Build Articles
K&A V-1 EDF Jet
By Carl Tulanko
March 07, 2008 - 05:31:24 PM

The K&A V-1 BuzzBomb EDF Jet as it comes from Warbirds-RC	The model arrived well packed	Clearing the bubble wrap reveals some of the components
The parts list for the V-1 is shown	High quality balsa in the parts bag is used throughout the kit	Begin construction by drawing the profile of the wing on 1/4" balsa. Draw six patterns
Rough cut out each spar. Three 1/4" thick spars are stacked at each wing end to make the tips	Sand the spars to shape, leaving them a bit oversized	Prepare several piece of masking for the leading edge pieces and tip spars
Extend the center line that was pre-drawn to the leading edge of the wing	Place masking evenly spaced across each leading edge piece and a single rib for each tip	Apply a good 15 minute epoxy to the leading edge balsa piece and rib
Apply epoxy to the wing tip	Apply epoxy to the leading edge of the wing	Place the wing down over the leading edge piece, making sure it is positioned evenly on both the top and bottom edge of the wing, then tape it on place
Position the rib at the wing tip and tape it in place, making sure it overlaps all the way around	Clean up any excess epoxy with denatured alcohol and paper towels, then allow the epoxy to set	Apply thick CA to a stacking rib

Place it over a second rib	Clamp it in place until the CA sets	Repeat the procedure for the second two ribs
Apply CA to the cap rib as shown	Install one set of the double rib over the cap rib and repeat for the second wing	Sand the top and bottom of the end rib to the airfoil shape of the wing
Sand the leading and trailing edges to match the wing	Use a large sanding surface to expedite shaping the leading edge airfoil. Taping a couple of pieces of 100 grit sandpaper together with thin clear packing tape on the back, then taping the paper to a table with duct tape makes a nice sanding surface	Be sure to sand the top, then the bottom, keeping the shape even across the span of the wing

Draw a end cap shape on a piece of paper and cut it out so there is 1/2" extending to overlap the wing

Place the drawn line of the tip at the seam of the cap rib and wing, then tape it into place as shown

Transfer the shape to the pattern with a pencil

You can whittle away some of the large excess balsa before sanding, but be careful not to remove too much	Use a sanding block to shape the end of the tip, keeping the end square	Darw a line at the point of the airfoil as shown
Use a piece of masking tape as a ruler and extend the line to the center of the trailing edge	Sand the top of each wing tip to a taper, down to the line	Sand the bottom of each wing in the same manner, tapering it to the outside line
Finish up each wing tip with some fine sandpaper for final shaping	Fine sand the entire wing, removing any sheeting overlap	Measure 1 1/4" out from the root of each wing and mark the inside location of each aileron. Measure 1/2" from each wing tip rear seam for the outside location

Measure 1" for the thickness of the Aileron

A piece of brass square was butted up against the trailing edge, then a 1" wide ruler was used to space the width of the aileron and a long ruler is used for cutting

You can draw a line for the Aileron location if you wish to make sure your ruler does not slip

Cut each end first, then cut the long run, making several passes and keeping your blade perpendicular to the table

Use one of the four 1/16" x 1/2" wide balsa cap strips to cap the inside of the wing's aileron area. Measure, then cut and fine sand to a good fit

Apply 5 minute epoxy to the Aileron area

Install the balsa strip, keeping it centered on the location. Use a straight edge if necessary to hold it in place while the glue sets. Cap the 1" ends with scrap balsa (not supplied) in the same manner

Lightly sand the top and bottom of the strip so it is flush with the wing

Trim 1/8" off the front of each aileron. A 1/8" thick ruler was used and a new sharp blade was held down on it as the aileron was held down on the table and pushed through the blade a little at a time. A few passes later and you will have a nice cut

Cut a piece of 1/32" x 1" ply in half for horn supports. Make two sets

Find the center of the aileron, center the ply square and trace its shape

Remove the area deep enough for the ply piece square to sit flush

Epoxy the ply pieces into the aileron area one side at a time and clamp in place until the glue sets

Trim 1/8" off each end of the Aileron and cap them with scrap pieces of 1/16" balsa

Sand each end piece flush to the aileron

Repeat for the other aileron and check the fit in the wing area

Sand a single bevel on the large side of each aileron

Bevel shown with the top that will sit flush against the wing top trailing edge

Slot each wing and aileron just below the 1/16" sheeting on the top. Make the slots about 1" wide

Sig Easy Hinges are used and each hinge is cut in half to make two pieces 3/4" wide

Hold a 1/2A sized horn centered over the ply inserts and drill the mounting holes with a 5/64" drill

Install the hinges in each aileron	Temporarily install a horn in each aileron	Install the Aileron in the wing. Make sure there is enough space at the ends for glassing or covering and paint
Make two 2-56 push rods with clevis' installed at the ends	Install a clevis in the horn with the pushrod centered on the wing	Use a receiver or servo tester and center your servo, then install the horn

Cut one end of the horn off and install the mounting screw

It is best to work on both wings at once. Make a mark 3" (near halfway} from the rear of the wing to find the center for the servo location. Use the pushrod to help with alignment

Draw a top line 7/8" from the center mark. Draw the lower line 7/8" from the center mark. Make sure the lines remain parallel to the leading and trailing edges

Hold the pushrod square and in place, then mark 1/4" past the left and right sides for a door width of 2" as shown

Square out the measurements (1 3/4" long) so the opening can be cut

Use a piece of 3/8" wood dowel or something similar to curve the corners if desired

Carefully cut the opening with a sharp exacto knife

Pry away the top sheeting and it will pop off the surface

You can use the pieces of the wing sheeting to trace a door pattern. Be sure to cut two of these from 1/32" ply

One of the doors is used as a center mounting frame, so measure in 1/4" from each side

Carefully cut out the center, using a Exacto and Chisel knife for the corners. Sand the inside and outside smooth

Hold both pieces together and round the corners of both hatches

Test the fit the inner door mount and sand as necessary. Also make a mark for forward end so you know which way to install it later

Check the fit of the outer door. It should be flush to the wing

Apply epoxy to the inner frame

Glue the frame in place in the wing opening

Use a very sharp Exacto #11 blade, cut through the inner square of the wing core, keeping the knife perpendicular to the top of the frame. Cut only down until you feel the blade gliding just across the inner side of the top of the wing

Use a chisel knife to remove the foam

Make sure the area is cleaned and ready for the servo mount

Insure the servo will fit and not rub against the walls

Cut a piece of 1/4" balsa and 3/32" balsa to make a floor wedge for the servo

Laminate the two pieces together with CA glue

Sand an angle on the bottom to make a wedge that will raise the front of the servo and make the servo sit parallel to the door opening

Side view shows sanded angle for the servo

Fit your servo and check for at least 1/16" clearance from the top of the servo to the top of the frame. This extra space will compensate for the thickness of the servo tape later in the build	Cut a piece of 1/64" ply for the floor of the servo	Epoxy the thin ply to the top of the wedge. Make sure you are gluing it to the correct side, or the wedge will not fit the wing opening
Clamp the ply until the glue sets	Apply thin CA to the top of the ply, then spread and sand to a plasti-coat finish. Sand the edges even with the balsa	Apply epoxy to the bottom of the wedge

Install the wedge in the wing servo area as shown. Note the thicker/higher part of the wedge should be toward the front of the wing

Install the door over the opening, then lightly sand

Remove the door and glaze it with thin CA, then sand to a plastic finish

Install the servo, leaving it loose and adjust so it is aligned with the pushrod

Place the door over the opening, then mark the location of the servo horn sides

Switch directions and mark horn throw as shown

Carefully cut out the opening for the servo horn from the cover door. Use a chisel cutter to get in the corners

Sand the inside slot area as shown

Install the door and check for final fit

Place a ruler from the corner of the servo tray parallel to the rear of the wing and make a mark as shown

Use a 3/16" drill and work a hole by hand to the servo area. Use the bit like a file to elongate the hole for the width of the servo wire plug

Open up the area inside the hole

Test that the servo leads can be run

Place the inside root end of each wing over one of the supplied ply end cap strips and transfer the shape of the airfoil to the ply

Rough cut the ply, leaving a little overhang for sanding to fit

Mix some good epoxy and glue each strip to a wing inside root

Make sure you transfer the marks for the aileron wire to the outside

Tape the strip in place until the glue sets

Once set, sand the root end of the spar flush with the wing

Where you marked the aileron location, open the hole with a 3/8" forstner bit

Remove the ply to reveal the aileron wire exit hole

Measure 2 3/4" back from the seam of the leading edge spar as shown. Tape the ruler in place and mark the location

The main spar slot is cut to a width of 4 1/2", so make a mark at this location

With a new blade, cut on the line, keeping the blade perpendicular to the surface of the wing

Hold the stick up against the ruler and make the second cut, so it is the width of the spar and 4 1/2" long

Use a ruler to finish the cut at depth

Use a hobby saw to cut through the spar

Hold the spar against the wing end, 1/16" above the bottom of the wing. Make a mark to indicate spar width and a small cut can be made with an exacto knife

Use a hook or screwdriver to remove the cut material

Cut under and just past the 4 1/2" mark so the spar can be hooked under the balsa at this location

Install the spar, running it just under the balsa at the right. It should be sitting level with the bottom of the wing sheeting

Repeat these steps for the other wing

Cut strips of balsa to fit in the slots of the wings

Check the fit of each balsa strip with the spar installed

Apply Medium CA to only the sides of each stick, then push them in from the top

Sand the stick flush to the wing surface

Remove the spar and sand the end tips flush as shown

Cover your wings by either fiberglassing them, or using a iron on film as shown

Lightly wetsand with 400 grit sandpaper the seam of the fuselage, nose, front and rear nacelle pieces

Wash the fiberglass parts in warm lightly soapy water to remove any release agents, then rinse in hot water

Apply body filler to the seams and any pinholes you may find

Sand the filler, then apply a light coat of primer. Fill any pinholes as needed

Use a protractor to measure the radius of the ring from the pattern

Draw a cross on each ply plate to find center

Draw the outer circle

Draw the inner circle from the pattern

Rough cut the formers using a scroll or hand saw

Use a sanding drum if available to make the fine sanding work easy

Stack the pieces and final sand for a snug fit in the fuselage and nose

Use a drill to make a starting hole for your coping or scroll saw

Cut out the center with your scroll saw

Fine sand the entire ring to lightly round the inner edges

Rough sand the nose piece with 60-80 grit sandpaper about 3/4" in from the end, just in front of the panel line ring

install a former until its back is flush with the panel line. You can use a light on the inside to check its location

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