Greetings all! I'm building my templates that I will use to cut the rib blanks, and am cutting the templates all at once. I have Eric Newton's Bearhawk Builder's Manual for the wings, and have looked over his site pretty extensively. A few things I'd like to clarify...
(1) All of the rib photos I see include a few extra holes that weren't placed on the Mylar drawing (#4 for Model B folks). For example, the very small (~3/16"?) holes in the upper right and lower left of this picture: http://www.mybearhawk.com/wings/centerib4.jpg
I'm presuming those are placed on all ribs to help with alignment in the formblock. That seemingly presumes that the lightening holes are cut prior to forming the flanges, else one could simply use the 3/16" holes that center the lightening holes to hold the ribs in the formblock while forming the flanges. Is this assumption correct? If so, I'm assuming that, should I do it this way, the placement of the jig holes is not to any particular critical dimension, save that they (a) are consistent for all ribs of the same type, (b) are far enough apart that it helps with alignment, and (c) don't cause unusual stress concentrations (e.g., don't put one right on the edge of where a flange bend will be). I realize I'll only need one extra jig hole in the nose rib and aileron/flap ribs, since the drawing does have a fore/aft jig pin hole already.
(2) Piggybacking on (1), what advantage is there to cutting the lightening holes prior to forming the flanges along the rib? Does this presume the router method of cutting the holes, and/or the press method for flanging the lightening holes? I ask because my current plan is to cut the lightening holes with a fly cutter, and to "Bob stick" the flanges for the lightening holes.
(3) Everything I read seems to show folks flanging the two lightening holes on the nose ribs. My plans don't seem to indicate that this is required, if I'm reading them correctly. I'm okay with doing it, but wanted to make sure that this wasn't a change from the original 4-place to the Model B.
(4) Eric's manual and website discuss "back ribs:" http://www.mybearhawk.com/wings/backribs2.jpg
I'm presuming that they're referring to trailing edge at the wing root, which is seen in this picture on the end closest to the jeep: http://mybearhawk.com/wings/wingtrnsprt.jpg
The Model B plans don't appear to have these ribs. Is my interpretation correct?
Many thanks for any assistance!
Nick
(1) All of the rib photos I see include a few extra holes that weren't placed on the Mylar drawing (#4 for Model B folks). For example, the very small (~3/16"?) holes in the upper right and lower left of this picture: http://www.mybearhawk.com/wings/centerib4.jpg
I'm presuming those are placed on all ribs to help with alignment in the formblock. That seemingly presumes that the lightening holes are cut prior to forming the flanges, else one could simply use the 3/16" holes that center the lightening holes to hold the ribs in the formblock while forming the flanges. Is this assumption correct? If so, I'm assuming that, should I do it this way, the placement of the jig holes is not to any particular critical dimension, save that they (a) are consistent for all ribs of the same type, (b) are far enough apart that it helps with alignment, and (c) don't cause unusual stress concentrations (e.g., don't put one right on the edge of where a flange bend will be). I realize I'll only need one extra jig hole in the nose rib and aileron/flap ribs, since the drawing does have a fore/aft jig pin hole already.
(2) Piggybacking on (1), what advantage is there to cutting the lightening holes prior to forming the flanges along the rib? Does this presume the router method of cutting the holes, and/or the press method for flanging the lightening holes? I ask because my current plan is to cut the lightening holes with a fly cutter, and to "Bob stick" the flanges for the lightening holes.
(3) Everything I read seems to show folks flanging the two lightening holes on the nose ribs. My plans don't seem to indicate that this is required, if I'm reading them correctly. I'm okay with doing it, but wanted to make sure that this wasn't a change from the original 4-place to the Model B.
(4) Eric's manual and website discuss "back ribs:" http://www.mybearhawk.com/wings/backribs2.jpg
I'm presuming that they're referring to trailing edge at the wing root, which is seen in this picture on the end closest to the jeep: http://mybearhawk.com/wings/wingtrnsprt.jpg
The Model B plans don't appear to have these ribs. Is my interpretation correct?
Many thanks for any assistance!
Nick
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