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....
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.