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Retract Installation
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XPS Retract Installation For

The Parkzone Habu

Using e-Flite electric retracts

You are welcome to link to this page, but please do not copy any files or link to them.  We make periodic improvements
to this information and only the very latest data should be available to our customers.  This information is copyright (C) 2010 by XPS.

NEW!  Added video link section at the bottom of this page!



Xtreme Power Systems sells the MOST POWERFUL Lipo battery packs for your Habu!  See our online store for pricing!






Getting Started


Your kit will contain the following pieces:

  • 3 left gear mounting plate pieces (two plates and a cross brace)

  • 3 right gear mounting plate pieces (two plates and a cross brace)

  • 1 nose gear plate

  • 1 main gear template

XPS Retract Kit Contents.


To complete the retract installation you will need the following:

  • 1 set of e-Flite electric retracts (left/right main gear, nose gear)

  • 3 servo extension leads (two 12" and one 18")

  • 12 small screws for mounting retracts

  • CA (thick and thin)

  • X-acto knife

  • Dremel tool with sanding stone

  • Measuring device

  • Screwdriver and other basic tools



Main Gear Plate Assembly


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 desired.



Mounting the Retracts on the Gear Plate



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!


Completed assemblies.  Note the notch for the retract wire.



Cutting the 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 struts.


Measure 3.50" from the plastic to the end of the strut.


Measure twice and cut once!



Using the Main Gear Template


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 side.


Trace around supplied template to define the area were the retracts will be installed.


The final result shown on the right.



Removing 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.



Removing the 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 the wing.

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 brace slot.


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 cleaned up.


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.



Installing the 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.



Assembling the Nose Gear


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 details.

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 rudder/steering channels.


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.



Removing the 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 positioned.

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 receiver.

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 to dry.

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 assembly.


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.


Finished installation!



Finishing It Up!


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 slightly inwards).

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 3700mAh pack!

If you have any comments you would like to make about the install, please contact our technical support department: tech@xtremepowersystems.net





Here are some videos of customers who have installed our retract kit.  Enjoy!





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