Been away from the shop a bit. Christmas with the family, shopping, work etc. There are important things in life besides airplanes I suppose :) That doesn't stop me from doing reasearch. Okay, you can call it browsing if you like.
I wanted to share a website I found called experimentalavionics.com
One of the biggest decisions to be made with my build is what avionics I want in my panel. This of course is guided by the three points of mission, cost and simplicity in that order, although they aren't mutually exclusive either. Simplicity generally leads to lower cost. Mission needs vs wants can also directly influence cost up or down. With a bit of work, the following items can be built very inexpensively, with off the shelf parts and instructions found online.
My aircraft mission is simple enough. I don't need to go fast or high (the Zenair 750 isn't pressurized nor is it a speed demon) and I won't be flying IFR (instrument flight rules). I do want good communications (it's actually what I do for a living!) and the ability to navigate outside the normal ATC coverage areas to some of those good fishing/camping spots.
I'm using a converted Corvair automobile engine. Instrumentation for this is simple too.
The idea of building my own EMS (Engine Monitoring System) from open source electronics/software fits both my budget and interests in learning. I have learned enough electronics skills over the years to build it (thanks to Mom and Dad for starting my learning in basic electronics by buying me this when I was a kid). Whether this becomes my primary engine instrumentation or a back up to the traditional analog engine guages will be decided later after I do some more research. It might look something like this:
A nice, easy to read display suitable for the 6 cylinder Corvair engine. The bonus is how much panel space I'd save and the ability to datalog the information for testing mods or diagnosing trends. Alarm annunciators (flashing warning lights or audio) can easily be added for any parameter that goes out of range. Cool!
The other panel items such as primary flight instruments (altimeter, VSI, etc) require more thought. I like traditional instruments for their familiar simplicity. For the same reasons as the EMS, a EFIS (Electronic Flight Information System) has an intriguing draw, but I'll likely have something like this as my backup instruments:
Again, easy to read, simple and space saving. 6 instruments and a clock all in one place.
A couple of cons that I'll need to consider are temperature operating range and failure modes. It gets real cold where I'll be keeping the plane when it's built (unless I win the lottery, then it's heated floor hanger all the way!)
As for failure modes, how comfortable am I putting all indicators in one place, where a single failure may result in losing everything at once.
The website that I linked above also includes preliminary discussions on intercoms for pilot/passenger communication and a WiFi based AHRS (Attitude Heading Reference System) that could link wirelessly to a tablet for navigation. Perhaps someone will adapt the AHRS to be an inexpensive ADS-B out module!
Lots to think about...
Happy New Year everyone :)
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 :)
Looking back I can't believe it's been almost a month and half since I posted to the blog. I've been busy waiting on some stuff I ordered to take the next steps on the motor rebuild and some travel to visit family in Ann Arbor Michigan took up a bunch of time as well. Well worth it though, we needed a quick family get-away to recharge.
Since my last post, I took my engine block into the machine shop to fix the snapped stud issue. They have a highly accurate CNC milling machine which will make short work of the snapped stud. The process will remove the remnants of the broken stud but this will also mean sacraficing the hole threads. I've now got the TimeSert install kit that I ordered which will repair the damage and create a new set of threads to insert the studs into.
Until I get the block back from the machinist early next week, I got some of the prep work needed for the studs done. The original short (lower) head studs from my core engines are in decent shape, but typically very dirty with some light surface rust. The push rod tubes are similar. Here is the before pic:
The perfect tool to clean these is the bench grinder. This one is a beautiful old school one. I prefer old tools that are made to last:
The wire wheel makes short work of cleaning of the decades of old grime and rust and is excellent for cleaning up the stud threads:
The push rod tubes from the core are really dirty. Under the grime, the tube was manufactured with two coatings on top of the bare metal, as shown in this picture from Google:
I had a go with the wire wheel on one of my tubes and this was the result:
I'm happy with how they cleaned up, particularly around the o-ring area. However, after seeing the picture from Google that I found for tonight's blog entry, I'm not sure if I've just removed the grime, or removed the zinc coating as well. Removing the zinc coating and getting down to the bare steel is what I want to do as this will allow me to paint (or maybe powdercoat) them white as described in the conversion manual. I'll have another look next time I'm in the shop. These may require a bit more work. The one in the picture I copied was sandlasted, perhaps that's what I'll end up doing.
Overall, the first twelve studs all came out really nice and clean - they should paint up real nice. There are some minor tool marks on each. I have a bunch more in the inventory, so I'll clean those up too and choose the best ones for the build:
The other task I've been pondering is cutting new threads on the end of those studs being inserted into the TimeSert holes of the block.
The studs on Corvair engines are made from a very high tensile steel alloy. The original threads at the block end are a proprietary GM thread called 38-16 NC5. These will not fit the TimeSert which are the more common 3/8-16 NC. So, for those holes that I'm installing TimeSerts, I'll have to use a die cutter and rework the threads to be 3/8-16 NC. The head end doesn't need to be altered.
I had a bit of time today, so I took one of the old long (upper) studs that are being replaced with new ones due to corrosion and experimented cutting new threads on it. Best case, I see how easy or difficult it is, worst case I ruin an old stud that I won't be using anyhow.
I clamped the stud tightly in the vise. When I do the good ones, I'll have to remember to put something in the jaws of the vise to prevent clamping damage marks. Here is a picture of the tools I used. I couldn't find where ron keeps his cutting oil (if there even is any), so I substituted a little 3-in-1.
There ins't a huge difference in the GM thread and the 3/8-16 I need to use with the TimeSerts. Carefully starting the die on the threads and using a fair amount of oil, I managed to cut or reshape the threads about under half way down. This involved the time proven method of turning the die down a little bit at a time, and backing off numerous times but it went marvelously well. Here's a close up:
When I got home, I test fitted this stud in a TimeSert and it threaded in real nice. I bit of LocTite 620 should make the repair as good or better than the factory fit. I've been worried about this process for a long time, but I think with a little attention and time, it's going to work out fine.
Next up, prepping the block for stud install.
The Google search bots are really going to love my posts now!
Remember my fellow Corvair engine builder Jeff Moores of Newfoundland (see previous post "time-to-get-back-at-it")? While at the Zenair Open House we talked over lunch about the struggles I had been having with head studs and Jeff reassured me that my issues were common issues in both his previous builds. He offered to send me some extra head studs that he had lying around his shop to replace the bad ones from my core. They arrived via mail on Tuesday and they are brand new! All for the price of shipping via snail-mail.
The more I continue pursuing a Corvair as my choice of motor, the more I'm starting to realize the value of getting to know other Corvair builders, both for their experience and generosity. This is the kind of group I want to associate with, not some faceless foreign owned engine maker that just wants my money and couldn't care less about my mission to learn. Thanks Jeff!
Next steps, dealing with the 3 stud holes that need to be fixed (see "progress-sort-of") . I've decided on using TimeSerts which are a threaded barrel insert repair that is accepted in the conversion manual. Definitely more expensive than Helicoils (another possible repair method) but I believe worth the piece of mind. Corvair automotve parts warehouse Clark's Corvairs rents the TimeSert installation tool kit and also sells inserts that are the proper length and a blind nut tool for proper torquing of the head studs. I think I'll order those now and get the repairs done soon in preparation for some case machining work I'm planning.
A couple of more hours in the shop today. Work continues on the 701 wing rebuild.
Stripped off the last of the paint where the wing and nose skins will be replaced. A wipe down with acetone and it comes out real shiny! Next step will be to scuff the aluminium and paint it with primer in preparation for mating the new skins.
While I was letting the stripper soak in for the above step, I finally got up the nerve to clean and trim the nose skin where the damaged piece was cut away. Working from the outside, I wanted to make sure to cut not only straight but well away from the underlying nose rib. To make the task easier, I laid on a piece of painters tape outlining where I was going to cut:
The curve of the nose skin makes this difficult to use hand shears or metal snips. Bring on the power tools! Ron suggested using the air powered saw:
When it's running, the blade on the air saw moves faster than the eye can see. It's fine tooth blade made short and clean work of the skin. The last inch or so I did with metal snips to prevent accidentally cutting into the wing spar (that would be a unmitigated disaster!):
A productive couple of hours.
I've sent off a quote request to Zenair for a complete tail kit of my own, minus the rudder pieces I already have.
It's been a while since I had anything to post. Between my paid job, a weekend camping with my daughter's Scout Troop, horse shows and Thanksgiving hikes with the family time has flown by the last couple of weeks.
Found a day free in the schedule on Monday so popped into the shop for a bit. Ron and Donna had been away the previous week so Brenda and I were watching over the shop and property. I was pleasantly surprised when I arrived Monday to see that Donna was kinda enough to put my plans set into a binder for me:
Ron and I had a good chat about my build plans. Comparing the 750 plans to his 701 plans we realized that they shared even more DNA than either of us thought. Obviously we knew that the 750 is the evolution of the 701 design but we are both struck just how common the airfoil (wing shape) and internal structures are. It's easy to see where improvements were made over time and how Zenair has evolved in their kit manufacturing processes (introduction of CNC production of kit parts and CAD drawings). Ron's group of builders are scratch building their 701 planes and have made all the forming blocks for the 701 parts. In other words, rather than buy the kit pieces, they are making (read bending) everything themselves from bulk aluminum sheet and other stock. Time consuming? Yes. Cost savings? Huge (the cost of individual kit pieces from Zenair is in the manufacturing, not the actual materials).
Ron seems to think that his 701 forms are almost exactly the same as those needed for the 750, perhaps with a bit of tweaking. Comparing the plans seems to back up this theory too. So the question becomes one of time vs. money. Scratch building takes time but saves money. Enough money of course always saves time. I'm caught somewhere in the middle, but if I can save some money without too much investment of time there is opportunity there. What makes it better is all the work of the making the forms is already done.
I'm going to defer this decision for now and perhaps order a couple of wing ribs from Zenair. I'll compare the 750 kit pieces with Ron's 701 forms and see just how close they are or what modifications need to be made. From there the decision should be easier. If it turns out the forms aren't appropriate, at least I'm a couple of pieces closer to the end....Ha!
So, onto Monday's task - start stripping the paint off the wing skins anywhere new skins will be overlapping. This ensures good strong joints and provides a clean aluminum surface for anti-corrosion primer.
First, apply the chemical stripper. I'm thankful to have a workshop space that isn't in the basement of my house - this stuff is strong!
After letting it sit for a while, a plastic scraper works fantastic to remove the layers of paint:
I didn't take any final pictures yet as I still have some clean-up to do with acetone and Scotchbrite pad. It's not pleasant work, but I learned the work involved if I change my mind about what colour paint I want for my airplane! While I waited on the stripper to work, I also reworked that rear channel I made that had cracks developing at the corners..... always keep busy.
I'm away next week on a work assignment (near the Zenair Canada factory!) so shop time will be limited again. I wonder if I can order those ribs and have them in time to pick up while I'm in the area? Hmm....
Friday finally got here and I departed home for my road trip to "parts south" at 1130am.
First stop, my long time friend Lynn's place just outisde Barrie. Lynn and I grew up in the same hometown of Holland Landing and her late father Wally owned the local airport. For several years Lynn was heavily involved with ultralight aircraft, as a builder, pilot and instructor. Now heading in a different direction in life, she contacted me with a list of items from sale from her collection.
As I arrived in her driveway, I was very pleasantly surprised to see that one of my best friends Mike (also from Holland Landing) was also there. It was just like old times - what a fantastic chance to catch up a bit. None of us has aged by the way ;)
Lynn had collected up a bunch of stuff for me and made a sales pitch I couldn't refuse. More on this in a bit.
Next stop, my parent's place to pick up Dad and head to Kitchener to see Scott about the 750 rudder he has for sale. I like taking Dad on these jaunts when possible. It's great to catch up and of course talk airplanes - it's certainly something in the DNA I got from him!
After a dinner in Guelph with Dad, we made our way to Scott's place in Kitchener. The deal for the rudder we agreed to got even sweeter when Scott included a box of Cleco fasteners, Cleco pliers and two heavy paper bags of A4 and A5 rivets - all for $100 cash! I didn't dicker or give him a chance to change his mind. START THE CAR!!
We wound our way back to Dad and Moms during Friday evening rush hour and seemed to hit every red light. Times like this remind me how much I enjoy living in northern Ontario. I decided to grab a nap for a couple of hours, but by 415am this morning, I was back on the road home (there are other things I have to get done before going back to work tomorrow!)
Once I got home and had some breakfast, I began the inventory process.... in a word, wow!
Here is a group photo of the items I obtained from Lynn and Scott. Top to bottom, left to right: A handful of the several reference books, bags of Cleco fasteners, over a thousand rivets (paper bags), Cleco pliers, drill bits "The Claw" aircraft tiedown kit and a "One Touch Tach" tool used for confirming prop RPM.
Amazing stuff for my project. In fairness to Lynn, I won't disclose what I paid for her portion of this stuff, but suffice to say, it pays to stay in touch with friends!
The big item of the trip however is the 750 rudder. Scott had attended a Zenair factory sponsored rudder workshop with the intent of getting a head-start on his 750 build, but as is often the case, life got in the way and he decided to part with his barely touched project. This rudder is already mostly built, including corrosion protection. Fortunately one side only has some temporary rivets on the skin that can be drilled out so I can confirm everything is good inside and run the wires for a navigation light. For $100 and the fact it was built in a supervised factory workshop I can drill a few rivets out to confirm. Unassembled rudder kits are more than $500 from the factory and there is at least $100 in hardware that he threw in.
Can't wait to show Ron!
But right now, the lawn needs to be cut.... again.
Snuck over to the shop for a couple of hours Monday morning. I'm trying to squeeze in time when I can and a few hours in the morning before I head to bed for my afternoon pre-nightshift nap works perfectly.
Work continues on the 701 wing repair/rebuild. I managed to fabricate my first replacement piece, a rear wing channel. It took some time to figure out how to use the sheet metal bending brake, but I got it done. Here you can see the original bent and mangled one on the right and my new one on the left. The previous builder for some reason made his channel with a thinner gauge of material than what the plans call for. I'm all for saving weight and money, but this is a critical structural component, not something I would consider worth skimping on:
Next was removal of the damaged nose skin. As part of the repair/rebuild, Ron is planning on extending the wing by a couple of feet. We'll cut out the damage, fabricate a tip extension to the main wing spar and add a rib where required. A new nose skin and upper/lower wing skins and will be cut and fastened to the originals. Of course, this means drilling out more rivets. I suspect there will be times this will come in handy when I make mistakes on my own build!
This picture shows the extent of damage. What do you think..... is this creased too far to be "popped out"?
I drilled out the rivets on the closest good rib to allow some flexibility when cutting the bad nose skin. We'll trim it cleanly back to the rib to enable a clean joint with the new extended skin. These empty holes will become part of the stronger joint as a result.
As always, I'm keeping my eyes open for good deals on things I need for my project. Surfing the classifieds section of the Ultralight Pilots Assocication website, I came across an individual selling a complete rudder section for a CH750 for an amazing price that was too good to be true! A quick game of phone tag and the seller and I agreed to meet on Friday this week.
On the road again..... can't wait to get on the road again.....
After a couple of weeks pouring over my new plans and discussing them with my friend Ron, tonight I begin the never ending trail of paperwork that needs to be filed with Transport Canada.
It all starts with a CO1B "Letter of Intent" that gets submitted to the MDRA inspection agency. MDRA stands for Minister's Delegates - Recreational Aviation. Essentially the federal transportation Ministry decided a number of years ago that they didn't have the resources (or knowledge) to efficiently manage the inspection/inspector process for homebuilt recreational aircraft so they created another level of bureaucracy (i.e. fees) for those who wish to build and fly their own aircraft. The one good thing about this government mess is that MDRA inspectors come from the homebuilt community and should understand what most builders are attempting to do.
So, first form done and submitted (don't forget to include the $80+tax filing fee, ouch). Now to wait and get confirmation that MDRA has started a "file" on my project..... then I can start my build.
Yesterday, I called Zenair HQ to inquire if my plans had been shipped yet. I spoke with Kaitlyn who confirmed my package left their facility via U.S.Postal Service Air Mail on Friday afternoon.
Today, using the tracking number she provided me, I logged into the USPS web-portal and discovered that as of Monday morning my package was somewhere in the bowels of the USPS International Service Center in Chicago. Further reading reveals the ISC where all outbound mail from the U.S. goes to be sorted for distribution. I also read that it can be a bit of a black hole and there are many reports of stuff going missing, never to be seen again.
Thankfully when I checked a couple of hours later and my package was showing as of Wednesday morning as being in Canada Customs. I'm normally more patient than this, but Canada Post and their postal workers union are deep into a nasty labour dispute with both sides threatening strike/lock-out action by midnight tonight! At this point I hoping my plans wouldn't end up stuck on some conveyor belt or parked truck.
Knowing that web-portals are sometimes slow to update, I took a chance and called my local Post Office (love small towns). The lady there confirmed for me that I indeed had a package awaiting pick-up!
Brenda was kind enough to drop by and pick it up for me (I was stuck at work). When I got home, it was waiting for me. To be honest, I kinda thought it would be a bigger box, but happy nonetheless it has arrived safe!
Opening the box explained a lot. The plans are curled a bit on one end to fit a standard shipping box:
A fully numbered and complete set of plan drawings and folder with builder resource information including a CD of assembly photos. Really nice stuff.
Who's a happy guy?
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.