X-15 1/14 scale 4″ tube Kit Instructions

The X-15  RC Rocket glider kit is modeled after the later version of the hypersonic reasearch vehicle that flew with the XLR-99 engine and without the extended lower ventral fin.  This version was used in the high altitude flights to 67 miles.  The kit  includes pre-slotted body tube, plastic  nose cone, pre-hinged control surfaces, pre-installed spars and pre-cut 6mm depron tail surfaces and wing.  Length 42″, wingspan 20″, weight 16-17 oz rtf.  It is 1/14 scale.  I had to make a few concessions to keep the tube and tail structure as strong as possible and make assembly and chine installation easier.  The kit is designed for Composite only  E-20 single use motors with the ejection charge removed.  Use of any black powder motor in any of my kits is not recommended, use at your own risk!

CG location for rocket flight with battery and motor installed: 1.75-2″ to the rear of the wing leading edge where it hits the chine with battery and loaded motor installed as ready for flight.

Since you will be removing the black powder ejection charge, it doesn’t matter if you get an E-20-4 or E- 20-7 pack since the last number is the delay before ejection which you aren’t using.

Please refer to the General information for all kits tab above, then read these instructions completely before starting assembly. ​​ High quality cut vinyl decals are available HERE select the white lettering for a black painted model.

  

Flight Video:

Unpacking your kit:

The kits are packed to protect them in shipping, it comes in two boxes, The contents are fragile so unpack carefully.   Carefully cut the tape holding the tubes and cone in place and unwrap/cut the protective wrapping.  The body tube is wrapped with paper to help hold the shape of the tube, only remove this paper once you are ready to install the wing and tail since the tube tends to flatten out after cutting the slots.  In the other box, carefully cut the tape holding the cardboard wing protector in the box and carefully remove it, don’t pull hard or bend it.  Then carefully cut the tape holding the cardboard top piece to the bottom.  There may be some sticky tape holding the cardboard to the bottom cardboard piece, carefully peel it being sure not to bend anything.  Once the top cardboard is free you can see the foam wing/tail parts, there are little fragile pieces in here, so unwrap carefully.  It may be best to use an exacto to lightly cut the plastic wrap and carefully remove it without cutting into the foam.  Make sure everything is free before you remove the pieces to avoid breaking anything.  Kits contain one or two scrap pieces for repairs if you damage anything in construction or flight, just cut and patch in a spare piece of the foam if needed using foam safe CA+.

Welcome to the world of rocket boosted radio control gliders.  This is not a model for a novice RC pilot, but anyone who is comfortable with RC flying of a medium speed model should be fine.  Read through the instructions, look at the photos and be sure you understand the step before comitting to cutting or glue.

Identify all pieces, the kit should contain:

Wing

Vertical stabilizer

Horizontal stabilizer

2 long 1″ wide chine 6mm strips

2 1.5″ wide chine covers (foam paper or plastic material)

4 cockpit profiles(9mm)

1 lower ventral fin(9mm depron)

1 long slotted body tube

2 rail buttons and blind nuts/screws

1 short body tube

1 coupler

2 pushrods

Nose cone

Motor mount tube

Velcro(for battery and rx/bec attachment)

1 styrene strip for reinforcing the ventral fin

Lead weight

1 foam mmt mounting strip

Spare depron

Notes before starting:

Foam safe CA+(Bob smith super gold + is good) is the only glue recommended for construction except for some epoxy just to hold the nose weight in place.  You will also need foam safe accellerator.

Fuselage Assembly

1. 1. If you want to bevel the leading and trailing edges of the wing and horizontal stab now, do so now.  Bevel ONLY the lead and trailing edges of the wing and horizontal stabilizer and the leading edge of the vertical stabilizer.  The rest of the edges should stay flat until the assembly is completed.  I’ve found it’s better to use a straight edge and sharp exacto to do a small 1/16″ to 3/32″ wide bevel cut on the edges of the foam instead of trying to sand them round.
   2. Insert the horizontal stabilizer into the slot in the rear of the fuselage.  The vertical tail slot in the tube will be UP and the spar will be facing down.  Insert the coupler into the rear of the model about 1/2″ to help the tube keep it’s shape.  Make sure the stabilizer is centered left and right and tack glue the rear in place making sure not to glue the coupler in place.  Once tack glued, remove the coupler and insert it from the front of the model down to almost the horizontal stabilizer, make sure the front is centered and tack glue that in place.  Remove the coupler and  apply a fillet of glue on the outside and inside.
   3. Slide the wing into the slot in the body tube.  The vertical tail slot will be UP and the wing spar will be “down”. Insert the coupler into the front of the tube about 1.5″ to help hold the round shape, make sure the wing is centered left and right and tack glue in place.  Remove the coupler.
   4. Install the front and rear rail buttons in the pre-made holes.
   5. Glue the coupler into the front of the body tube about 1 1/2″, it should abut the rail button and stick out about 1.5″, then fillet the wing joint.
   6. Glue the forward body tube onto the rear.
   7. Glue the vertical stab into the rear slot keeping it perpendicular to the wing and fillet inside and out.
   8. Glue the small foam motor mount centering strip onto one of the lines on the motor tube.  Test fit the motor mount into the rear of the model.   The motor tube is supported left and right by the horizontal tail slot and on top by the vertical stab tab.  The tab on the mount is pointing down.  You may need to sand the tab slightly till the mount will just insert snugly, make sure the vertical stab stays vertical then glue in place.  The motor mount should stop against the front of the horizontal stab slot and be inset about 3/4″.  Make sure the motor tube is attached well but don’t overdo it and don’t use epoxy, tail weight is a killer and there isn’t much force on the motor tube during launch.  The foam is plenty strong enough to support the forward thrust and no thrust ring is needed.  I’ve flown many flights and the forward foam has never melted or failed.
   9. Glue the styrene strip onto the lower ventral fin starting at the front, this helps provide some landing protection.  Glue the lower ventral fin on the rear bottom of the fuselage on the line marked.
   10. Trim the two long chine pieces to length, they should abut the front of the wing and stop at the front of the body tube.  They will be approximately 12.5″ long.  Save the cut portion you will use that for the filler piece between the wing and tail.
   11. Set the model with the wing along a table edge and put something like a book to hold the wing and model in place on the table with the body tube about 1/4″ away from the edge.  Put a bit of wax paper under the front of the wing and glue the chine to the body and against the front of the wing.  The edge of the table will help make sure the wing and chine are aligned straight.  Repeat on the other side and then fillet the top and bottom of the chine.
   12. Cut and fit the two short rear chine pieces inbetween the wing and tail using the parts you cut off the long pieces, and glue them in place and fillet the top and bottom.
   13. Test fit, then trim to length and glue the two chine cover plates down against the stabilizer foam, rear chine foam and  wing.  Do not glue to the body tube at this time. The shiny side should be visible. At the front you may need to bend the cover down to touch the curved portion and the front portion will overlap the chine to allow trimming later.  Note the curved portion will go against the body tube at the front and have to be pulled down till it just is even at the front with the tip of the chine.  Now glue the chine cover to the chine and hold in place. Once set, wick CA under the chine cover and glue it to the body tube, wipe off any excess immediately.  Once set, trim the chine cover to match the chine profile.  There are no chine covers on the bottom of the model to save weight and avoid having to trim around the servo mounting, in flight and normal viewing you won’t even notice.
   14. Glue the four cockpit pieces together.  Use the provided templates to cut the top view to shape, then bevel the front of the cockpit on both sides and round the rear portion as per the photos.
   15. Glue the pushrods/control horns into the holes premade into the bottom of each control surface, note the pushrod should be closest to the fuselage, there is a left and right and they will angle inward.  See picture for clarity.
   16. Early kits had rotary hand molded white cones, current kits contain 3-d printed black cones.  The 3-d printed cones require some sanding/filling if you want a smoother finish.  Since this is a flying model and since I’m using flat black paint on my model I chose to save weight and leave the surface slightly rough and it looks fine.
   17. Wrap some 320 grit sand paper over the body tube and nose cone and gently sand the bottom of the cockpit till it conforms to the body tube and cone.
   18. The cockpit is glued so the front of the cockpit is 4″ forward of the front of the body tube, the rear portion will glue to the body tube. Tack glue the front and back to the cone/body using foam safe CA+ but be sure not to glue the nose cone to the body tube.  If there is a small step between the body tube and nose cone simply press the foam in and it will conform to the step.  Carefully slice the cockpit at the body tube joint to separate the cone and body tube at the cockpit, then apply a fillet at the edges to fill any gaps on each piece.  I carefully applied a few coats of foam safe CA+ to the cockpit to harden it and make it take paint/filler better.  Add a little at a time to avoid heat/melting.
   19. Lightly sand  the chine edges to round them.
   20. If the nose cone shoulder is a slightly loose fit, simply use masking tape to make a friction fit.

The basic construction is now complete.

Radio Installation

Note:  Your radio needs to be configured for Delta mixing, this means that the servo arms will move the same direction during elevator stick movement and opposite for aileron stick movement.  Connect your servos to the receiver one in the aileron connection and one on the elevator connection and apply power.   Use a servo arm at least 9/16” long and with holes small enough that there won’t be slop with the pushrod wire when installed.  I use the hole furthest out on the servo arm, to maximize movement. On some servos there are a long two-ended servo arm, you can trim off one end if needed to get sufficient length.   Zero out any trim settings on the transmitter. The model once the motor has burned out is nose heavy and loses pitch authority in glide so you want as much up elevator travel for trim/flare as possible.

1. Install the free end of the pushrod to the servo output arm, again making sure the servo electrical wire is toward the fuselage side of the model and pointed toward the rear.  If the wire is too tight, you can twist an exacto knife in the servo arm hole to make it larger, but be careful and do not make it too large.  The servos will butt against the body tube and glue to the bottom of the horizontal wing and chine filler between the wing and horizontal tail.  Repeat for the other side. Once connected, tape each servo in place so that the control surfaces are centered.    Flip the model right side up and look at it from the rear.  Moving the transmitter stick back(up elevator) should move both stabilizors TE’s up.  Moving the transmitter stick to the right should move the right TE of the stabilizer up and the left one down.  If you can’t get the servo reversing to give you the right polarity try swapping aileron/elevator inputs to the receiver or turning the servos over and swapping the servo arms to the other side of the output shaft. If that is correct, continue.
2. Flip the model upside down and supported.  The servos may be attached to the model using double back servo mounting tape(not included) or by directly gluing the servo to the wing with CA+ or a small amount of epoxy.  Double back servo tape can loosen over time and with exposure to heat, I prefer to glue the servo in place.  With the radio still on, put a small amount of glue on the servo, being careful not to get any near the output shaft. And set it in place on the model keeping the control surface centered.  Do the same to the other side.  Make sure the glue is set before continuing.
3. Flip the model back right side up.  Make sure the control surfaces are centered, use trims if needed.  Now measure the control surface movement.  Full elevator and aileron movement should be 1.125-1.25” in each direction.   Since the model will be nose heavy, extra stabilizer movement helps to give sufficient authority during glide.  Roll rate is not extremely fast during glide so you need plenty of movement.  Set up dual rates with lower movements if you are worried but boost with higher settings till you are comfortable.
4. If you have a flap/elevator mix you can program up elevator to a switch setting.  The model needs approximately  1/4” of up elevator during glide.  Boost will use completely neutral settings for the first flight.  If you can’t set the up elevator to a switch on your radio you’ll have to manually put in glide trim which is hard to do while flying the model.
5. Attach a servo extension to each servo.  Cut a small slot into body tube on each side near the receiver and pass the servo wire that is attached to the servo into the body tube and forward to the end of the body tube.
6. Attach the servo back to the receiver.  Attach the servo inside the body tube far enough in that the nose cone wont’ interfere using the included velcro. Mount the battery inside the nose cone shoulder using the rest of the velcro.
7. Make sure your controls are still moving the right directions and proceed.
8. Insert a loaded rocket motor into the motor mount.  Use the heaviest motor you plan on flying.
9. To paint the model you can remove the receiver and battery, rail buttons and t-nuts and mask off the servo plugs and Velcro strips on the model.   I use and recomment ONLY Model Master(testors) or testors small rattle cans for painting directly on the foam.  Model master flat black is perfect. I paint the edges first since those tend to soak more paint and need re-coating first, then do the flat areas.  It took slightly more than one can to do my prototype.
10. Use a silver or black sharpie to add panel lines if desired.
11. If you use the stickershock markings, it helps once applied to use a hot hair dryer to soften the decal then push down with a finger to really set them into the model.  Be careful when applying over painted foam as when removing the backing tape you need to roll the backing off carefully while pushing down firmly.  If you pull straight up you will pull the paint off the wings and the decal won’t stick any more.  The x-15 at times had the little yellow arrow and blue ball on the nose, the nasa logo was typically burned off during flight so that is left off of the decal, and sometimes had X-15 text on the nose, the decals from stickershock include both.  It also contains round and angled cockpit windows, on the high speed flights the left window was angled and covered by a door and the right window was rounded.  Or you can use both angled or both round windows, I’ve seen both depending on what time in the program it was.  The larger windows fit this model, the smaller ones fit my X-15-3 delta kit.
12. Re-install the receiver, rail buttons and battery and loaded motor.
13. Support the model at the balance point indicated for boost at the top of the page in red.  Make sure the model balances slightly nose down.  Add small amounts of included lead to the nose as needed to achieve a slightly nose down balance.  If you wind up nose heavy you can move the receiver and battery back to the middle or tail of the model and cut a hatch in the body tube to access it to avoid adding tail weight and making the model heavier than it needs to be.
14. Do not fly the model with it balancing it behind this point.  The adage is, a nose heavy model flies poorly, a tail heavy model flies once.
15. This model is designed and tested to use the Aerotech composite E-E20  24mm motors with ejection charge removed.  Simply use a small amount of tape to friction fit the motor to keep it from falling out after burnout.  It has also been flown on F-24 Aerotech 24mm reloadable motors in the standard 24/40 casing without ejection charge but the motor will stick back further and will require more nose weight due to the casing and the fact it is not as far forward.

Flying:  See the General Instruction link at the top for flying instructions.  Be ready on the first few flights to keep the model straight till you have the trims set perfectly for boost and glide.  For this model it will boost fast on the recommended motors.  Make sure your First flight trim is neutral and that you do not have the glide “up” trim engaged before every flight.

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