Battlecruiser RC Parkjet Plans

Here are plans for your personal use. Click on the link for a pdf download of the parts tracings.   Klingon Battlecruiser plans​​​

CG location for Parkjet flight:  8.5” forward of the rear end of the body tube.  

I used a grayson hobbies microjet V-3 motor with apc-6×4 prop, and a castle creations talon 15 esc.  The talon is extremely lightweight.  I used a venom or eflite 3s 800mah 25-30c back velcro’d on the right side of the model next to the fuse and even with the front of the wing.  Flight weight was 14 oz rtf.  29″ long, 23.5″ wingspan. Flight trim required a few clicks of right trim to counter torque.  Mounting the battery on the right side helps minimize the right trim.

Reminder that these parts were scanned full size, but printers normally cannot print to the edges, and they will shrink the image and put some border around it, this will yield a smaller than original print and may cause mis-alignment, make sure you turn off page scaling in the printer before printing, and that there is no scaling or auto-expand or fill to the sheets and that you print without borders.

Build light, I’ve included carbon where it is needed for flight loads. I use velcro to hold the RX and bec/esc in place, as it allows easy changing out if needed.I don’t use clevis connectors, but use .039 music wire and Z bends that fit tightly and glue my servos in place. Less to fail or go wrong. there is zero slop and it is light and simple. Please feel free to send me feedback on any issues or success you have.  Note this was designed to use 5.5mm Model Plane Foam(MPF)

 

​​​

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 commiting to cutting or glue.

Identify all pieces you need to cut out from 5.5mm MPF Model plane foam or depron

Foam Pieces:

1  wing

2 wing doublers

6 Warp Motor pods

3 wing top pieces(two slotted, one not)

2 angle pieces for the wing top

1  bridge top

2  bridge bottom

1 bridge wrap

1 fuselage neck

2 side fuse pieces

2 rear standoff  pieces

 

1 vertical stabilizer

Other pieces you need:

2 control horn​s

2 pushrods

1 body tube bt-50h 26″ long available from balsa machining service.

1 .03 styrene lower plate cut to fit the bottom of the bridge when complete.

1 inner 24mm coupler tube 26″ long available from balsa machining service.

Velcro(for battery and rx/speed control attachment)

3M blenderm tape

Lead weight

1/8″ or 3mm by 24″ long carbon fiber rod

ESC(talon 15 or similar)

Motor(grayson microjet V-3 with apc 6×4 E prop or similar)

Notes before starting:

You may use 220-320 grit sandpaper and a sanding block to slightly round the edges of the foam on the vertical stab and fuselage neck, and to lightly break the edges of the fuselage sides, angle plates and rear skids.  It just makes them look a bit nicer.   Do any sanding before assembly or as suggested in the instructions.

Assembly:

  1. Look at all parts and understand what pieces go where.  There are a few pieces that are laminated together before assembly.  Those are laminated with 3m-77 spray.  You apply this lightly to both sides let dry for 1-2 minutes till tacky then press together.  Be sure not to spray too close to the foam or it can cause some melting.  If you get any overspray on foam you don’t want glued CA accellerator typically will soften the adhesive and you can wipe it off with a paper towel. The model was designed to use foam safe CA+ glue and accellerator(I use bob smith brand)  and 3m-77 spray adhesive only.  If the instructions say “glue” that assumes using foam safe CA+  the 3m-77 will only be used for specific steps.
  2. Glue the three circles together for the bridge detail.  Glue the two round ended 2″ by 1/2″ bridge detals together.  Sand the top of the circle stack round and all sides of the long bridge detail piece and set them aside for later.
  3. You will then glue the three pieces that form the upper wing assembly that the vertical stab goes into.  Two pieces are slotted, one is not, the unslotted portion is the bottom, the slotted pieces go on top.  Use the 3m-77 spray to laminate two pieces together and then do the final piece to this assembly.   Using a scrap of foam make sure the top two pieces with the slot are aligned so when the vertical stab is inserted it is vertical.
  4. Lightly sand the three straight sides so that they are smooth.
  5. Insert the vertical stab temporarily and mark where the front of the stab hits the upper wing stack. Make a mark on the top plate then sand or cut with an exacto the front curved portion of the stack back at an angle to the line you just made.  This is just a decorative slope.
  6. Sand the two top side corners of this assembly at a 45 degree angle that is approx 1/4″ wide.
  7. Sand the vertical stab edges round.  Make sure the vertical stab is flat, if there is any curve to the foam, gently bend it with your hands in the opposite direction to straighten it,  and then glue it into the slot in the upper wing assembly making sure it is vertical.
  8. Sand the two small side plate edges slightly to break the corners then glue them even with the rear of the stack one on each side against the angle you sanded earlier.  The angle pieces should not stick out very far from the sides of the stack at the bottom or they will interfere with the elevons.  See the picture.  If you set the assembly on a table, and you look from the side, the bottom of the angle plates should be at least 1/4″ above the surface of the table and only stick out about 1/4″ on each side compared to the upper wing base.
  9. Find the upper and lower bridge plates.  Measure and make a center line on each piece.  using the center line as a guide, glue the smaller bottom piece to the larger top piece leaving a 1/4″ gap from the front of the top piece.  You need this gap to leave room for the side bridge strip/wrap which will be installed next.
  10. Find the straight strip that will wrap around the bridge.  Find the center of this strip and make a mark.  Use your hands to form this strip into a curve by gently bending between your thumbs.  Using the center mark as a guide, line it up with the center line on the front of the bridge top/bottom assembly and wrap it around both sides.  The ends should be even with each other.  If not, adjust your center line on the wrap so that the ends will be even when glued in place.  Apply CA+ and and glue it in place, curving it as you go.  Try to make sure the sides are straight up and down as you glue it down.  Hold it till it sets or have someone use accelerator to set the glue.  Set the assembly aside.
  11. Motor pods, there are six long rounded rectangles that form the warp pods.  Using the 3m-77 spray adhesive you will laminate 3 pieces together to form the warp pods.  You spray the 3m-77 on both pieces, let dry for 1-2 minutes then press them together.  You cannot separate them after touching them together so make sure you do this carefully.  If there is any warp in the pieces try to reverse the pieces before gluing so that the warp will be removed.  Then spray and laminate the third piece together with the two you just laminated.  You want these to be as flat as possible.  Sand the edges even and flat.  Repeat for the other pod.
  12. You will then mark the pieces so you know where to sand them round.  Each warp pod should be placed so that the outside is even with the wingtip end, and the warp pod sticks out 1/2″ to 3/4″ forward of the outboard wingtip at the front.  Using a sharpie, mark where the warp pod will be glued.  This part will stay flat and unsanded.  Carefully round all other edges, you may want to use an exacto and a straight edge to trim the corners that will be sanded at a 45 degree angle lightly to make the sanding go faster.  You will need to do the same thing for the other warp pod on the other side.  Set these aside. Note you have to make a left and right warp pod!
  13. Groove and glue/tape the spar in place on the bottom of the wing, then cut and bevel the leading edges of the elevons and tape hinge them to the wing.  Lay the wing upside down on a table.
  14. Locate the wing doublers.  One will be glued to each side of the wing, the leading edges will be aligned, note there should be an approx 3/4″ ” gap between the two sheets in the middle for the body tube.  The doublers don’t go out to the wingtips so that they make a step to help align the warp pods when gluing.  Using masking tape and some wax paper or paper towels, mask off the areas of the wing that are not covered by the doublers.  Using 3m-77 spray, spray the doublers and the wing and remove the masking. Note when you spray the doublers there needs to be a right and left side so make sure you spray glue on the correct side to make a pair.  Apply each wing doubler in place taking care to keep it aligned with the leading edge of the wing.  Once they are installed you may sand the leading and trailing edges round if desired.   Do not round the wingtips at this time.  Lay the wing upside down on a table so that the spar and doublers are up.  Measure accross the wingspan in two places and mark a line down the center of the wing.
  15. Mark a line down the center of the bottom of the neck piece.  This will be used for aligning it with the wing centerline.  If you sanded the leading edge of the wing round, you will need to sand the rear of the neck piece at an angle so that it will make good contact with the wing.  Place a piece of waxed paper under the wing, and using a straight edge make sure the neck makes good contact with the wing and that it will be straight with the centerline of the wing.  Making sure the wax paper is under the glue joint, glue the neck to the wing keeping it straight.  It is very fragile at this point till you glue the body tube down so handle carefully.
  16. Test fit, then glue the body tube assembly so that it is even with the rear of the wing, makes solid contact with the wing and neck and is level and straight.   Make sure the neck is centered on the body tube at the front.  The tube will stick past the end of the neck, that’s ok the bridge will glue to the tube later.
  17. Glue a fuselage side plate on each side of the body tube so the step is on the doubler.  This helps provide some extra gluing surface for the wing/body tube joint.
  18. Glue the rear plates against each side of the fuselage plate toward the rear of the model with the angle facing forward.  These help keep the model from sagging in the middle as it lands.  Glue them just forward of the rear of the fuselage side pieces.
  19. The warp pod assemblies glue on the wingtip against the wing doubler.  Make sure they make full contact and are straight compared to the fuselage tube.  Glue a pod on each side.
  20. Flip over the wing and sand the wingtip round  to blend it into the warp pod, then lay the wing upside down again.
  21. Make holes for the Control horn prongs, about 1/2″ from the inboard end of each control surface.
  22. Apply CA+ to each of the control horns and press them in place in the bottom of each control surface into the pre-made holes.  Note the control pushrods go on the inside of each control horn nearest the body tube  The holes in the horn face forward and the pushrod should be closest to the body tube.  Apply a fillet around the control horn and the top of the prongs on the top of the wing.​
  23. At this time it is easier to go to radio installation since the wing can sit flat on the table while you install the radio gear.

 

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 via the esc/flight battery.   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 use this arm and trim off one end.   Zero out any trim settings on the transmitter.

  • Connect a servo to each pushrod.  If the pushrod is too tight, you can use twist an X-Acto knife in the servo arm hole to make it larger, but be careful and do not make it too large.  Once connected, lightly 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.  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 foam safe CA+.  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 moderate 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. Note**  The servo electrical wire should point toward the front of the model, you want the pushrod to be perpendicular to the hinge line, the servo will be near the edge of the wing doubler.  See the photo for an idea of how it should look. The servos will be 2″ to 3″ away from the fuselage.  Disconnect the servos from the receiver.
  • Tape the servo wires down against the step in the wing doubler using the blenderm tape.
  • 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 3/4” in each direction, aileron movement should be 1/2″ in either direction.
  •  Lay the model upside down on a table.
  • Glue the ply plate to the rear of the body tube and mount your motor.
  • Attach the speed control to the motor and receiver.
  • Attach the servo wires to the receiver and make sure the controls are still working as they should.
  • Using velcro attach the flight battery, receiver and esc to the model. I placed the battery and esc on the right side of the fuselage, the battery was far forward as possible next to the fuselage and under the wing.  I placed the receiver on the left side of the fuselage.   You will need to route the ESC control wire over to the other side of the model.  You can cut a notch in the side fuselage foam and route the wires over the tube and tape them down or you can cut a 1/2″ by 1/8″ slot on both sides with an exacto through the fuselage foam and tube and route them through.  I’ve found you can tuck extra wiring into this slot, then cut a spare piece of foam oversized and push it in place to hide the slot if desired.
  • Glue the bridge to the forward body tube.  The inner bridge piece butts against the front of the neck and the top of the bridge overlaps the neck piece.  When glued in place properly there will be about a 1/2″ gap from the front of the tube and the front of the bridge wrap.  This gap is used to place nose weight when balancing.
  • The plastic plate for the bottom of the bridge will be painted separately then taped in place for balancing.  Once your nose weight is added as needed, you can tack glue the plate in place.
  • Glue the vertical fin/upper wing assembly onto the top of the wing with the rear even with the rear of the wing.  You want to make a mark on the assembly for the middle and use a straight edge to make sure you are keeping the assembly in the middle and the vertical stab exactly lined up with the body tube and bridge assembly.  Make sure you are centered at the rear as well between the two elevons.  Make sure the elevons clear the angled plates glued to this vertical stab assembly, if not trim the inboard ends of the elevons so that they do clear.
  • Glue the bridge details to the top of the bridge.  The major assembly is complete, you will do a pre-balance and then paint the model and do a final balance before flying.  Paint adds about 1/2-3/4 ounce and the model can become tail heavy after painting.
  • 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 rightside up on the pencil erasers on the balance point indicated above.  Use pieces of the included lead weight as far forward into the tip of the nose to balance it, as needed.  Glue the lead weight in place so it does not shift during flight. Tape the plastic bottom plate in place when you balance so that it is included in the balancing.  The model should balance slightly nose down.   When done you can temporarily use masking tape on the inside of the plastic bottom plate to hold it in place during painting.  Do not glue it in place till you have re-checked balance after painting.
  • I can only recommend testors/model master enamel spray at this time, others I’ve tried damage the foam surface.  I recommend flat colors as they dry faster and the surface imperfections of foam aren’t as noticable.
  • At this point remove the battery, receiver, motor and esc and mask the servos/wire ends and velcro patches for painting.
  • I used flat black spray for the vertical stab to help hide it during flight. Use a large plastic garbage bag and cut a slot for the tail, enclose the model in the bag and just mask the small portion around the base of the vertical stab. Try not to get overspray on the rest of the model as it will require more gray to try to cover and get an even color.  Spray the vertical stab.  Once dry, remove the bag,  then cover the vertical stab with plastic wrap, and a small amount of tape at the bottom.
  •  Then lightly spray the model, you want just enough to look gray without adding a lot of weight. I used Flat Dark Aircraft Gray #1226.    Don’t paint too close to the model or you risk melting the foam.  The foam sanded edges and surface have a texture, it will not be possible to get a smooth shiny paint job like on normal smooth surfaces but that’s totally fine.    When removing the masking for the vertical stab, If any paint pulls up just touch up with a small brush.
  • You can use a black fine line sharpie to add panel lines or details if desired.
  • Apply the markings to the model, the two silver markings go on the angle plates and the logo goes on the left wing.  Once applied use a hair dryer on hot to lightly soften the markings and then rub them down with your finger to help them set down fully into the wing/paint.
  • Re-attach your battery, receiver, esc and motor, and tape down the wiring for a nice clean installation.  Then re-check the balance.
  • Support the model at the balance point indicated for boost.  Re-balance the model and add nose weight if needed.  Glue the lead weight in place so it does not shift during flight.  Do not try to fly the model too nose or tail heavy.  Remember, a nose heavy model flies poorly, a tail heavy model flies once.  Once balanced glue the styrene sheet in place.  If you find the model twitchy on boost you can add more nose weight, simply pop the styrene sheet loose at the front and add weight and re-glue if needed.  Alternately you can tack glue the plate in place, and glue permanently after test flights to be sure it flies the way you want.
  • On my model I added a slow flashing 5mm green led into the nose.  The led package shown in the pictures runs off of direct 4-5v.  I simply took a 24″ servo extension, clipped off the receiver end, soldered to the diode with the red wire on the long lead and black wire on the short lead and shrink wrapped the led leads to prevent shorting.  On the other end I removed the plastic female outer plug leaving the internal plug with exposed pins.  I clipped off the extra pin and and plastic leaving a two prong plastic plug.  This plug can go directly into the balance plug of the flight battery, make sure the black lead is matching the negative or black lead on the balance plug or you can short out the diode.  I drilled into the nose of the model, inserted the wiring and glued the diode in place with bob smith foam tac glue.  Routed the plug through the body tube and out the slot I used for routing the servo wire and esc wire  to the receiver side.  The light isn’t very visible in flight until you are close to landing, but it looks cool.  Alternately you could use the other end of the servo extension wire and plug it into a spare receiver slot again using the red and black wires.  You take a slight risk that if the diode fails and shorts it will short your receiver power coming from the esc.

Flying:  My model needed no up trim for level flight at medium throttle, I hand launched at about 30-40% throttle at a level attitude and required 4-5 clicks of right trim to counter torque.   For landing I just chopped the throttle and let it settle with a slight flare. If you are landing on a hard surface you may wish to mount a skid on the bottom of the forward bridge to help prevent road rash.

© 2018 Dynasoar Rocketry                                                     Hosting provided by Armored Planet