[May 9, 2007]

I took yesterday off of the project to take care of all kinds of stuff, except for the plane. Today I got the good news that the only thing my new Buick needed to pass inspection was a $4 lightbulb. I have never gotten through an inspection without something bigger being wrong. I guess I have no excuses to not buy a tungsten bucking bar now.

I started bending the longerons tonight. After my first few wacks, I noticed that the duct tape on my vice wasn't cutting it to protect my precious longerons. So I found this plastic and taped it to my vice. I was a little concerned that my little 3.5" vice wasn't big enough to bang out these longerons. However, it worked fantastically. I am glad I didn't blow a bunch of money on a new vice.

These are the slight gouges I put in the longeron on the few handful of blows. I really wished that I looked at the longeron after the first few blows, but oh well. They will polish out in a few passes with a scotchbrite wheel.

OK, there are some alignment marks that you make on the longerons and match up on the template. The first is at 38 7/16"....

And the second one is at 69 9/32". Wait a minute? When I saw that the marks didn't line up, I thought I measured incorrectly. But I took a tape measure and double checked the marks. Turns out that the template is wrong. The template indicates more like 68 1/8". I don't know which one is the right one to line things up with. I am going to call Van's and see how to line this thing up. I am thinking it is the forward mark, because the aft canopy deck aligns perfectly with the longeron when it is bent according to the 38 7/16" mark.

When bending the longeron, they tend to bend in 3 dimensions. One of the dimensions is the one you want it to go, the other is a bend perpendicular along the other face of the angle. Finally, things twist around. To get the bend along the perpendicular face out, I laid the longerons across a 2x4 sitting upright and pushed down on either side, removing the bend. Removing the twist was easier. I used my smartlevel and a crescent wrench to untwist the longeron. Couldn't be easier.

I finished off the night by getting the right longeron almost perfect. Before I futzed with it too much, I wanted to call Van's and get their opinion on the alignment issues on their template. But so far, bending these things is a piece of cake. I really don't know what all of the fuss is about. I would much rather bend longerons all day instead of priming and deburring.

I spoke with Gus at Van's and he said to basically ignore the paper template. Use the F-721B aft canopy deck as the real test for the bend. Aft of the 721B should be straight back. Makes sense to me. He said that the paper template can occasionally be off, but when I said mine was off by about 1.5" he was a little dumbfounded.

OK, I got home and there is definitely more bend to be made aft of the canopy deck. So I just followed the template and ignored the 69" mark discrepancy.



Last Modified: June 24, 2024