Build Articles
HET-RC - ME-262 Twin EDF Jet
By Carl Tulanko
November 05, 2007 - 07:56:55 PM

The HET-RC ME-262 Twin Minifan EDF jet as it comes from Markos at Warbirds-RC	Opening the box reveals well packed contents	All the parts shown are included in the kit, even fixed landing gear
This kit will be retrofitted with some of the "New" RA-260 Retracts from Airpower and Warbirds-RC	Opening the main bag reveals all the components necessary to get these air retracts flying	The retract units themselves are very small, however, they are stout. The units are made from very thick aluminum alloy and are much sturdier than other brands of retracts we have used in the past. They also come with 1/8" gear wire
The entire Airpower RA-260 retract setup weighs only 3.5oz and that includes the 1/8" gear wires and all air assist accessories	Construction begins by finding the location of each wing Nacelle. A piece of cardboard is included in the kit and is 110mm wide, which is a bit too wide. Hold the cardboard flush with the end of each wing and draw a reference line	Install a nacelle on each wing up to the 110mm line. Make sure you use the correct nacelle as there is one for each side
Measure the side of the nacelles at 108mm from the end of each wing root	The 108mm measurement moves the nacelle closer to the fuselage as the original 110mm caused aileron binding agianst the rear of the nacelle as shown	Draw a new outside line, which should be 2mm closer to the wing root. Make sure the rear of the nacelle clears the Aileron area
Draw on the top of the wing the location of each nacelle	Measure 1/8" inside the outer line on the bottom of the wing and cut to remove the covering material	Cut along the leading and trailing edge, making sure you leave a good 1/8" or more for re-covering
Remove the bottom covering as shown	The covering reveals the fixed gear mounting block, which is used as reference for retract installation	Measure 3 1/4" from the root of the wing to the rear side of the hardwood block and make a mark
Measure 7/8" from the rear of the block and mark this location	Make a second mark at 7/8" as shown	Draw a line through both the 7/8" marks to the root of the wing
Draw the horizontal top line at the 3 1/4" mark across as shown	Cut the Main Door Cutout pattern from the templates and place the back of the door along the vertical line you drew and the top should be lined up with the 3 1/4" horizontal line	Transfer the front pattern of the door to the wing as shown

Mark and draw a second line at 1/8" past the first line to allow for the thickness of the Secondary Spar	Cut the balsa from the area that was just marked	Remove the balsa sheeting and foam from the area
Check your measurement and make sure it shows 3 1/4"	The Trailing edge of the block to the rear should measure 1" as shown	Use an exacto knife to cut into the hardwood block along the door pattern line
A chisel cutter can be used to cut loose some of the wood	An Exacto knife can be used from the side of the block to cut the rest of the length	Once cut, remove the excess wood
Cut away the remaining block to the door line using a chisel knife	Sand the area smooth to remove splinters and burrs	Use a hobby saw and cut the root rear spar down to the balsa. Try to keep the cut parallel to the main spar hole in the forward area of the wing root
Cut the front root area in a similar manner	use a knife to cut along the inside of the wing root and remove the excess	Sand the bottom of the area flush to the wing sheeting
Insert a piece of 1/8" ply sheeting and draw a line on the sheeting. Cut the Secondary Spar to length as shown in the templates	Cut a piece of 1/4" x 3/8" hardwood block to a length of 1 7/8" ; Note that the wood shown in the pic is 3/8" square and had to be cut to the correct 1/4" x 3/8" dimensions	Draw a line along the block as shown to match the one in the templates
Sand the surface smooth	Cap the top of the block with a 1/16" thick piece of aircraft ply	Clamp the assembly until the epoxy sets
Use a knife to cut away the foam underneat the top side of the wing as shown	Cut back the foam about 1" or more; clean up the hole for the aileron servo wires	Remove the extra piece of balsa as shown. Cut it from the fuselage opening to the outside top of the hardwood block

Cut a 3" long piece of 3/8" square hardwood and use it to mark the foam on the right side as shown. Remove the foam below the line so the block can sit recessed in this area under the wing sheeting and even with the top opening

Install the main spar

Install the wing in the fuselage

Transfer the outline of the wing's cut out area to the fuselage

Use a sharp knife to remove this area from the fuselage. Sand the inside edges smooth once finished

Measure 1/4" down from the seam of the fuselage on the bottom of the jet and draw a line parellel to the seam

With the wing installed flush, make a line from the rear of the wing opening to the fuselage	Make a line from the front of the wing opening to the fuselage, matching the angle	Install the template with the top at the 1/4" from the seam horizontal line and the bottom between the two marks you just made. The rest of the pattern should align with the wing door area as shown
Transfer the pattern to the fuselage area	Carefully cut out the pattern in the fuselage. This will take some time, possibly an hour or more and may take 30-40 passes with an exacto knife on each side. It takes a couple blades to cut through the entire area. If you run into a glue area, try to pop the fuselage free of the glue rather than cut through the glue, which will be reinforced later. Also note that one side will expose some of the main spar support plywood and glue. Take care not to cut into the ply	Lightly sand the area that was cut out and clean it up

Measure in 1/8" from the front inside door run as shown	Cut the balsa to the elbow, but leave the foam core in place	Cap the area with a 1/8" wide by 1/16" thick piece of basswood strip. Epoxy it in place
Cut out the wing door from the pattern	Check the fit on the door	Add Epoxy to the Retract wedge top and outside
Install the wedge as shown, with the inside of the wedge aligned with the bottom end of the harwood block	Cut a second wedge, 3" long from 1/4" x 3/8" hardwood using the supplied pattern	Cap the wedge on the top with a 1/16" thick strip of aircraft ply

Clamp the assembly and allow the epoxy to set	Install the secondary spar, the long wedge and the retract and check their position. Install the fixed gear wire in its hole and check that the angle of the retract wire is similar to the fixed wire ash shown. Also, slightly sand the inside of the long wedge if the retract is too tight	Use a screwdriver to push the roll bar level forward in the retract and then fold the gear wire into the wheel well. Check that the wire runs paralled to the wing door area and that is is fairly centered in the wheel area
Apply epoxy to the 3/8" square block and install in in the opening you cut so the bottom is pressed against the inside of the root spar	Use the secondary spar to hold it in place while the glue sets.	The block support is shown glued into place
Apply epoxy to the side and bottom edge of the secondary spar and install it in place. Do not apply epoxy to the bottom part of the spare that is exposed and plugs into the fuselage	Clean up all excess epoxy	Apply epoxy to the long wedge bottom and the one side facing the spar

Epoxy the long wedge in place, so the back is even with the other wedge and the bottom should come near the end of the wing root

Clean up all excess epoxy with a scraper and paper towels

Install the AirPower RA-260 retract. It should just fit between the two wedge blocks

Cut another piece of hardwood block to fit behind the two wedge mounts

Apply epoxy to the area as shown

Install the cross block support and epoxy in place

Clean up any excess epoxy	Lightly sand the secondary spar so it is flush with the wing sheeting	Position the retract so the front of it is 1 15/16" from the root edge of the wing as shown
Use a pencil to mark the location of each mounting hole	Use a punch to start the mounting holes	Place a piece of masking tape on the end of your drill bit, no more than 3/8" from the end. Do not drill past the tape as this will act like a depth gauge so you do not drill through the top of the wing. Drill the four mounting holes with a 1/16" drill, angling the bit from the side view so it is perpendicular to the wedge

Temporarily install the door and mark its top location as shown	Fit a 1/32" ply plate as shown, just above the marks you made	Place a EZ-Hinge in position and mark the areas that need trimmed down to size the hinge to the hole
Measure and draw a centerline down the hinge	Place half the hinge over a 3/16" thick piece of balsa and trace the outline of the hinge to the balsa. Note that the hinge sides were cut slightly angled to allow for clearance on the sides	Use a ruler to scrape away and compress the balsa topcoat on the block so the hinge is recessed and the top of it sits flush with the balsa block
Round the back bottom side of the balsa block so that the Aileron Servo cable will not hang up when passed by it	Tape up half the hinge to the centerline, then epoxy it to the balsa	Cap the top of the hinge with the 1/32" ply coverplate while the epoxy is still wet

Install the block while the epoxy is still wet under the top wing area so the front of it comes even with the top of the door as shown. A piece of tape is used to hold the ply plate and balsa block in position until the glue sets. Use a ruler underneath as shown to insure the block is pressed up against the inside of the wing	Cut a piece of 1/8" square basswood to a length that allows the inner retract screw to still be installed	Epoxy the stick in place and use the door to measure how low to place the stick. The top of the door should be even to the wing's surface
Cap the top of a scrap piece of 1/8" balsa with some 1/8" basswood stick	Measure and trim the balsa plank to height and cut to size. Make sure it sits recessed below the top of the wing	Sand a bevel at the end of the balsa plate
Glue the plate in place, with the basswood stick on top as shown. IT will cover the wing foam and should sit recessed so the door is flush to the wing	Clean up the excess epoxy. The plate will cover the wing foam and should sit recessed so the door is flush to the wing when placed over this stop plate	Apply some epoxy to the fixed gear slot in the hardwood block
Use some scrap 1/8" square basswood stick to fill in the space	Cut the excess basswood so it blends in with the angle of the hardwood door cuts	Epoxy a piece of 1/16" x 1/8" basswood stick at the angled location to prevent the door from receding to far, but ratheer give it a landing for which to rest
Place the door over the retract area and check for fit. It should be recessed enough to sit below the surface of the wing. Sand the landings to fit if necessary	Cut a piece of 1/8" ply to a width of 1/4" and to the length and shape as shown. this will act as door retention and an alignment guide	Bevel both the front and rear inward to allow for alignment of the door

Install the retract and colapse the gear. Rub a pencil across the top of the gear wire as shown	Position the door bracket in place and lift the gear wire	The gear wire transfered its location to the bracket
Cut a short piece of 1/8" ply and epoxy it in place to the back side of the gear(right)	Cut a second block and use it to wedge the gear wire between it and the other block. Apply thin coat of CA to the top of the two blocks to prep them for drilling	Drill 1/16" holes through the center of each small block and out the bottom of the bracket. Epoxy a small diameter piece of elastic cord in one hole, then when set, epoxy the other side in, keeping some tension on the cord so it dries while semi-taught
Slip the asssembly over the gear wire. Use small pieces of masking tape to keep it from shifting position on the wire	Apply epoxy to the top surface of the bracket assembly	Use tape to hold the gear wire down and out of the way
Position the door in its opening and tape in place	Tape the top of the door over the hinge	Lift the gear wire until the bracket touches and glues to the inside of the door. Allow the glue to set
Door Bracket is shown correctly installed	Locate the area of fuselage you removed for the gear and wheel; this will be used as the doors. Trim the top of the fiberglass door as shown and keep both pieces	Measure 1" from the inside flat area of the door and cut the smaller door away from the larger
Lightly sand the smaller door to smooth the ends	epoxy a piece of 1/16" thick ply that is 1/16" wide along the short side length of the door	Make a wire hinge from 2-56 pushrod and bend as shown in the templates
Place the wire in position as shown and cut an inner 1/16" ply piece at least 1/8" wide. It will be placed above the wire to wedge and hold the wire in place	Cap the assembly with a final piece of 1/16" thick ply wide enough to cap the assembly	Ply ends are shown glued in place
Mark a center line on the wide ply plate. Use a saw to slot only down to the hinge.	Bend a piece of micro pushrod as shown	The pushrod is a fraction longer so it can push into the thin ply brace at the bottom, then slide into the slot you cut with a saw as shown at the top

Cut a small piece of 1/16" thick x 1/4" wide ply so it fits between the two ply braces. Slot it so it will cover the micro wire

Epoxy the short ply over the micro wire as shown

Bend the wire 1/14" past the rear of the door

Position the door temporarily in place. Remove any fuselage glue that will get in the way over the next few steps

Cut a piece of 1/8" thick ply to 3/8" x 1/2" in size and drill a 1/16" hole on one end as shown

Cut the rear hinge bracket from the template and glue the bottom side with a thin piece of 1/16" ply, followed by the hinge rod and capped with another piece of ply.

Remove the excess ply from the bracket witha saw	Rear hinge shown ready to install	the wheel door is prepped by adding a strip of 1/16" thick x 1/8" ply to the long edge