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Building and Flying Related Boards › miniMax, Hi-Max, and AirBike General Discussions
The Forward Spar Carry-Through
3 posts
David WoodsideJuly 8, 2025, 2:51pm
Greetings all!

For those of you who may be building a Mini-Max or who are otherwise knowlegable, I think there's a more logical way to install the front spar carry-through than what's described on the plans and work instructions.

My modification is to cut the 2-deg bevel in the RS-11 as instructed, but then put the beveled surface AGAINST THE WORK TABLE instead of away from the table's surface.  That beveled surface will be at the top of the fuselage.

Positioning the RS-11 this way on the table automatically causes it to align with the adacent RS-8 pieces in the fuselage sides which are already at the same 2-deg angle.

Later, when the wings are first being attached, the RS-300 aluminum carry-through is mounted to the UNBEVELED, bottom surface of the RS-11 instead of to the beveled surface.

The holes in the aluminum have been pre-drilled, and they will naturally be drilled perpendicular to the aluminum's surface.  Then, when the RS-300 is clamped to the RS-11, extending the holes will cause them to be on the centerline of the RS-11.

Referring to the RS-11, the work instructions say to "...bevel the bottom at 2 degree angle per drawing 13."  This implies that the RS-11 should be installed PERPENDICULAR to the top fuselage longeron and work table, with the unbeveled surface on the table.  Doing that will cause the RS-11 to not be aligned at the same angles as the RS-8 pieces.  It makes more sense to align the RS-11 with the RS-8 which is already at the needed 2-deg angle.

This method results in the perfect width-wise alignment of the RS-11, the RS-300, the RS-8 on the fuselage, and the spar caps and end RS-9 pieces on the spars, and the wing will be at the 2-deg angle of incidence.  All one has to do is "flip" the RS-11 piece shown in the drawing so the beveled surface lies flat on the table.

I haven't installed these pieces yet, but while pre-fitting everything together I made this discovery.

Note that for the V-Max, there is also a second RS-11 doubler that attaches to the RS-11 that's above the aluminum, but that doubler doesn't interfere with my modification.  However, the bevel would need to be extended across that doubler piece so that the fuselage skin will lay flat across both pieces.  I'll glue the two RS-11 pieces together, then cut the bevel.


"Strive for perfection; accept airworthiness."
gangeliJuly 9, 2025, 6:05am
That makes perfect sense David.
David WoodsideJuly 9, 2025, 10:27am
Thanks gangeli.   It turns out that, as a practical matter, it really doesn't matter which method is used.  Only 1/2" of the overall 1-1/4" depth of the RS-11 extends below the fuselage longeron.  If the RS-11 and RS-8 are not aligned, the wing's root brackets can still "capture" the aluminum carry-through.   If the RS-11 was much deeper, the alignment of the two pieces would be more critical and the extra material width created by the misalignment in that location would exceed the span of the brackets.
"Strive for perfection; accept airworthiness."