Making new spars for a 7BCM

s35pilot · Post by **s35pilot** » Wed Dec 31, 2008 09:54

Thanks guys, no more concerns......I'm getting back to work on the wings today!
Happy New year to all!

Post by **joea** » Wed Dec 31, 2008 09:58

Tim,

More PHOTOS please!

Post some New Years Aeronca porn! You know... bare spars, and robust ribs!

Joe A

s35pilot · Post by **s35pilot** » Thu Jan 01, 2009 11:13

Happy New year! Yesterday, I had a chance to work on the wings, here is what I'm working on. Even having all the plans for the wings, I decided I would keep the left wing together until I had the right side back together. That worked out well, but meant, I had to do the whole parts prep process
twice. All old parts and the new ribs are deburred, rubbed with Scotchbright pads and cleaned with Alumiprep #33 and primed with 2 part Akzo epoxy primer ( I did make sure it is compatable with the Stits poly fiber process).

Parts cleaned and ready for primer.

The primer is catalyised and dries to the touch in minutes

These are the aileron end rib stiffener I made these from spar end cut offs.
I have the first coat of varnish (brushed on) next, I will spray 2 coats.

A friend of mine(that I meet while doing this restoration) he is the guy with the Waco, also, has a banner towing business with 12 Scouts (he has rebuilt 8 sets of the Scout wings, gave me this suggestion.
I made these little blocks that will be epoxied in at the Butt ribs to prevent the rib from rolling over when the fabric is srunk. I noticed that both Butt ribs were damaged when I took the old wings apart.

Here is a photo of one of the damaged Butt ribs, hard to believe that the fabric could do this.

Nathan K. Hammond · Post by **Nathan K. Hammond** » Thu Jan 01, 2009 12:40

Tim, your work looks amazing, and attention to detail is really impressive.

One question though; why did you epoxy all the aluminum instead
of using alodine? Just curious, cause I'm trying to save weight in places
so I can add it in others. And I hate coving up those shiney new ribs.

nkh

s35pilot · Post by **s35pilot** » Thu Jan 01, 2009 14:18

Nathan, I was familiar when priming because of building my RV 7 (all metal) I had the primer and the old ribs were primered (original from the factory), I'm useing about 1/2 of the old ribs, I thought, it would be best to have all the ribs the same, a look issue, I guess!

Post by **joea** » Thu Jan 01, 2009 14:22

Hey, from where I sit... it "LOOKS GREAT!"

Nathan K. Hammond · Post by **Nathan K. Hammond** » Thu Jan 01, 2009 16:02

Good enough for me!

nkh

David Johnson · Post by **David Johnson** » Thu Jan 01, 2009 16:33

Tim, did your drag wire holes work out OK? Good to see you going again. We are all enjoying watching your beautiful work. I am not that disciplined! We prime all our stuff too. Champion Service Letter #3 shows a brace to keep the tip bow from pulling in on the end of the aileron. I didn't know if you had it or not. We put the brace on every wing we work on. Sometimes we use aircraft plywood for the filler (2-699?) to keep it from bowing as much with fabric on. Keep up the good work! David J. P.S. I have drawing 2-10001 if you need it.

s35pilot · Post by **s35pilot** » Thu Jan 01, 2009 22:42

Hi David, the drag wires slipped in place very well, thank you for your comments.
I do have the diagonal brace 2-10001 and thank you for the drawing.

Nathan K. Hammond · Post by **Nathan K. Hammond** » Fri Jan 02, 2009 00:11

Good idea on the butt rib blocks; my ribs showed the same kind of damage.

nkh

David Johnson · Post by **David Johnson** » Sat Jan 03, 2009 11:14

I have always thought the deformed butt ribs were a result of dope finishes that have shrunk way tighter than modern stuff will. DJ

s35pilot · Post by **s35pilot** » Fri Jan 23, 2009 00:41

Here is how and where I start for trammeling, I find a common point of referrence from the wing attach bolt centers for the front and rear spar.
1/2 the dia. of the bolt plus 3" and make a mark to transfer to the bottom of the spars(I use my digital caliper....I should have taken a photo), this gives me a place to start my first trammel points. I do this prior to installing any ribs to the spars for easy layout (your are not having to measure around ribs)

As you can see here the front spar has a 3/8" bolt 1/2 the dia. is .186 hence the 3.186 and the rear being a 1/4" bolt 1/2 .1245 this one is 3.1245 (these figures are from my calipers and my bolts).

I place a piece of tape on the bottom of the front and rear spars at the compression struts, then draw a pencil line in the center of the spar.

I use a trammeling points on a piece of wood to mark parallel points to front and rear spars.

I use a center punch set very light to put a tiny divit point in the spars (this makes it very accurate for the trammel points to drop into). You can see the marks I made for the rib layout, when trammeling is complete I will nail all the ribs in place.

Here is Bob and I ( and Boomer) starting at the wing root, we just worked our way out until all sections are trammeled perfectly square.
I leveled the saw horses and trammeled with the bottom of the wing up.

powers · Post by **powers** » Fri Jan 23, 2009 09:48

Great work! The pictures of that shop make me feel bad about the pictures of my shop (garage). I noticed that map on the wall with a red line going all around the country. Did you fly that route or are you showing off?

s35pilot · Post by **s35pilot** » Fri Jan 23, 2009 10:10

Thank you! In the summer of 2006 I made that trip around the country, my plan was to start the southern way and stop in Oshkosh but, due to weather, I had to start north and that put us near Oshkosh a week early so, decided to spend a few days in Washington DC and then down to First Flight (Kittyhawk), instead of EAA, still had the trip of a life time 13 days, 5,658.2 miles, 45.7 hours.

Robert Henley · Post by **Robert Henley** » Wed Feb 11, 2009 10:36

David Johnson wrote:Tim, did your drag wire holes work out OK? Good to see you going again. We are all enjoying watching your beautiful work. I am not that disciplined! We prime all our stuff too. Champion Service Letter #3 shows a brace to keep the tip bow from pulling in on the end of the aileron. I didn't know if you had it or not. We put the brace on every wing we work on. Sometimes we use aircraft plywood for the filler (2-699?) to keep it from bowing as much with fabric on. Keep up the good work! David J. P.S. I have drawing 2-10001 if you need it.

David

Does the brace in service letter #3 require a hole drilled through the small end rib? I am waiting for the brace to show up from Wag Aero and the drawing doesn't show that end rib.

Thanks for your help.

Robert