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Curtiss JN‐4D ʺJennyʺ 41.25ʺ
Curtiss JN‐4D ʺJennyʺ 41.25ʺ
R/C Scale Model Instructions
CONTACT INFORMATION
Designed by: M.K. Bengtson
Prototype by: Bert Ayers
Manufactured and Distributed by:
Bengtson Company
e‐mail: sales@aerodromerc.com
Web Site:
www.aerodromerc.com
Copyright© 2005‐11 M.K. Bengtson All Rights Reserved Rev 07/11
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Summary of Contents for Curtiss Jenny
- Page 1 Curtiss JN‐4D ʺJennyʺ 41.25ʺ Curtiss JN‐4D ʺJennyʺ 41.25ʺ R/C Scale Model Instructions CONTACT INFORMATION Designed by: M.K. Bengtson Prototype by: Bert Ayers Manufactured and Distributed by: Bengtson Company e‐mail: sales@aerodromerc.com Web Site: www.aerodromerc.com Copyright© 2005‐11 M.K. Bengtson All Rights Reserved Rev 07/11 ...
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Page 2: Building The Model
Curtiss JN‐4D ʺJennyʺ 41.25ʺ Page 2 BUILDING THE MODEL Curtiss JN 4D “Jenny” Use the plastic bag that the kit comes in to cover the plans Thank you for purchasing the Curtiss Jenny model for in each of the building steps. Slit the bag down the side electric flight. and sealed end to open it up into one large sheet. Laser cut parts can best be taken out of the balsa sheets by using THE MODEL a#11 x‐acto blade to cut the minute bridges in the laser A semi scale adaptation of the Curtiss Jenny, this model is cuts. designed to be easy to build and exciting to fly. Pushing them out without cutting the bridges may break the part. The model above was built with 1/8” square strips cut from the excess areas of the 1/8” laser sheets. CA glue for the balsa parts and epoxy for the lite‐plywood parts were used on the pictured model. TAIL SURFACES The tail surfaces are a good place to start – to get acquainted with building with laser cut parts. Find all the “S” parts on the 1/8” laser sheets, cut the small bridges where the laser didn’t cut and finish cutting the part. The part should pick out of the sheet with no effort. All the Finished Model By Bert Ayers “S” parts make up the vertical stabilizer and rudder parts. Some 1/8” square stock will be needed to make the ribs. POWER SET UP Cover the plans with the shipping bag and pin down the The model can be set up to be powered by the 6V S400 parts. CA glue together. Allow to set for 5 minutes and motor and the Mini‐Olympus 2.33:1 Gearbox with a 8x4 remove from the plans. APC prop. Battery power pack can be 8 600mah NiCad ... - Page 3 Curtiss JN‐4D ʺJennyʺ 41.25ʺ Page 3 Tail Surface Construction Detail Now that you are an expert at building with laser cut Wing Construction Detail parts, we can proceed with more complicated structure. The top wing varies in that it has ailerons. The aileron WINGS leading edge is laser cut part ULE. The aileron ribs are The wings require a little prep work before assembly can wedge shaped and not marked with a number. The holes begin. The 1/8” x 3/8” bass spars and 1/8” square spars as in the ribs are to run the aileron servo wires to the center well as 1/4” square balsa Leading Edge and 1/8” x 1/2” section. balsa Trailing Edge stock are not supplied in the kit. One top wing spar and one bottom wing spar can be cut from one 36” piece. Cut all spars to correct length. The UTE laser cut piece can be glued to the bottom 1/8” square top wing spar. Cut out the L1 ribs and glue in the 1/8” locating dowels. Cut out the L4 , R4 and R7 ribs and glue on the side pieces that reinforce the strut joints. Mark and cut the rib notches in the trailing edges. Wing Construction Detail The bottom wings (L1 to L2) have 1/16” sheet balsa on top. To join the top wings together, a center section is build with a 1/16” plywood brace. Scrap 1/8” x 1/4ʺ balsa is used on the insides of both R8 ribs to reinforce the cabane strut joint. The plywood brace has dihedrl in it. Note the line where the aileron servo is that indicates where and how much to block up for the dihedral when epoxing the wings and center section together. Wing Construction Detail Now we are ready to cut out all the remaining wing parts. Start with a bottom wing to warm up for the tasks of the top wings. Cover the plans with the shipping bag and pin down the 1/8” x 3/8” bass spar and 1/8” square rear spar. ...
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Page 4: Fuselage Construction
Curtiss JN‐4D ʺJennyʺ 41.25ʺ Page 4 manner on these panels, always checking that everything fits within the space. Screws were this builder’s preference—other ways are OK. Fuselage Construction Detail Cover the plans with the shipping bag. Begin by building the rear section. Pin down the 1/8 square balsa strips and Servo Construction Detail cross members. Let CA glue set for a few minutes, remove pins, then fold plastic sheet over glued parts and build another section right on top of the first section making both sections identical. Servo Construction Detail Sand the wings to the profiles shown on the plans (L.E. and T.E.‐rounded tips) Hinge the ailerons, rudder and elevator in your favorite manner. Fuselage Construction Detail Join the two sections over the top view plan with the cross FUSELAGE CONSTRUCTION members. Taper the tail post on the inside a small amount. The fuselage is built as two structures, a front and a rear Check and recheck to make sure everything is VERY section, which is joined over the plan. This system not square. only keeps each stage simple, but it also helps to ensure a Next, build the front fuselage and add the cabane struts straight fuselage. while the sides are flush with the plan. This method insures that the struts are in proper alignment. Copyright© 2005‐11 M.K. Bengtson All Rights Reserved Rev 07/11 ... -
Page 5: Landing Gear
Curtiss JN‐4D ʺJennyʺ 41.25ʺ Page 5 Time to join front half to back section. This builder hung the plans (top view) over the end of the table so that the front section aft of the the rear cabane strut sat flat on the plans and was able to glue the rear section (top down) to the front section, keeping everything square to the plans. A small weight kept front section in place. Add formers F2, F4, F5, F6 and F7. The 1/16” balsa top decking needs to be pre formed by soaking in hot water and taped over a similar radius as formers F2. Allow to thoroughly dry before removing from mold. Make a pattern out of card stock that fits perfectly over fuselage. Transfer pattern to formed balsa deck, trial fit to fuselage. Do not cut out cockpit holes until decking is glued to fuselage. Add the 1/16” stringers Front Fuselage and Cabane Construction Detail to rear fuselage. Front Fuselage Motor Mount Construction Detail Join the front sections together using F1, 2‐UC (good time Pre Form Top Decking to drill holes for lacing undercarriage to fuse, while their flat), motor mount (mark top of motor mount to make sure it is epoxied in proper direction of motor thrust) and 3 F2 spacers. These are all the same width. Epoxy together—check and double check‐ that everything is SQUARE. When epoxy is cured, epoxy in F3 and F8, these are not as wide as the forward members and will be tapered in a very small amount. Front Fuselage Construction Detail LANDING GEAR Bend the 1/16” music wire to fit the patterns on the plans. Make a temporary fixture to solder the wires together. Draw lines on the plans to determine where the axle wire ... -
Page 6: Install The Radio Gear
Curtiss JN‐4D ʺJennyʺ 41.25ʺ Page 6 Landing Gear Construction Detail Landing Gear Detail Find the wheel parts. Use a brass tube to center the 1/32” INSTALL THE RADIO GEAR rim plates on the 1/4” balsa wheel core. Add the 1/8” ply This is a good time to install the radio gear while the collars. Massage the Neoprene foam rod into a circle, then fuselage is uncovered and access to the interior is easy. CA glue the ends together. Take time to get it into a DUMMY MOTOR smooth joint. Assemble the dummy motor from the balsa parts supplied and sand to shape. Not all parts of the engine are supplied as some are best fabricated from other materials. INTERPLANE STRUTS Find the 1/8” lite plywood interplane struts T1 and T2. T1 goes to the front wing position and T2 is for the rear wing position. Sand to round front and back of struts. You can trial fit the whole Jenny skeleton to see how everything fits. Wheel Kit Construction Detail Roll the neoprene tire onto the balsa core. CA glue the neoprene to the 1/32 “rim plate. Use CA sparingly, as it really likes the neoprene. Transfer the spoke cone pattern on the plan to heavy card stock (make 4). Use a ballpoint pen to score each line on the back to make an impression Ready to Cover of “spokes”. Fold the paper along the crease lines to exaggerate the raised lines. Cut one spoke line to the center and overlap to the next spoke line to make a cone, glue. White glue is used on the cone attachments. The inside cone may be attached to the wheels. The outside cones may be attached at this point if wheel collars are to be used. Alternatively, after installing the wheels on the ... -
Page 7: Final Assembly
Curtiss JN‐4D ʺJennyʺ 41.25ʺ Page 7 FINAL ASSEMBLY Turn the plane over and set on the table on its wheels. Use This model is designed to be easy to assemble. Assembly the same blocking for the tail post to raise the tail section. starts with the model inverted. Block up the center Trial fit the horizontal stabilizer/elevator (hinge the section of the top wing 3/8” upside down. This supports elevators in your favourite manner‐if you haven’t already the dihedral. Holding the fuselage upside down fit the done so). Make sure the leading edge of the stabilizer is cabane struts into the four holes in the center section of parallel to the wings. Measure from the wing tips to the top wing. Blocking up the tail post the appropriate same place on the stabilizer tips. Triangulate. Should be amount helps to hold everything in place. Make sure the equal on both sides. Manicure the fuselage saddle/tail fuselage sides are square to the wing center section. post if necessary to achieve a parallel. Adding material is Measure (triangulate) from the tail post to the wing tip on better than taking away in this area. Epoxy when satisfied. both sides to make sure both are equal. When satisfied, put epoxy in the cabane strut holes, re‐measure and let epoxy cure. Leave everything in place. Trial fit the interplane struts and wing locating dowels on the bottom wings. Do the tail post measurements on the bottom wings also. When satisfied, epoxy together. The builder of this model added another step to check for accuracy. He made three fixtures to assure correct incidence on the wings. These fixtures were drawn right off the plans. Two were taped to the fuselage to assure the top wing incidence and another used to assure correct wing to wing distance when gluing the interplane struts. Checking for Accuracy The vertical stabilizer/rudder is epoxied onto the top of the horizontal stabilizer with S1 fitting in the slot in E9. Use a square‐‐‐the vertical stab/rudder must be 90 degrees ... -
Page 8: Contact Information
Curtiss JN‐4D ʺJennyʺ 41.25ʺ Page 8 Battery hatch 1. CG location. Tail‐heavy models never fly well or at Fashion a battery hatch from 1/32” ply. all. 2. Down and right thrust. Motor and gearbox tips. 3. Straight and non‐warped wings. The mini‐Olympus gearbox is very durable and reliable CONGRADULATIONS, YOU HAVE BUILT but it does have a few weak points. A BEAUTIFUL CURTISS JENNY! 1. There is often flashing on the gears making rough spots or binding which robs power. Take a sharp CONTACT INFORMATION Exacto knife and remove this until your gearbox turns smoothly. Distributed by: 2. Excess flashing also occurs where the motor is Bengtson Company mounted that makes alignment poor and again robs e‐mail: sales@aerodromerc.com power. Take the Exacto and carve away this excess Web Site: www.aerodromerc.com until the motor fits easily. 3. Loose setscrews on the main shaft and motor let power slip away. Tighten all these set screws carefully. TOO MUCH will distort the pinion gear and makes another binding. CA the pinion on the motor shaft if necessary. Recheck this after a nose ...
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