Build Articles
HET-RC - F-104 Starfighter EDF
By Carl Tulanko
July 22, 2007 - 09:50:06 PM

The HET-RC F-104 Starfighter Minifan EDF as it comes from Markos at Warbirds-RC	Opening the box reveals a well packed and rather long model	Every that comes with the ARF is shown
Shown is a closeup of the wood and hardware included with the kit	The F-104 Starfighter fuselage assembly	Construction begins with wing preparation and installation. Remove the tabs from your servo and place it over each opening. Mark the outer shape and enlarge the opening width

Cut forward to the wing spar as shown. A small portion of balsa may need to be removed near the Aileron, but cut to the spar first.	Use a mixing stick to push out the foam blocking the servo wire hole	You can also use a ruler to remove the foam from the inside
The flat of the ruler should be drawn across the balsa surface to remove loose foam and glue	Sand the opening smooth with 320 - 400 grit sandpaper	Apply a thin coat of CA to create a smooth surface for the servo
Once the CA has dried, sand smooth again to a plastic like feel	Install the wire through the wing and into the fuselage, then check the fit of the servo	Mark a Left and Right main spar and install them in each slot in the fuselage

Install each wing and check that it is fully seated on the wing saddle. If it will not seat flush against the fuselage, sand the fuselage side of the spar, then take a little off the end of the spar until the wing sits flush	With each wing installed, check the trailing edge for alignment and proper incidence. One wing was off in this kit and needed adjusted	When sanding the spar, make sure you sand only enough on the inside so that it remains centered from top to bottom in the slot, then perform the remaining sanding at the tip. Use a sanding block to keep each end straight or the wing can rock in its position
To adjust the wing, use a small round file to elongate the wing dowel pin hole in the fuselage. Remove a little at a time and check alignment. Continue to elongate until the rear of the wing is centered and runs evenly across the top and bottom of the fuselage wing saddle	A properly aligned wing is shown	To tighten the dowel in the new hole, drill a small hole above or below the wing depending on which side you had to sand the slot
A toothpick is added and allows a snug fit of the dowel pin into the elongated fuselage dowel pin hole	With the wing installed, apply some masking tape even with the rear of the wing	Sand this area up to the tape to remove paint and allow for better glue purchase
The rest of the wing saddle is sanded with 60-100 grit. Be careful not to remove too much, which will weaken the saddle	Masking tape is applied around the wing saddles for both wings	Trim the tape flush to the gluing surface of the wing saddle
Add a fresh piece of masking even with the rear of each wing	The wing area is shown ready for epoxy	Apply masking tape flush to the end of each wing. This will catch any epoxy spill over and keep the wings clean
Drill some 1/8" holes in each wing saddle, spaced about an inch apart and inside the glue area. This will allow rivots to form and add strength to the joint	Mix some epoxy and set some of the mix aside, then add some fiberglass mil to thicken the remaining solution. Fifteen minute epoxy was used for each wing installation	Apply the regular epoxy to the wing spar slot in one wing

Apply epoxy to the spar in the area that will be inserted into the wing	Install the spar in the wing and clean up the remaining epoxy. Note that the epoxy may "hydraulic" in the hole, so push and pull the spar a few times to work it in so it is seated flush	Use a stick to apply the thickened epoxy mix to the wing saddle
Apply regular epoxy to the exposed spar area	Apply regular epoxy to the wing spar area	Apply regular epoxy to the remainder of the wing in a thin film so it will soak into the spar
Install the wing on the spar and flush to the fuselage	Use denatured alcohol and paper towels to remove excess epoxy	Wing is shown installed. Allow some time for the epoxy to set
Drill holes in the second wing saddle as shown	Install regular epoxy in the wing spar slot on the fuselage	Apply regular epoxy to the spar and install as shown. Make sure it hydraulics and bottoms out so it sits flush inside the fuselage, then clean off the excess
Apply thickened epoxy to the remaining wing saddle	Use a stick to apply regular epoxy to the exposed wing spar	Apply regular epoxy to the wing spar slot and wing spar as shown
Install the second wing on the fuselage	Remove excess epoxy with alcohol and paper towels	Allow the epoxy on the second wing to set
Remove the tape from each fuselage saddle and wing	Wing installation shown completed	Check the aileron servo wire holes and clean with a short piece of rolled up sandpaper if necessary. Install the aileron servos and make sure that the horn is spaced far enough away from the wall so it does not rub. Remove the servos and set them aside

Measure the opening of the servo well and add 1/4" overhang to each of the four sides	Make some servo hatches by cutting two pieces of 1/32" ply to the dimensions you just measured	Apply a drop of thin CA to the bottom corners of each hatch, then sand smooth once dried
Apply CA to the top of each hatch and allow it to soak in, then sand them to a plastic like finish and paint if necessary	Stack both hatches and hold them together with masking tape, then drill 1/16" holes at each corner, about 1/8" in from the sides	Use tape to mark the location where the hatches must be placed so they overlap the opening about 1/4" on each of the four sides. Drill 1/16" holes into the wing using the previously drilled holes in the ply as guides

Mark on the inside one hatch for the left and one for the right and also draw an arrow on each hatch to show forward placement	Open up the holes on both hatches with a 3/32" drill. Sand the surface of the holes smooth if necessary	Clean the mounting surface of each wing servo with Acetone. HS-81MG metal gear servos were used for the Ailerons
Connect each servo to a receiver or servo tester and use a horn to make sure the servos are centered	Remove each horn, then cut away the unused side of each horn	Install the horn on each servo and make a left and a right assembly. Install each servo temporarily in the wing and make sure the horn is centered and pointed straight up. Even though the horns may be centered outside the wing, the servos themselves wind up being tilted downward toward the front of the wing, so you may have to move the horn back toward the Aileron a notch for it to be centered in the well. The servo horns need to be centered in the well or they will not have full range of motion!
Cut two pieces of servo tape and install them on the respective bottoms of each servo. Install the horn screw in each servo	Run the servo wire for one wing through the hole into the fuselage area	Remove the backing from the servo tape, then install the servo in place, making sure the horn has clearance and does not bind on the side of the well opening

Position the hatch in place, then slide it upward and mark a 3/16" slot on the hatch for a horn opening	With the opening drawn, cut out the ply and use a file and sandpaper to clean up the opening	Position the hatch over its mounting holes and check the fit of the horn, then sand as necessary. The opening needs to be about 3/4" long
Install the hatch with some #2 button head screws	Run the other servo's wires through the opening and into the fuselage	Remove the backing from the servo tape
Install the servo in place, making sure the horn has clearance and does not bind on the side of the well opening	Install the hatch and cut out the slot in the same way you did the first hatch	Install the second wing hatch and check for horn clearance. Both hatches are shown installed

Measure and mark the center on each of the Aileron hinges

Draw a line down the center of each hinge

Install each hing into the wing up to the line. Open the slots with a razor if necessary and position the hinges at least 1/2" in from each end

Instal an Aileron, making sure there is clearance on both ends. Make sure the hinges remain square in the slots and are not pushed into the fuselage

Tilt the Aileron downward so there is enough deflection, then apply thin CA to each hinge from the top and bottom. The CA should wick into the slots

Install the second Aileron, making sure there is clearance on both ends

Tilt the second Aileron downward so there is enough deflection, then apply thin CA to each hinge from the top and bottom. The CA should wick into the slots	Install a clevis on each of the two pushrods and center them on the threads	Drill the Aileron servo horn out of necessary so the clevis has a nice and tight fit
Install the clevis on a servo horn	Install the second clevis on the other servo horn	Remove the tape from maufacturing that is holding the hatch in place

Remove the bottom hatch	Use a piece of tape that is placed parallel to the servo and place the pushrod parallel to the tape	Install the horn as shown on the inside of the wire. Use a drill to make a 3/32" hole
Install a screw in the servo horn. It is a good idea to pre-thread the servo horn caps by using a screw to cut threads in each cap	Install the horn in place as shown	Use the pushrod to keep the horn straight, then tack it in place with CA
Drill the second hole for the horn screw	Install the second screw and check pushrod alignment	Install the cap that you pre-threaded in place as shown. Do not overtighten the screws

Use tape to align the second pushrod and drill the holes for the second aileron horn	Install the screws in the aileron horn	Position and install the horn in the Aileron and screw on the cap. Be careful not to overtighten
Clamp the end of the Aileron so it is even with the wing	Connect a servo to a receiver or servo tester, then center the servo	Mark the location of the Aileron horn hole on the pushrod
Begin making a Z-Bend at the mark	Finish the Z-Bend and trim off the excess pushrod. Clean up the end tip with a grinder	Open up the Aileron horn with a drill so the pushrod will fit
Install a pushrod on the Aileron horn	Clip the clevis in place on the servo horn. A piece of fuel tubing is used as a safety retainer on the clevis	Clamp the end of the second Aileron so it is even with the wing
Connect a servo to a receiver or servo tester, center the servo, then mark the location of the Aileron horn hole on the pushrod	Make another Z-Bend at the end of the pushrod as you did with the first Aileron	Drill the Aileron horn and fit the pushrod, then clip the clevis to the second servo horn. Completed Aileron installation is shown

Use a grinder to carefully cut the remaining screw threads flush to the plastic cap Do not overheat by cutting to hard or you can deform the cap. Do a little and allow the screw to cool	Apply some thick CA to the top of the threads to prevent snagging or cutting	Mark center lines down each of the four Elevator hinges
Install the Horizontal Stab in the slot from the rear until it is flush with the vertical stab joint	IMPORTANT: Make sure the Stab is perpendicular to the vertical stab before proceding. Use a pencil to mark the stab and fuselage at all points where they join and mark both the top and bottom sides	Remove the stab and cut just inside the pencil mark to remove the excess covering material. Do this to both the top and bottom
Lightly sand inside the pencil marks on the vertical stab where the horizontal stab will reside for a good glue purchase	Rough up the top and bottom of the vertical stab slot, taking care not to change the shape of the slots	Install the horsizontal stab and measure at the rear both sides to insure it is centered

Tape the stab even to the joint to catch excess epoxy	Finish by taping the vertical stab above and below the horizintal as shown	Place the model on a flat surface and use tape to hold the center in pace
Run masking tape over the exhaust tube and slightly forward, then pull tight so the pivots back and the rear is flush with the surface	Use a square to rotate the model and adjust the vertical stab so it is perpendicular to the surface	Remove the horizontal stab
Use 15 minute epoxy so you have enough time to adjust and apply epoxy to the top and bottom of the vertical stab slot, as well as the forward sides of the stab	Apply epoxy to the horizontal stab on the forward slot and rear exposed surfaces	Install the horzintal stab on the fuselage
Clean any excess epoxy with paper towels and alcohol	Insure the rear of the stab is centered and the same distance from the vertical stab on both sides	Use a ruler and make sure the horizontal stab is parallel. Adjust if necessary before the epoxy sets
Horizontal stab sown installed	Install the hinges in the horizontal stab up to the center line	Cut off the Z-Bend on the pushrod wire, then make a very small loop and a half with needle nose pliers

Loop shown, which should be just round enough for the wire to pass through	Cut a 2 1/2" piece of wire from the other end and install it in the loop so that 1" protrudes from a side	Use soldering flux, good solder such as Deans and a high power gun and solder the joint. Make sure the short wire remains perpendicular to the long wire before the solder hardens
Solder joint shown completed	Trim the other end so the you have 1" of rod on each side of the joint	Cut two 1" pieces of plastic sleve from the pushrod assembly and install them over the wires as shown

Box cut and file the rear of the fuselage so it is square	Mark the top rear of the vertical stab with a punch	Use a 1/16" drill to open a small hole at the marked location