H E Double Hockey Sticks

[taildragger]

I bent the thick rear stabilator spar cap hockey sticks to exactly 14.3 degrees. However, there is a .5 degree twist between the bend. My arbor press shifted during the bend. Questions:

1) is this OK to use, as-is? Would this make the stabilator angle of attack .5 degrees off?
2) Shall I twist it back with a vice and mandrel?
World this small tweak work-harden the bend too much and make it brittle?
3) Shall I re-order and re-bend?

[Scott Todd]

Twist it back. That much is not a big deal and it won't hurt the material.

[Bryan Cotton]

To prevent the hockey sticks from twisting, I screwed down 4 pieces of wood. Worked great.


This was from the first page of my thread.
viewtopic.php?f=39&t=578

I made a total of 3 hockey sticks.

If I understand your issue, that might be hard to bend back. But I did some tweaks after to make it perfect as I could.

[bvolcko38]

I bent my hockey sticks with utmost care and best precision I could muster. When it came time to install the tail surfaces I was quite dismayed, they did not mate up well at all. I fabricated tapered shims out of scrap 6061 t6 and used longer bolts for the extra thickness of the shims. She flies straight!!

[Murray Parr]

I too bent my hockey sticks to precision but when I went to install them I still had to tweek them as they didn't mate up at all. Maybe just get them close and tweek some more as needed.

[taildragger]

Thanks for your thoughts. I am a mechanical drawing engineer and am surprised Sonex doesn't have any tolerance callouts in their drawings, especially for critical parts. Professional mechanical drawings ALWAYS have tolerance shown for ALL callouts. Sonex should:

- Add tolerance callouts for all critical parts
- Include tapered shims in all kits to adjust critical control surfaces and stabilizers
- Design in adjustability in wing and tail surfaces to mitigate tolerance compounding (AKA twisting)

My two cents.