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Gorilla Wing Construction
Wing Construction
Step 1:
The Gorilla wing is composed of four foam pieces. A left and right EPP leading edge and a left and white pink foam
trailing edge. Step one is gluing the EPP leading edges to the pink foam trailing edges.
Suitable glues for this task are Polyurethane (Elmers or Gorilla Glue) or 30 minute epoxy. We prefer polyurethane glue
for its increased strength.
Note the pink foam core is slightly longer than the EPP. This is ok. Make sure the two pieces line up flush at the root end
of the core then trim off the excess at the tips once the glue is dry.
It is important to have a good bond between the EPP and the pink foam. You may wish to use a Top Flite Woodpecker
tool to lightly dimple the surfaces to which the glue will be applied to make sure you have a surface for the glue to
adhere to. Apply glue to the pink foam only. Smear the glue into a thin film over the pink foam core surface.
Make certain of your alignment. You want the wing airfoil to be accurate and true. Use masking tape to hold the two
foam pieces to each other. Make sure the parts are even at the root’s core.
After the glue has dried (overnight) trim the pink foam of the wing top even with the EPP core. A wood block sander or
belt sander works well for this task.
Hints:
Step 2:
In this step we will cut out the foam for the bladder tank and for the receiver. The bladder compartment is in the right
wing half; the receiver is in the left wing half.
Create a template for the bladder compartment and receiver out of poster board. The bladder compartment should be 1-
1/2” wide by 6” long with rounded ends. It should be shaped like the photograph at left.
It is important that the corners of the bladder compartment not be right angles as this creates a potential stress riser in
the foam. Make the corners rounded.
The receiver template can be made by tracing around the receiver you will use onto poster board then cutting it out.
Lay the bladder template onto the top of the right wing core. It should be three inches from the root of the core and ¾”
below the spar slot. Trace around it with a felt tipped marker.
Put the wing core back into its lower shuck. This keeps you from getting hangar rash on the bottom of the wing core and
also gives you a level surface to work on.
Let’s cut the bladder compartment. Set the depth of your Dremel router so that it will go entirely through the wing top to
bottom at the thickest part of your bladder compartment. Turn it onto medium speed and plunge it into the tracing of the
bladder tank. Follow the line you traced onto the foam for the compartment using your Dremel. Once you complete the
cut use your shop vac to clean up any dust and debris.
Follow the same process for the receiver cutout but do not cut all the way through the foam, only cut as deep as needed
for the receiver to site fully in the foam. You may need to cut slightly deeper if your receiver has the connectors going into
the top.
Our next step is to drill holes alongside the spar slots for our tie wraps. These holde should be 1/8” and be spaced 1”
from the wing root, 10” from the root, 20” from the root, and 28 inches from the root.
Your holes will look something like this:
The holes should be on the edge of the spar slot. Insert the eight 8" tip wraps from the bottom of the wing over the rod
slot on the top and back through the wing, then insert the tie into the clasp. Leave them loose and push up so that all
the slack is on the top of the wing as shown in the photos at left. After the tie wraps are installed glow Polyurethane glue
into the spar slot - do the top of the wing first! After the glue is in the slot insert the glass rod from one end of the wing
and twirl the rod in the glue so that it is fully wetted out. After you have laid the rod into the slot push the tie wraps down
and flip the wing over and do the bottom of the wing and its glass rod in the same way you did the top.
Once you have placed the lower rod in place tighten the tie wraps down so that they draw the top and bottom rods fully
down in the rod slots. It might be better to describe the process as "snugging" them down. You want them tight enough
to hold the rods but you do not want to drive the rods any deeper into the foam. Clip off the excess tie wraps and then
using a blunt object push the knot into the foam so it is buried. Now wipe any excess glue over the rod slots off and mist
a light coat of 3M77 Spray Contact Adhesive over the slot and the foam one inch on each side.
Put a strip of 2" wide 3M bi-directional packing tape over the slots and the area you just misted. You may also use your
heat iron set to 225 degrees to active the adhesive of the top to bond it to the foam. Your wing should now look like the
photo on the left.
We now install two "hardpoints" in the wing to keep the rubber bands that hold the wing to the fuselage from crushing
the foam. Cut these hardpoints from sheet of 1/4" birch ply. The front hardpoint should be 4-1/2 to 5" long, and 5/8 to
3/4" wide. Lay this hardpoint on the foam, trace around it then use your Dremel Router tool to create a cavity into which
to glue the hardpoint. Use epoxy for this step and hold it in place with masking tape.
The trailing edge hard point is also cut from 1/4" birch ply and should be 5" wide and match the thickness of your wing
core. Trim the TE of the wing to fit and epoxy the rear hard point in place using masking tape to hold it in place.
Our next step is to attach the ailerons to the wing. Before we attach the ailerons we add some "armor" top the wing.
Apply a strip of 2" wide 3M bi-directional tape to the wing trailing edge. Apply it so that can be wrapped around the top
and bottom of the wing forming a strong trailing edge. Do the same thing with the leading edge. Once you have added
this reinforcement it is time to install the 2" wide balsa ailerons. The wide ailerons are an important feature of this
design. Do not use narrower ailerons and expect the same performance.
We are going to "top hinge" the ailerons. To top hinge we need to bevel the aileron from its top surface to the bottom. Ag
good rule of thumb is to bevel backwards a distance equal to the thickness of the aileron stock. The dotted line in the
illustration below shows how the bevel will look when finished.
There are many ways to bevel the aileron. I use a Master Airscrew razor plane to take the majority of the wood off then
dress the surface with a sanding bar with 80 grit paper. Others use a belt sander and some folks have been able to find
beveled stock that works without you having to do the bevel yourself.
The red line shown in the illustration represent the location of the 4" wide bi-directional tape. If you cannot find a source
of 4" wide tape use two inch and use multiple strips to accomplish the same coverage. The bi-directional tape will
adhere well to the strip of bi-di you put on the trailing edge earlier and it will give the aileron a layer of armor to protect it
in combat. Once you have put the top bi-directional tape on the aileron and wing flip the aileron onto the top of the wing
and use another length of bi-di to seal the bottom of the aileron. This is necessary to keep the aileron from pulling away
from the wing and moving up and down in the air.
After you have attached the ailerons you may decide to cover your wing completely with bi-di tape. Its heavier to do this
but it does offer incredible protection from mid air damage. If you decided to go with colored tape only then mist a good
coverage coat of 3M 77 on the wing and cover it with packing tape. The last photoo shows what your completed wing will
look like.
click here for Part II - Fuselage Construction
Step 3:
Joining the wing cores and installing fiberglass spars.
Once both panels have the holes for tie wraps drilled into them it is time to dress the wing roots for dihedral.
We want the wing cores to look like this when viewed from the front:
To accomplish this we have sand an angle into the wing roots. Lay the wing core with the bottom side up on your
workbench. Use a sanding block to make the wing root perpendicular to the table top of both cores. Fit them together
and sand until the fit is perfect then join the panels with epoxy. Hold the panels together with making tape until the epoxy
cures.
Gather up your 8” tie wraps, we need eight of them. Put them into the holes you have drilled with the knotted end on the
bottom of the wing.
Step 1:
The Gorilla wing is composed of four foam pieces. A left and right EPP leading edge and a left and white pink foam
trailing edge. Step one is gluing the EPP leading edges to the pink foam trailing edges.
Suitable glues for this task are Polyurethane (Elmers or Gorilla Glue) or 30 minute epoxy. We prefer polyurethane glue
for its increased strength.
Note the pink foam core is slightly longer than the EPP. This is ok. Make sure the two pieces line up flush at the root end
of the core then trim off the excess at the tips once the glue is dry.
It is important to have a good bond between the EPP and the pink foam. You may wish to use a Top Flite Woodpecker
tool to lightly dimple the surfaces to which the glue will be applied to make sure you have a surface for the glue to
adhere to. Apply glue to the pink foam only. Smear the glue into a thin film over the pink foam core surface.
Make certain of your alignment. You want the wing airfoil to be accurate and true. Use masking tape to hold the two
foam pieces to each other. Make sure the parts are even at the root’s core.
After the glue has dried (overnight) trim the pink foam of the wing top even with the EPP core. A wood block sander or
belt sander works well for this task.
Hints:
- start your glue application at the wider part of the wing core (the root) because when you first apply glue it comes
out in wider bead than it does after getting started.
- Use masking tape to hold the EPP leading edge to the pink trailing edge. If you begin on the top and keep
pressure on the spar slot the wing will stay in alignment. The bottom of the wing is flat so pressing down on it
keeps the EPP and pink foam in alignment to each other. When you flip it over to add tape to the bottom of the
wing also hold pressure on the spar slot to maintain the alignment of the front and back parts of the wing.
Step 2:
In this step we will cut out the foam for the bladder tank and for the receiver. The bladder compartment is in the right
wing half; the receiver is in the left wing half.
Create a template for the bladder compartment and receiver out of poster board. The bladder compartment should be 1-
1/2” wide by 6” long with rounded ends. It should be shaped like the photograph at left.
It is important that the corners of the bladder compartment not be right angles as this creates a potential stress riser in
the foam. Make the corners rounded.
The receiver template can be made by tracing around the receiver you will use onto poster board then cutting it out.
Lay the bladder template onto the top of the right wing core. It should be three inches from the root of the core and ¾”
below the spar slot. Trace around it with a felt tipped marker.
Put the wing core back into its lower shuck. This keeps you from getting hangar rash on the bottom of the wing core and
also gives you a level surface to work on.
Let’s cut the bladder compartment. Set the depth of your Dremel router so that it will go entirely through the wing top to
bottom at the thickest part of your bladder compartment. Turn it onto medium speed and plunge it into the tracing of the
bladder tank. Follow the line you traced onto the foam for the compartment using your Dremel. Once you complete the
cut use your shop vac to clean up any dust and debris.
Follow the same process for the receiver cutout but do not cut all the way through the foam, only cut as deep as needed
for the receiver to site fully in the foam. You may need to cut slightly deeper if your receiver has the connectors going into
the top.
Our next step is to drill holes alongside the spar slots for our tie wraps. These holde should be 1/8” and be spaced 1”
from the wing root, 10” from the root, 20” from the root, and 28 inches from the root.
Your holes will look something like this:
The holes should be on the edge of the spar slot. Insert the eight 8" tip wraps from the bottom of the wing over the rod
slot on the top and back through the wing, then insert the tie into the clasp. Leave them loose and push up so that all
the slack is on the top of the wing as shown in the photos at left. After the tie wraps are installed glow Polyurethane glue
into the spar slot - do the top of the wing first! After the glue is in the slot insert the glass rod from one end of the wing
and twirl the rod in the glue so that it is fully wetted out. After you have laid the rod into the slot push the tie wraps down
and flip the wing over and do the bottom of the wing and its glass rod in the same way you did the top.
Once you have placed the lower rod in place tighten the tie wraps down so that they draw the top and bottom rods fully
down in the rod slots. It might be better to describe the process as "snugging" them down. You want them tight enough
to hold the rods but you do not want to drive the rods any deeper into the foam. Clip off the excess tie wraps and then
using a blunt object push the knot into the foam so it is buried. Now wipe any excess glue over the rod slots off and mist
a light coat of 3M77 Spray Contact Adhesive over the slot and the foam one inch on each side.
Put a strip of 2" wide 3M bi-directional packing tape over the slots and the area you just misted. You may also use your
heat iron set to 225 degrees to active the adhesive of the top to bond it to the foam. Your wing should now look like the
photo on the left.
We now install two "hardpoints" in the wing to keep the rubber bands that hold the wing to the fuselage from crushing
the foam. Cut these hardpoints from sheet of 1/4" birch ply. The front hardpoint should be 4-1/2 to 5" long, and 5/8 to
3/4" wide. Lay this hardpoint on the foam, trace around it then use your Dremel Router tool to create a cavity into which
to glue the hardpoint. Use epoxy for this step and hold it in place with masking tape.
The trailing edge hard point is also cut from 1/4" birch ply and should be 5" wide and match the thickness of your wing
core. Trim the TE of the wing to fit and epoxy the rear hard point in place using masking tape to hold it in place.
Our next step is to attach the ailerons to the wing. Before we attach the ailerons we add some "armor" top the wing.
Apply a strip of 2" wide 3M bi-directional tape to the wing trailing edge. Apply it so that can be wrapped around the top
and bottom of the wing forming a strong trailing edge. Do the same thing with the leading edge. Once you have added
this reinforcement it is time to install the 2" wide balsa ailerons. The wide ailerons are an important feature of this
design. Do not use narrower ailerons and expect the same performance.
We are going to "top hinge" the ailerons. To top hinge we need to bevel the aileron from its top surface to the bottom. Ag
good rule of thumb is to bevel backwards a distance equal to the thickness of the aileron stock. The dotted line in the
illustration below shows how the bevel will look when finished.
There are many ways to bevel the aileron. I use a Master Airscrew razor plane to take the majority of the wood off then
dress the surface with a sanding bar with 80 grit paper. Others use a belt sander and some folks have been able to find
beveled stock that works without you having to do the bevel yourself.
The red line shown in the illustration represent the location of the 4" wide bi-directional tape. If you cannot find a source
of 4" wide tape use two inch and use multiple strips to accomplish the same coverage. The bi-directional tape will
adhere well to the strip of bi-di you put on the trailing edge earlier and it will give the aileron a layer of armor to protect it
in combat. Once you have put the top bi-directional tape on the aileron and wing flip the aileron onto the top of the wing
and use another length of bi-di to seal the bottom of the aileron. This is necessary to keep the aileron from pulling away
from the wing and moving up and down in the air.
After you have attached the ailerons you may decide to cover your wing completely with bi-di tape. Its heavier to do this
but it does offer incredible protection from mid air damage. If you decided to go with colored tape only then mist a good
coverage coat of 3M 77 on the wing and cover it with packing tape. The last photoo shows what your completed wing will
look like.
click here for Part II - Fuselage Construction
Step 3:
Joining the wing cores and installing fiberglass spars.
Once both panels have the holes for tie wraps drilled into them it is time to dress the wing roots for dihedral.
We want the wing cores to look like this when viewed from the front:
To accomplish this we have sand an angle into the wing roots. Lay the wing core with the bottom side up on your
workbench. Use a sanding block to make the wing root perpendicular to the table top of both cores. Fit them together
and sand until the fit is perfect then join the panels with epoxy. Hold the panels together with making tape until the epoxy
cures.
Gather up your 8” tie wraps, we need eight of them. Put them into the holes you have drilled with the knotted end on the
bottom of the wing.
