Lofting

[geraldmorrissey]

Some items came up in lofting the empennage tooling. As expected, I found errors in the paper dwgs when scaling dimentions. Ref Patrol dwg sht 22. Across the dwg sht, the 18" width, the error is about .040 SHORT on the 24" dim or .160 because the scale of the view is 1/4. Doesn't sound like much but it adds up. Witbout adding this adjustment, your horizontal stab ribs will be .160 too short inbd and .125 short outbd. The elevator ribs will also be short. Over the 24" length , the dwg sht is about .060 LONG on the 59" dim or .240 Some dimensions off a factory horizontal stab assembly for some of the rib lengths would help. A measurement between the L.E. tube CL and the spar tube CL where the web of the rib intersects the tubes would do it. It would be useful if someone could check my math. My dwg could be different then yours.
Thx
Gerry

[davzLSA]

Hi Gerry, I lofted a set of horizontal stabs and a set of elevators. The way I did it was to use the straight spars of both surfaces as a datum. I then attached the ribs at the intervals indicated on the plans. Then I used a batton to make the curve for the leading edge and of the horizontal stabs and the trailing edge of the elevators. I did this all on paper first to full scale to check measurements. I was surprised how well it worked out.Just my 2 cents.

[geraldmorrissey]

I finally got the horizontal stab dimentions for the leading edge tube C/L worked out. It's a combination of measurements, adjustments for errors on the paper dwg and finally splining through points. If anyone wants the data, message me. My posts containing numbers get scrambled for some reason. Trying to work that out. On to the elevator. Thanks davzlsa I used your method and it worked out fine.
Gerry

[davzLSA]

Hey Gerry, I happy I was able to help, that is what this forum is all about. I hope I can be of assistance in the future. Gerry I wanted to tell you about my first try with welding these parts. You really need to be sure you have the spar of the horizontal stab and the spar of the elevators clamped tightly to a very strong piece of angel iron because if you dont when you go to weld the ribs the nice straight spars will be pulled out of straight. Ask me how I know?

[geraldmorrissey]

Davz thanks for the tip. Any images of your fab of the empennage would help. I have completed my assemby fixture, Any advice on tube bending? Steel tube bending is not on my list of skills.

[Chewie]

It's smaller but here's how I did the tubing for the hinge mounts.