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this section, as it will significantly reduce the strength in the longerons in a highly stressed area.  Do
some final cleanup sanding to finish blending the fuselage and noseblock together, and then seal
the noseblock with three coats of nitrate dope to seal, including the back faces.

Final sand the fuselage box assembly to remove all mismatches between the longerons and other
members.  Finish with 220 and 400 grit sandpaper, then coat with two coats of nitrate dope, sanded
with 400 grit paper between coats.  Dope the inside surface of the nose area as well.
 
Cover the fuselage with tissue, attaching to all the cross members as well as longerons.  This type
of fuselage will eventually see lots of tissue repair with use, and having the tissue bonded to the
structure in cells will make this aspect much neater and faster to accomplish.  Shrink the tissue and
finish the fuselage with two coats of thinned non-tautening nitrate dope.  Cement the two F-5 wing
rails onto the top longerons where shown on the drawing.  For a finished look, cover these with
tissue strips to match the fuselage color after bonding in place.

Install the 1/16 aluminum D/T guide tube on the end of the tail filler block using a spot of thick
CA at the top and bottom, dusted with microballoon filler.  Install the two  3/32" scrap balsa
D/T band stops on the bottom of the fuselage as shown on the side view.  Reinstall the
incidence adjustment screw in the tail filler block.

Stabilizer Rigging

The rig of the horizontal stabilizer is somewhat critical in plan view.  The effect of having two
vertical stabilizers mounted off center to the fuselage means a high degree of turning force for
small angular changes in the horizontal stab position.  For this reason, the keys shown on the
strike plate are necessary to insure consistent trim of the model.  Without, little variations in
seating the stab on each flight will likely result in inconsistent turning performance, and some
frustration on the part of the builder to get the model in trim.

Using 3/32 scrap material, make a small block with tapered sides to match the size of the
plywood strike plate already installed on the bottom of the stabilizer.  Bond this in position
over the strike plate.

Position the stabilizer assembly on the stab platform and determine as best you can an
equalized position for the two fins, as close to parallel to the fuselage center line as you can. 
It is possible to set the stab slightly skewed such that the right tip is slightly forward of the left
tip for built in right turn trim if you so desire, but we recommend setting up with a parallel
condition to start and leaving rudder tab adjustments as a last resort to obtaining a right hand
glide pattern.  Once the position is obtained, press down carefully on the trailing edge of the
stab to allow the head of the incidence screw to make an impression into the balsa block
glued to the strike plate.  Allow the stab to tilt up, and using a new sharp razor, carefully make
a forward / aft slot in the block to the width of the screw head impression.  Test the fit of the
slot over the screw head, and keep lightly cutting the slot until it is wide enough to snugly grip
the screw head, and deep enough to let the screw head hit the strike plate.  Use a small file
or emery board to develop a tight but slipping fit of the slot with the screw that allows the stab
to pop-up easily upon D/T release, but with no lateral slop that would impact the turn trim of
the model.  Once this accurate fit is obtained, you can carefully sand down the thickness of
the keys to be no taller than the thickness of the screw head.
.  

D/T Timer Setup

Summary of Contents for CBMD-002

Page 1: ...Construction Manual Kit No CBMD 002 www cbmodeldesigns com Copyright CB Model Designs 2008 CB MODEL DESIGNS ...

Page 2: ...the trailing edge segments during assembly The same suggestion applies to the leading edge segment installation as well as both boundaries of the wing will be well controlled dimensionally if this is done When the tip bows are dried remove any blocking near the polyhedral joint to allow access for trim of the bow Use the laser cut leading edge segment end as an angle gauge to mark the cut line for...

Page 3: ...ttle easier to assemble the polyhedral joint and W 1 joint rib Install the inboard panel turbulator spars again allowing for material excess at the dihedral and polyhedral scarf joint locations Carefully remove an outboard panel from the plan Use the outboard joint rib gauge from the laser cut sheet to install the joint rib W 1 against the end of the inboard wing panel still on the board Align car...

Page 4: ...each rib and spar tissue grain in spanwise direction Apply one coat of non tautening nitrate dope thinned 50 after shrinking tissue with alcohol or water mist Horizontal Stabilizer Construction Begin assembly by placing scrap balsa strips along the leading and trailing edge lines of the stabilizer drawing to control the boundary of the leading and trailing edge segments as done for the wing Assemb...

Page 5: ... to the bottom of the horizontal stabilizer Once the fin installation is completed shrink the tissue covering and apply one coat of thinned non tautening nitrate dope to seal At the stab center section apply two additional layers of tissue over the bay that will be in contact with the stab platform on the fuselage to improve mounting stability and allow a strong surface for stab tilt shims applied...

Page 6: ...glue is suggested for fuselage frame assembly Moistening the ends of the 3 32 square and 1 16 x 3 32 members prior to glue application will improve joint strength by allowing the glue to penetrate the end grain Allow the fuselage frames to dry completely before removing from the building board Use a 220 grit sanding block to lightly sand the inboard side of the frames to level any mismatching vert...

Page 7: ...if the fuselage springs or twists at all If you took your time on the assembly and worked carefully the center of the joint should remain exactly where you had it restrained Carefully remove the rest of the support blocking you may have had in place and remove the fuselage box from the plan Add any remaining cross members that were too troublesome to get to from the upper side including the lower ...

Page 8: ...ough the pilot hole and bond together with thin CA Make a mark on the upper edge of segment A for reference to the top of the block Now install the remaining segments using the tube as a guide and best fitting to the laser etched outline of the previously installed segment bonding with thin CA Install segment G with the corner notched The corner piece itself is to be installed into the mating fuse...

Page 9: ...n For this reason the keys shown on the strike plate are necessary to insure consistent trim of the model Without little variations in seating the stab on each flight will likely result in inconsistent turning performance and some frustration on the part of the builder to get the model in trim Using 3 32 scrap material make a small block with tapered sides to match the size of the plywood strike p...

Page 10: ...mer arm and adjust the tension in the lanyard knot to extend the spring approximately 3 8 to start Observe the timer for movement it should be very slow prior to releasing observe for approximately 25 30 seconds to release from the 12 00 position If it runs faster than this you will need to loosen the knot and lengthen the lanyard slightly to slow down the timer and reduce spring tension If the ti...

Page 11: ...ht Next install the two scrap 3 32 retainer stops on either side of the fuselage Pin prick the tissue in the area these install to improve joint strength prior to bonding In practice the dental band attaches against one retainer stop stretches around the noseblock against the pin heads and onto the opposite stop Finish the noseblock with colored tissue or dust with Design Master floral spray or co...

Page 12: ... evident in the glide start adding shim to the right side of the stab platform to tilt the right stab tip higher than the left until a flat right hand glide pattern is obtained about a 30 foot radius If stab tilt is not quite enough to gain the right hand turn reduce washout in the left wing If this still is not enough add small amounts of right rudder tab until the right turn is satisfactory If n...

Page 13: ...e model in a cardboard box or other storage container Models stored in this manner will look fresh for many months and perform consistently Motor setups If you have never built and flown rubber powered models visit our website to view an article concerning the methods of making motors installing and maintaining them Otherwise some basic recommendations for motors follow 13 grams of 3 16 SuperSport...

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