XPS Retract Installation For
The Parkzone Habu
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THIS ENTIRE MANUAL BEFORE
STARTING THIS PROJECT!
Your kit will
contain the following pieces:
XPS Retract Kit Contents.
To complete the
retract installation you will need the following:
1 set of e-Flite
retracts (left/right main gear, nose gear)
3 servo extension
leads (two 12" and one 18")
12 small screws for
CA (thick and thin)
Dremel tool with
other basic tools
Assemble the main gear plates as
shown in photos. Take note that the text
"left wing" and "right wing" should be facing
upwards with the cross brace underneath the plate.
The cross brace maybe difficult to
just press in. This is by design. Line
up the holes and tap on the cross brace into the
gear plate (using a rubber mallet or similar tool)
until it is fully seated into the gear plate.
Repeat for both halves of the gear plate.
Assemble both left and right sides. Once
assembled, verify that you have two units (left
side and right side) that match the photos below.
Once you are convinced they are assembled
correctly, use thin CA to glue the joints
together. Thin CA will wick into the wood
and form a strong bond. You may want to sand
the top side of the gear plate if the posts stick
through. The purpose of the sanding would be
to make it look cleaner.
Press cross brace into gear
plate and tap flush.
Press second plate into cross
brace and tap flat
Assemble both sides and glue
with thin CA. Sand top side of plate if
Retracts on the Gear Plate
NOTE: WE HAVE
HAD MANY REPORTS FROM CUSTOMERS STATING THAT THE
SETSCREWS HOLDING THE STRUTS IN PLACE DO NOT HAVE
THREAD LOCK (BLUE LOCTITE)! THIS RESULTS IN
THE STRUTS COMING LOOSE AFTER SOME POINT IN TIME.
THE ONLY WAY TO REPAIR THIS IS BY RIPPING OUT THE
RETRACT! PLEASE MAKE SURE TO CHECK THE
SETSCREWS PRIOR TO INSTALLATION!
Determine what size screws you
will be using to mount the retracts to the gear
plate. Since everyone has their own
preference for screws, these are not supplied
with this kit.
Enlarge the holes in the gear plates to properly fit
the screws you will be using. Place thin CA
into the holes to prevent the wood from splitting
when screwing in the screws.
Pay close attention to the photos below, noting
that there is a "left" and a "right" side retract.
The difference between the two is the coil in the
strut. You must make sure that the strut
matches the pictures or the coils will be
backwards! Place the retract on the top side
of the retract plate. Screw in all 4 screws.
Complete both sides.
Left wing assembly.
Note the strut coil!
Right wing assembly.
Note the strut coil!
Note the notch for the retract wire.
Struts to the Proper Length
The strut lengths needs to be
cut down to 3.50". Measure from the
base of the plastic retract as shown in the
photos. Cut the strut using a Dremel tool
with a cut off wheel. DO NOT cut the
nose gear strut! Repeat for left and right
Measure 3.50" from the
plastic to the end of the strut.
Measure twice and cut once!
Using the Main
You will need to have a flat
surface for the installation of this kit. Lay a towel
down to prevent damage to the foam. Remove
the wing from your Habu. Lay the wing with
the top-side facing down so you can see the bottom of the
wing. Take the supplied template and lay it
over the stock gear mount plate. See photos
for reference. Match up the shape of the
template with the stock gear plate and trace
around the template with a pencil or pen.
Flip the template over and use it for the other
Trace around supplied
template to define the area were the retracts will
The final result shown on the
Stock Gear Plates
Removal of the stock gear plates
takes some work, but it can be done with some
patience. Using an X-acto knife, cut
completely around the gear plate. Angle the
blade slightly inwards, and using a up/down motion
(like a jig-saw) cut the foam the full depth of
the blade (no, you will not poke through the other
side). Once you have cut completely around
the gear plate, attach the stock wire landing gear
(if not already attached). Pull on the wire,
wiggling the plate in all directions. Take
your time, the plate really will come out.
Once the plate has been removed, lay the supplied
template back over the outline you made earlier
and cut on the outline about 1/8" deep.
Cut around the stock gear
plate. Remove it by wiggling
back/forth/left/right and pull until it comes out.
The stock gear plate removed.
Lay the template over the
original outline and cut around it. The
result will look like the picture on the right.
Main Gear Foam
The best method to remove the
foam is by cutting it using intersecting angles.
This cuts wedges of foam and makes removal easier.
Always cut a lot less than you would expect!
The foam flexes, and the object is to have as
tight of fit as possible. Removing too much
foam will make the installation impossible!
TAKE YOUR TIME!
You will need to make a pocket
for the retract to sit in. Refer to the
images below. Set the retract into the slot
for reference and mark the width of the retract
unit. Draw out the basic shape of the
retract. This is the foam that will be
removed to create the pocket. Cut and check!
The worst thing you can do is cut too much foam!
Using the template, cut the slot
for the cross brace. It is important to make
this slot only as wide and deep as the cross brace
itself. This is a crucial part of the
strength of the retract assembly, so it must be
mounted solidly in the foam.
In order to have the best
aerodynamics, the landing gear plate should sit
about 3/32" below the surface of the wing.
This makes the retract unit itself (the black
plastic) sit flush with the bottom of the wing.
If you don't care about aerodynamics then you
could mount the gear plate so it was flush with
After the pocket has been cut
and the retract assembly fits properly, it is time
to cut the wheel well. Cut the full depth of
the blade straight down to make a perfect circle.
Now, cut slots like you were cutting a pizza.
Angle the blade to cut wedges and remove the foam.
Use a Dremel tool with a sanding
stone to clean up the foam! This is the
absolute best way to get a nice and neat
installation. It's also very quick.
Just be careful not to allow the foam to melt!
Too much heat will warp the foam through to
the other side! Take your time,
and always test fit as you go!
Use angular cuts to remove
foam as wedges.
Mark the foam to indicate the
length and width of the retract.
Cut away the foam to make the
pocket. Use the template to cut the cross
Test fit your retract plate
assembly often during the removal of the foam!
Keep cutting the pocket and
surrounding area so the retract assembly sits
below the surface level.
Note the slot for the cross
brace. Start cutting out the wheel well.
Cut slots into the foam and
then use angular cuts to remove the foam pieces.
Test fit the retract assembly
and cut slot for retract wire.
Test fit the wheel. It
should sit slightly below the surface of the wing.
Use Dremel to clean up the foam.
Wheel now sitting below the
surface of the wing. Final result when
Cut the other side. A Dremel
tool with a sanding stone is the best way to clean
up the foam!
After cleaning up the foam,
this is how your installation should look.
For a really clean
installation you can use a drinking cup cut down
to fit as your wheel well liner.
Main Retract Assemblies
Once you have the foam ready, it
is time to figure out the wiring for the electric
retract. You will need a 12" extension for
each electric retract. The best location to
hide the extension plug is inside of the wheel
well. Make a small pocket in the wheel well
towards the FRONT of the wing. Cut a thin
slot for the wire to run from the wheel well to
the center of the wing. You will need to
lift the tape up that covers the center of the
wing and run your extension leads into this slot.
Replace the tape when done.
Before you can glue the retract
plate in you must fit the wheel on the strut.
Use the axels included with your e-Flite retracts.
You can use the wheels that came with the Habu's
fixed gear, but you must drill the center holes
out to be a larger diameter to fit the axel size.
You will need to cut down the length of the axel
so that it is flush with the wheel collar.
See pictures for details. Tighten the wheel
collar, leaving enough play for the wheel to
rotate on the axel. Slide the axel on the strut and finger tighten the
screws to hold the wheel in place. You
now need to connect the retracts to your receiver.
Toggle the retracts up and down and adjust the
axel position so that the wheel retracts into the
wheel well easily. You may need to slightly
move or twist the retract plate in order to get
the wheels to perfectly line up. Make sure
that the retract assembly is fully seated into the
wing during your fitting. Once you are
satisfied with the wheel position, tighten the
axel screws. Note: it is a good idea to
apply Blue Loctite on the screws to prevent them
from backing out during normal usage.
Remove the retract assembly, and
using thick CA glue the entire perimeter of the
retract plate and both sides of the cross brace.
Be careful not to get glue on the retract units
themselves (unless you plan on never removing
them), especially around the pivot points.
You may also want to apply CA to the foam itself.
Press the retract plate into place. Make
sure that the wheel goes into the wheel well
correctly. It is recommended that you leave
the wheels in "up" position while the CA dries.
This allows you to make sure the wheel is centered
in the wheel well while the CA is drying.
Press the extension plug into
the wheel well pocket and either tape or glue the
extension plug in place. This completes the
main gear installation. If you want to add a
nice wheel well liner, you can cut down a 2"
plastic drinking cup. The samples we used
were purchased from Walmart.
Make a pocket for the servo
extension plug and wires.
Test fitting the servo
extension and wiring.
Left picture shows normal
length axel. Right picture shows the length
after cutting it with Dremel.
Get the stock nose gear plate
that contains the steering servo from your Habu
(remove it from the Habu if attached). Now,
disconnect the steering linkage and unscrew the
servo from the stock nose gear plate. Save
these screws as they will be used later. See
picture of stock nose gear plate.
Enlarge the retract and servo
mount holes for the size servo you will be using.
Remember, too small of a hole will result in the
plate breaking apart when screwing in the screws.
Wick thin CA into the holes to strengthen them.
Because CG is a concern when
adding nose weight to an aircraft, you can save
weight by not using the bolt-on axel assembly.
Instead, just bend the nose gear strut at 90
degrees. The advantage of using the axel
assembly over bending the strut wire is that you
can adjust the height of the nose gear relative
the rest of the fuselage. No matter which
method you choose to use, the center of wheel
should be 2.85" from the base of the nose gear
pivot point. See detailed photos for this
measurement. You will need to now reverse
the strut wire so the coil is the direction shown
in the pictures.
Mount the retract to the plate
using 4 screws. Mount the servo to the plate
using the two original screws removed from the
stock retract plate. See the photos for
Unscrew the servo arm retaining
screw and set it aside. Remove the servo
arm. Remove the clevis from the steering
rod. You will need to cut off part of the
threaded rod. Cut off about .2" of the rod.
Screw the clevis back on the rod. Attach the
clevis to the retract steering arm. Since
there is no way to wrap the rubber clevis keeper
around the clevis with this setup, the rubber
keeper can be removed. You will need to melt
the pin (that snaps the clevis together) so that
the clevis does not come apart. See picture
for details. Connect your radio system to
the steering servo. Make sure that the servo
is centered and attach the servo arm.
NOTE: There are two ways to setup the
steering. To use separate receiver channels
for the rudder and steering, the servo arm will be
positioned over top of the retract unit (opposite
of how it is used in the stock steering setup).
If you intend to use the stock Y-cable setup so
that the rudder and steering on the same channel,
you will need to keep the servo arm pointing away
from the center of the retract (how it is in the
stock setup). You will need to trim the arm
to make it shorter. Screw in the servo arm
retaining screw. Test the retract to make
sure that there is no binding while going up and
down, and also check that the steering works
correctly with the gear in the "down" position.
This completes the nose gear retract assembly.
Stock nose gear plate.
Remove this servo.
Measure 2.85" and bend strut
wire if not using the axel assembly.
Finished strut wire bend.
Retract and servo mounted for
stock steering setup.
Arm will be turned around for separate
Stock steering rod length.
Remove clevis and shorten rod.
Shorten the rod length by
about .2", and then reassemble clevis on the rod.
Use a soldering iron to melt
the plastic pin to hold the clevis closed.
Put the servo arm back on the
servo, making sure the servo is centered.
Arm setup for separate rudder/steering channels.
Nose Gear Foam
Remove the plastic nose gear
plate mount by carefully pulling up on it.
It will take some work, so be patient!
Test fit the nose gear retract
assembly as shown in the photo below. You
can see exactly where the retract needs to be
IT IS ABSOLUTELY CRITICAL
THAT YOU DO NOT CUT TOO MUCH FOAM! In
these example pictures, too much foam was cut from
the sides, resulting in a difficult installation!
Always test fit after cutting!
If you can flex the fuselage or
even pop apart the fuselage halves slightly, this
will reduce the amount of foam necessary to cut
away. The goal is to get the nose gear
retract assembly located about 1.5" below the
fuselage at the nose gear hole. If a simple
slot could be cut out and room made for the servo,
you would not need to remove any additional foam
from the sides. Refer to the pictures.
Use a Dremel tool with a sanding
stone to clean up the foam but don't sand too much
foam! The plate must side firmly on the
foam, so the floor where there plate will mount to
must be flat.
Test fit the nose gear retract
assembly as you cut away or grind away foam.
Test the fit frequently. A small pocket is
required for the servo to sit in. If you are
using the stock steering setup, you will need to
also cut a small path for the servo arm to move. Refer to
the pictures. Once satisfied with the
fit, use a Dremel to clean up the foam and then
remove the foam where the nose gear wheel sits.
Use your radio system and check to see if the tire
fits inside the fuselage as shown in the pictures.
Remove only as much foam as necessary. Plug
in the nose gear steering servo and plug in the
retract extension. Make sure the wiring goes
through the fuselage for connection to the
Using thick CA, glue the
perimeter of the nose gear retract assembly and
push the assembly into place. Immediately
fit the original plastic nose gear door plate over
the strut and push it in place. Use your
radio system to make sure that the nose gear can
go up and down. Adjust the assembly
forward/backward/up/down to make sure the wheel
goes up and down correctly. Wait for the CA
Once the CA is try, retest the
operation of the nose gear. Trim any excess
plastic that might prevent the proper motion of
the strut wire. Remove the nose gear door
mounting plate and apply thick CA to the foam
where it sits. Now put the nose gear door
mounting plate back in place and allow the CA to
dry. The installation of the nose gear
assembly is complete!
Remove the nose gear door
mounting plate and test fit the nose gear retract
The nose gear retract
assembly should sit 1.5" below the fuselage.
Cut the foam from the sides,
but not too much! Make a shelf for the nose
gear assembly to lay on.
Make the floor flat and make
a pocket for the steering servo.
Two more views of that pocket
required for the steering servo.
The floor in the nose must
have the foam removed for the tire to fit.
Use a Dremel tool to remove
the foam where the nose wheel sits.
Mount the wheel on the strut
and test fit the nose gear retract assembly.
Another view of the test
fitting. Don't forget to plug in
the nose gear servo and retract extension!
With the nose gear in the
"up" position, the tire should just barely be
visible from a side view.
Too much foam was cut away
from the sides resulting in a big gap. Glue
in the original foam in case of a mistake!
This is where the strut
should be located when fully installed.
Cut off the tabs from the
plastic nose gear mounting plate and position it
in place before glue dries.
Plug the retract wires into the
3-into-1 harness and plug that into your
receiver's retract channel. Re-assemble your
Habu and check for the proper operation of the
retracts. Adjust as necessary. Make sure
that your Habu sits flat or with a slightly
elevated nose. Adjust the axel positions if
necessary. Also adjust the position of the
wheels so that they are pointing straight (or
Adding the electric retracts
will make your plane more nose heavy. The
stock Habu is already quite a bit nose heavy.
We found that adding about 1 1/2 oz of weight to
the tail (underneath the elevator/rudder assembly
or inside of the plastic tail cone) makes the CG
perfect, requiring just a bit of down elevator for
inverted flight. We measured the CG using
our XPS Pro 4S 3200mAh battery pack. Our
packs are light, and provide the run time of a
If you have any comments you
would like to make about the install, please
contact our technical support department:
Here are some videos of
customers who have installed our retract kit.