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Post by schines on Sept 5, 2011 20:54:48 GMT -5
Hi,
I spent a fairly productive day making parts today. I worked for about 45 minutes on the part labeled "section A-A" on page 7 of the II S plans and was about to weld it in when I realized that I don't know what it is for! I can't find any other reference to it in the plans or the construction manual. I hope I didn't do all that drilling and shaping for nothing!
Scott
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Post by n3480h on Sept 5, 2011 22:00:53 GMT -5
Scott, Section A-A on page 7 of my IILS plans details the construction of the bushings for mounting a jackscrew adjustment for inflight trim of the horizontal stabilizer. The bushings are welded into a crosstube between the upper longerons. I did not like the two point mount and elected to install a third mounting point for a firmer mount of the triangular jackscrew plates.
My plans do not show a jackscrew adjuster. If you have the Sonerai.net archives, there are several pictures of different builder's jackscrews. If not, some of the old Pipers have such a trim mechanism. Mine has a pulley in it with 1/16" cable to a trim wheel in the pilot's position. The system raises or lowers the leading edge of the horizontal stabilizer, within the limits of the slotted brackets welded on the outside of the upper longeron.
Tom
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Post by schines on Sept 6, 2011 13:17:47 GMT -5
Thanks Tom. At least that mystery is cleared up. Now I have to decide if that is the way to go. I guess I can always install the piece anyway, then it will be there if needed.
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wafer
New Member
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Post by wafer on Sept 20, 2011 21:31:30 GMT -5
Scott-
If I could add, A-A is for the two bolts that hold the horizontal stabilizer in place and allows you to adjust the horizontal stab on the ground. Refernce pages 13 or 14 (pending if you are building square or rounded tail), and the horizontal stab 3 and 5/8 apart 3/16 holes you drill. As Tom pointed out, it could also be used for a jackscrew adjuster trim arrangement that folks later added to allow in flight trim feature.
Mike
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Post by n3480h on Sept 20, 2011 21:51:28 GMT -5
Thank you Mike, that is a more accurate and helpful description. I have to confess that once I saw "inflight adjustable trim", tunnel vision set in, lol. Good that we have a wide knowledge base in our membership.
Tom
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wafer
New Member
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Post by wafer on Sept 24, 2011 6:16:33 GMT -5
The jackscrew addition is very popular!
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Post by schines on Sept 24, 2011 19:50:51 GMT -5
So is it necessary to adjust the horiz. stab. in flight or is it just to relieve stick forces as the CG changes like a trim tab? Has anyone built in a proper trim tab, or is that too much work?
-Scott
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