More Leading Wing Edges…   October 17th, 2008

Another picture of leading edge riveting….pretty easy stuff here…

Posted in Leading Edge, Wings | Comments Closed

Riveting Leading Edges to Spar   September 23rd, 2008

Well, it’s time to start putting the wings together for the last time!

The first step is to take the previously-assembled leading edges and rivet them to the wing spar. The problem is that The holes for the leading edge ribs are so close to the main ribs, it’s hard to get a rivet set in there (or even the clecos!!) at a 90 degree angle.

After doing a lot of reading, and finding out the factory ‘allows’ the use of blind rivets, I decided to go ahead and use cherry commercial rivets for the leading edge. Because it is so hard to get even a rivet puller in there, I put the rivets in from the top (inside of the leading edge) and contorted my hands and rivet puller inside the leading edge.

Some gung ho people call this ‘cheating’, but I can’t help it but think I’d rather have a nicely pulled blind rivet than a half-assed solid rivet with dents (as well as the possibility of damaging the spar as well)

Here is a picture of what it would look like trying to drive a solid rivet. Notice the holes are so close, not even the clecoes are in there straight. Some people recommend grinding down to offset rivet set to get closer to perpendicular, but from the looks of this, I would actually have to grind down about 1/4 to 3/8’s off the gun itself to be able to get the set close to perpendicular to the spar. No thank you….

Van’s recommends LP4-3 and LP4-4 rivets, which you can’t find anywhere except at Van’s. I instead used Cherry Commercial rivets from Aircraft Spruce. I used BSP4-3 and BSP4-4, which are slightly stronger..according to the data table anyway…

After the leading edge was finished, I found it hard to get the skin to perfectly line up with the holes in the main and rear spar. Even though I have a jack made up of two blocks of wood and a screw-rod, it was still hard to get everything to match. So, with Fabiola’s help I took the wing off the jig and laid it on the table. Every hole now matched perfectly, and I think it was easier to squeeze the leading edge to spar flange rivets.

Posted in Leading Edge, Wings | Comments Closed

Fixing Leading Edge Crack..   February 7th, 2008

I asked around and got lots of advice on how I may want to fix this. I posted a picture of the dent and asked for help at Van’s Airforce, and within less than a day I had several suggestions of what to do. I ended up following the advice given by Mark Hegy (I guess the “A&P Gulfstream Aerospace.” in his signature swayed me just a little :-). He basically said to use ‘soft rivets’ and then use a blue and blue scotch-brite discs to polish the rivet/skin.

First I ordered some AN426A-4-3 rivets from Aircraft Spruce. Actually, I ordered about 397 more rivets than I needed (They won’t sell me less than 1/8 of a pound!). Even so, this was my first time putting in a $2 order, and was pleasantly surprised they sent it to me via USPS and charged me only something like $2.50 for shipping, which is very close to what the stamp on the box said.

With the rivets on hand, I took a piece of scrap aluminum, set it between two blocks of wood, and dropped my bucking bar on it (hey — I had to do a practice run first, right?!).

I went through all the steps on the scrap piece, and since I liked the results, decided to try it on the wing. So, this is what I started with — a right leading edge with a small but nasty ding/crack near the tip…

I got some 120 grit sandpaper and a small piece of 2×4, and made me a sanding block. I sanded off the tip of the ding, which made it a lot easier to drill it from the outside. Drilling from the inside would have been a bit challenging because of the angle at which the drill would have to be in order to be perpendicular to the skin).

This is the ding after getting sanded down. It is mostly flat, with just the crack and some very thin aluminum in the area.

Then I drilled a hole in the middle of the crack. I started with a #40 drill and then final drilled to #30. This completely removed the crack.

After deburring the hole, I used a ‘pop-rivet dimple die’ to dimple the hole. I decided to dimple and not countersink for a couple of reasons. First, the hole completely got rid of the crack and *most* of the dent, and I would rather not remove more material than necessary. This is one of the reasons why I definitely agreed with Mark Hegy’s original suggestion to practice on a piece of scrap first.

With the dimpled hole, I put the rivet in, put some masking tape on it to hold it in place, and set it with the rivet gun. I set the air pressure on the gun to 20psi and only had to give it a few hits before the rivet was fully set. Now I REALLY know why they call these ‘soft’ rivets!
***Very important*** Do NOT drop bucking bar while fixing dropped bucking bar dent!!!!!

Finally, I used first a red and then a blue scotch-brite disc to make things look pretty.

And here is the final result. From a distance, it will be very hard to tell there is a rivet in there.

Posted in Leading Edge | Comments Closed

On to the other Leading Edge   February 4th, 2008

Today I fitted and clecoed the right leading edge. I even managed to rivet the entire bottom side. Same process as with the left leading edge, so no pictures!

Posted in Leading Edge, Wings | Comments Closed

Riveting the Leading Edge   January 29th, 2008

After about a week of letting stuff dry, I started the process of riveting the leading edge. I first assembled the ribs and skin back on the spar, using two ratchet straps. I then removed the leading edge from the spar and put it in the cradle.

I discovered that by using a bit of masking tape on the rivets, not only do they stay in place as you rivet, but it also keeps the skin from getting marks or scratches from the rivet gun. Before, I would put masking tape on the rivet set, but it starts desintegrating after a couple of rivets, and it is very hard to take off. By putting the tape on the rivet, the rivet set stays clean and it comes off very easy later.

It took me a couple of days to get all the rivets. Here is the finished product:

And if you still can’t quite place where this goes on the plane, here is another picture with the piece oriented in the horizontal plane. This piece belongs on the left wing, so imagine you are looking at the front of the plane. On the picture below, the tank mounts just to the left of the leading edge (and together form the complete wing leading edge. The rest of the wing goes behind the leading edge, and the wing tip goes to the right of the leading edge.

Posted in Leading Edge | Comments Closed

Countersinking Spar Rivet Holes   January 21st, 2008

Before fitting the leading edge again for final assembly, I countersunk all the holes where the leading edge attaches to the spar. The construction manual doesn’t really talk about this, but the leading edge skin holes have already been dimpled, so in order for things to fit tightly, these holes need to be countersunk (the spar is too thick to be dimpled!!!)

The task is very straightforward — just set the correct countersink depth and start drilling. The only thing to be aware of is that the countersink depth will change slightly depending on how hard you push, and may even drift just a tiny bit over time. I used a rivet to check for the correct depth every four rivets or so.

There are 65 holes on each side of each spar, so that’s total of 260 holes, just for the leading edge. There are a few hundred more where the main skin attaches 🙂

Posted in Leading Edge | Comments Closed

Priming Leading Edge Ribs   January 13th, 2008

I have put both fuel tanks away, and I am ready to go back to the leading edges. I spend all day today priming the ribs and skins. I am still using the Stewart Systems water-based primer.

The wing jig was briefly converted into a rib-holder. I draped tarps on both wing skeletons to keep paint from getting on them.

After speaking to an AFS rep at Oshkosh last summer, I am going to wait for about a week until I start putting the leading edges together. Given the relatively cold weather, this should be plenty of time for the primer to harden.

Posted in Leading Edge, Primer | Comments Closed
I finished with the right tank and the one other thing left to do was to dimple all of the skins. I bought a DRDT-2 from ExperimentalAero. This sucker cost as much as my pneumatic squeezer! After using it for about an hour, it was obvious it was worth every penny. Here’s what it looks like:

Normally, you would use a similar C-frame, but instead of using a handle, there is a shaft you whack with a hammer…painful and easy to put a hole where you don’t mean to. This thing is very easy to use. Just put the skin on it and pull down on the handle. I did both leading edges and both tank skins in two short sessions.

Posted in Dimpling, Leading Edge | Comments Closed

Leading Edge Joint Plate   September 4th, 2007

The leading edge rib on the edge closes to the gas tank also has a strip of aluminum where the gas tank screws into the leading edge. This rib doesn’t come pre-punched, so I had to mark where the rivet holes would go before fluting it. I just put it next to the leading edge and marked the approximate location of the holes.

The next step is to insert the rib and the strip into the leading edge. Sounds easy, but the skin is so tight it’s a real bieatch to get everything in there lined up and straight! Even so, I managed to get it in there after a lot of trying…

Finally, once everything was straight, I drilled through the skin and into the rib/strip.

Now I just have to do the other wing…

Posted in Joint Strip, Leading Edge, Wings | Comments Closed

Still Fitting the Leading Edge…   September 1st, 2007

I got my trusty Redneck ratchet straps and put them around the leading edge. I used some cardboard to keep the straps from scratching the skins.

By the time the holes line up, those straps were TIGHT!

With the holes all nicely lined up, it’s just a matter of clecoing all the holes to make sure the skin remains tight when the straps are removed. Later I removed every other hole for drilling.

Posted in Leading Edge, Wings | Comments Closed