Pre-war Chief spar making

[Rafael]

Leasons learned and advices:
1. Buy all new drill brits of all kinds needed and do not use old ones. Did several dirril test and the difference was remarcable in the hole quality.
2. You can never have ehought saw horses and roller stands.
3. You can never have enought space around you to deal with spars that long.
4. Polyfiber varnish will strenght the wood a lot.
5. You can never have enought light.
6. You can never have enought fans to bent out the varnish.
7. Finally putting the spars drawings away feels real good.
8. I did varnish the inside of all the holes only with the first coat of varnish to seal the wood. All bolts will have a thin layer of wax to protect them form the humidity left in the wood.
9. Reamers are needed to "re-size" the holes after the previous step and ebay is a great source for them, about $40 for all the ones I needed.
10. Hard work pays off. Shinny as glass and smooth as a babys butt
11. When you get the spar blanks as the guy that cut them to give you scrap pieces of spar material. I got several of them and I used them to practice drilling them to get a feel of the wood and also to see the quality of the hole. I also used these pieces to fine tune the jig that I made to make the holes for the drag wire holes (spacing, location, size,)

[SFC Hiatt]

Great work, thanks for the photos and information.

Chris

[Rafael]

Thanks Chris!!, hope this helps guide someone and give them some idea and orientation in how to do this instead of learning as you go. Now the next step is to figure how to nail the ribs to the spars. I have bought 2 different kind of tools and replicate one that a friend told me he used and worked good.
Tool number 1: The funny looking plyers are brad setters ($10) and I think it will aloow me to put the nails straight in as nailing angle is blocked by the cap stringers that make the ribs.
Tool number 2 is a spring loaded tool, got 5 different ones in ebay for $20. You just pull on one end and let it go. It works really good on the non rib test I did and the head of the nail fits on it and cant damage the wood around it.
Tool number 3: is the recomended tool. Went to the local hobby store and I bought the steel rod and tub. The nail just hided inside of it and given the small diameter the deflection angle is small and there is no chance of it sliping off the nail and damaging the wood either. Any one has done this before? any advice? ideas?

[Aerco]

Next step was light sanding on all sides and killing the edges. Then I draw the location off all the ribs and erased all other left over pencil lines. I used the Polyfiver varnish, first coat brushed, then 3 coats sprayed with sanding after first and second coats. Nice, shinny and smooth

Question: did you mask off the spars at the rib locations? If not, how will you glue the ribs to the spars? Remove the varnish where necessary?

[Rafael]

Hi Peter:
No the ribs are nailed not glue. Per 7-31 note 'C" it indicates to nail them. The original was also like that I have drawn the rib locations on the spars and then varnish them. I brushed the fisrt coat, sanded it, sprayed 2 more coats and sand it it again and then sprayed a third coat and a 50/50 final forth coat. That incrased the thikness of the spar just enoght to make a nice fit with the ribs. Hope this help

[Rafael]

Well assembly of the first wing is going smooth, about 75% done now. I was not able to use the original bushings at least in this wing as original rear spar was actually thinner than it is suppossed to be (Fish paper or similar material was added at the strut point to compensate). So a friend of mine machined new bushings for me to custom fit every station as there are small differences between them.
Actually while sliding the ribs thru the spar you can tell the small differences in thinkness of it, talking here 2 thousands of an inch max.
The wing tip rib per the rib gig has the same spar outline than the other ribs, meaning that the top of the spar is slanted forward on the fornt spar and aft in the rear spar. I cut the the tips of the spars witha band saw and did not compensate for this so I will need to do some sanding to fic this. But with all that said just a minor glich

[Richard]

Ron Percy of Rainbow aviation, told me yesterday, he working on making the process to manufacture spars for pre-war's chief's.

I was wondering if the metal ribs that were used on some of the earlier Aeronca trainer's would work on the 65ca wing? I saw a set in a hangar several years ago, from a wind damaged a/c

Richard

[shorty]

Did you build your own ribs?
Are they Mahogony, or Spruce? With cardboard, or birch gussets?

About 30 years ago I started a pre-war Chief project. I had to build several ribs, as they were rotted. My BIL worked for a furniture manufacturer, and came up with enough Mahogony "kite sticks" to build about 100 ribs. After picking through them, I had enough to build every rib, plus many extras. Another friend gave me some 1/32" birch plywood to use for gussets. After I had about 10 ribs built, I had the IA come by to look at my work. He told me that the workmanship was excellent, but I should have used Spruce, instead of Mahogony.
Not having the funds for Spruce, I said "ta heck with it". (My 2nd cousin now owns th' Chief)
Fast forward about 27 years, and thanx to the NAA, I found that the origional ribs were made of Mahogony. And depending on the year, had either cardboard, or birch gussets.
Had I (just a kid) Known that then, I'd still be flying my Chief.

Good work by the way. Keep it up.