Bowed angles

[racaldwell]

I am making parts for the forward fuselage and I took the remaining four 1"x1"x1/8" al. angles from the storage rack this weekend. I laid them on the table and just then noticed how bowed and twisted they were. I managed to untwist one by clamping an end in the vise and twisting the other end more than 180 deg. but the bowed pieces I could not get straight. I am wondering if the cross members in the forward fuselage will hold the longerons straight? They seem easy enough to hold the fairly straight on the table so maybe these are useable. Have other folks used angles that look like the strectcher operator was at lunch when their angles were extruded? I have asked Sonex about it.

Rik Caldwell
Xenos 0057

[Sonex1243]

I had the same problem with my upper and lower longerons for the forward fuselage on my Sonex. Not sure of the Xenos, but, I took the twist out like you did and then just made sure the angle edges followed the bottom skin ( minus the .025 for the lower cabin floor skin) and the upper longeron followed the dimension called out as I piloted them straight to the table in the flat. I believe this is what Sonex tech told me to do with my exact same problem awhile back. Hope this will help.

[peter anson]

Yep, me too. I actually gave up on building a wooden aircraft because I didn't think I could cope with the amount of warp in pieces of wood when I cut lengths from a larger section. Imagine my surprise when I found that Al extrusions were often crooked too. Even my wing spar caps had to be pulled into shape before drilling.

Peter

[racaldwell]

Good to know, thanks. Yes, the bow seems to go fairly straight when held in position. Sonex replied that the other parts should hold the angles in position. I hope so.

I have been working in one of Hydro Aluminum's extrusion plants for the past 25 yrs. There is no way any material would go out the door looking like these angles do. OK, I'll not go into a rant and accept it is what it is.

Rick Caldwell
Xenos 0057

[peter anson]

Hi Rick, the distortion may be a result of heat treatment after extrusion. The common architectural extrusions sold in Australia are 6060-T5. They are dead straight but soft as butter. I think the process for 6061-T6 is to "age" it at about 200C for around 10 hours after extrusion. They will pull into shape OK.

Peter