and 3rd flapperon arm. This joint area really turned out nicely. Still need to rivet the trailing edge joint where they overlap:
I purposely left the lower outboard wing skin un-rivetted so I can have un-fettered access to the wing tip area for fit up and final attachment:
Measured up the rivet line for the front wingtip attach bracket and drilled out to A3:
Wing tip in place, with the lower outboard skin in place to check alignment:
With the wingtip in place, I discovered that the rear channel attach bracket wasn't sitting flush against the wingtip. I re-fabricated a new one to match correctly (pic is of original):
With the tip in place again and the lower skin removed, I marked the location of the rivet holes from inside through the spar and rear channel brackets. Then I removed the tip form the wing, back drilled at the marks up to A3. I added a strip of masking tape where the holes are to protect and prevent cracking of the plastic and placed the wingtip back in position and fastened with clecos:
Lower skin back on, drilled the outboard edge to A3 and cleco. I won't be final drilling these up to A4 until the wingtip lights and wiring are done, probably just before inspection. Trailing edge has since been trimmed to match since picture was taken:
At the root end of the wing, I started making up the template for the nose root skin. I had originally cut the actual skin from 016 based directly on the measurements in the plans. But noticed when I went to fit it, I had made a critical cutting mistake near the spar attachment and I wasn't happy with the overall fit anyhow, so it goes to the scrap bin for other small parts.
Making a cardstock template from the plans with a bit extra on the edges allows much easier fit up. with some masking tape backing on the edges, the template can actually be clecoed to the wing. Initial stages of fit-up are very promising, the final template will be transferred to a fresh piece of 016 for the final piece, once I trim it perfectly.
Almost there, many MANY small steps along the way. In the next week I should be able to put this wing into storage and start work on the left wing. Testing continues on lighting and fuel sensors.
Thanks for following along. Onwards.....
Some good hours in the shop this past week.
The wing tip inner liners came out really well:
Next up for the wingtip is final fitment and pilot drilling the rivet lines top and bottom of the wing and into the spar tip support L and rear channel L.
I decided to try my hand at brazing some aluminum in preparation to assemble the wing fuel tanks. I started with a couple of scraps of 025, the same aluminum the tank walls and body are made from. The goaI was to simulate a welded seam:
To accomplish a good brazed joint on any metal, the surfaces of both pieces need to be cleaned completely to take off any oxidation. I used the Dremel with a stainless steel wheel brush to clean both:
The shorter strip will be on top of the longer one and offset to simulate a lap joint, so I cleaned the centre of the longer one:
My choice for flame heat is MAPP gas - from what I'm told it is hotter and cleaner than propane:
Gently heat up the aluminum joint focusing on the seam where the brazing will be. It needs to be hot enough to flow the brazing rod into the joint. Anyone who has done soldering should be familiar with this. The brazing rod melts at a much lower temperature than the aluminum. Unfortunately it is difficult to capture the brazing rod melting into the joint.
My first attempt wasn't very good. I found it hard to flow the brazing rod into the seam evenly. The bending of the aluminum wasn't from the heat, but from tapping with hammer after it cooled. The "weld" held but not very well (it broke much easier than it should have) and appears to be full of pinholes - not good for sealing a fuel tank seam!
Another attempt with two circular scraps was even worse....
I did manage to get a very strong bead along the edge furthest from the vice. I think a big part of the issue is that the cast steel vise is acting as a very large heat sink, drawing the heat built up in the aluminum from the torch away and into the vice quicker than it should. I'll need to consider this when I have the tank pieces clamped together, but I clearly need more practice before I can trust this as a leak proof fuel tank.
I've decided I also need more time to test the pressure sensors before committing to using them in the tanks, so I'm going to put the tank assembly off until later and focus on finishing this wing and the other one.
I've added the root skin to the right wing:
The root skin goes from perfectly flat at the rear channel to very rounded over at the spar. The root nose skin closes up the front corner of the nose. It's going to be fun!
One issue I ran into is the upper root skin in proper position, won't sit flat on the spar root doubler. Forcing this convex skin flat to meet the doubler only serves to crinkle the skin, so I had to reach out to some fellow builders to see if they had this issue and how they dealt with it. I have an simple answer, more on that in my next blog.
This picture shows how much the upper root skin tapers down at the root. You can imagine the root nose skin shaped somewhat like a cone as it tapers both inboard from the nose rib to the root nose rib:
Getting very close and happy with my decision to put off making the wing tanks. I definately need more time with the torch and brazing rod in hand to make good consistent brazed joints. Like everything else it will come with practice so I'm not worried. This will also give me time to get some serious testing done on the pressure sensor set up which I still believe will work as I designed.
Thanks for reading along. Onwards....
My pressure sensors finally arrived! I'm stoked to experiment with these models as I believe they have the measurement resolution and electrical specs for my Arduino fuel gauge solution.
First up, unboxing and evaluation. First thing out of the box I was really surprised at how large they are. It didn't have any physical measurements on the ordering page, but I had the mistaken impression from the pictures online they would be somewhat smaller and lighter, similar to the 10psi sensor I ordered initially. the new one is larger, a bit heavier (not unreasonably so) and doesn't come with an integrated cable:
They will still fit my application space, but I'll probably need to consider some sort of mounting bracket to secure it with the fuel line. Overall build quality seems real good. Two sensors, exact same spec, just like I ordered - 1.5psi, 1/4 inch NPT thread connection, 0.5V to 4.5V output:
Looking closer at the electrical connection end, standard cable compression sleeve entry and what appears to be a small screw holding the cap on the top:
Backing out the screw I thought would allow the cap to come off to reveal the electrical connections inside.....
........but the cap is actually a full 4 prong indexed plug on it's own - the machine screw secures the cap/connector to the sensor body. I like that in the design!
Another nice design detail is the rubber gasket on the bottom of the connector, protecting the joint with the sensor.
The terminal block pops out of the cap to reveal good quality screw terminals which are numbered to co-incide with the pin outs on the lable of the sensor. #1 for 5V+, #2 for sensor circuit ground and #3 for output signal. There is a 4th terminal with a electrical ground symbol - I suspect this is for sensor body ground, but I'll need to test to be sure:
I do know I need a better and more scientific set up for true testing and calibration, but here's what I did tonight to try it out. I used the same poly tube and connections as I did the for 10psi sensor tested previously. I slowly added water to the tube (in the upright position) and monitored the sensor connected to the Arduino micro-controller. Using the same Arduino script as before, it is clear to me this sensor is not only much better suited range wise to what I need (1.5 psi vs 10psi), it also seems the output signal is much more stable. I suspect this output stability is part build quality and part correct range specific, but I'm happy where this experiment and my related theory is headed. The photo doesn't capture the graphed output on the laptop, sorry. I'll try and get some screen captures when my test method/system improves.
Still much testing to prove the effectiveness of this method for measuring fuel tank quantity to come. This is another example of stuff I'm learning on this journey :)
Delayed time getting into the shop this week. Couple of busy and long days at work left me no energy for plane building (shocker really), and then my first CoVid vaccine (Moderna) kicked my ass for a day and half. Back in the shop on Sunday, but limited energy so things moved kinda slow.
Started the day pulling off the upper skin and deburring all the ribs, triling edge skins and upper wing skins:
Let the nose skin back up a bit to deburr it as well:
Clecoed the skin back down and pulled the A4 rivets for the wing stiffeners. Taking the skin off for inspection later won't be an issue having these complete so got them done:
Primed the edge of the upper wing skin where the tank skin will join over top:
Primed the root support L - did it in grey primer as it will show through the join in the tank and root skins:
Rolled out the nose skin again and applied a bit more green primer that got scuffed up a bit when I was cutting and deburring the slat support slots:
I wanted to strengthen the wing tip plastic so that when it gets riveted to the wing the rivets tails won't pull through or worse crack the plastic. Several builders reinforce this area using 016 strips around the perimeter and I did the same. First though I wanted to back the area where the wing tip nav-lights mount for much the same reasons. I don't know at this point if the nav-light will be riveted or screwed through the plastic, so I made a doubler plate out of 025. Had to rough it out then use the bench sander to trim it down until it fit inside the form to lay completely flat:
Once I had the first one, I made a second one the same for the left wing:
Next up, I went about cutting some scrap 016 into strips to match the inside edge widths of the wing tips. This took some time and I had to break the perimeter into several manageable sections due to the complex curves of the nose section:
This is the hardest section. The inside edge not only narrows dramatically, but curves sharply inwards at the same time. I used a cardstock template clipped on to the edge area, tracing the outer inside edge first:
Carefully flipping it over, I then traced the outside edge (which is the inner edge inside the tip):
This very rough size cardstock template is what I ended up with:
Trimmed out with scissors, I continued to trim it down until I was satisfied with the fit when pinned to the inside curve of the wingtip:
Traced out on 016 scrap and the tail end was left purposely long as I can adjust the length of the next piece easier than fussing with this one:
All the edge pieces, deburred and edge sanded smooth. Inside surfaces scuffed up with 150 grit sandpaper and cleaned with lacquer thinner. More scuff than required for primer, something for the EkoBond adhesive to grab onto:
Being new at using this stuff, I decided to do the nav-light backing plate first. EkoBond on both surfaces after scuffing up both with 150 grit sandpaper:
You have to be careful as the grip is very strong once it starts to get tacky - not much room to re-position once in place, but I got it where I wanted first try:
In hindsight, I probably overdid it with the clamps, but happy with how it turned out:
Overnight curing and that plate isn't coming out!
Same process for each of the strips. I was smart enough to number them to match them up when the time came to place them. If you look close, you can see streaks of blue in the green on the lower left where the EkoBond is still setting up (turning green like the rest):
Started with the complex curves near the nose first then trimmed the long straight pieces at the trailing edge end where needed. Several binder clip, spring clamps and clothes pins keep everything clamped together while it cures:
Perimeter backing strips complete. When I return to the shop on Wednesday night this will be cured and ready for final fit up on the outboard end of the wing. Pulled rivets now have something to grab on:
Between steps (waiting for blue to go green), I got the inboard lower trailing edge trimmed using the Dremel and a cutoff wheel. It's becoming my favourite tool it seems!
Good progress despite feeling like a bag of dirt the last couple of days.
My new pressure sensors arrived in my work mailbox today, so I'll have them shortly for testing. I have high confidence in my theory of how they will work in the fuel system and how to read them using Arduino micro-controller and display.
Onwards... thanks for reading.
p.s. - I'd be wrong not to mention the passing of Chris Heintz, designer of Zenith Aircraft who passed away a couple of days ago, peacefully with his wife at his side. His legacy in aviation stretches from work on the Concorde (yes THAT Concorde) to starting a small aircraft plans business that has grown over 40 years to become the Zenith Aircraft Company, the makers of the aircraft design I am building. His contributions to this hobby and general aviation as a sport can not be overstated. Such a kind and humble soul.
Blue skies and tailwinds Chris - and thank you for making dreams possible for people like me :)
This build is like a Dr. Seuss rhyme sometimes, repetitive and fun but smoothly flowing along.
Been a over a week since my last blog post. I got to the shop for a couple of evening visits and weekend day, so progress continues. Home internet has been flaky until tonight, so I've been saving pictures and updates for this post.
Now that the nose skin is fit, I needed to figure out a way to line up the slits in the nose skin where the slat pick-ups protrude through from the nose ribs. The lower half of the nose skin is already rivetted to the spar so I have to cut those slots with the skin still attached.
I started by laying the skins flat at the edge of the workbench:
Here is a slat pick-up at the outboard end of the wing, clecoed into it's spot on the rib. I chose this one to do first to prove out the plan for making the slots - there is only one pick-up through the outer nose skin, making manipulation of the skin easier.
Carefully measuring the slat pick-up in it's final position tells me the bottom edge at the rib is 70mm infront of the front most lower rib rivet. The top edge of the slat pick-up is 160mm from the front most lower rib rivet - that means the total length of the slot around the curve of the nose rib is 90mm, starting at the 70mm mark:
With the knowledge the nose rib is perfectly square to the spar (I double checked), I took out the top cleco and simply tilted the pick-up forward and down to establish the location of the slot referenced to the rib:
A ruler confirms the extended line paralell from the rib matches the slat pick-up
Here are the measurements sketched out on the inside of the nose skin along that extended reference line. This will be the location of the slot:
I doubled the line to the width of the slat pick-up. This thin rectangle will be the bounds of the slot:
An A4 hole gets drilled at each end, then the slot is cut out with a Dremel tool:
To prove the measurement is correct, re-attached the slat pick-up to the nose rib, then I re-wrapped the outboard nose skin back and secured it to the spar and nose rib. The slot fit is tight, but if careful I can slip the nose skin over the pick-up - it lines up very nicely!
All the rivet holes in the nose skin still need to be deburred as does the slot, but very happy my head scratching over this paid off:
With the knowledge my method works, I final rivetted the nose skin support Ls in place on all 3 slat supports at their nose ribs:
All the fitting of the slat supports done previously were done to a template when off the wing, and the slot holes should be in the same places, but I measured each to be sure and they were indeed the same. So I repeated the process for the two inner ones:
Slots for the outer 3 cut and fit up real nice once the skin was wrapped over and secured again:
The inboard slat pick-up by the wing root does need a slot - the nose skin wraps to one side. The root nose skin is attached on the other side of it:
Final sized the trailing edge to the rear channels, and add the joining rivets where the trailing edges overlap:
Took the wingtip out and trimmed the upper skin and trailing edge. This still needs some more trimming once the wing tip it final fit - lots more to come on that front.
This is the open fuel tank bay. I took the bay cover off to assess fuel tank fit in preparation for building them, lots to plan for here.
Sitting down with a cold drink of water, I couldn't help admire the symmetry of a wing being built and wonder hole many holes/clecoes and rivets I've done so far!
Right sized the nose skin rivet holes up to A4:
Started adding the requisite 4 rivets into the support L behind the nose skin at the slat pick-ups. These will eventually be A4 size, but I need to find the long drill bits for the middle two!
Took this picture of the wing structure looking in from the wingtip. Just noticed a smiling man-in-the-moon face looking back at me way from the other end!
Nose skin, nice and tight to the nose ribs and rivets holes properly spaced:
Took the trailing edge clecos out, deburred them and the rear channels. Then laid out some newspaper for priming the edge that will tuck under the upper wing skin:
As I been pondering fuel tanks, I been thinking on how to plumb them to incorporate the pressure sensors now on their way from where I ordered them. I recieved some other plumbing parts this week. From right to left - tank flange, finger strainer, 3/8NPT-AN6 swivel adapter, AN6 "T" with 1/4NPT takeoff and (for now) brass 1/4NPT union to join to the sensor when it arrives. I'll likely swap out the unions for blue anodized aluminum to match the rest:
All the fittings loosely together - all joints will be tighter and sealed with fuel safe joint sealer once installed:
The other part of my order arrived too. I plan on brazing the tank sides and skins together and the fittings using aluminum brazing rod. I ordered this highly recommended brand:
These rods essentially work like solder, but at a much higher strength and temperature. The rods melt at a temperature much below the melting point of aluminum, so you heat the pieces you want to join and flow this into the joint, then let it cure (solidify). I've haven't done this before, so I'm certainly looking forward to trying it, learning and making my own fuel tanks! Trying to figure out how to capture that process on video to share it.
Progress, but so many little details. It's hard not to feel bogged down, but this blog helps remind me how far I've come on the build and my learning.
Thanks for following along, stay tuned for more!
Seems like it took forever for Saturday to get here, despite being off work on Easter Monday.
I decided to pull out the fuel tank side for the right wing and start test fitting the finger strainer. Fuel tank assembly will have to be done soon. If you recall from when I made the tank sides, I made sure to mark the location of the fuel outlet hole. Shown below is the outside of the tank wall. The flange on the tank actually faces outward for welding:
The finger strainers I was given are actually the large size, the plans call for small or regular size. This doesn't change anything with regards to operation, the fuel lines will still be the same size.
I placed the finger strainer directly over the outlet port mark and it will fit fine (it's facing the wrong direction in the picture, the mesh goes inside the tank):
Here is a better look after I flipped over the tank side (now showing the inside of the tank wall):
The welding flange that the finger strainer screws into is too wide to fit and keep the strainer close to the bottom edge of the tank.....
Here the complete assembly roughly laid out. The strainer screws in through the threaded mount flange from the other side with just the mesh inside the tank:
If I trim off a bit on the bandsaw I can get it even closer to the bottom of the tank and still leave enough for welding and threading in the strainer. This will be done when I get the rest of the fittings for drains, etc., and I can assemble the tanks for welding.
Picked up some new ratchet straps and started the process to wrap the nose skins:
This is a very familiar process which i used on the horizontal stab, flapperons and slats. Long boards help spread the wrapping force equally across the skins:
I still need to figure out how I'm going to cut the slots in the nose skin for the slat brackets. The one at root is exposed so I'm going to use it as the example and copy the measurements across to the other three moving outboard from the root. It will take some time, but I'm confident it will work.
This was my first chance to see if the template I made for the outboard nose skin matched up to the wing tip. Here is a look at the wingtip in place. The curving edge of the nose skin fits very well!
I still need to trim the upper skin still and the trailing edge to match properly. Again, the template I made is a great help:
I still need to finish drilling the nose skin at the spar, but the outboard double ow of rivets on the spar tip is done to A3. I also have the first rivets in the nose ribs along the nose skins. I have enough in there now to release the ratchet straps:
The long boards will stay in place for now until I finish drilling out the nose skin/ribs and at the spar. But it looks even more like a wing now!
More to come! Thanks for following along!
Couple of hours in the shop today, continuing on fit up of the wing tip.
First up, I wanted to trim the wing tip a bit smoother. I marked the extent of the trimming out with masking tape and cut the line carefully with the Dremel tool, including some minor trimming at the trailing edge taper. Clamping it to the bench with wood screws and scraps of shim worked well. I put a container of clecos behind it to prop it up a bit:
I don't have some after pictures, but once trimmed back to the tape, I used some sandpaper to smooth everything out:
The plans ask for some standard L to be attached to the end of the spar tip and rear channel. I wasn't happy that would be wide enough to support the wing tip, so I made a custom wide L from some scrap 025 I had: Drilled the A3 pilot holes in the L:
Then I used finger clamps to hold it in place and back drilled through the spar tip, then upsized them to A4
The L's support the back of the wing tip.
The rear channel area is a bit tight and I mis-drilled the L at this location. It needs to sit more proud of the channel than shown below, so I made a new one (not shown). I also had to grind a bit off the tip of the rear channel so it could be inserted inside the wing tip far enough:
The wing tip now sits in the correct position. I was concerned that the nose skin would properly wrap around the nose of the wing tip, but everything measures up correct, so it should be good. I'm not final riveting the wing tip in place until the top skins, trailing edge and nose skins are complete.
I laid out the rivet line across the outboard lower skin and pilot drilled the holes to A3. I also roughly scribed a line across the inside of the upper outboard skin. This will need further trimming, but I've been fighting with it a bit when putting the wing tip in an out.
Knowing the outboard nose skin will fit correctly once it is wrapped around, I finished off the spar and nose rib rivets in this section:
I left the last outboard rib and spar rivets un-done in case I need to slip the outboard main lower skin out of place. These will get done once the wing tip is in final rivet:
The wing tip looks real nice in place now that both outoard skins a trimmed closer to what they will look kine. I still need to trim the trailing edge both lower and upper to match the wing tip. Before I drill the rivet holes for the wingtip, I want to back it somehow to prevent the pulled rivets from cracking the plastic. I was thinking some small flat washers on the tail side of the rivet, but I think instead I'll run a narrow strip of 016 aluminum along the inside and drill through the plastic and the strip as a backer. I also think this is a good spot to use a hand puller instead of a pneumatic gun:
I mentioned yesterday, I wasn't entirely happy with the grip length of an A5 rivet in this hole. I drilled out the A5 and will replace it with an A6 which has a longer grip length.
My testing of the 10 PSI pressure transducer that I ordered is going well, however I found the resolution of the 0 to 10 PSI sensor to be to large a range for what I need. I found some 0 to 1.5 PSI ones online last week at a "decent" price so I pulled the trigger and ordered a couple. I'm looking forward to testing them as I believe this will be the solution I'm looking for to measure fuel tank levels.
Next up, some final work on the lower surface of the right wing, including some cleaning of the aluminum. Then the wing gets flipped right side up for nose skin wrapping and trailing edge set up.
More to come this week.. Thanks for following along!
Easter weekend is here already. This CoVid BS is getting real tiring, but at least the nicer weather is here.
Spent a "Good Friday" in the shop, working on the right wing. I was going to leave the rear root doubler clecoed in place and finalize it later, but I decided the fuel routing can still be done with it in place. I staggered the clecos and pulled the last of the A5 rivets in the rear channel face:
I final riveted the root nose rib into place and added the splice plate. I also final torqued the spar pick-up plate bolts:
I added and final torqued the wing strut attach angle bolts top and bottom where they go through the spar caps. The first picture shows the A4-7 bolts that hold the spar pick up attachment that are yet to be installed (I put them there to remind me they are coming up soon):
With the bolts all installed along the fron spar, I reattached the lower skins in preparation for final rivets, including the freshly primed wing stiffeners -I won't be rolling the lower skins anymore, this is final assembly on the wing skeleton:
Couldn't resist adding in the wing tip again to see how it's going to look and also figure out the trailing edge:
I'll have to do some more thinking on how to trim this up. There is a large bulge at the trailing edge that will need to be trimmed away, but it's hollow so I want to make sure trimming it way isn't going to compromise it's integrity going forward or lead to cracking:
It's extra work, but I like to put clecos in any holes along a line of rivets that need to wait for a rivet. It's a good reminder to think twice before pulling a rivet too soon in the process that would have to be drilled out later:
All the rivets along the rib lines and wing stiffener lines are done. I left the perimeter of the skin at the main spar and along the trailing edge joint open as well as anything close to those as I may need the flexibility to reinstall the trailing edge where it tucks under the main skin.
Next up were the nose skins. These need to be attached permanently as all the front strut attachments are riveted through them, the skins and the spar.
Strut support angle clecoed in place. The hole where the strut pickup comes through the skin was already deburred at this point (I forgot to erase my Sharpie note). This is a complicated joint which takes some thinking about order of operations to ensure rivets are done while the holes are exposed.
I clecoed the strut doubler in place and I got the two A4 rivets and the A5 spar rivet in the support angle done before adding the strut pickup and several others towards the rear. Those two just in front of the spar line would be impossible to reach if the strut pick-up was bolted in place as well as the A5 on the angle to the left of them:
I slid the strut pick-up through the skin from the outside and had to carefully curl the skin back with a piece of twine to provide the work room to add the pick-up bolts. The topmost bolt in the picture needs to feed the other way through the hole, otherwise the nut and tail of the bolt won't clear the skin when it lays flat. These were then torqued to spec:
With the skin laid back down and riveted to the spar, I realized I should have done the other A5 rivets close to the spar pick-up. It's way to narrow to get any rivet puller in there:
Only two A5 rivets had this issue, so I pulled them in the opposite direction. Not ideal, but perfectly acceptable solution (I'll mark that down so the other wing looks the same!). I also pulled the single A5 rivet just below the strut pick up hole - I think it might need to be replaced, I'm not sure it's long enough for a complete grip, maybe I'll up-size the hole to A6 here:
Really happy how this assembly turned out- tight and just like the plans describe.
The slot I cut in the trailing edge to go over the rear strut pick-up worked perfectly as well, but is a real pain to to slide over the rear pick-up AND tuck under the main skin - it's just to tight to do easily. I think I will be permanently attaching the trailing edge as well. Adjustment up and down can be made when the top side of the trailing edge is tucked under the top skin. There should be enough room to work in there from above for the fuel line routing as well:
With the nose skin in place, I can add the front jury strut pick-up:
Finished of the spar line rivets:
Pulled the A4 rivets on the lower side of the nose skin into the nose ribs where I could.
The wing is really starting to feel solid! The front lower corner in the picture is where the wing root nose skin will reside. It will be done after the top of the wing is completed.
I've decided to hold off a little longer on the outboard skin and the outboard nose skin until I can get a better idea on the trim and finish of the wing tip. I still need to trim the outboard end of the trailing edge skin to match as well.
Overall a mostly productive day, inching ever closer to the point I can flip this wing back over the way it should be and start the final processes to close it up for storage.
Thanks for following along, more to come over this long Easter weekend.
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Husband, father and 911 dispatcher. Long time pilot with a licence that burns a hole in my pocket where my student loan money used to be. First time aircraft builder. Looking to fly my own airplane.