There is a famous saying in homebuilt aircraft circles.... "95% done, 95% still to go".
I'm starting to understand that saying. I can see the finish line still on this 701 wing repair, but everytime I think today will be the day that we put it back into storage, something else gets remembered, discovered and repaired.
So here is a quick photo run down of what I've done in the last couple of trips to the shop:
Flipping the wing over (again) I started the fun process of creating the new wing root skin. I put the plan drawing dimensions into CAD on the computer, but struggled to find someone locally who could print it to scale accurately (at 1:1 scale, it's almost 1 metre long by 300mm wide). As it turns out, the plans are really only a guideline to how this will need to be cut thanks to the original builder not closely following the plans anyhow - so hand drawing them out was the better solution.
Next up, cutting the root skin as per the template I've drawn from the plans. I tried a trial fit with the bristol board and it's close but like everything else on this wing, it'll need some adjustment to match up with the original plans.
More to come soon!
Once again, I find myself disappointed that I haven't been keeping my blog up to date. Almost a month has gone by - if you've been following along, thanks for staying with me.
The last couple of weeks have been busy in the shop, I can honestly say I think we are coming to the end of the 701 wing repair/extension. It's been a very VERY long road, but worth every minute learning how to read Zenith blueprints, bend metal, plan ahead and correct mistakes (both my own and those of the original builder).
In my last blog post, I mentioned we were going to try using the router to cut the 040 thick aluminum sheet. I have to cut 3 strips that will be bent to make up the corner supports of the horizontal tail frame box, and using the bandsaw or scoring method would be difficult at best because of the size.
I laid out the 040 sheet on the table. Unfortunately, I didn't take any pictures of the set up, but essentially I planned to use the same method as I used for cutting the nose skin slots - a long straight edge to guide the router along.
What I didn't expect was the router bit to snap immediately on contact with the aluminum. Frustrating as I was very careful in set up, feed speed, etc. In the pics below you can see it snapped up close to the shank, not down by the tip where it contacted the aluminum. I'm guessing it can't handle the stiffness/thickness of the 040 despite cutting the 016 very easily:
I decided to put this testing away for now - I'm going to have to obtain a replacement bit anyhow. I'll do some more reading/research to see what I can do to improve my chances. I'll have to get back at it soon, I need these pieces for my tail, the first thing going on the bench when we're done this 701 wing.
Back to the wing.
Using the same method as the inboard nose skin, straps and wooden strips are used to bring the skin down tight to the spar and nose ribs. It actually wrapped a lot easier than I thought it would, but careful even tightening of the straps was key.
With the skin in position, I used the hole duplicator and matched the nose skin holes to the spar. Surprisingly, the rivet hole spacing is correct - at least the original builder got that part right.
With the bottom of the nose skin secured, we flipped the wing over to get at the top side. Same process here, straps, blocks and careful tightening.
If you look at the picture above, it's clear I need to trim the wingtip nose skin. It's a complicated curve, even more so than the upper and lower wing tip ends because it also curves from top to bottom to form the shape of the nose.
Adding to the challenge is that the original fiberglass wingtip can't be installed yet as we are using it as a template negative mold to make more.
So, how to cut the skin to match the wingtip nose, without actually installing the wingtip nose? There are a couple of things I can look at for reference.
First, the other wing for this 701 is in much better shape and the wingtip is still intact:
Unfortunately, I'm not going to take the nose skin off the good wing, just to make a template for the wing repair. We also can't assume it's correct - remember, it came from the same builder!
Second reference, the plans! Only problem here though is the plans reference measurements from the last wing rib to various points on the nose skin curve, where X is the distance from the spar line, and Ynose is the distance from the last rib to the point on the curve:
Seems simple enough, but we've added an extension and added two more ribs. So where to measure from, hmmmm.
With the skin in place, I marked the skin where it overlapped the upper spar cap - essentially this marks the end of the upper spar cap and is the X=0 point in the table above.
The nose skin was removed again - clecos from both sides, straps, blocks, and all (the skin had to be deburred anyhow). Now that I had a good X=0 point, I measured back from there 505mm, simulating where the outermost wing rib rib would have been. I made a scribe line from top to bottom at the 505mm mark, then marked out each of the X points. From these I could now mark each of the matching Ynose points on the curve.
To make the line a smooth curve, I connected the points with a french curve drawing ruler. Once i was satisfied I had the measurements correct and the curve was a smooth as possible, I used hand snips to carefully cut away the excess skin. I left it a bit long as it's always easier to trim it back once the fibreglass nose is in place.
Before putting the nose skin back on, I ran a pair of wires from the root to the tip, leaving enough to work with at both ends and correctly labelled. The wires are secured firmly (but not tightly) to the nose ribs by a dual wire tie standoffs.
The other thing we wanted to do before fastening the nose skin permanently, was to rivet in a backer plate behind the wrong slot I had cut. This backer will give us a surface to place body fill putty in the slot.. When it dries, the holding rivets will be ground flush and the nose skin sanded smooth.
The wing skins go back on, the straps are tightened again and the skin lines up perfectly. Clecos are added, and the final riveting is completed on the lower side of the nose skin. The wing finally looks substantially complete!
The next step to finish was to replace the damaged lift strut pickup support bracket. I made a new one out of 032 (the original builder used 025), drilled and clecoed for fit
So, what's left to do? Finish installing the fuel bay cover and rivet the upper side of the nose skin. The upper wing root skin will be done once the wings are installed and wing incidence/dihaedral is set (more on that later).
Very happy to see this wing going away for storage by the end of this week.
Next up, my horizontal tail. Here are the frames for two other 701's Ron is working on. I'm getting my parts gathered and will be building my tail alongside these ones:
A productive couple of weeks. Hopefully my followers here will finally get a chance to see me working on my airplane. I wouldn't be able to even begin without the skills I've learned here on the wing repair/extension. I'm very thankful for the opportunity to learn - that's what it's all been about :)
Sunday was a good day in the shop, and both Ron and I can see the finish line with the 701 wing repair and extension. Just a few more small items to go.
As Ron gets close to covering his Aeronca Scout with fabric, we've been discussing his plans to make a fabric/pain rotisserie rig for the shop. You may recall from way back in this blog an engine stand I bought for my Corvair. With my engine parts in Florida for rework, we're going to modify my engine stand and Ron's engine stand to become the end pieces for the rotisserie. This rig will allow us to mount any fuselage, wing or other large parts for priming and painting and being able to rotate them will be very helpful.
The inboard nose skin is ready to be installed. I clamped the skin in place, lined up along the spar. To draw the nose skin tight, ratchet straps are used, pulling the skin tight across the ribs. It's important to place the straps directly over the nose ribs to prevent caving in the nose skin before it is riveted.
Straps are equally tightened until the nose skins lay tight against the nose ribs and spar:
Folded protectors distribute the force across the trailing edge, thin scraps of wood protect the surface skins from the ratchet and strap hooks.
Using the hole duplicator, I matched the new nose skin to the original spar holes on the upper side of the wing. These were drilled to final size, the nose ribs to A3 until final fitting. The 3rd rib is drilled, but missing clecos so I can fit the outboard nose skin where it will overlap the slat pickup.
Once measured up, the outoard skin needs to be slotted to allow the slat pickups to protrude through. The easiest way to do this is with a trim router and spiral up-flute milling bit. I laid the outboard skin out on the table and set clamped a straight edge in place as a guide. Two strips of plywood under the sheet on either side of where the slot will be cut support the thin aluminum sheet and are thick enough to raise the bit above the table
After cutting all 3 slots perfectly straight, a valuable lesson learned - even if you right down the measurement, that is no guarantee that what you wrote down is correct :(
I measured the first slot as 395mm from the inboard edge, but for some reason I wrote down 595mm. From that point on, every time I double checked before cutting the slot, I measured/checked it as 595mm. Bringing the sheet back to the wing, my error was immediately obvious.
After pacing around the shop wondering how I could have possibly messing up the measurement, Ron told me he could fix the error fairly easily with a simple patch - go ahead and cut the right slot. This is part of learning and too much sheet metal to start over.
With the correct slot cut, all the slots lined up perfectly with the slat pickups - minor crisis averted.
Before working on securing the top side of the outboard nose skin, we thought it best to finish securing the inboard nose skin, that would give us a solid reference point for the outboard skin. We flipped the wing over and end for end on the bench. To get the nose skin flat, a thin strip of wood is placed under the ratchet straps. Once lined up and tight against the ribs, I again duplicated the spar holes and drilled the ribs to A3 size. Everything lined up excellent.
Even this nose skin, as small as it is lengthwise makes the overall wing so much more rigid. A good sign.
While waiting to discuss my slotting error I also unrolled my 040 sheet and start marking out the 3 horizontal tail doublers I need. I was initially really surprised at the amount of tape Aircraft Spruce used to secure the roll, but quickly understood why! There is a bunch of pent up spring energy in that roll, and I had to be real careful about wrangling it onto the flat floor for measure/cutting. The longest piece I need from this sheet is 1440mm long, so it was safe to cut that length off the end of the 12 foot long sheet. I marked and rolled the balance back up (that was a task!) and put it back into storage.
Aircraft Spruce ships all their sheet aluminum with a protective plastic sheet coating on both sides. Depending on how long the sheet has been on the shelf, room temperature, and other factors determines how easy it is to remove this coating. I think next time I'll gently warm it with a heat gun or hair dryer - this stuff sticks too good. For now, I've only removed a few inches from the edge I'm cutting from.
Even cut down to length, this sheet is awkward to put in the bender for scoring, and it's thick enough to making scoring a very long process. Instead, Ron and I think we are going to try using the router we used on the nose skin slots to accomplish the long cuts. If this works as we think it will, we'll use the same process for the wing spars (032) and maybe the fuselage sides/tops - anywhere a long straight cut on a large piece of material is needed. As I said above the tool makes really clean cut edges that require little in the way of deburring.
One other thing I've been doing is adding some of the complex shapes from the plans into CAD. Like my smaller parts (ribs, plates, etc.), these will be printed out to provide templates. One example is the wing root nose skin. I use a free downloadable 2-D CAD program called LibreCAD - it is very simple and more importantly it will accept the X/Y co-ordinate system common in the Zenith plans:
If you like doing things in 2-D CAD, you can download a free copy of LibreCAD here.
For those that have been asking, my finger is healing up nicely :)
More soon, thanks for reading.
After a week of resting up my arm, I took the day to go to the shop to see what I could get done.
First up, I decided to tackle the patch we need to make for where the original upper wing skin got torn at the root. This was either in the crash (likely), recovery of the wreckage (more likely) or propagated from the non-existent edge deburring by the original builder (probably most likely, but no way to prove it).
I had previously stop drilled the end of the tear and trimmed back towards the root edge. Using a lid from a coffee can, I traced the approximate shape we want the patch to cover:
I cut the patch to match the blue outline. The line is an appoximation of the open space we are trying to cover:
Final holes to A4 size, deburr and rivet. I used an edging tool to roll down the trailing edge. This tightens the patch against the skin:
The final photo of the patch - nice and tight:
Next up was finding another length of 016 for the outboard nose skin. While rolling up the remainder, the coil slipped a bit, catching my finger with the fresh sharp edge.... ouch! Feel kind of stupid and should have known better to wear gloves. Fairly deep cut, but took more skin layers than anything and I was able to tape it up and stop the bleeding without to much effort. Just in a bad spot on my good hand. Learning as I go right? LOL
I didn't take many more pictures today, just wanted to keep working. Did manage to get the outboard wing nose skin cut to rough size and deburred. Next up I'll have to cut the remaining slot bracket holes and get both of these nose skins mounted.
One thing I did take a picture of though.... one of my rolled sheets of 040 that I bought last summer. I'm getting it ready to roll it out and cut some more parts for my 750 tail. This time I'll wear gloves :)
Thanks for reading, more soon :)
Finally got back to the shop yesterday and got some work done on the 701 wing repair. Looking out our window lately makes travel to the shop..... fun. Makes me look forward to having some flying fun on skis!
Before starting up again on the 701, I decided to have another look at the 750 cabin frame I picked up last weekend.
The edition 2 cabin frame was changed/updated to edition 3 by Zenith in an effort to increase head room and apparently allow for a design gross weight increase. From a Wikipedia defintiion, aircraft gross weight is the total aircraft weight at any moment during the flight or ground operation. An aircraft's gross weight will decrease during a flight due to fuel and oil consumption. An aircraft's gross weight may also vary during a flight due to payload dropping or in-flight refueling (neither of which applies to my 750 - imagine in-flight refueling... oh the places I could go LOL).
The changes included removing the diagonal tube that crosses the top of the cabin and replacing it with two shorter corner tubes at the front corners of the roof - these new corners serve the dual purpose of becoming hand holds for climbing in and out of the cockpit. Both the old diagonal tube and the corner tubes are made of the same diameter and wall thickness tubing, so when I make this modification, I won't have to buy new tubing, I'll just use the removed diagonal.
The other change I've read about is that a larger spar carry through tube is required for the gross weight increase. This is the major component of the cabin frame and where the wings attach to. It's the main structural component that gives strength to the wing-fuselage interface - very important obviously as I plan on using this plane off strip, also putting the 750 on floats eventually and definitely want that extra strength and rigidity. Some others that have done this upgrade to edition 3 cabin frame have noted their spar carry-through tube needed to be changed to a larger tube. That's a lot of welding.
The cabin frame I have must be a late model edition 2. I measured the spar carry through tube and it matches my edition 3 plans in both diameter and wall thickness! This saves me a ton of work and materials. Once the corner braces are done, this cabin frame is good to go. Good news!
Measured up the inboard nose skin for the 701 wing. We have to use an inboard and outboard nose skin due to the extended wing. I tried using the original damaged wing skin as a template, but like most things the original builder did, it's measured wrong. I decided to cleco the old skin in place to see how far they were off the plans (my repairs to the nose ribs and spar caps are correct to the plans now). Yup, they were no where close and certainly didn't debur anything.
Once the skin is cut to rough size, I had to start to do the figuring out stuff regarding the slat attach brackets. The goal is to make the slot just the right length and position for the bracket to project through. Think twice, cut once is what they say, but in this case it becomes think many times, cut many small times and think again until it's just right. Repetition plays well here.
I placed the original wing root skin in place - look how far they were out from spec. If it had been right, they wouldn't have drilled the skin rivets in the wrong spot on the ribs - they should be on the flat spots between the relief bends. The root skin is too badly mangled to salvage, a new and proper one will be made.
The upper skin now completely done and riveted. The last few will be done when the new root skin is made. We'll likely wait on this until this wing is mounted on the fuselage to ensure proper fit.
Was going to go back to the shop again today, but I've somehow managed to strain my right arm to the point I can't left a drill or grip a set of cleco pliers.. I suspect I overdid it when shoveling off our house roof the day before. Some say it's part of getting old. So today is a day of rest and recuperation.
More to come, thanks for reading!
Getting close enough to getting the 701 wing completed, it's time to start planning the rest of the tail group on my 750. That means ordering some aluminum!
I called the supplier (Aircraft Spruce Canada) and ordered all the 016 I need for the entire build, a sheet of 025 to replace what I've used from Ron and some elevator trim tab hinge. The plan was to go last weekend, but the huge storm that dumped on southern Ontario precluded the trip so instead we loaded up the truck and headed south this weekend.
We arrived in Brantford and convenient for the girls, an equestrian riding store is about a kilometer away from ACS. I dropped them off and headed to ACS to pick up my order and some items for Ron.
The staff at ACS are fantastic - I had asked them to roll the aluminum as small as possible in order to fit it under the tonneau cover of our truck and keep it out of the winter weather. They are masters!
In addition to stopping at ACS, I had been in contact with another 750STOL builder in Burlington - Ghazan Hieder. Ghazan has been slowly working on his kit for about 10 years and self admits that any upgrade that comes out from Zenair he buys, so when edition 3 cabin changes were announced, he bought the plans and updated parts, making some edition 2 parts available. He had advertised on the Zenair Builders website he was giving away an edition 2 cabin frame and windshield, so I made arrangements to meet up with him while down south to take possession of these two valuable items.
He was glad I called as he had hoped to find another builder who could use these items - and I was glad to take them off his hands. All the research I could find shows only minor modifications need to be made to the cabin frame and the windshield is another easy mod.
Ghazan also offered me an early edition nose wheel fork and nose strut - he'd replaced his with Viking steel spring mod, something I'm considering too. If I can't use the strut he gave me, it will work for one of Ron's 701 builds.
Brenda helped me load everything into the truck as best we could, but we decided to put the windshield in the back seat until we could work in the daylight the next morning.
With better lighting, it was easy to pack everything safe ans secure. I borrowed some moving blankets from a buddy and laid them out in a way to protect the plastic edges of the windshield and the sharp edges of the cabin frame.
Getting it home safely worked really well, thanks to Brenda's amazing packing skills!
Unpacking it all at the shop, here is a better look:
Needless to say, I am truly thankful to Ghazan for his generous donation. He could have just tossed these away (frankly I'm surprised no one else came forward to take them) but he didn't - he just wanted someone else to use them on an airplane. Estimates are hard to nail down because I have no idea what this stuff would cost to ship, but conservatively? I saved about $800+ by picking up these surplus (to another builder) parts!
One of the coolest things I've learned about the homebuilding community is how keenly interested everyone is in other people's builds and more importantly successes. I have or am learning the skills to make these work for my build and that works for me, whereas Ghazan is happy to build from a factory kit. Either way we share a common bond - dream, build, fly!
Thanks for reading!
January is definitely here! -32C today (that's about -25F for you imperialists) in the sun, without the wind. Brrrrr..... good day to be in the shop with the woodstove!
I thought we'd be on the road this weekend with the family, picking up supplies at Aircraft Spruce, but a major winter storm threatened to clobber southern Ontario and delivered over 40 centimetres of snow, right where we were headed. Glad we stayed home - we'll head south next weekend.
While I'm working on the 701 wing repair and making parts for my 750 STOL, Ron continues work on his Aeronca Scout. I hope to learn his methods for welding steel tube, he is a master craftsman. The rear fuse frame has been painted and the new wooden stringers are just about to be installed. Looking real good!
Got the trailing edge complete on the 701 wing. The plans call for squeeze rivets here - small ones!
With the trailing edge aligned, finger clamps are used to maintain the edges of the top and bottom skins. Spring loaded centre punch marking the location and spacing of the rivets, holes drilled and clecoed
With the wing now flipped upright, we need to strip off the last of the oh-so-pretty paint. The stripped works real well on the white, but the red primer underneath is painfully difficult to remove.
After 4 hours of applying stripper, scraping and scrubbing, the wing is now clean enough for priming once it is ready. I was so fed up I didn't take a picture. What a pain.
So far I've got 17 "standard L" blanks cut, so I used some time to day to bend them.
I made two test bends and used these as measurement jigs by taping them to the ends of the blanks. This provides the correct inserted depth in the bending brake.
Half an hour later, I had them all done and I'm happy how they turned out. They still need to be deburred, but that will be easier now that they won't flex all over the place. These are used all over the contstruction of my 750, so I'll score this under "other".
Spent the balance of the afternoon measuring and planning the installation of the nose skins for the wing. With the extension, we'll need to use two separate skins, one inboard and one outboard with the joint offset from the spar extension joint.
This will take some planning and some thought which I've started on. The end of this repair/extension is tantalizingly close.
Next weekend we're headed south to pick up some materials and parts.
Thanks for reading, more to come soon :)
In my previous post, I spoke of the standard 4 foot long L's that I have to make. There are apparently a lot of them, some sources claim up to 64 required for the plane, some as little as 35. They are simple to make and I'll need some quantity of them anyway, so today I worked in my downstairs shop to see if I could come up with a way to start producing these as I have some spare time.
I rolled my workbench out from the wall to give myself some room to work at the ends of the bench and locked the casters in place.
The cutting tool I made previously is perfect for this task (more information here).
The workbench already has some bolts I use for the drill press mount, but here I decided to use them as a front edge spacer. The first cut was measured and marked out on the aluminum sheet. Once I had the sheet in place, I was able to position the straight edge angle in the correct position so that the aluminum is cut to 36mm, the correct width for the "L" before bending.
Using the cutting tool, score the aluminum from one end to the other. Important note - if you are planning on using this method be sure you do not put any side loads on the blade - pull across the surface and let the tool do the work. Side loading the blade may cause it to snap. (Photo credits showing me doing the work goes to my supportive daughter Natalie!)
I found it took about 10 passes to create a good score line on the 0.025 aluminum. It creates quite a bit of "swarf" - the small pieces of metal removed from a workpiece by a cutting tool.
Once scored enough, I un-clamped the sheet and shuffled it forward - being sure to remove the front dog bolts - and placed the score line directly over edge of the bench and re-clamped it down.
To prevent the sheet from buckling upwards as I bent it at the scored line, I clamped down the edges and also held a piece of 1/3 on top
It took about 30 minutes or so to complete the first one and more like 10 minutes for the second one as everything was already set up.
I continued to produce these for a couple of hours and managed to make 12 in total. They still need to be bent and deburred, but I think this is good use of time and certainly cheaper than having the cut and bent in a machine shop. For now, I'll make up to 30 of them until I can confirm with Zenair the total count that would come in an ordered kit.
Here is a pic of the collected swarf (including some dust bunnies from the shop floor)..... more to come!
Ducked over to the shop tonight to work on making some 0.025 aluminum parts.
My original intention was to to start making the numerous (64? Are you kidding me!) 4 foot standard "L"s needed for my build, but I decided I wanted to accomplish something more tangible.
I cut out the 0.025 skin for the elevator trim tab. I'm going to leave it flat for now until I have more time to concentrate on bending it. It's a fairly complex bend over a narrow piece of aluminum, so it will pay to think it out well before committing to the bender.
Next I started and completed the wing spar tips. By laying them out opposite to each other on the aluminum sheet, I saved a some cutting and and prevented waste.
Once I had them cut out the next challenge was to bend opposite flanges with the correct web space between. Thankfully I had done this before on the 701 wing extension, so it was fairly simple.
After making the correct bends (I had to think about which side was which) I laid out the measurements for the lightening holes. Once satisfied, it was back to the fly-cutter.
Depsite my efforts to size the hole correctly, I had a bit of a rough time flanging the holes evenly. They will need a bit more work from the flanging die. Other than that they turned out real nice.
That's it for tonight, thanks for following along!
A quick glance at my countdown timer to the right of this column tells a scary tale of how little time I have to get this plane done.
Originally designed as a motivator, I haven't really been paying attention to it. Now with just over 400 days to go I really have to get moving.
After battling with a broken snow-blower belt on New Years Day, I managed to get over to the shop for a it of building therapy.
A couple of quick photos of what I got done on the 701 wing repair - getting so close to moving it into storage and starting assembly on parts that I've made for my plane.
Unfortunately, Ron was gone for the night and I couldn't find the right squeezer anvil head for these rivets, so it will have to wait until I can ask them. It's probably right under my nose, but rather than rush when I was tired tired it can wait until next time.
Going to order some more aluminum this week. I'll post more to my blog about that next time.
Happy New Year everyone, thanks for reading!
Time until takeoff
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.