In thinking about covering, I see there are several bolts that would do much better if they were flipped over. For example, the leading and trailing edge bolts are much better with the head toward the bottom. As I understand it, this isn't a traditional bolt direction for airplanes. Nonetheless, I flipped every bolt on the right wing that is better upside down. Aircraft Spruce also got an order last night for a dozen bolts that needed a length change. Sandlin specs almost exclusively even dash-number bolts, but a half dozen -13's were needed and a few others looked better too. The aileron doesn't fold over very nicely with a long AN42B eyebolt either. Despite being $8.95 each, I bought a couple that were 1/4" shorter to accommodate the aileron folding over. The bolt shank is long enough still that the threads aren't in shear. Minor, but makes a difference to me.
Looking toward covering choice, I'm leaning toward the Oratex that Yando Goat (Alan Beavis) used. This covering looks to be consistently lighter than regular Stitts or Stewart Systems and is completely non-toxic (i.e. no positive pressure air system or masks needed). The rub is that the price is somewhere around $67 a sq yd ... and covering requirement for Goat is around 40 sq yd for the wing alone. I've read a lot about the covering online and impressions are generally positive or a variant of "it's not like I'm used to, therefore it's not as good." If you have an opinion or experience, leave a comment! I might need to go read more on the airchair forum...
That's about where things stand. Next interesting item up is the ribs for the ailerons and flaps. Oh and working toward bonding on the ribs to the leading and trailing edges. Here's a couple pictures of the glass tape before epoxy.
Edit: Here are Alan's comments about Oratex reprinted from here:
Please read these observations with the knowledge that this is the first aircraft I have covered (apart from a couple of model planes in my youth).
The appeal of the Oratex was the lack of "nasty" chemicals, the finished fabric weight being able to be calculated and what looked to be a straight forward covering process with a quality finish. This had to be weighed up against the cost and that there would be a shortage of "experts" to go to if I needed help. I didn't keep exact numbers, but the material, glue and tapes cost $3000 - $3500AUD. At least $1000 of that was transport/customs fees. Not cheap to get stuff sent to Oz. I estimated it would've cost $1800 ish if I bought the Stitts products from the supplier here in Oz. As a test I ordered enough to cover the tail boom and tail feathers and would make a decision on the wings after trialling it.
The process is simple enough, but it does involve a lot of time waiting for glue to dry before activating it with the iron and the glue needs to be applied to both the fabric and frame. If you want details on the process go to http://www.oracover.de/index.php/downloads/viewcat/18-1-instructions.html and download the Oratex UL600 instructions. Unlike the Stitts process, once the glue has been activated with heat the process is irreversible so I proceeded slowly at the start until I became familiar with the process and developed my skills.
It's not possible to glue the fabric to the frame after shrinking as with the Stitts so this needs to be considered prior to covering.
Obviously I was happy with the quality of the finished product as I ordered the rest for the wings.
The material is available in 900mm or 1800mm widths. I ordered a 10m roll of the 1800mm initially and then a follow up order of 30m for the wings. I probably have about 4m left after finishing. I went through about 3 litres of the heat dispersant glue and several rolls of different widths of their tapes for reinforcement and frame protection under the final covering.
Here's a time lapse video of the covering of the top surface of a wing. The glue has already been applied to the frame as well as the fabric and rivet and bolt heads covered with tape. It represents about 5 hours of work, but unfortunately the camera ran out of space before the shrinking was finished, but you'll get the idea.
http://www.youtube.com/watch?v=7p7BIDTHzfo
cheers Alan
