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!
You know that satisfaction of reaching an important milestone when working on a large project? The joy that is only tempered by the fact you know you still have a long way to go? That's what today felt like..... incredible :)
After deburing, cleaning and priming all the parts for the horizontal stab, everything was reassembled and checked for square - all good and ready for rivets!
My daughter came to the shop to capture the first rivet being pulled on my 750! I don't think I can wipe the grin off my face. All the work I've been doing to form parts from paper to CAD to cardboard to aluminum to bending - it all comes together here.
There it is - rivet # 1 of MANY more to come. Before I close up the stab, I'm thinking of somehow identifying this rivet - a small inscription or label or something. All small steps may seem to make the journey a long one, but progress is defined as forward motion towards a goal. Happy builder am I!
With the first one down, the rest are quick to follow....
The rear bracket riveted in nicely. I'm going to wait to final rivet the attach bracket and gusset until I have the elevator complete and can match them up to ensure the pivot holes lined up for drilling. Same with the front attach brackets, but that's more for aligning the skins.
Very happy how this is all coming together. Next up, I'm going to start building the elevator skeleton using the exact same processes. Drill, fit, debur, repeat. When both are complete, I'll start working on adding the outer skins. I'm also starting to think of a system for activating the elevator trim system that should be an improvement on the plans.
Thanks for reading.
With the 701 wing gone from the shop and into storage, the bench is now clear for my 750 tail group and I can get to building my airplane using the skills and knowledge I've learned. This blog post will try and capture several days of shop work over the past week - it's been busy and to the uninitiated observer looks like it's moving really fast, but there's a bunch of work that goes into this that pictures will never capture.
The factory tail spars come predrilled, with all the rivet spacing laid out - this saves a bunch of time on layout, but you still need to consider order of operations and keeping everything square. Slight imperfections in scratch built parts means measuring everything closely.
And here it is.... my 750's first drilled hole (back drill from rear spar hole to doubler) and cleco. This is the basic procedure and first step of everything to be assembled to come.
Each doubler is done the same way, A3 hole in the spar as guide, A3 drill through doubler and clecoed. I pleased my doublers fit as nice as they do.
With everything together, drill again, this time upsizing to A4 and again to A5 where needed and cleco. It's quite repetitive but this ensures nice clean and centred holes. The other thing we did was line both edges of the table with angle iron clamped to the edge. 2x2 HSS tubes laid perpendicular across the table provide a level reference point (flat table) to work with.
With the spars upright and referenced flat, I started to trial fit the rear and nose ribs. These to are back-drilled from the spar to the rib flange, then up drilled to A4 and clecoed. A quick measurement confirms my scratch built ribs are correctly sized and by default the spars are spaced correctly. Excellent!
Spars and inside ribs are drilled and clecoed in place, so next are the tip ribs. The key here is make sure they are square to the spars and the spars are square to the rest of the assembly. The front end of the tip rib is connected to the front spar (left side in picture) by a fabricated 025 "L" bracket. It takes a bit of ingenuity to make it all square and drill it, but not overly difficult - and certainly a TON easier that repairing the completely un-square 701!
To help square everything up before final drilling of the tip ribs, we added some uprights to the bench (there were eventually 4 of these, one at each spar end front and back).
The use of standard "L" around various parts of the airframe allows for small adjustments to square everything up as well. Kinda explains why I need so many of these (see this post).
Here is where the tiip rib attaches to the stabilizer spar. Drilling this takes some thinking about which order to do it first, but the uprights hold everything in place while the drilling is completed. Another check of measurements first, then final drilling to A4 size clecos.
With everything squared up, the horizontal stabilizer rear bracket assembly is prepped for installation. This 063 thick aluminum plate is fun to bend, but again if you think it through it isn't that difficult. The tabs are bent inwards to 98 dregrees from flat. This is an important measurement as these tabs are where the horizontal tail attach to the fuselage. I used a protractor and drew out an example angle on paper to confirm both tabs were correct before test fitting it on the rear spar.
Clamp the bracket in place and back drill from the pre-drilled spar holes.... all good.... right.... wait a minute... damn...did I just put this in upside down?!?!
This is where paying close attention to the plans was important. A traditional horizontal tail looks like a small wing - flat on bottom and curved on top. The Zenith STOL aircraft have inverted tail airfoils, where the flat side faces up. There are a number of reasons for this that I won't get into here, but what makes this confusing is that it goes against common thinking. Multiply that by the fact the plans for the ribs and forms are drawn with the ribs flat side down, it'e easy to get confused which way is up! I'm also building the horizontal stab flat side down to take advantage of the flat table to get everything square.
So, what saved my bacon? The predrilled factory holes! The fact that they are symmetrical and the bracket is centred on the spar horizontally means I just had to invert it before up drilling to A4 and eventually A5 holes. What could have been a nightmare was avoided, but I'll be much more careful next time!
With the bracket turned up to the correct orientation and DOUBLE CHECKED AGAIN before drilling, I worked on right sizing the holes and clecoing things in place. Another check and everything is now where it needs to be.
Next to go on is the centre elevator hing bracket, one of three attach points between the stabilizer and the elevator. The attach point is at the tip of the triangle and will be drilled later when we match up the elevator.
Supporting the hinge bracket is a support gusset, which was chaleging to bend correctly - again the plans give a somewhat confusing view, but a little figuring, fitting, and adjustments finally got things where they needed to be. It's getting crowded in this area with all the clecos!
Like the ribs, clecos can be moved inside the spar or to the other side of whatever it is attached to - clecos don't seem to care and that's a good thing :)
Making notes on the parts as you go through assembly helps to remind you in the future. Here you can see I wrote a note that an "AN-bolt", not a rivet goes in this spot - a reminder that the hole is drilled to a specific size that is slightly larger than an A5 rivet. Before anyone comments that my grammar sucks, the term "AN" stands for a particular type of fitting (in this case a bolt) used to connect flexible hoses and rigid metal structures. It is a US military-derived specification that dates back to World War II and stems from a joint standard agreed upon by the Army and Navy, hence AN.
The final parts to be added to the horizontal stabilizer being measure/confirmed and laid out for bending - accuracy here is critical to make sure all three attach points for the elevator and the two from attachment for the stabilizer to fuselage are correct. This will make rigging the plane easier at final assembly and a straight plane ALWAYS flies better!
I flipped the stabilizer over, making it easier to attach these brackets. Alignment bother vertically with the proper amount protruding above the spar and horizontally in relation to the centreline of the spar is critical for tail alignment. Looking at this picture is decieving, the brackets are perfectlyperpendicular to the spar - I know because I measured it 5 times and confirmed orientation 5 times.... no second chances here.
Next I measured up the stab/elevator hinge attachment brackets for rivet hole spacing and drilled them out. I thought I might drill them as a stack, but I was concerned about alignment so I did the individually. The plans are very clear here on where they attach to the rear spar and they installed accurately without issue. So nice working with newly made, undrilled parts!
So,with everything drilled correctly, together with clecos and measured as correct, it all comes apart for final deburring, cleaning and corrosion protection. Now was a good time to lable anything that might get confused when it goes back together for riveting.
Well, that's a lot of work done, approximately 14 hours in total. I'm updating my build time tracker on the right of the page as I go.
Next up, prime everything for corrosion protection. In hindsight, I think I'll wait to prime/corrosion protect parts until all the drilling/deburring is done - the drill and debur swarf tends to get stuck to anywhere the primer is already applied (it's somewhat sticky even after curing) which makes cleaning more time consuming when it doesn't have to be. After that reassembly of the entire horizontal stabilizer for final riveting - my first rivets on the 750 will be so satisfying :)
Thanks for reading, more to come!
It's finally "done", the 701 wing repair/extension was completed a couple of nghts ago, but I'm just getting to the blog now. Here's a quick update of what happened Thursday night to finish it off.
Off the table and to be prepped for storage. Ron and I will add some plastic sheeting wrap over the ends to keep any birds out while it's stored in the barn.
I'm so glad to be done this repair/extension, but I can't deny how much I've learned. Now the table is clear and I can focus can be on building my 750!
Stay tuned more to come!
Can't believe it's been over a month since I posted to the blog. The second half of October and first couple of weeks of November have escaped us. Unfortunately, I felt like I had't gotten anything done in that time, but going through my photos, I see there is more done than I thought.
I had to go away for a week due to work, but I decided to make good use of my evenings in the hotel. I took my wing rib blanks and final sanded them as I watched TV. Got some laughs and strange looks from my co-workers when I told them I was building an airplane in my hotel room!
When I cut out the rib blanks the bandsaw kinda chewed up the inside corners of the ribs:
So when I got home and back to the shop I came up with a jig for cleaning these up. I drilled a slightly larger hole in a scrap piece of wood and set the sanding drum up on the drill press to fit inside. This gave me a working surface almost like an inverted router:
The sanding drum cleaned up the corners really nice and I finished them off by hand sanding.
On preparation for finish bending of the tail group pieces, I had to drill the tooling holes in the forms. Best clamp them together evenly and drill each on the press:
When I tool out the tail group blanks, I noticed that I still needed to add the second tooling holes to many of them:
To save time and ensure accuracy, I decide to drill the stack of blanks together, using the available tooling hole as a reference point. A bolt and wing nut held the stack together and a form block and clamp were used to place the tooling hole accurately:
With the tooling holes established, the second bolt is added as well as the back half of the forming block. Here is an elevator rear rib bolted up and ready for bending:
The whole sandwich is mounted in the vice:
A soft faced (plastic) dead-blow hammer is used to round the aluminum over the edge of the forming block until flat:
Remove the form block and voila! My first formed part for my airplane! YAY!
Four of these ribs are required, so repeat the process 3 more times. Two left and two right complete:
I'm real happy how these turned out. They are pretty simple compared to some of the other parts in the tail group, but they are nice and straight, so my efforts to make the form blocks accurate paid off.
The next thing I wanted to do was get more of the thicker parts traced and cut out. Ron figured a 2 x 2 sheet of 0.125 aluminum would suffice for the parts I needed.
The sheet comes from the supplier covered in a thin plastic covering on both sides which is a pain to remove:
This particular piece of aluminum had been sitting around the shop for a while and fell victim to a few scratches and dings. Once I cleaned off the rest of the plastic and adhesive residue I circled any areas of concern and got to work tracing out the parts, nesting them as best as I could, starting with the flapperon arms:
Eventually I managed to fit 25 pieces on the sheet. It's tough to know the absolute best layout to minimize waste, but I'm only missing a couple of pieces which can be done later:
That's it for this update. Next up, more 701 wing extension work, bending more tail group parts and rough cutting the 0.125 parts.
So, I got my block/case back from the machine shop. It was worth every penny to have a professional with a CNC milling machine do the work of drilling out the two broken studs. His work was incredible and he went as far as to countersink the holes slightly for the TimeSert barrel inserts. Nice, clean and straight holes, important details:
With that done, it was time today to tackle installing the TimeSert barrel inserts that will make up the replacement threads for the head studs on these two holes. I've spent more hours than I should have pondering this critcal step, but it wasn't nearly as difficult as I allowed my imagination to believe it could be.
TimeSerts are an elegant solution for replacing damaged in-hole threads in a variety of materials. They are in my opinion much better than Helicoil wound wire inserts. I ordered the TimeSert install kit from Clark's Corvairs and the recommended length (0.75 inch) TimeSerts from a local industrial supply shop. The kit contains all the tools you need to install these:
First step, drill out the hole to the correct size. The importance of having this hole straight can not be understated. Although drilling aluminum is easy, best to use a drill press:
The brand new bit that came with the kit was very sharp and made short clean work of the holes.
Next up, the shoulder countersink bit. The countersink the machinist put in was quite deep enough. The bit has a cutter which creates a countersink shoulder for the top end of the TimeSert allowing it to sit flush on the surface. Again, the drill press is the only smart way to do this:
Careful application of preasure on the very sharp cutter results in a nicely formed shoulder.
Next up, threading this aluminum hole with the tap provided in the kit. This tap (also brand new) has four cutting flutes and a flat nose to ensure the hole is completely threaded to the bottom. This is delicate work that is only done by hand, so it was important to make it perpendicular to the case, ensuring straight threads in the hole. I used lots of 3-in-1 oil to ease the tap through and keep the threads clean from debris. The secret is to cut 1/2 a turn, back out 1/2 a turn and repeat:
Once both holes are tapped, it's important to ensure they are cleaned out of any cutting debris. A blow gun and compressor is perfect.
At this point everything looks good. Next up is the insert mandrel.
What makes TimeSerts so effective, is their engineering. The bottom couple of rows of the insert are formed in a way that allows the insert mandrel to cold-roll the threads, pushing them outwards and into the surrounding material, locking the insert in place:
First, a couple drops of oil on the mandrel to ease the insert forming the new threads, then thread the insert partly onto the mandrel:
Once placed in the newly cut holes, the insert threads in easy, up to the shoulder stop. Continue moving the mandrel forward (in) until it bottoms out:
Back the mandrel out and the TimeSert stays in place, now permanently attached to the aluminum walls of the hole. Looks perfect!
Was it really that easy? YES!
After cutting the matching threads on the two upper (long) studs that will be used with these inserts, I test fitted one. A good clean fit that will be made real strong with LocTite 620 as per the conversion manual.
I can't explain how relieved I am to be past this part of the head stud saga. Next steps will be fastening all the studs in permanently with LocTite 620. Before that, I need to clean the block completely as there are still areas that can use some detail attention. The suggestions are to either hot tank the block at a tranmission shop, use varsol with stiff brushes and 3M pads or maybe media blast it. Ron has a sandblasting machine, maybe that would be easiest. More food for thought.
The other task I completed was the removal of the oil pick-up assembly. It is press fit into the aluminum:
A little gentle tapping from the oil passage end of the block witha pirce of dowel, and it came right out:
Overall, a very productive 3 hours. I'm tagging this blog entry as a milestone because it has been bugging me for months to get past it. Barring any further surprises, this will be my airplane engine.
Now back to making other airplane parts :)
First off, I ordered my plans set today! Hopefully it won't take long to be shipped from Zenair. Once I have them, I'll have my very own serial number and I can start going down the road of endless inspection paperwork that needs to be on file with Transport Canada. I'm trying to decide if I want to reserve a good registration (call letters) or wait and see what they assign..... but that's a bit premature.... ha!
Four more hours in the shop today. Continued to open up the salvaged 701 wing. Wasn't too surprised to find damaged structure inside. This is the top of the wing at the root where it attaches to the fuselage. It likely got twisted back from the impact out on the tip of the wing. Lots of rash damage, probably from improper handling after the crash.
Flipped the wing over and with some drill effort, off comes the wing root fairing, fuel cell inspection cover and lower wing skin. Whomever built this wing wasn't much of a craftsman (or craftsperson). Lots of rivets where they shouldn't be, and lots of rivets missing from where they should be. We also discovered the rear spar channel is way under gauge from what the plans call for. Seems like someone decided to take a shortcut.
Next step was to drill out the rivets holding in the incorrect rear channel:
It came out easy, but it too has holes in all the wrong places.
Easy to fix/replace, but after seeing this, we are truly wondering what else we are going to find.
Next up, straighten the inboard main wing rib (on the left in the above picture). It will require another strip of aluminium (called a doubler) to reinforce the damaged area after we straighten it.
I just two afternoon sessions, I've learned a ton thanks to Ron but I've got a ton more to learn yet!
It took some time, but I finally got back into the shop. The last few weeks have been real busy between work and family commitments, and I'm trying to keep moving forward.
This afternoon, I took another crack at removing the last two head studs. Unfortunately, they continue to be stuck half-way out of the block, and by stuck I mean they don't seem to want to go either way (all the way in or all the way out):
Next, I'm going to try something suggested by some on the interwebs - make a penetrating oil with equal parts acetone and automatic transmission fluid. So far PB Blaster hasn't worked, so why not? It apparently works very well in exactly this situation. So add acetone to the shopping list and check the shed for ATF, I'm certain I have some.
Rather than dwell on this, I thought I'd take the steps to separate the case halves. If you recall, I mounted the block sideways on the engine mount to prevent the crank and cam from falling out of the block as it separates. They came apart surprisingly easy with some light tapping on the non mating surfaces with a rubber mallet:
Getting a good look inside now! Crank is likely trash, way too much rust and pitting on the connecting rod throw bearings. The cam? Hard to say, but it looks bad too and maybe it can be salvaged but probably not. Disappointing, but I already have two good cores for exchange form the 110hp core engine, so no big deal. Found more rodent debris and I think this core has been sitting dry (without oil) for a long time:
Also conspicuously absent are any bearings. Looks like someone decided they didn't need to be replaced yet. That's okay, I'll need specifically sized new ones once the crank and cam are serviced.
Carefully removing the old crank and cam reveals some surface rust on the block bearing surfaces. I think this is more of a transfer of rust staining from the crank and cam and hopefully they should easily clean up:
I was a bit worried about the bottom edge of the block, but then realized that this mating surface is inside the engine (above the oil pan), so small leaks here although not ideal, are not an issue. A close look at it looks like this is the spot someone previous used to pry apart the halves:
They look better once I used the shop-vac to clean away the last of the mouse debris. The inside of this block seems pretty clean otherwise:
One final thing I did while putting away the crank was to try giving it the "ring test". It's something I learned from the FlyCorvair.com DVD. A simple test used to check a crank for cracks (especially hidden ones) is to hold the crank from one end and give it a light tap with a hammer. A good crank will "ring" for up to 20 seconds once tapped lightly.
I tried this.... my cranks rings, but not consistently. The first time it rang for a few seconds, the second time a bit longer but the third? "Clunk". Perhaps I'm not striking it consistently. Either way, this crank is likely junk with all the rust pitting. Just wanted to try it.
But at least it's all apart and I'll be able to start moving towards assembly of my new power-plant!
Next up.... taking out the oil gallery plugs (if they will come out!), start power-washing and hand cleaning everything....
Completed a milestone today with inventory. All parts catalogued, numbered and tagged using the numbering system from the conversion manual. Similar items placed in totes, totes numbered accordingly. All stacked and awaiting cleaning, measuring and disposition:
From top to bottom:
I've also got a bin full of associated hardware bolt, nuts, old gaskets etc.:
All of these were loose items in a pail and are typically filthy and rusty as to be expected from a 50 year old engine. They will need to be cleaned and assessed before making a decision on keep or toss.
Next step will be to build a parts cleaner.... stay tuned :)
So here is a first look at some of the highlights of my find.
There are a LOT of parts to go through and inventory, but I can't begin to explain how stoked I am about my acquisitions.
Most of everything is either salvageable as is, prime for exchange as a core for re-manufacture, or trade-worthy for other things I will need.
Casting numbers (T1208RH) on the dis-assembled core block indicate a 1965/66/67 110HP "automatic transmission no smog" block manufactured on December 8th in either 1965, 66 or 67.
The casting numbers (3878566) on the heads from this core indicate 110HP from 65, 66 or 67.
These are prime candidates for conversion. Two things I haven't found in the boxes yet are the camshaft (but that isn't a game-stopper as it will be replaced by a custom cam anyhow) and the push-rod tubes (cheap to purchase new). Everything else important seems to be there.
The original cylinders, pistons and rods from this 110hp core are in great shape and will be excellent core exchanges.
The crankshaft is the correct model (8409 cast iron) for conversion. It has already (as far as I can tell and was told) been drilled for the prop hub and safety shaft. I'm not sure if it has been nitrided or not, should be easy to find out. Huge savings having this already complete.
The new in box pistons I got with this lot have been superseded in the latest conversion plans with dished and forged aluminum pistons. Perhaps these can be traded or sold.
I paid a bit extra to obtain the prop hub assembly. It includes the machined safety shaft called for in the conversion plans. A new one from William Wynne costs over $500USD, I got it for $50CAD. Great deal!
The second core is still almost completely assembled and appears on the outside to be super clean. The valve covers even have some of their factory chrome finish left on them. The cooling fins are real nice and straight on both the cylinders and the heads.
Casting numbers (T1214RM) on the dis-assembled core block indicate a 1965 or 66 140HP "manual transmission no smog" block manufactured on December 14th in either 1965 or 66. It would be neat to know if both this and the other 110HP block were made within 6 days of each other!
The casting numbers (3878570) on the heads from this core indicate 140HP from 65 or 66.
This block is also a prime candidate for conversion. The heads however would have to be directly replaced with 95HP or 110HP heads. They will be of value to someone, probably a car rebuilder (140HP heads are rare). Of course the crank and camshaft are still inside and the push-rod tubes are there as well. I haven't looked inside this motor yet Everything else important seems to be there on this core too.
Although not pictured, Paul also included new in the box set of chrome piston rings and a David Clark headset (which appears new from the box!).
So, I think it's fair to say I've got a running head start on my engine project. A complete inventory is next. Time to buy some storage totes :)
On another note, I'd be remiss in not mentioning the support for this mission that has been given to me by my wife Brenda. She always seems to guide me away from to good to be true deals to hidden ones like these. Thanks - I love you.
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.