Cut / Notch Order

[bobthebuilder]

Hi guys,

The picture below illustrates the last station where the rudder post and stab spar are to be fitted.



I was thinking about cutting and notching the bottom longeron to accept the rudder post, and the last diagonal to accept the stab spar at this point.

Is it recommended to do it at this stage, or should I rather wait until after the two sides are jigged upside down on the table, joined and bent?

 

[Tom H]

Bob, not sure how your idea would work. Seems that you have to do the same thing on the other side, mirror image.

On my build, I assembled the two sides, connected them together, left and right with the various cross members, all tacked together. Then, put upright on the table, and using center lines, plumb bobs, squares, etc, fit the rudder post

Not sure what airframe you are building, but, on the S2LS, I made a mistake on the two upper longerons meeting the rudder post. If I remember correctly, each of those are supposed to meet the rudder post side to side, not coped to the post. I coped the upper longerons to the rudder post, and it makes the interior space real tight for later elevator control arm/pushrod connections.

 

[bobthebuilder]

Hi Tom,

I'm building an S1.
You are correct in that the two sides would need to be handed if I went about it by notching first.

On the S1, the bottom longerons are coped to the tail post. This is why I wanted to cope now. I thought it would be easier to cut and grind the longeron tube before its welded up.

The big "But!" Bouncing around in my head is, can I really build accurately enough to get two prefabricated sides to meet perfectly over such a long span? Bending the two sides to meet at the tail is a hand bent exercise.

I prefer your method of jigging it up at a later stage.

Thanks for your input.

 

[Raceair]

Bobthebuilder….Your project looks great….I usually tack the two sides together at the tail post, putting tacks on the front side of the cluster, so I can go back and use a dremel tool to notch / fish mouth the bottom longerons . You can take your time here, and get the fit pretty good. I also drill a hole in the table on the fuse. centerline at tail post, same diameter as post, and let the post slip down the hole a couple inches, which aids in alignment also. That piece sticking down will later be angle cut and fish mouthed for the tail spring socket…Remember to only tack weld the top longerons, as they eventually do not continue all the way to the post, but get cut off when stab. spar is attached…...Ed

 

[Raceair]

Forgot to mention that my description was for jigging my fuselage in the upright position, which hardly anybody does these days…I did it so I could use carpenters squares clamped to the tail post sides, as the tail post would be sticking up, and easier to make plumb…..Ed