Another successful week in the shop.
I continued to work on forming and flanging wing parts. Last blog post I had started the forming of wing ribs, starting with the root ribs. Here they are out of the forms - I'm happy how they turned out and using the hardwood dowel to work the metal flanges into the flutes on the forms made forming the curvatures of the flanges much easier.
As I mentioned before, I'm using Ron's 701 nose ribs forms. The trick here was to pre-flute the blanks as the 701 forms don't have flute channels cut in them.
In the vice, I start by bending the flat trailing edge flange over as it is straight and does'n require any fluting. Then the bottom flange, working forward towards the nose.
as I got close to the nose, I carefully worked the nose flange over, drawing the aluminum across. The metal backing plate on the forms really helps in the this regard.
A little cleanup with a small tack hammer backed up by a body work anvil and some tweaking with the fluting pliers and the nose ribs are ready for lightening holes.
Six left and six right, enough for both wings
Lightening holes are cut on the drill press using the fly-cutter, set to the diameter of the flange dies (which are exactly to plans - in the case of the nose ribs is 115mm)
Lightening holes cut and deburred, awaiting flanges.
Next up, the wing ribs. I used the exact same process here as the root ribs with a couple of modifications. I stacked all the blanks together and drilled the pilot holes as a stack to ensure consistency in the forms. Each of the ribs has 3 lightening holes, however two of the blanks have no third hole, so I pilot drilled those separately from the rest, but using the same layout as the others.
First blank/form in the vice and from here the forming is the same as the root ribs - using a hardwood dowel to massage the flutes. All ribs are made from the same form, regardless of lightening hole requirements. I added a small clamp at the tail end of the form to keep the forms tight.
All my wing ribs formed and lightening holes cut awaiting debur and flanges. The two wing ribs on top are the two that only require front lightening holes, the rest underneath have three holes.
Took the day Thursday to travel to Sudbury and pick up a sheet of 063 aluminum and some flat stock needed for the wing and strut pickups. I also grabbed a small chunk of 0.188 plate for the fuselage pickups. This supplier is much cheaper than Aircraft Spruce and much closer to home.
I was pleasantly surprised to find the sheet came on a well strapped pallet which fits nicely in the back of our truck. Over packaged for a single sheet, but it didn't cost anything to me, so that's good!
When back at the shop Friday, I planned on cutting off the pieces I need immediately for the spar doublers. I laid out the rough dimensions while the sheet was still on the back of the truck. This allowed me to nest them a bit and save waste. All set to rough cut but unfortunately mother nature had other plans and a downpour forced me to abandon the plan and just unload the sheet off the truck for next time in the shop.
The flat stock is perfect for the spar and strut pickups, and the flat plate works for the rear wing/fuselage pickups.
I'm so fortunate to be able to use the tools and jigs and bending equipment of Ron's, it's saving me untold hundred of dollars. One of the best examples of this are the flanging dies Ron had custom made at a machine shop.
In the front of the picture below are the two halves of the 115mm diameter flange die - female side on the left, male on the right. It's easy to see the shoulder on both that creates the flange on the lightening holes.
The process is easy. Place the blank over the male side....
Invert the female side and place it on top (carefully - the dies are heavy tool steel and dropping them will permanently damage the blank and maybe the die as well!)
A shop press would work well here, but two large C clamps and the bench-top edge work just as well. Make sure to use two clamps the same so equal turns on the handles makes even clamping force on the dies. I did four turns on each at the same time, going about a half turn each time and it worked well.
The distance to compress the dies together isn't much. Top photo before compression, bottom photo at the end of travel.
Take the dies apart and the flange is complete - total time about 2 minutes each once I got into a rythym.
The process is repeated for the wing ribs, using the correct flange die size where appropriate.
The smallest flanging die only requires a single C clamp centered over the hole. Credit to my daughter Caitlyn for taking some of the following photos of me working!
After about 90 minutes, all the wing, wing tips, root and nose ribs for both my wings are now flanged and ready for fitting on their spars.
Something really cool looking about the symmetry of wing and nose ribs laid out side by side on the table
Next up, I'll get the 063 spar web doublers cut from the sheet I bought, bent and fit one to the spar. Then I can proceed to add the spar pick up, the strut angle and strut pickup. With everything fit, I'll drill/flange the lightening holes, begin drilling all the holes to correct A5 and A4 where needed. After that, disassemble, debur, prime and reasemble for final riveting. Just a few more steps!
Thanks for following along, it was a productive week indeed!
Busy couple of weeks since the last blog update, but lots to share.
I continue to assemble the wing spars and gather the remaining materials and make parts for the wings.
With the spar webs cut, it's time to layout the lightening hole locations along the web, and cut the spar cap angles. These form the top and bottom of the spar. It starts with a centre line along the length:
Measuring outboard from the root edge, I made a hatch mark for each of the lightening hole locations:
With the locations laid out, I stacked one spar web on top of the other, secured them with clamps and drilled pilot holes through both - this means all lightening holes in each spar are in exactly the same location.
Next up was cutting the bottom and top spar cap angles using the chop saw. I left them a couple of mm long to allow for filing and sanding the ends smooth as the chop saw cuts fairly rough..
Here are the first pair, roughly laid out on the right spar web. You can see in this picture I've marked up each of the webs with a Sharpie so that I keep everything straight as to which way is up/down/fore/aft and a rough idea of the lightening holes. This is important as I want to use the factory edge on each of the spar webs on the bottom edge of the spar and as my reference for measuring the height of each assembly.
With the lower spar cap lined up with the factory edge and clamped in place, I laid out the rivet lines on the spar cap angles. These holes will eventually be filled by A5 solid rivets. I measured and double/triple checked the layout to ensure everything matches the plans. It's easy to be off a couple of millimetres at the beginning that translates to being off several millimetres at the other. The rivet pitches also vary a bit near the middle of the spar too where the spar web doubler and strut pick-ups are located so those have to be carefully considered too.
Drilling all the A3 pilot holes in the spar caps left a LOT of swarf!
At the bottom of the spar at the root I only drilled one pilot hole to begin the process of lining up the spar cap angle. There are several holes and bolts needed here in the spar cap angle, but I have more components to add including the spar root doubler and the spar root pickup. It will be easier to back drill from the opposite side - pilot holes for spar root pickup will be laid out and drilled on the drill press for accuracy and ease.
To start the process of matching up the lower spar cap to the web, I used a straight steel block. The web sits on a board to back up the drill bit, tight against the block and under the spar cap angle. The spar cap angle is exactly even with the end of the web, forming a perfect corner. Drill through the pilot hole to A3 size - this hole will eventually drilled out and filled with an AN bolt.
I secured the inboard end of the lower spar cap with a cleco, then used the same steel block to line up the web and lower spar cap again moving outboard. A clamp kept everything straight as I drilled the next holes:
Every tenth pilot hole was drilled though the cap and web. A long piece of HSS square tube confirms everything is remaining straight as I go:
With the spar cab and web confirmed as straight and true, I finished drilling the rest of the holes between, checking for straightness each time:
I left the section un-drilled between each end of the spar web doubler location (shown as red angled lines). I'll wait to confirm fit of the doubler and the front strut pick up angle once they are made and fitted. I may back drill these like the spar root depending on how the fit up goes.
With the lower cap in place, i started to layout where the top spar cap will be on the web and the associated rivet lines. yes those are my red Crocs.... don't judge.
The upper spar cap is initially cut long enough to overhang the web where it tapers. This will be trimmed off later to match the doubler which gets added here at the root (more on that later). The rivet layout at this corner is non standard, so for my first hole, I chose the first standard rivet spaced on along the cap. I used a ruler underneath everything to make the spar height exactly 209mm as per the plans and secured it:
Pro Tip: Be careful your pilot hole isn't over top the ruler when you drill through the web! Better that than a finger I suppose!
With the spacing between spar caps confirmed and triple checked, I used a carefully cut wooden spacer to make each of the subsequent holes along the upper spar cap exactly parallel to the bottom one. I started with a wooden block close to the length needed to fit between the caps, squared the ends on the band saw, then slowly sanded each end until it fit snug but perfectly between the two.
I copied the process all the way along, doing every tenth rivet and double checking the spar height each time. The caps are perfectly parallel and the spar height is bang on 209 mm. I finished of the rest of the holes to A3, skipping over the section where the spar web doubler will be. All the holes, top and bottom are A3, eventually will be up sized to A5 for solid rivets. The whole spar assembly as it sits now is already very strong.
Flipping the whole assembly over, I checked the rivet lines and confirmed the spar height as correct. I also started to formulate a plan for the spar root assemblies, spar web doublers and how to trim the upper cap angle taper effectively.
Next up is the spar tips. Made from 025, I bent these a while back when I was working on some 025 sheet work. They too have lightening holes, which I laid out and completed with the fly-cutter on the drill press.
Both tips with lightening holes cut and ready to be flanged. These holes are exactly the same diameter as the ones that will be in the spar web, so I marked the cutter with a flag note stating it was already set. Once I get the spar lightening holes cut, I'll flange them at the same time as these.
To ensure the spar tips are perfectly square and parallel to the spar, I flipped the spar back over and clamped a spare piece of angle to the bottom spar cap angle, measured exactly where the tip should overlap the spar end and marked it for pilot holes.
The red line on the left is the rivet line for the spar tip where it attaches to the spar web. The red line on the right is the rivet line station for the outer wing and nose ribs. It has a different rivet spacing, so I'm leaving that alone until the ribs are ready for installation. This will allow a small adjustment to compensate for any variance on the pickups in the slats, which will be installed on the wings later.
Four A3 holes evenly spaced between the spar caps. These will eventually be A5 pulled rivet holes.
Flip the spar back over. Layout the rivet holes in the ends of the spar caps as per the plans. Clamp it all together. I found it helpful to extend the whole thing over the end of the bench for this.
Back drill through the spar caps through the spar tip and secure with clecos:
Extremely happy with everything so far. The spar is dead straight, dead on 209mm tall throughout it's length and distance from root to tip is exactly as in the plans. Straight and rigid enough to stand on it's own! I'm waiting to pick up some aluminum sheet and flat stock later this coming week to make the spar pick-ups, the spar web doublers and front upper strut fittings..
I had a couple of hours for the shop one morning, so I decided to start modifying my wing rib templates. I've had these made for many months and now that I'm ready to start forming wing ribs I wanted to re-visit their layout. I'd experienced some issues forming the slat ribs and thought I could address this on the Wing ribs. I marked the location of flute relief on both the left and right side templates. This will eventually make forming the curves on the bottom and top of the ribs easier.
I started cutting the flutes using a small drum sander on the Dremel tool. It worked really well (more on these later).
Back in the shop the next evening, I started to form up the 032 spar root doubler. It was relatively easy to make as I had experience from installing a missing one on the 701 wing repair (click here for that part of my story).
It starts with bending a flange on the outboard end, then trimming the doubler to match the taper of the spar web, leaving enough width to bend a second flange to match the taper.
With the doubler bent correctly, I laid out the rivet lines for the upper perimeter and back drilled through the web out to A3, using the bottom spar cap angle as a guide to keep everything straight. (it's hard to see it here as it is underneath the inboard spar web):
Flip the spar over and lay out two rows of rivet lines, 5 rivets between spaced between the spar caps:
With the spar doubler drilled, clecoed and and confirmed as correctly positioned as in the plans, I removed it again in order to better see where I need to trim the upper spar cap angle. I marked a line on the angle using the web as my guide.
The next part was quite challenging - using the chop saw to make the accurate angle cut on such a long and un-wieldly piece of angle. I managed to get it close enough, but boy the chop saw makes ugly work of the cut:
The black line represents everything actually left to trim back for a perfect match to the spar taper. I used an angle grinder to gently remove more material using the spar doubler as a guide until it was perfect:
As I got close, I switched to a hand file, taking it down until it was perfectly level. Some final sanding to round off the sharp edges and it is complete:
Putting it all back together, I began laying out the rest of the root doubler rivets and drilling them out to A3. The plans here are kind of lacking about the spacing, but I believe I got it close to what is intended. These will be A5 rivets and the spacing I've left between them it well withing tolerances. I've written what I've used for measurements on my plans so it will be the same on the left spar.
I upsized these to A4 with the exception of the 3 at the tip. I'll leave these as A3 until I can align the inboard root rib and nose rib. This assembly will only get stronger with the addition of the root attachment plate.
As per the plans, I added two standard L angles on the back of the spar at the required location. These add more torsional rigidity to the spar assembly as a whole.
First I marked the centre line of where the angle attaches at each location on the spar:
I cut and deburred two pieces of L to 209 mm long, then used the rivet holes in the spar tip as a guide as they are the same layout (4 rivets between the spar caps):
It doesn't show here, but I drilled pilot holes in each of the L pieces, then used the layout line on the web to align the L in each of the spots and drilled it out to A3. They too will become A5 eventually.
Ron had a look at the flutes I cut in my rib forms and suggested I widen and soften the edges a bit. To do this I used a hand file.
The file was very effective but left the flutes a bit rough.
A little hand sanding of each and they cleaned up nicely.
Both the wing and the root rib bottoms taper slightly up from the front bottom corner. In order to lay out the lightening hole and tooling hole locations correctly, I set up one of the forms on the bench and used a scrap of angle and a carpenters square as a straight edge for measuring against. As this is my first go at using these forms, I decided to do the two root ribs first in case I discover procedural issues. Better to change plans now if needed, but I think this will work.
The four vertical lines measured laterally from the square end. The tooling hole locations measured vertically up from the straight edge provided by the angle. I drilled the four holes out to 15/64ths diameter, same as the bolts I will use to clamp the forms together when bending the blanks into ribs. Left to right, the first 3 holes are also the centre of the lightening holes, the fourth is a tooling (bolt only) hole:
Flip the stack over, clamp the forms together straight and use the new holes to back drill though the other half of the forms, ensuring both left and right rib consistency.
With the forms and templates ready, I start to stack them and a blank together. From top to bottom in the picture below - right side form, left side form and wing root rib blanks. The blanks don't have holes yet and the stack is now pointing in the opposite direction (left to right - tooling hole, and 3 lightening hole centres).
Line up the root rib blank on one side of the form......
.... followed by the other form, lined up directly over top the other. Normally this alignment is accomplished via the bolts and holes. My blanks don't have tooling holes as I wanted the holes to first match on both forms otherwise what's the point?
With everything lined up exactly where it should be, I clamped the sandwich to the table and using the form holes drilled pilot holes through the blank:
This results in perfectly located holes - all four will initially be bolt holes for forming the rib.
With both root rib blanks having their tooling holes complete, I can bolt it all together and put it in the vise for forming:
Gentle and firm blows with the dead blow hammer, bends the flange over the sides of the form. A piece of hardwood dowel rod helps direct the forming blows, massaging the aluminum into the flutes, taking up the extra aluminum from the curve of the form and creating the desired shape across the top and bottom of the rib:
The flutes really help make the rib nice and straight, but it also make is tougher to remove the form. Not bad enough to avoid the flute work! Once out of the form, fluting pliers can be sued for final adjustment. Once flat and out of the form, the 3 forward bolt holes become pilot holes for the fly cutter.
Knowing the procedure works as I intended with the root rib, I repeated the hole alignment procedure for the wing ribs and it turned out perfectly. I'll get to pilot holing the rib banks soon in preparation to form the ribs..
The nose ribs of the 701 and 750 are close enough that I can use Ron's forms. I remembered this while looking for my nose rib forms - that's why I didn't make them for myself! Ron and two other builders were making their nose ribs at the same time, so they bolstered their form with a metal plate close to the nose. This absorbs and backs the small tinsmith hammer blows required to get the thin nose flange rolled over much better than the wood alone.
Ron's forms are already drilled for tooling and lightening hole centre, so the process changes only slightly. This time, I laid a nose rib blank on the drill backing board and centred the form on the blank.
With it clamped in place, I drilled out the holes, using the form as a guide. Then I repeated this step 11 more times for a total of 6 left and 6 right rib blanks.
Ron's forms do not have flutes cut in them, but Ron says they had no issues forming their ribs without flutes. I will need to know where the flutes need to be crimped using fluting pliers, so I marked out 6 left and 6 right for future forming:
A couple of parts I've yet to make are the front upper strut fitting and the spar root fitting (2 of each, one set for each wing). These are substantially thick pieces of aluminum, each a 1/4 inch thick.
One challenge scratch builders have is a good reference of materials needed for a build. Kits come with everything already cut and mostly bent. To make scratch building affordable, one needs to purchase materials in complete sheets then cut them down to size. Buying in bulk saves major bucks.
Thankfully, I received a really good spreadsheet from another scratch builder early on in my build process, which has been invaluable in giving me some idea of the materials needed.
I've been following along pretty closely to the spread sheet of material, but it sometimes has a bit discrepancy compared to the plans. But as we all know, the plans are king.
My spreadsheet states the spar root fitting is 38mm wide by 240mm long - this coincides nicely with the spreadsheet and can be made from 1-1/2 inch x 12 thick aluminum bar stock perfectly (38mm is 1.49606 inches, close enough for me!)
My spreadsheet also states the front upper strut fitting is 40mm wide by 203mm long. This means I'd need bar stock just over 1-1/2 inches wide (1.5748 inches). This sucks because the next width in bar stock is 2 inches, meaning a bunch of wasted material if I have to cut it to width.
I spent too many hours thinking about this and trying to figure out if maybe I'd be better to order some 1/4 inch plate and cut them all out from that, which means more work and chance for error. It was then I looked again at the plans and realized the spreadsheet is wrong. Both are 38 mm wide, meaning I can make all four from a single strip of 1-1/12 wide bar stock. Cool! (I've adjusted my spreadsheet!)
So the 1-1/2 inch bar stock has been ordered along with some 063 to make the spar web doubler and some 0.188 plate for the wing attach brackets on the cabin/fuselage. It pays to shop around, these materials are about a quarter of the total cost ordering it from Aircraft Spruce and 8 hours closer too! I'll pick it up this week from the supplier. I'll probably get them to quote some 020 that I still need for the wings and fuselage skins.
One material that is cheaper to get at ACS are aircraft grade hard rivets. What you see below is way more than I need, but it's good to have extras. $68 something including tax and the time to go get them. I was going that way anyhow to pick up something for Ron, so it saved us both a little on shipping too. The picture below is what I got for the money. The writing on the label is the weight in pounds, not the cost per rivet.
Another consideration I've been pondering is fuel capacity and what that means for my build. Will the standard size fuel tanks be adequate for my expected fuel burn and range? I need to think about this as it affects how and where the fuel tanks get installed in the wing.
I reached out to William Wynne, the Corvair guy and he advises I can expect to flight plan for an average of 6 gallons per hour fuel burn at normal cruise speeds. Looking at the specs from the Zenith website, standard dual wing tanks are 24 US Gallons (2 x 12 gal.) - meaning not including unusable fuel in the lines and any reserve I can expect about a 4 hour range on average.
The extended tank option from Zenith (plans sold separately?!) increases this to a total of 30 US Gallons (2 x 15 gal.) - an increase of about an hour of endurance. The tanks are essentially a little bigger but still fir in the same wing bay.
Some have added a second standard tank in each wing, meaning a total fuel capacity of 48 Gallons!
That sounds great, but there are some serious pros/cons to consider. Extra range and fuel is always a good thing. But how long do I want to a leg to be - i.e. will I need to stretch/pee/eat before 4 hours? It also costs more to make larger or dual tanks, and it complicates the plumbing of the fuel quite substantially. There is also the consideration it may decrease the usefull load (how much can I take in baggage and gear - fuel weighs a lot) and that it costs fuel to haul fuel.
I'm all for the extra range - it never hurts to have more fuel than I need. I'm just not sure it meets my mission and if I eventually plan to put the plane on floats, then what? That has impacts on gross/empty weight on it's own, without considering the extra weight of fuel.
I don't have to decide yet, but will have to soon. Maybe I'll reach out to Jeff Moores in NewFoundland - he has a 705 Cruzer on floats and see what his experiences are. I'm leaning towards the middle option for a slight increase in range without complicating the plumbing.
So.... long blog today. I hope you are enjoying following along. More to come soon including some decisions on fuel tank size.
It has been almost a month since my last blog post, but work continued on the slats over that time. No real need to blog about it as the process was the same for all four with the exception that the outboard slats were slightly longer externally. The internal skeleton and assembly steps were the same.
A pciture of the last slat on the bench awaiting trailing edge bend before debur, prime and rivet.
Also in the last couple of weeks I played a bit more with the 3D printer. It seems I've run into an issue with the filament jamming in the extruder. Very frustrating stepping away to do other things while the printer works on something, just to come back and find nothing coming from the nozzle!
I took the extruder apart and it was clear it wasn't feeding correctly as evidenced by the "knot" of melted filament between the extruder and the hot end.
I spoke to a work colleague who is very invested in 3D printing as a side business and showed him some pictures. There are two things that most commonly cause this are a gap between the hot end feeder tube and the extruder, or worn extruder parts. As the extruder parts are 3D parts themselves from the manufacturer, his suggestion was to spend some money to upgrade to an all metal extruder and hot-end.
Looking further into this, I decided to not to proceed any further with using this printer. The printer is not mine (it belongs to the local library) and I'm not quite ready to invest the time or money to upgrade something that is already esentially obsolete. I still plan on printing parts for the airplane eventually, but this printer is has become a bit of a distraction from the airplane itself. Also, newer model printers are getting cheaper by the minute and easier to use with built in functionality that makes printing exactly what I need more sense, so I'll look at investing in one of my own eventually. I've accomplished what I set out to do - proof of concept and making it functional again for the library. 3D scanning is also functionally feasible, but it too needs more time to getting it working the way I want it so it too will be shelved for the meantime.
A question came up from another builder on the forum on how I've managed to bend the trailing edges so cleanly. The entire procedure of assembling the slats can be seen on a previous blog post but for the sake of explanation, I used a small diameter rod along the inside of the fold held in place with some spacers Ron and I came up with. The are scrap strips of 0.016 aluminum with a a small curled up end.
I used wide painters tape to hold the strips in place, the curl of the strip against the rod. The picture make sit look like the curl is taller than the rod, but it is not. If it were, it would leave a mark on the inside of the skin so caution is warranted here
Strips and tape are cheap, good to have several across the entire width of the slat skin:
The inboard slats (the shorter ones) eventually tuck inside the outboard slat enough to be riveted together once they are mounted on the wings. Here they are back to back and upside down on the bench lined up but not yet tucked together - this really gives the idea how long and wide the wings will be!
Looking at my "completed sections" drawing, I'm pleased to be "mostly done" the control surfaces.....
.... and happy to see an empty bench, even for a few minutes! Now to begin one of the bigger sections both in size and number of parts - the WINGS!
I brought a fresh roll of 0.032 (on the bench) and 0.042 (coiled beside the bench) down from the storage barn, to start laying out the components for the wings. Like everything else, I want all the parts made and ready to use in assembly to minimize the time on the bench.
First up, the wing spar webs from 0.032. The two spar webs are almost a full length section of a sheet and requires accurate cutting so the spar assembly is straight and true. They make up the centre part of the spar between to 6061-T6 angles on the top and bottom (more on later).
I cut the first web using a plunge saw with metal cutting wheel and it turned out fairly decently. The saw isn't as accurate or clean cutting as I would like leaving me some extra work with a hand file to clean up the cut edge by hand before deburring and sanding smooth. With a bit of work, it eventually cleaned up nice and straight. I cut the second spar web by hand using the large hand shears - it took longer to cut, but I found that if I was careful I could be more accurate cutting by hand and it took a lot less time to debur and clean up the cut. I used each side of the factory edges of the sheet to be and edge for each spar web giving me a perfect factory edge to measure from..
With the spar webs cut to size, I measured and cut out the tapers at the inboard ends of the spars where they will meet the wing (the bottom of the spar web faces the ruler in the picture below)
The thickness of the 0.032 and 0.040 sheet make them awkward to roll/unroll, so it makes sense to cut the other pieces out while the sheet is on the bench.
In the picture below you can see the remaining 0.032 sheet after cutting out the spar webs (coiled at top of picture), the spar root doublers (bottom of picture) and the four rear spar channel blanks (middle of picture). The two thinner strips on the right at 0.040 blanks that will be bent into angles as inboard rear channel doublers.
The 0.032 rear spar channels and the 0.040 doublers are too long to bend at our shop, so I've taken them to the same shop who bent the flapperon spars for me previously. I'll get them back this week.
I also needed to cut out the left and right 0.063 strut support brackets (bottom right in photo below). So while I had the sheet on the bench I also cut out some of the other 0.063 parts for the fuselage - the fuselage parts will be put into storage until I need them, but at least they are done. I ran out of space on the 0.063 sheet I had to layout/cut the spar web doublers, so I'll have to get some more from storage to get these done.
So despite no blog updates, I have been working away. Control surfaces are "done" and work on the wings is underway. Looking at the completed parts picture I posted above I'm very pleased how far I've come since starting. I'm not sure I can put a concrete answer on how much I've got done, but of the approximately 275 aluminum parts to make, I've got about 145 done which is very roughly 53%. Understand that's just parts made, not bent, assembled, drilled, debured, primed, riveted.
As always, thanks for following along.
A really good couple of days in the shop this week.
With the first slat underway, I was time to begin the task of wrapping the top skin over the ribs. To make this easier, Ron has built a "slat box" as show below. Made from plywood, it is essentially a reverse or negative pattern of the top surface of the slats. Green painters tape is added to any contact point to prevent scratching the skins:
Before getting the slat mounted in the box, I had to tuck the underside into the folded over trailing edge. It's tight, and I used a thin piece of wood as a slide to get it tucked under. The resulting pinch of the trailing edge fold is enough to keep everything together for mounting in the box.
Now it fits in the box and can be strapped down to complete the final wrap over.
I used a piece of HSS tubing to act as my spreader across the rear of the slat.
A look inside the each end confirms things are close enough and I can begin drilling the top side rivet holes.
To access the top side (which faces down in the box) I tilted the box on it's side:
Strategically cut access holes in bottom of the slat box line up with the 3 internal ribs so I can get at least 3 rivet holes drilled through the skin into the ribs:
The fourth hole is to far down inside the box to drill it accurately, but that can wait until everything is out of the box.
Put the box back upright and added some more blocks. This allows the force of the straps to transfer down more vertically, tightening everything up and I can begin to drill and cleco the trailing edge down on the underside:
Take the assembly back out of the box again and finish the top side rivet holes I couldn't access before. The finger clamp holds down the rear curve of the skin to the double bend flange underneath:
Layout the rivet line across the top rear. These will be A4 rivets with 50mm spacing:
To ensure I had everything locked down where it needs to be, I flipped everything over and drilled out everything to A4 on the underside:
Back ipright again, drilling the topside rear rivet line, A3, then up to A4 on 50mm spacing. I also completed the front rivet holes in each of the nose ribs. Everything is tight and square.
And it all comes apart again for final debur and priming:
One of the challenges I'm facing is how to make the inside of the slat structure accessible for the inspector to see my workmanship. The fold-over design of the skin makes leaving it open like the flaps, elevator etc impossible. I discussed this with Ron and confirmed with Roger at Zenith that adding a lightening hole on the flap ribs was acceptable here. I'm not looking to save weight, just want an easy way to see inside. This viewing can be done with a scope.
I carefully added some small holes in the centre of the slat ribs using a step drill. This will allow a camera scope inside.
I flanged the hole slightly to add strength:
I scratched off some of the primer doing the holes, but they cleaned up nicely and I re-primed them.
The new access hole creates a new small problem. The skin support L now protrudes over the hole:
the quick solve for this is to trim the L a bit before riveting. I also trimmed it back a bit on the top of the bend flanges to ensure clearance for the top two rivets.
Primed the skin and once dry started the re-assembly which goes back together fairly quickly
With everything drilled out to A4 and clecoed, the slat skin is tight to the ribs and looks good for riveting. The access hole turned out really nice - there should be lots of room to look inside using a scope.
Very pleased how this turned out using the steps I came up with worked well, I'll be following the same order when I build the other three. Again, I'm rather surprised by the size these are, it gives a good impression about the wing dimensions.
One to the next one, it all starts with alying out the bends. Thankfully I wrote down the measurements and bend order from the first one - that will make the next three the same.
Very happy how the first slat turned out considering how complex and tight the bending that is expected of the skin. It's not a complicated structure, but "fun" to do.
Back in the shop soon to get the rest of the slats done. I'll be continuing work on the 3D scanning/printing project too, exciting things coming up. Thanks for reading.
A really productive day in the shop today. Managed to finish off the last flapperon (inboard right). A milestone part of my build is complete. Here is a family pic of them all together:
The opposite end shows the open ends of the outboard flaps (on the left below). This is where the aerodynamic tip inserts will go during final assembly:
With everything complete on the flaps, I stacked them up for wrapping in plastic sheet to protect them:
Once wrapped up tight, they go up in the barn for storage until needed back out for inspection and set-up on the wings. Stacked on some of my rolled aluminum, from botton to top, my completed assemblies are stabilizer, elevator then flaps.
One thing I want to try is 3D printing some of my parts and the aerodynamic flapperon tips are the ideal candidate for this technology.
I wrote previously in my blog about 3D scanning some original parts and using the 3D model from the scan to print them. I discovered that although my home server has enough processing power and memory for 3D scanning, the video card currently installed does not quite have enough chops for the job. A replacement I ordered arrived last week from Amazon and I set to the task of installing it. For some reason, the server will not power up (it has been sitting idle for a couple of months while I waited for the new video card). Bummer, I will have to investigate this further before I can start experimenting with 3D scanning.
Meanwhile, our local library allowed me to bring home their 3D printer. It broke several months ago and they have no money in the budget to repair it or hire someone to fiddle with it, so I offered to see if I could get it working. No idea at this point what it will take to get it working (it is an early model) but I told them in return for trying some prints from my 3D scans, I would both work on getting it working for them and pay for any parts that might be needed. From what they have told me, the extruder nozzle is clogged and the print bed may be damaged.
Very happy to have the flapperons done. Next on the build table will be the slats which I am led to believe is one of the more challenging sub-assemblies of the entire build. But that is what I got into this for - to learn :)
In an upcoming blog I document the 3D printer un-boxing, rebuild and repairs.
Thanks for following along.
Back in the shop after a couple of nightshifts at work. The shop is definately where I like to be, working away on the airplane and away from the constant din of COVID doom and gloom. We are streaming music via a bluetooth speaker to avoid any outside news. The crazies that call 911 with stupid scenarios around social distancing rules are starting to really annoy me, but that is for someone to worry about right now while I'm on days off.
With everything on the flap assembly correctly drilled to correct size, it's pulled all apart again for deburring. I decided it was best to drill the flap pickups for the connector bolt while they are off the flap that way I can ensure consistent position of the hole. I noted these measurements in my plans (Zenith don't tell you the dimensions of the hole placement on the angle, just that it's an AN3 diameter bolt hole).
Placing the pick-ups back to back and clamping them together for drilling through makes for an easy way to make them consistent.
With everything deburred, I cleaned of the Sharpie markings off with acetone, scuffed up everything with a purple 3M Scotchbrite pad and wiped everything clean again. The aluminum sure looks clean now!
I was going to use Cortec primer again here, but decided interior pieces can be sprayed with green chromate based primer. I did any edge that would be in contact with other aluminum. Kind of wish I had done this with the elevator - much easier that the Cortec and easier to see coverage is complete. The outside surfaces of the flap pick-ups are done in grey paintable self-etching primer as they will be painted with the flaps later. For the flap spar, the outside of the flanges and the areas where ribs attach were also done.
I cleaned up the flap pick up holes as well using the same process. Green primer on the inside, grey on the outside. The grey primer looks thick in the picture, but it dried thin and smooth.
It doesn't take long for either primer to dry, so assembly can begin almost right away again. Kinda weird seeing everything in green but it will be inside the flap!
Here you can see the flap pickup angles painted primer grey.
A5 rivets here really tighten up this joint/structure. The entire weigh of the flap counts on this important interface.
With the entire inner flap skeleton now riveted, I added the skin back on and began riveting it all together again. This picture below shows the control horn and doubler in place, already primed and ready for riveting. It also shows the "toe-in" of the root rib and how the skin was trimmed to match. I took measurements and documented the rivet placement so I can match the other inboard flap.
Here is another close-up of the protruding flapperon pick-up angle. Really happy how the hole turned out. When prepping everything for final paint, I might consider filling the gap with some flexible putty or something to clean it up entirely. Not required but would prevent water or something getting in there.
From here, it's the process of riveting alternate holes on the bottom surface, working from the trailing edge forward towards the spar. Next, remove the remaining clecos, rivet any remaining holes and the bottom is complete.
Next time in the shop, I'll be flipping it over and drawing the nose skin down for temporary rivets across the top surface. It will be set aside and I can start the next one.
Only 3 more flaps to go. They should go much faster now.
Thanks for following along. Find your way to self isolate - make something!
So, a lot has been happening in the world in the last week or so.
The Novel Corona virus, better known now as COVID-19 has seen exponential spread across international borders from it's origins in China. Unless you have been living under a rock or are reading this blog in some distant, future archive (thanks by the way!), news and anxiousness is rampant about what is now officially declared a pandemic. People are scared, some more than they realistically need to be and world financial markets are feeling the squeeze.
Mandatory closures of schools, businesses and government facilities are becoming commonplace as we work to "social distance" ourselves from others. Large groups, social gatherings, events and meetings are highly discouraged if not outright banned Efforts are underway by people everywhere to prevent the spread of the virus and protect those who may not have the benefit of good health and the ability to fight off this particularly nasty bug - it can and has been shown to be fatal. Unfortunately there are those ignoring common sense which is leading to more anxiousness and unease. This has even lead to a very strange phenomenon of the panic buying bulk toilet paper!
I've said before how much my shop time is my happy time. It's my place to decompress from my emergency services job. While a good portion of society has been told to stay home from work, my colleagues and I continue to work shifts in a busy 9-1-1 communications centre and although the calls for service have yet to peak as I think they will, we are an essential service and will continue to come to work and answer the calls. It's scary but I think we'll come out the other side of this craziness better off as a society from the lessons learned.
So, what better way to practice "social distancing" and "flatten the infection rate curve" of COVID-19 ng than to get to the shop and work on my build! Here's what's happened since my last blog post.
A couple of weeks ago, I traveled south to visit Dad and made a side trip to Princess Auto and Aircraft Spruce for tools and hardware. I needed an inch/pound calibrated torque wrench and was happy to find a good quality one on sale - score!
I stopped at Aircraft Spruce and picked up my online order of the remaining aircraft hardware I need for the build, other than some back-ordered nut plates and stainless machine screws. Obviously this isn't everything I'll need (the interior will require some fabric fasteners etc), but what you see in the picture below is the lion's share of bolts, nuts, washers and cotter pins called for in the plans.
I've primed and final riveted the elevator outer hinge pins
With the elevator all closed up I started fitting the trim control rod and servo arm
Here is a good look at the servo arm and trim control rod. I'm not happy with how they fit together as there is too much slop or play between the pin and the arm, so I'll likely put some JBWeld metal epoxy in the arm hole and drill it out to match size the rod arm pin.
The rod as it comes from the hobby store is plenty stiff enough to work in this arrangement, but comes much too long. I attached the trailing rod end to the trim tab actuator bracket. With the elevator trim in the neutral position, I held the road alongside the rod end, trimmed the rod to length on the bandsaw and ground it smooth on the bench grinder.
I specifically left the rod long enough so that I can trim is shorter if needed. The plans call for the elevator to deflect 20 degrees up and 40 degrees down from neutral. Before I can set the system up, I'll have to thread the this end of the rod for the safety nut. I may change the "neutral" position of the servo arm to favour the 40 degree pull - it will take some playing around to get it just right. The servo programming is the easy part!!
Some final clean up of the stabilizer was completed and I temporarily closed it up with rivets, just like the elevator. The insides will have to be inspected by Tansport Canada before all the final rivets are done. Stabilizer fences are just temporarily attached for storage purposes and may need to come off to open it back up for inspection, but I may get lucky and they can stay on for final riveting.
The following pictures show the completed tail assembly with outer and centre hinge pins installed. It lined up perfectly and shows no signs of binding - very pleased! (it's sitting on the bench upside down compared to how it will be mounted on the plane - it just sits better that way).
So! The tail is now complete. I currently have roughly 150 hours of work into it. Once wrapped in heavy plastic it will join the rudder up in the storage barn. There's about another full day's work once it's cleared for final close up to complete, with a lot of that having to wait for fitting to the fuselage.
I feel so productive and safe from the world's dangers in the shop right now. With all the temporary closures, I couldn't think of a better place to stay safe from COVID-19 - working on the some temporary closures or my own :)
Thanks for following along. Next up flaps and slats!
A bit of time in the shop this week. Dismantled the elevator (again) and deburred the holes now that everything is drilled to right size. It's points like this in a project that make you feel both accomplished and behind at the same time. You realize all the work you've done to this point by the number of holes you've drilled, but taking it all apart for deburring seems like a backwards (but necessary none-the-less) step.
Deburring the trim tab after it is bent is problematic. The holes for the hinge can't be drilled without having it bent to shape first. How to debur the holes on the inside angles (see yellow arrows)? Make a tool!
Normally we'd use a rotary debur tool, but access is too tight. To get access, I came up with this idea.
1. Slot a piece of wood
2. Insert sandpaper
3. Slide onto flange
4. Gently and carefully slide back and forth along the length of the flange. The goal here is to remove the burrs, not to sand the flange. It worked really well!
A follower of the blog had asked me why the elevator skin looked wrinkled in the pictures on the bench and the look of wrinkles is due to the protective plastic coating on the sheet aluminum. I've now peeled that back anywhere there are rivet holes so I can properly debur them. I'm leaving the remaining plastic on the skins to help prevent scuffs and scratches as I work with them off the skeleton.
With the elevator skin off the spar, now is a good time to fit the trim servo. The bracket I made will work, but now that I'm fitting it I've discovered something I hadn't thought of. If I have to remove the servo for replacement or repair, orienting it this way (mounting screws are sideways in the bracket) means it will be painful if not impossible to remove it through the access hole!
I decided it best to create a new bracket similar to the one Ron is planning for his 701:
It took a couple of tries to get it right, but it turned out well!
I'll need to add a grommet or strain relief at the pass-though hole to prevent the servo wire from chafing:
The servo will sit on an angle, parallel to the inside of the skin surfaces - the more direct the push/pull rod can be to the trim tab control horn the better.
As I sit on nightshifts at work, I have some time to ponder what else I can do with the Arduino. The ideas are truly endless and easy to implement. One thing that really excites me is the ability to display data on little screens. For example, here is a picture from the internet where an Arduino programmer has an OLED (Organic LED) panel emulating a basic cell phone display. OLED displays are super cheap and highly customizable and some models are capable of displaying in different colours.
Here is another example of a development board with an OLED display connected to an Arduino mini exactly like the ones I'm using. They are very small in size, but can be used to display lots of things at really bright contrast and resolution.
Here's an animated guage from the interwebs being used for something someone was developing:
If animation can be done, animation in colour can't be much more difficult.
I'm pondering a small display like this on my instrument panel, with a custom display graphic. Perhaps a overhead drawing/graphic of my airplane with animated lights that blink in co-ordination with my navigation/strobe/wig-wag lights! How cool would that be? Here is a (very) rudimentary idea about what it might look like. I can't animate this picture, but I think you get the idea - the red/green nav/beacon/strobe lights would blink or in the case of the landing lights alternate back/forth when in wig-wag mode. Maybe I can animate the prop too hahahaha!:
Maybe instead of the bar graph LED showing elevator trim like I already have planned, I can integrate the bar graph onto an OLED display, either by itself or with the light display above:
My engine gauges will be traditional mechanical versions - much more robust. Everything I propose here is for non-critical indications.
I've got a long way to go before I have to worry about this stuff anyhow, but it is cool to think this is easily and cheaply within reach for a simple hobbyist like me!
Some my regular readers might have noticed I've removed the countdown timer from the right navigation bar of the blog. I originally intended this to be a motivator for me. I had set the goal of first flight to be my 50th birthday, but that is never going to happen. I got behind in my build with changes at work etc., so I'm removing it for now as it doesn't reflect reality. I'll continue to strive to get the build done.
Next up, priming the elevator pieces and reassembly for riveting!
Thanks for reading :)
Back in the shop tonight, finishing up some of the smaller details on the elevator.
Got the motivation to cut the trim tab slot out of the trailing edge of the elevator. The plans call for a slot for almost the full length of the trailing edge. This doesn't leave much of the trailing edge remaining done this way, so after some discussion with Ron, I decided to shorten the trim tab somewhat.
Cutting the skin is tricky - have to be real careful not to damage the trim tab spar. I decided to drill some pilot holes to work towards, then clean the edge up close using a Dremel tool. It took several assemble/disasemble cycles to get it just right but it turned out nice a square. A round file helped to round out the inside corners.
I've decided to add some trailing edge ribs on the rear elevator skin and inside the trim tab as well. This not only supports the skin where I changed the cut, it also looks nicer and will be cleaner aerodynamically.
It took a few tries to get it right - there is no template in the plans for these, I'm making my own. I'm happy with the fit and feel.
Next on my list of small details was drilling the trim actuator hole in the trim spar and elevtor lower skin. The step dill was again very handy for this:
Took the spar out of the elevator skeleton to drill the matching slot:
Back together for final fit. The slot stays the same as the plans. I think I might try and come up with some sort of flexible cover for the trim actuator rod hole to prevent bugs, dirt, snow or rain from getting in there.
Started the initial fit of the elevator nose skins. These need to be in place to confirm the correct spacing between the elevator and the stab. Happy with the fit but surprised how much of the nose skin tucks under the rear skins - but that's what the plans call for and my nose ribs are correct!
With both nose skins temporarily in place, I set the elevator against the stab again to confirm (again) the alignment of the upper and lower horns and centre hinge bracket - all good.
Forward and rear brackets drilled and added - this really stiffens up the elevator centre assembly!
All in all a productive night. I'm headed back to the shop in the morning to continue to knock off the small details - it all adds up!
July was a washout with regards to getting anything done in the shop, so not much available content for the blog....
A home project to replace the shingled roof on our house with metal took up 2 weeks of my July holidays and work travels took up a good portion of the rest of the month. Day trips with family need to happen too. This Monday to Friday temporary assignment I'm currently doing at work is good that the work is both challenging and really interesting, but it only leaves weekends to enjoy the summer. As of last week, I've been advised that I'll be returning to shift work at the end of September. I don't want to go back to the communications centre, but on the bright side, my schedule during the week gets freed up substantially (4 days off every week), allowing me more shop time.
Speaking of work travels, I had a chance to check out the Chapleau Ontario airport. Although there wasn't much to see (MNR fire base was quiet), I did notice this cool sign posted by the local flying club:
July and the beginning of August hasn't been a total loss I suppose. I did manage to get some work done on the elevator and horizontal stab.
When I fastened the skin to the stab skeleton, I marked out where I needed to trim the trailing edge. The extra was on purpose - it allowed for proper length and square fit. Now that fitting is complete and correct, I can trim it back:
With the trimming done, the rear slot is cut. This is where the elevator cables pass through the stab:
I notched back the spar doubler a small bit, leaving clearance for the rivet. Everything was deburred, cleaned up and primed after this photo was taken. Fortunately only had two places where this was an issue.
With the stab skeleton ready, I deburred the stab skin holes on inside and outside - there are a ton!
Cortec primer on the rivet lines was next. I really like how it applies - next to no smell, easy clean up and cures almost clear:
With the primer curing, I turned my attention to the elevator skeleton. Some final measurements to ensure it's built square and it is ready to taken apart again for final debur and prime.
The elevator skins are made of 016 aluminum sheet, folded at the trailing edge and fastened to the top and bottom of the spar. It consists of two sheets of equal length meeting a the centre:
To allow the rudder to move left and right, the skins are cut out at the centre box where the rudder hinges are. It's difficult to perceive in this picture, but once folded the cut out makes sense.
It's important to radius the corners of the cutout, so I started with a centre punch then a pilot hole and followed that up with a 3/8 drill hole.
Cut outs complete for the left elevator skin. Easier to see how this will look when folded. Round file and debur tool to clean things up. This is a exposed edge, so I final sanded it with 360 grit:
Careful use of the bending brake got the fold most of the way, then I used a small diameter aluminum rod to finish the fold to the 5 degree bend called for in the plans:
I used the same piece of pipe to curve the elevator nose skins that I had used for the horizontal stab - much easier this time.
By this point the primer has cured on the elevator skeleton. Re-assemble and check for square - all good to final rivet. I'll wait to final rivet the tip ribs once the skins are on and I can align the elevator and stab hinges:
With the prime cured on the stab skin, it is reinstalled for final riveting. I've decided to river the curved side (lower) and leave the flat side open for inspection. It's kind of weird order - first place the skin over the spar pick ups and cleco everything down tight:
Flip everything over and cleco down the flat (upper) side:
Flip it back over and complete the riveting on the curved (lower side). Really happy how everything is coming together and how straight everything looks :)
The stab is essentially complete at this point. Remaining items to be done are final rivet the hinge assembly (waiting elevator match up), cable pass-through slot in leading edge and fairleads (rub strips). I've also decided to add wing fences to the stab tips which have valuable aerodynamic benefits and really cleans everything up. More on the fences later.
Next up, get the elevator skins fitted up, then cut the trailing edge for the trim tab and install the servo.
Thanks for following along, more to come soon!
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.