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The manual calls for establishing neg 1 to neg 1.2 degrees relative to the BL-50
level line. My conclusion is that I don't have the skill or the equipment to
achieve this level of accuracy!
Consider the following: Bearing in mind that my digital smart level is good to .10
You need to scribe a level line on the BL-50 rib. OK, how many cumulative errors
can creep into this proceedure? What is the degree of accuracy used when the full
size BL-50 rib was created in Drawing E? How about the width of the level line on
this drawing? Now consider the fact that this full size drawing of the BL-50 rib
does NOT match my real world rib by as much as .125 in some areas. So in the end,
you manage to scribe your level line and it may or may not be accurate.
Now before you can proceed further, you need to create a temporary jig which will
hold your digital level, on the top HS surface. Hmmm, how many more errors can
creep in at this point? Theoretically you establish the TE chord plane by bisecting
the TE (3 possible errors creep in here). Now measure from this point up to the top
of your jig. (1 more possible error) Find and mark the LE chord, perhaps with the
help of a dial indicator (2 more possible errors). Again measure up from the LE
chord mark to the top of your jig. The end result (hopefully) is that the top of
your jig is parallel to the HS chord line ( numerous possibilities for more error
here)
Now consider that the HS distance from TE to LE at BL-0 is 16.5" which means that a
1/10th degree error here in making your jig parallel to the chord equals 1.7mil
rads or about 20 mil. ( more creeping errors here)!
I think I see another black hole coming...fortunately it can be fended off with
Coors.
.....Now if I were building an RV and happened to screw up the HS incidence, I
could unbolt, add or subtract shim washers and be done with it!
Angier Ames
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LML website: http://www.olsusa.com/Users/Mkaye/maillist.html
LML Builders' Bookstore: http://www.buildersbooks.com/lancair
Please send your photos and drawings to marvkaye@olsusa.com.
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