Fireball XL-5 9mm kit

The Fireball XL-5 RC Rocket glider kit is based on the supermarionation show from the 1960’s/70’s. It has a light wing loading giving it a very nice glide and easy/stable boost. It comes with a plastic nose cone, 2.6″ white tubing for the body and 9mm depron wing and wingtip surfaces, and 6mm depron for the stabilizer. Construction is very simple and takes about an hour and a half. Elevons are pre-hinged and the body tube is pre-slotted for the wing and tail. The wing spar is pre-grooved for the spar. You will need two 10 gram type servos, two 16″-18″ servo extensions, a receiver, and a small 500mah single cell lipo battery. You will need a transmitter with delta or elevon mixing. Length 33″, wingspan 20″, weight rtf 11.2-11.75(painted) oz. Decals available HERE

CG location for rocket flight: 13.25″ forward of the rear end of the body tube.

Identify all pieces, the kit should contain:

1 wing taped together

4 styrene canards.

1 Vertical Stabilizer

1 Motor mount

1 Nose Cone

1 wing spar(carbon fiber)

1 coupler

2 Body Tubes

2 wingtips

2 control horns/Pushrods

1 motor mount centering strips, 6mm by 2.75″

Velcro(for battery and rx/bec attachment)

3M blenderm tape

Lead weight

Spare depron

Notes before starting:

Reference to CA+ means foam safe CA+, normal CA+ will melt the foam! Normally you need to use accelerator to get the CA to set on the foam since there is nothing for it to soak into and activate.

Epoxy is not needed in this model. Weight is critical and the model is designed for the thrust and flight loads. Weight in the rear end is bad and will require additional weight in the front of the model.

On this 9mm depron it is easy to tear the edges if you sand too agressively. I’ve found it’s easier to use a straight edge and bevel the edges with an exacto first, then use a light touch with 320 grit standpaper. Practice on the spare piece included with the kit to see how it behaves. Go slow and do little pieces at a time not large back and forth strokes.

Unpacking your kit:

The kits are packed to protect them in shipping, but the contents are fragile so unpack carefully. Carefully cut the tape holding the tubes in the box, then unwrap/lightly cut the plastic wrap to free the tubes, the spar may be packed in the tubes and the baggie with the little parts and nose cone will be in the tubes as well. 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+.

Assembly:

There is a wrap on the main body tube to help hold it’s shape, once the slot is cut it wants to flatten, leave that in place till you are ready to insert the wing, then remove it.
Glue the centering strip on the motor mount on any one of the lines
Unfold the wing and glue the joint using CA+ and accelerator, make sure it is flat.
Glue the wing spar in the pre-slotted area on the bottom of the wing with CA+ and then tape over the spar and wing joint with the included blenderm tape.
Install the rail buttons at this time.
Insert the coupler into the rear of the body tube just 1/2″ or up to the slot for the wing, this is so the rear of the tube is round which is helpful for centering the wing.
Test fit the wing in the slot in the rear body tube, if it is snug, sand or trim as you don’t want it to drag/damage the wing as you are inserting it. Note, the rail buttons are on the top side of the fuselage and visible wing spar is facing down, the vertical stab slot will be up. Make sure the wing is centered left and right at the front and rear, then tack glue the top and bottom at the front and rear of the wing, making sure not to glue the coupler in place!! Remove the coupler when the glue has set.
Now put he coupler in the front of the tube in a similar way and center the front of the wing, then tack glue in place. Remove the coupler and then glue it in place in the front of the tube, it will stop against the wing.
Now glue the wing in place on both sides top and bottom, do a little at a time, once the slot is cut in the tube, the tube tends to flatten, you may need to squeeze the tube slightly as you go to keep it round.
Test fit then glue the vertical stab into the slot in the rear body tube. Make sure it is perpendicular to the wing.
Insert the motor mount from the rear and into the slot in the wing, the tab will vertical at the bottom. The wing and vertical stab tab will help center the tube. It should be recessed about 1/2″ into the body tube when fully inserted. You may need to sand/trim the motor mount tab till it will slide in freely.
Run glue on the motor mount tabs to glue them to the body tube the the other places the foam contacts the motor mount. You don’t need a lot of glue here as the motor pushes against the rear of the wing which is glued in its’ slot so it can’t really go anywhere.
Glue the forward short body tube onto the coupler, there is a small alignment mark on the bottom to make sure the pieces are aligned, these tubes are cut by hand so aligning the mark makes sure the joint has no gaps.
Test fit and trim then glue the two wing tips to the wing using the pre-cut tabs/slots.
Glue the control horns in place on the bottom of the control surfaces, the holes face forward and the pushrod should be closest to the body tube.
Glue the four canards into the slots in the nose cone. They are not placed uniformly around, they are placed so in one orientation they should not make significant contact with the ground when landing.

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 flying wings lose pitch authority when nose heavy so you want as much up elevator travel for trim/flare as possible.

Connect a servo to each pushrod. If the pushrod is too tight, you can use twist an exacto knife in the servo arm hole to make it larger, but be careful and do not make it too large. 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 elevons up. Moving the transmitter stick to the right should move the right elevon up and the left elevon 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.
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. The servo and pushrod should be at 90 degrees to the hinge line so that it moves easily and fully.
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 movement should be 1” in each direction, aileron movement should be 1/2″ in either direction. Since the model will be nose heavy, extra elevon movement helps to give sufficient authority during glide.
If you have a flap/elevator mix you can program up elevator to a switch setting. The model needs approximately 3/16″ to1/4” of up elevon during glide. If you can’t set the up elevator trim to a switch on your radio you’ll have to manually put in boost and glide trim which is hard to do while flying the model.
Attach a 16-18″ servo extension to each servo.You just need to be able to route the wire to the front of the tube to attach it to the receiver.
Make a 1/8″ wide by 1/2″ long slot in the bottom of the wing/fuselage on each side and pass the wires through to the inside and toward the front. On my model I just made a U shaped cut, folded the cardboard forward, inserted the wire then folded the cardboard back over the slot/wire. I then taped over that with blenderm tape to avoid having a large open slot. See photo for more clarity. You can also just cut the slot out completely and cover it over with tape after inserting the wire.
Attach the servo wires to the receiver and make sure they are going the right direction. Tape over the slots in the body tube.
Use the included Velcro to attach the receiver inside the front of the nose cone shoulder.
Use the included velcro to attach the battery inside the shoulder of the nose cone.
For painting, I only use Testors enamel small rattle can and cannot recommend any others as it may cause melting/surface deformation. Do not spray too close or too thick as the solvents can damage the foam, spray in light coats. Paint will add 1/2 ounce to the flight weight. Make sure to mask off the servos. Make sure no paint will get on the servo output arm. I used Testors enamel Red and Silver rattle can spray paint. If you have an airbrush, water based acrylics may work, but I have not used these, test on a piece of scrap foam in any case before applying to the model.
Paint the red wingtips first, then mask off the rail buttons and wingtips and paint the rest of the model silver.
I found the silver paint will pull up very easily with any masking or when applying the decals if you aren’t careful. I use a soft cloth to rub all the areas on the cone and body tube to try to remove any of the loose silver. when applying the decals you have to put them in place correctly as you can’t pull them up and reposition them or they’ll just pull the silver paint away and you won’t have any adhesive left on the decal. When removing the backing paper you have to press down firmly and roll the paper off so that it doesn’t pull the decal straight up and the paint with it. When putting the tail stripe on apply one side first and wrap it over to the other side so that when you apply the other decal it will make contact with the vinyl from the first side and not just the painted foam surface.
On my second version I just left it white, it’s lighter and I think it still looks quite good.
If using the stickershock markings, the squares with the yellow stripes are for the canards, apply them, then trim the vinyl around the canard shape on each side. The yellow shapes for the wingtips are applied and are oversized at the front to wrap around the sides, use a hot hair dryer to soften the vinyl when applying and stretch it around the edge as you apply then trim the edges. The tail strip, lettering, cockpit and blue stripes are self explanatory.
After applying the vinyl decals use a hot hair dryer to soften the decal and push it into the foam or cardboard surface to help it set.
Insert your heaviest loaded rocket motor into the motor mount
Support the model at the balance point indicated for boost. I use two pencils with the eraser pointed up and held in place with a small hand vice. Place the model upside down on the pencil erasers on the balance point. Use the included lead weight to balance it. Do not try to 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. Make sure you do this after you painted your model as the paint weight changes the CG.
For flying use a little masking tape to friction fit the motor so it won’t fall out.

Flying: See the General Instruction/Information 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.