Building Tips and technical articles. > Building techniques
Notes on building the Brodak Mo' Best kit.
Perry Rose:
The wing span is 58 inches not what is posted on the plans and box. If you follow directions use the Brodak wing jig or equivalent. Use an incidence meter to verify that both ends of the jig are the same. don't rely on a "flat surface". Be careful when using the laser cut leading and trailing edges. Make sure you have the inboard and outboard sets in the proper orientation. The center ends have a stub that can cause confusion. Don't cut it off yet. The fuselage front sections have a cut out for the wing. use that to mark the leading edge radius and shape the leading edges before gluing the wing halves together. Also when gluing the fuselage fronts together use one of the cut outs to align them for gluing. Set one half on a flat surface put a scrap of 1/8 balsa in the wing opening, place one cut out on the balsa in the opening and use that to align the second half. After gluing use a scrap of 1/64 ply to reinforce the wing opening, front and rear. Not in the wing opening, there are flat spots outside the opening. If not it may break when wiggling the wing into the opening. Drill the hole for the landing gear in the torque blocks in a drill press. Use a piece of 1/8 wire to align it when you epoxy it in place. Trim the torque block to match the rib opening on the left wing to give the leadout wire all the room it needs before gluing it to the rib.
I'm going electric with a printed motor mount so I'm going to use 1/16 ply on the nose doublers with triplers on both sides to fair the mount into the fuselage. It's a nice kit.
Perry Rose:
One thing I learned from Pat Johnston. Install shear webs between the wing spars ,being careful of the leadout wires, and across the trailing edge. It makes the wing a lot stiffer.
UPDATE 12/19/21
In the end I wasn't carefull enough. The rear leadout rubbed on the shear web and caused trouble making clearance for the cable.
ray copeland:
Perry, thanks for the building notes as i plan to build my kit this winter. I have to ask since i am not sure what a shear web is or where they need to go. Do you mind doing a pic or diagram, please and thank you, Ray
Dave Hull:
An overview-type explanation:
https://www.airfieldmodels.com/information_source/math_and_science_of_model_aircraft/rc_aircraft_design/shear_webs_in_model_aircraft_wings.htm
Dave
Perry Rose:
Yes, what Dave posted. The trailing edge webs go between the trailing edge sheets, they don't stick out into the covering.
Also on the bellcrank to flap horn push rod, the kit has a rod with a "Z" bend at one end. I open the middle hole in the bell crank a bit and stuck the "Z" into it. Friction free. on the horn end I used a Du=Bro 4-40 Threaded Coupler #336 and a Sullivan 4-40 clevis. It's a solder on coupler, don't forget that the rod goes into the coupler 3/8 to 7/16". If you think the rod will bend in flight push on it and see what it takes to bend a 6 inch piece. I plan on a carbon rod for the elevator push rod. I don't like fair leads.
On the fuselage sides the wing chord line goes right through the screw hole in the tail weight box. I draw a line from the wing trailing edge to that hole and make a dimple or small hole three inches from the trailing edge of the wing so I can accurately locate the flap fairings. It saves with the bench trimming later on.
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