· a 1 inch slit in the control surface all the way through after you have beveled the surface....

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32” 9mm EPP GBR 3d Airplane

The air is thinner up here!

Wing area 247 square inches without ailerons 357 square inches with ailerons

Wing loading 5.04 ounces per square foot at 12.5 ounce AUW including aileron area

Wing loading 7.31 ounces per square foot at 12.5 ounces AUW without aileron area.

“Made in Colorado, for flying in Colorado”

The perfect everyday flyer for the park.

Set to low rates for learning 3d, or crank up the rates for advanced 3D maneuvers.

This airplane excels at Knife Edge, Waterfalls, Pinwheels, High Alpha flight, Rolling Maneuvers,

Inverted Flight and of course Hovering!

Durable construction with carbon spars so you can fly, rather than fix!

www.RockyMountain3D.com

Not all EPP Airplanes are Created Equal


GBR 32” Build instructions

Included parts for GBR 32inch: 4 control horns, 4 control horn interlocking tabs, 8 z-bend ends (1/32” wire), 8 pieces of heatshrink, 2 aileron 2mm by 4” carbon control rod tubes, 2 tail 2mm by 9.5” carbon control rod tubes, 1 square 3mm by 24 1/2” fuse carbon tube, 1 flat ribbon 5mm by 11 ½” flat carbon spar for Elevator, 1 flat ribbon 7.5mm by 11 ½” carbon spar for horizontal stabilizer, 1 flat ribbon 7.5mm by 28” Wing spar, one plywood motor mount, 4 EPP 9mm motor mount “u” pieces, 1 EPP 9mm top fuse, 1 EPP 9mm bottom fuse, 1 EPP 9mm horizontal fuse, 1 EPP 9mm wing, 1 EPP 9mm scrap piece (part to be used for center of motor mount, 2 Depron Aerolite 6mm Ailerons, 1 Depron Aerolite 6mm elevator, 1 Depron Aerolite 6mm Rudder, Required parts to finish:

Foam safe thin CA glue

CA Accelerator

Regular Medium CA (not foam safe) This is usually cheaper than foam safe so I like to use medium and thin on EPP and the control rods, but you can use foam safe for everything.

AND uhu-por (Hobby Store) or welders glue (Lowes) or Quick Grip (Michaels) or some other glue suitable for gluing EPP (Hot glue can be used for some of the build and makes servo install quick and easy)

¾” wide hinge tape (I like Blenderm or Dubro hinge tape)

Velcro

Ruler

X-acto Knife

Wax Paper

Flat working surface

Some type of weights (bigger lipo batteries for example)

Sanding block with 80 Grit or an Easy Bevel for cutting hinge bevels and sand paper Electronics:

Four 6 gram servos such as HS45hb or HS55,

3 cell 800-1000mah lipo,

35 to 50gram 1200 to 1600KV brushless motor


18 to 20 amp speed controller,

9 to 11 inch GWS dd prop or suitable prop for power setup chosen. (I like 1500 KV 50 gram motor with 3 cell lipo battery and 9” prop)

Please read each section fully before starting your work!

Note: Not all pictures may match the model of airplane you are building, and are there to show technique.

Install Spars on Wing, Fuse, Horizontal Stabilizer, and Elevator.

To install the square carbon tube into the fuse, first clean out any loose material in the spar slot. Then run

a continuous bead of Welder Glue into the slot. Now push the square tube all the way into the slot. You

should see glue pushing up around the sides of the tube. Wipe your finger down the tube to remove any

excess and to smooth out what is left. You do not need to fill the void with glue. The spar will not sit flush

with the top surface of the fuse. Weight the fuse so it is flat and straight and let glue dry. Overnight is

best. You can also use medium CA for this, but CA makes EPP brittle, so I like to use the flexible glue.


INSTALLING THE FLAT RIBBON CARBON SPARS:

To install the flat ribbon spars, you will need to cut all the way through the part at a 90 degree angle

(straight up and down) at the right location and length, and insert the flat ribbon making sure it is in the

center as much as possible and is not creating any warps or bends

Place wax paper down on a flat surface under the spar before gluing.

It is good to place some heavy items on the surface to keep it lying flat, and then glue the center section

first with thin CA and work outward to the ends. Make sure to pinch the material together so the foam is

nice and snug against the spar while gluing. I like to use some accelerator to speed up the process. Lay

another piece of wax paper over the top of the spar and weight the surface until glue is dry.

Note: on the 7.5mm wide spars it is good to place a small bead of medium CA in the middle and both

sides of the whole length of the spar. You can wedge the tip of the ca bottle between the foam and spar

on each side. Since the spar is so tall, it is hard to get the thin CA to wick all the way through the thickness

of the 9mm EPP wing without making a mess.

Horizontal Stabilizer spar is located 1 inch from the trailing edge and centered. When gluing, it helps to butt the

trailing edge up against a ruler when squeezing to keep the foam tight and straight against the spar.


Wing spar is located 4 inches from the center of the leading edge and centered. This is also the CG location.


Remember to pinch the foam together onto the spar when gluing, and work from the center out to the ends and

place wax paper on the table below the spar.

Place wax paper over the top of the spar and weight the wing so it does not curl while it dries.

Cut slot for Elevator spar 0.35” from the hinge line centered on Elevator. ONLY USE FOAM SAFE CA to glue spar.

Use a ruler to hold the edge straight while pinching the Depron together while gluing.


Bevel all control surfaces to at least 45 deg. You can also bevel the mating surfaces to 45 to allow for

more throw. You can use a bevel tool such as the ez-bevel or carefully sand a bevel using a sanding block

and 80 grit sandpaper.

Be careful to bevel the proper sides, especially on the Ailerons!

It is good to test fit the pieces together before beveling to double check you are beveling the proper sides.

You want the bevel to be on the side you will be installing the servo.


Hinge the Elevator. When hinging Depron to EPP using tape, it is a good idea to pre-treat the EPP surface

the tape will be in contact with first. You can prep the surface with Welder or equiv glue by running a

small bead of glue then quickly rub it thin. You do not need much. Then let it dry for 5 to 10 min. Now

when you use the hinge tape it will adhere very well to the EPP. Treat the top side and the bottom bevel

if you are going to tape both sides. No pre-treatment is required for the Depron. If the Depron is oily or

dirty, you can wipe it down with rubbing alcohol to clean it off. If you do not like tape hinges, use your

preferred method for Depron hinging.

I like to tape the top flat surfaces first. It is ok to have a slight gap since the tape will be the full length of the hinge.


Now flip over the piece and fold the control surface back onto itself and tape the other side. Do not get the glue

on the Depron, or it will melt it. Be careful to not leave big creases and folds in the tape. Slowly smooth the tape

on one side and work your way to the other surface.

Repeat this hinging process for both the Ailerons.


Install control horns on elevator, rudder, and both ailerons.

About the control horns: I designed these for 6mm thick material with a 45 deg bevel cut into them. You cut about a 1 inch slit in the control surface all the way through after you have beveled the surface. Then slide on the tab and slide in the assembly so the 45 angle on the control horn matches with the bevel on your control surface. This is designed to add strength to the joint. Also, the point exactly aligns with the servo clevis holes so you know the clevis is directly above the hinge line. If you want to do some other type of hinging bevel, you can just snip off the triangle point and install however you want. There is a small tab on the bottom so you can have the slide in support tab on the top, bottom, or both. I found only one is needed, and I like the top best..you get the most strength that way. USE ONLY FOAM SAFE GLUE I use Bob Smith Foam Safe Thin CA and apply some to the slit after it is installed. Apply a little under the tab and then put one drop on the joint between the tab and the horn. That is all you need, this way. If you ever have to remove it, you can break the foam away and lightly twist the tab and they will come apart again. Then you can sand off or carve off the glue, and use them again. I have not broken one yet. If the fit is too tight when sliding the tab onto the control horn, you can slightly sand the slots. This can happen with slight variations in material.

If the fit is too tight when assembling the tab, lightly sand the slots on both pieces.

Notice the bevel, and see how the horn aligns with the bevel


Make a slice about 1 inch long all the way through the foam where you want the control horn installed. If you slightly twist the X-acto blade, you can slightly widen the slot for an easy fit.


When installing the control horn on the elevator, do not cut through the spar, but cut in front of the spar and behind the spar. Now the control horn’s slot can slide over the spar and have a solid bond and transfer the throw force throughout the length of the spar on the elevator.

Here are the locations for the Control horns: (location may change depending on your servo mounting) Rudder: 2” up from bottom Elevator: 3/4” from center Ailerons: 3” from inboard edge of Aielron

Now make one cut with X-acto blade on the vertical stabilizer to allow the foam to be spread apart so you can insert the horizontal fuse section as shown. Bring the fuse pieces together so the tabs align, then press the tabs into the slots. Do not glue yet.

Note on using Welder, Quick Grip, or Uhu glue: This type of glue works best when you can apply glue to both mating pieces. Press them together and pull them apart a few times and let dry apart for 5 to 10 min, then press firmly back together. These are contact cements. If you let them dry too long, they will bond right when you touch them together. This glue works great on EPP because it stays flexible. I use this in the field for repairs. If you put a bead of glue on one surface, press them together a few times, making sure glue is on both surfaces. Then let them dry a bit; they will tack together rather quickly. Full cure strength takes 12 hrs, but it is usually good to fly in about 20 min if this method is used. Test this method out on the spare piece of EPP to get the feel. Tear a piece off and experiment fixing it.


Dry fit the fuse together Slide the fuse sections together and insert the tabs to lock it into position, then attach wing into tabbed slots.

If you place the wing onto the fuse using the locating tabs, you will see what area will need glue to attach the wing to the fuse. Now you can glue the horizontal fuse to the top vertical fuse piece. Pull the tabs through the holes so the top fuse is flush with horizontal fuse piece. Now apply glue to wing and fuse area, and attach the fuse. After applying glue to these areas, you can place the wing flat on the table with the last part of the tail hanging over the edge. Allow the glue to dry while on the table, so you can be sure they are straight and at 90 deg from each other. Make sure the EPP is pressed together to make a good glue joint. You can use thin or medium ca and accelerator or any of the glues. I like to use Welder, but it needs to dry longer.

Glue the slit in the vertical stabilizer back together. (Make sure you hinged the elevator first)


Install the fuse bottom by aligning the tabs and glue into place, making sure it is straight and 90 deg to the

fuse. I like to use a couple of boxes that are the same height, to support the airplane for the rest of the build. I used 2 transmitter boxes shown in the below right picture.

Install the aileron control horns. This airplane can be built with one 13 gram servo (example HS65 servo) installed on the top of the wing in the fuse, or you can use two of the smaller servos so each aileron has its own servo. I prefer this method so you can program in elevon mixes if you want. I will show locations for the double servo install. The control horns will be at a different angle for the single servo install and you will have to make longer control rods which are not included in the kit. To find the location, simply draw a line from the control horn to the aileron and install the control horn there on top rather than on the bottom as shown below. I like individual servos so I can program in flapperon mixes ;-)

Building control rods is simple. After installing servos, set the control horn to 90 deg from the servo body and tape or hold the control surface so it is straight. Now install a Z-bend into the control horn and the servo arm. Slip the straight end of the Z-bend wires into the carbon rod, and center the carbon rod. Now wick in some thin CA to hold the position of the Z-bend wires. Remove the control rod and slide 2 pieces of heat shrink tube onto the control horn. Place a good sized dab of medium CA onto the wire and carbon, and slide the heat shrink tube over the glue, and shrink with a heat gun.

Notice the bead of glue, and then slide the Shrink tube over the wet glue.


Shrink with a heat gun.

Glue 2 of the motor mount “U” shaped pieces together. Make sure they are square and aligned together. You can set them on edge on a flat surface to get them nice and square when gluing them together. Then you will have 2 pieces 18mm thick. Now cut a piece from the scrap EPP to add to the center section. This piece should be between the 2 glued halves. You will use these to make the motor mount area. I like to use welders or uhu to glue these together. This section will strongly mount the motor, but also act as a small shock absorber, to help lessen damage to the motor during crashes.


You may want to weight this down with another piece of spare EPP between the layers, while the glue dries, so it glues tightly. Then, glue on the Plywood motor mount.

Glue the motor mount onto the fuse. Dry fit first before adding any glue. You can make slight adjustments

to make sure it is flat. Some people like to have a little down thrust and right thrust. You can make that

adjustment at this time, and let the motor mount dry.


When measuring for servo placement, measure from the servo horn screw. This will assure you have the correct distance for the supplied control rods.

Install servos into the fuse and wing by tracing the servo in the mounting location, and then cut through the EPP so the servo can fit through and be glued on the mounting ears. If you pull the servo up enough to get the glue gun nozzle under the mounting ear, you can squirt some under each ear and then press in the servo. The glue will squirt up through the screw hole creating a hot glue rivet. Then use the hot glue gun tip to add a little to the top and over the ears onto the foam. If you feel that is not enough, you can use hot glue and glue around the perimeter of the servo. Not much is needed.

Wing servos are located 3” out from fuse and forward of the wing spar.


Elevator servo is located 10.5 inches from the elevator hinge line to the servo arm mounting screw.

Rudder servo is located 10.5 inches from the rudder hinge line to the servo arm mounting screw.


Mounting ESC, receiver, and battery with velcro.

I use low profile Velcro brand velcro. Prep the area the velcro will be applied to with welder glue, the

same way the hinge tape area was done.

Mount the receiver and speed controller on one side, on the bottom half of the fuse, close to the center.

Mount the battery on the opposite side from the receiver and speed controller, and on the top side of the

fuse. This will help to distribute the weight more evenly.

The battery location is determined by the CG of the airplane. For the first few flights, you may want to

have the CG ¼ to ½” in front of the wing spar. Then, fine tune the CG in flight. The perfect CG is when

you can fly the airplane flat and level, both inverted and upright. If when flying inverted, and if the

airplane dives, you are nose heavy (move the battery towards the tail). If the airplane climbs, you are tail

heavy (move the battery towards the nose). A perfectly neutral CG will give you knife edge flight, with no

pull or push from the canopy.

This picture does not show the wire routing. You can route the wires neat and secure with some hot glue or

blender tape.


About control surface throws:

This is a 3D machine. I like to have as much throw as your setup can handle, and about 30% Expo. For

smoother or pattern like flying, it is recommended to have a low rate setting to reduce the throws by 30

to 50%, depending on your preference. If you are learning 3d, it is a good idea to have the rates on 50%

from full throw until you get the feel for the quick response, and have a good handle on using the rudder

and modulating the throttle.

About Paint:

The EPP can use any style of paint. The Depron control surfaces need foam safe paint such as Short Cuts

brand. Short Cuts paint works great on everything. I like to have the bottom or the top all white, and add

color to only one side. This makes it easy to distinguish top from bottom while flipping and flopping

around!

If you are ready to take your flying to the next level, leave it all white and learn to trust where you have

flown the plane, and if you get lost use slight movements to quickly determine the airplane orientation. I

have found this really helps to cement in your flying skills and muscle memory on the sticks.

· a 1 inch slit in the control surface all the way through after you have beveled the surface....

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