Sometime you just gotta hold your breath....

[mhorowit]

...and do it

[VictorBravo]

Re: Sometime you just gotta hold your breath....

Go get 'em Mike! You're doing incredibly well and are showing a very rare amount of perseverance. We're all truly proud of you!

[Hank Jarrett]

Re: Sometime you just gotta hold your breath....

The guy who did the welding on my plane said he thought I was going to have a heart attack the first time I had to cut a fuselage tube. I would rather have cut my own arm off. After the whole mess was jigged up and welded back together all was right with the world. Just make sure your IA is involved at each stage.
Hank

No, we aren't ever going to forget, and neither are you. You are going to have one sweet ride when you are done.

[mhorowit]

Hmmm or Oops?

Before removing the tailpost, I built an alignment jig. Thinking that with the vertical fin in place, I could make fine adjustments on the tailpost position.
Please note that the fin appears to cock to port, while the tailpost lies in the plane of the centerline.

Should I take the angle out of the fin? How did it get there? - Mike

[Marv]

Re: Sometime you just gotta hold your breath....

Mike i beleive the fin is that way to compensate for engine torque. Marv

[Hank Jarrett]

Re: Sometime you just gotta hold your breath....

I don't think he is talking about the right/left offset, but the bend side to side of the hinge line tube.
When we were repairing my 45 I got the wing and cabin area straight and square first and then worked my way back one frame at a time squaring each one in turn by aligning them to the cabin area (when I bought the 45 it was up-side-down with a smashed fuselage). As I worked my way back pulling the fuselage frame straight my rear post ended up out of line too, but the lower longerons had damage and I assumed they were the reason the tail was bent. When we welded back the fuselage longerons we jigged the stern post straight and when we were done everything was trammeled up so the alignment was perfect (at least as close as we could measure).
In hind site I seriously doubt the damage caused the offset. I have looked at a lot of fuselages and very few looked perfectly straight at every frame. If the wings are straight and the fin and stab are perpendicular and square to the wings it really doesn't matter if the frames are off a little in between. I have a feeling at the factory they had someone stand out in front of the fuselage with some alignment sticks and just bent the fuselage till the tail and wings were aligned properly. When the stringers are on and the fabric is covering everything you can't see it, but if the tail and wing are off, the plane will never fly straight.
Just get the fuselage as straight as you can and then make darned sure the stab is level to the wing and the fin front and rear mount tubes are square to the wing and stab. You will end up with a plane much straighter than one that hasn't been repaired.
hank

[mhorowit]

Re: Sometime you just gotta hold your breath....

Mike i beleive the fin is that way to compensate for engine torque. Marv

Marv - that's what I was thinking; however, the post was centered. The question arises because the holes in the forward support of the fin are such that the fin does not lie in the plane of the centerline. Let's see what the group says. - Mike

[mhorowit]

Re: Sometime you just gotta hold your breath....

I don't think he is talking about the right/left offset, but the bend side to side of the hinge line tube.

Hank - would you please describe the offset? What is the hinge line tube - same as the fin? - Mike

[crispy critter]

Re: Sometime you just gotta hold your breath....

Mike,
I'm not exactly sure what your asking but this might help. The vertical stab should be straight up & down. The tail post should in line with the center and straight up and down. The front vertical stab mount is suppose to be off set favoring the pilots side. There is no off set in the tail post.

[N96337]

Re: Sometime you just gotta hold your breath....

Looks good Mike, like Kevin and Hank said, just measure, level and go for it. Like they say in the wooden boat industry...measure twice, cut once. I'd do just what Hank's saying, starting at the front gear attach cross tube.... get it level, and get a way of holding it there, then go to the next back, level it, hold it there, and on to the next.... You might lay a "center line" forward to back as well, to keep everything aligned in all dimensions. Looks like you're off to a great start!
JH

[Hank Jarrett]

Re: Sometime you just gotta hold your breath....

Tail post, hinge post, hinge line, stern post, last tube in the fuselage over the fence. They are all the same. The last tube in the fuselage frame that the back of the fin plugs into should be vertical when you are done and perpendicular to the gear lugs and wing mounts. Set the front lugs (wing and gear) level and move the stern tube till it's vertical. Make the stabs horizontal and perpendicular to the fin.
If you are going to really trammel (that is the real term for what we are doing here) the plane, the aft edge of the ribs just outboard of the aileron to the stern post should be equal distance and the wing tips should be the same distance up from a level floor (or a level string across the top of the wing should be level when the fuselage is level side to side). There should also be the same twist in each wing as measured at the strut fittings.
The only thing that isn't square and symmetrical is the front post for the fin. If the prop turns counterclockwise from the front (like ours do) the front post for the fin may be offset to the left to counter torque. The problem with using fin offset is it will only balance torque at one airspeed and power setting.
Hank

[mhorowit]

Re: Sometime you just gotta hold your breath....

Thought I'd post a follow up. I built the tailpost on the workbench with many backs-and-forths to insure all was still in alignment, then did the final welds (still on the bench), only to find that between the tacking and the welding something became distorted, so I tried again, this time welding strips all over the place to hold the relationships. Seems to have worked as she fitted to the A/C with only a little nudging then I tacked her in place (I'm using internal sleeves to connect the tailpost to the fuselage). I began to finish the welds when I scared myself... I wasn't sure I was incorporating the inner sleeve into the weld, so I stopped and have gone back to the practice bench. Someone in the EAA chapter had cut up either a Piper or a Tcraft so I have as much 4130 scrap as I need and have been practicing the splice. Unfortunately, I have to wait until noon on Sunday to fire up the angle grinder so I can see a cross section and see if things have flown together. So there we are at the moment. - Mike