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.