Fitting the Leading Edge   August 25th, 2007

With the main skins done, I started working on the leading edges. Van’s recommends building a cradle to hold the leading edges, so I got to it.

Here is how I used a rib to get the right shape out of MDF.

I used a jigsaw to cut out the outline, stuck some 2×4’s to it, and got this:

The idea is to put the leading edge skin in the cradle, and then insert and cleco the ribs. Once the ribs are clecoed to the skin, the whole thing is mounted on the spar to drill the skin to spar holes. Of course, the skin is so damn tight, I didn’t think this method was going to work.
Instead, I mounted the skin on the ribs right on the spar. I clecoed the ‘flat’ side (bottom side) of the ribs to the skin, one cleco in every hole. To get the top side as tight as it needs to be, I’m going to use ratchet straps to pull it in. This is what George Orndorff suggests in his training videos.

Posted in Leading Edge, Wings | Comments Closed

Wing Walk Doublers   August 21st, 2007

The wing skins need some reinforcement near where they attach to the fuselage, as this is where you step to get in the plane. The reinforcement is just another sheet of aluminum under the top wing skin. The piece from Van’s is much larger than needed, and not prepunched.

So, after match drilling the top skin, I took it off and put it on the table. After marking the final length, I used a hacksaw to make the first rough cut. It would sure be nice to have a bandsaw!

The final cut was made with tin snips. I used some masking tape to cover part of the snips, so as not to scratch the aluminum.

After cutting to the right size, I placed the doubler under the wing skin, and just match drilled it, clecoing the holes to a piece of MDF to make sure nothing moved.

Here’s the obligatory picture to show I’m actually doing all this stuff myself.

Finally, the doubler and skin, ready to be clecoed back on the skeleton.

Posted in Doubler, Wing Walk, Wings | Comments Closed

Drilling Wing Skins   August 20th, 2007

I spent most of the weekend drilling the wing skins. Lots and lots and lots of holes to drill.

Here is a picture of one of the wings with the skins on…

Posted in Wing Skins, Wings | Comments Closed

Measuring (and removing) Twist   August 10th, 2007

With one set of skins on the wing, I hung two plumb bobs from each end of the wing, and measured the distance from the string to the rear spar. The idea is that when the distance is the same for both plumb bobs, the wing does not have any twist to it (ok, maybe ‘minimal twist’) . To adjust the distance, you adjust the angles clamped to the spar (which is why I used threaded rod to hold them up.

When I set this up, waited for the plumb bobs to settle, etc, I was surprised to see the difference between the two measurements was less than 0.1″. The only adjustment I had to make was about 1/2 turn to the nut holding the threaded rod for the inboard side of the spar.
Posted in Wings | Comments Closed

Fitting the Skins!   August 7th, 2007

The wings are looking more and more like wings. Each wing has several skin sections. There are two skin on the top and two on the bottom, in addition to the leading edge, and of course the fuel tanks. I started with the inboard skin and all went well. When I tried on the outboard skin, I was surprised to find the skin was hitting the angle used to hold up the spar.

I tried filing down the angle, but pretty quickly realized I was gonna be filing for a loong time…

Instead, I got another piece of angle and fabricated an extension. The two pieces of angle are held together with three 3/8″ screws.

Plenty of room now…

Posted in Skins, Wing | Comments Closed

Wing Skeleton Alignment   August 5th, 2007

The clecoes were waiting for me when I got back from Oshkosh, so I went to work on assembling the wing skeleton.

Then I got me some Cajun Red Fishin’ Line at Wal-mart, and ran it from one end of the spar to the other, to check for sagging.

I used two pieces of 4×4 and a 3/8″ threaded rod as a jack to support the middle of the wing and remove the sagging. This makes it a lot easier for the pre-punched holes to line up with the skins I’m about to put on…

Posted in Fishing Line, Jack, Wings | Comments Closed

Aileron Bellcrank Bracket   August 5th, 2007

I just realized I don’t have enough clecos to put together the wing skeletons, so I’ve just ordered a buch more of them. The best deal still seems to be Brown Aviation, at $0.36 each on orders of 100 pieces or more. So, while I wait for more clecoes, I decided to get the Aileron Bellcrank Brackets ready. All I had to do was make sure the brass rod can freely slide into the fitting, and then ream it for the 1/4″ bolts.

When I first tried to slide the brass rod into the bracket, it would only go in about 3/4 of the way.

I took a piece of Emery Cloth and wrapped it around a drill bit (no tape, etc..just held it with my fingers). I then inserted the bit into the bracket and started twisting the bit (actually, holding the bit steady and rotating the bracket around the bit).

After about 20 minutes of crankin’ on it, I was able to insert the brass fitting all the way into the bracket and have it move freely.

Finally, I used a reamer in the drill press to get the hole to the right diameter.
Posted in Aileron Bracket, Reamer, Wings | Comments Closed