Twin Otter ARF Assembly Manual Specifications Wingspan..................................................................................... 82.0 in (2080mm) Length.......................................................................................... 65.0 in (1651mm) Wing Area.......................................................................... 738 sq in (47.61 sq dm) Weight........................................................................ 11 1/2–12 1/4 lb (5.2–6.0 kg) Radio..................
Table of Contents Contents of Kit and Parts Layout.................................2 Included Hardware.......................................................3 Introduction..................................................................4 Important Warranty Information...................................4 Recommended Setup–2-stroke Glow..........................4 Recommended Setup–Electric Power (EP)................4 Radio Equipment Requirements..................................4 Transmitter Requirements....
Included Hardware Packaged in Kit Fuselage assembly with hatch 1 Fiberglass nose cone 1 Right wing 1 Left wing 1 Right stabilizer with elevator 1 Left stabilizer with elevator 1 Right nacelle 1 Left nacelle 1 Rudder 1 Cowling 2 Right main landing gear with screws 1 Left main landing gear with screws 1 Nose leg assembly with screws 1 Landing gear fairings (left and right) 2 Wing struts (left and right) 2 3/4 x 19 1/2 inch
Introduction Hangar 9’s latest introduction, the Twin Otter is a scale model of the UV-18 ‘Twin Otter’, the military version of the DeHavilland DHC-6. The trim scheme is based on the three UV-18B planes used by the US Air Force Academy cadet parachuting program which carry a pilot, copilot and up to 17 jumpers. There are only three owned by the Air Force.
Using the Manual Product Registration Workspace Preparation This manual is divided into sections to help make assembly easier to understand, and to provide breaks between each major section. In addition, check boxes have been placed next to each step to keep track of completed sections. Steps with a single box () are performed once, steps with two boxes () indicate the step needs to be repeated, such as for left and right wing panel, or two servos etc.
Elevator Servo Installation Parts Required Stabilizer halves (left and right) Micro servos with hardware (2) Snap keepers (2) Clevises (2) Silicone keepers (2) 4-inch steel pushrods (2) 8 x 8 x 14mm servo mounting blocks (4) #2 x 3/8-inch woodscrews (8) Radio Tools Required Ruler Sidecutters 1/16-inch drill bit Pliers Felt-tipped pen Thin CA Mixing sticks Z-bend pliers Step 4 Enlarge the outer hole in the servo arm using a 5/64inch drill bit i
Step 6 Use a pencil to mark the servo location on the inside of the hatch. Step 8 Set the servo in place on the mounting block with a 1/32-inch gap between the servo and the hatch surface. Mark the servo mounting hole locations on the blocks with a pencil. Step 10 Use a #1 Phillips screwdriver and the hardware provided with the servo to install it on the hatch. Be sure to maintain a 1/32-inch gap between the servo and the hatch surface.
Step 12 Use a #1 Phillips screwdriver to thread a #2 x 3/8-inch woodscrew into each of the mounting holes in the stabilizer. Remove the screw and apply a small drop of thin CA to each hole to harden the wood and help retain the screw. Allow the CA to cure without using accelerator. Step 13 Feed the elevator servo lead through the forward holes in the ribs to the stabilizer root and set the hatch in place.
Step 18 Remove the pushrod from the elevator horn and use pliers to make a 90-degree bend in the pushrod at the marked location. Trim the bent portion to a length of 1/4-inch with sidecutters. Step 20 Optional Setup: You may choose to use Z-bend pliers to form a Z-bend in the pushrod in place of the 90-degree bend and snap keeper.
Step 2 Locate the large 4-way servo arm. Use sidecutters to remove three of the arms, leaving one long arm. Use your radio to center the servo and install the arm using a #1 Phillips screwdriver. Step 3 Prepare a second servo for the right-hand aileron with the arm facing the opposite direction. 10 Step 4 Use a 5/64-inch drill bit in a pin vise to enlarge the outer hole in each servo arm.
Step 8 Place the servo on the mounting blocks with a 1/32inch gap between it and the hatch. Use a pencil to mark the servo hole locations on the blocks. Step 10 Use a #1 Phillips screwdriver to install the servo with its provided hardware. Step 9 Use a 5/64-inch drill bit in a pin vise to drill the servo mounting holes. Apply a small drop of thin CA to each hole to strengthen the wood and help retain the screw. Allow the CA to cure without using accelerator.
Step 14 Use a #1 Phillips screwdriver to install the aileron hatch with four #2 x 3/8-inch woodscrews. Step 16 Slide a silicone keeper onto a 4-inch steel pushrod then thread on a clevis so it is centered on the threads. Step 18 Remove the pushrod and use pliers to make a 90-degree bend at the mark. Trim the bent portion of the pushrod to a length of 1/4 inch using sidecutters.
Step 20 Use a piece of low-tack tape and a felt-tipped pen to label the aileron lead where it exits the wing root.
Step 4 Use sidecutters to remove the excess servo arm beyond the enlarged second hole. Step 6 Use a pencil to mark the servo mounting locations on the hatch. Step 8 Place the servo on the mounting blocks with a 1/32inch gap between it and the hatch. Use a pencil to mark the mounting hole locations. Step 5 Remove the flap hatch from the lower wing. Note the orientation of the hatch by the black portion of its covering.
Step 10 Use a #1 Phillips screwdriver and the hardware provided with the servo to install it on the hatch. Step 11 Use a #1 Phillips screwdriver to thread a #2 x 3/8-inch woodscrew into each of the hatch mounting holes in the wing. Remove the screw then apply a drop of thin CA in each hole to strengthen the wood. Twin Otter ARF Assembly Manual Step 12 Slide a silicone keeper onto a 4-inch steel pushrod then thread on a clevis so it is centered on the threads.
Step 16 Perform steps 2 through 15 to install the right-hand flap servo. Note that the servo position on the hatch is different for the right-hand side. When performing step 5 position the servo 1/4 inch from the edge of the hatch rather than 1/8 inch as for the left-hand side.
Step 4 Slide the nacelle into place and push it all the way against the wing. Use low-tack tape if necessary to hold the nacelle in place while the glue cures. Hint: Cut a 2 3/4 inch piece of dowel and insert it between the motor box sides to help the nacelle make complete contact with the wing ribs.
Step 4 Use a drill motor and 9/64-inch drill bit to enlarge the four mounting holes. Step 5 From inside the nacelle, insert a 4-40 blind into each of the mounting holes. Use a 4-40 screw, #4 washer and 19mm standoff to draw each of the blind nuts into place with a 3/32-inch hex wrench. 18 Step 6 Measure 5/8 inch from the right-hand side of the firewall and mid-way between the upper and lower mount holes. Make a mark with a felt-tipped pen.
Step 10 Feed the extension lead through the wing to the wing root and pass the motor leads through the firewall. Use double-sided adhesive tape to attach the ESC to the right-hand side of the battery compartment. Step 11 Place a #4 steel washer on each of the 4-40 x 1 1/4-inch Allen head machine screws. Apply a drop of threadlock to each of the screws then use a 3/32-inch hex wrench to install the motor and 19mm standoffs. Mount the motor with the leads to the right-hand side.
Cowling, Propeller and Spinner Installation–EP Step 2 Use a felt-tipped pen to mark a line on the tape 1/4 inch forward of the aft edge. Step 4 Use a 1/16-inch drill bit in a pin vise to drill a hole at each of the marked locations. Remove the tape. Step 3 Measure 5/8 and 2 1/4 inches above the top of the blue trim line and make two marks with a felt-tipped pen. Step 5 Place the cowling on the nacelle and use the trim stripes as an alignment guide.
Step 6 Use the holes in the cowling to drill mounting holes in the nacelle using a pin vise and 1/16-inch drill bit. Remove the cowling and apply a small drop of thin CA to each of the mounting holes in the nacelle. Allow the CA to cure without using accelerator. Step 7 Use a 5/64-inch drill bit in a pin vise to enlarge the mounting holes in the cowling. Twin Otter ARF Assembly Manual Step 8 Use a #1 Phillips screwdriver to install the cowling with four #2 x 1/4-inch woodscrews.
Step 1 Position the firewall drilling template against the firewall and flush with its edges. Tape it in place with low-tack tape then use a felt-tipped pen to mark the 2-stroke engine mounting holes. Step 2 Remove the template and use a 1/16-inch drill bit in a pin vise to pilot drill the mounting holes. Note: When drilling the upper hole use care not to drill too far beyond the firewall and into the fiberglass of the nacelle.
Step 7 Use a ruler to measure the vertical centerline of the firewall and mark it with a felt-tipped pen. Measure down 1 9/32 inch from the top of the firewall and mark a horizontal line. Step 8 Use a drill motor and 5/16-inch drill bit to drill a hole 5/32 inch each side of the centerline. Twin Otter ARF Assembly Manual Step 9 Use a round file to remove the material between the holes, creating a slot measuring 5/16 x 5/8 inches.
Step 13 Invert the nacelle and position the engine on the mounts so the face of the drive washer is 3 1/2 inches from the firewall. Step 14 Mark the engine mounting holes on the mounts then remove the engine. Use a drill motor and 1/8-inch bit to drill the mounting holes. 24 Step 15 Place a #4 steel washer onto each of the 4-40 x 1-inch Allen head machine screws. Place the engine on the mount and insert the screws. Slide a second #4 washer on each screw then thread on a 4-40 nylon locknut.
Step 19 Use a 5/64-inch bit in a pin vise to enlarge the outer hole of the servo arm, then install an EZ link. Use needle nose pliers to press the keeper into place. Step 20 Set the servo in place in the nacelle and mark the mounting hole locations with a pencil. Twin Otter ARF Assembly Manual Step 21 Remove the servo and use a 1/16-inch drill bit in a pin vise to drill the mounting holes. Apply a drop of thin CA to each of the holes to strengthen the wood.
Step 25 Use sidecutters to trim the threaded portion of the throttle pushrod to a length of 3/8 inch. Then use pliers to bend the pushrod to the dimensions shown. Step 26 Slide a silicone keeper onto the pushrod then thread on a nylon clevis up to the bend. 26 Step 27 Slide the pushrod through the hole in the firewall and into the EZ link on the servo. Attach the nylon clevis to the outer hole of the carburetor throttle arm and secure it with the silicone keeper.
Step 30 Connect the fuel tank vent line (pink) to the pressure nipple on the muffler and the feed line (green) to the fuel inlet on the carburetor or needle valve assembly. Cowling, Propeller and Spinner Installation–2-Stroke Parts Required Wing Panels (left and right) Cowlings (2) Clear cowlings (2) Propellers (2) Spinners (2) #2 x 1/4-inch woodscrews (8) Step 2 Cut openings in the clear cowling so that it can be mounted without obstruction from the engine.
Step 4 Shown here is the cutout for the muffler. Use the nacelle cutout made in step 29 as a guide for the muffler opening in the cowling. Step 6 Install the spinner backplate and propeller and secure them with the propeller washer and nut. Use a #1 Phillips screwdriver to secure the spinner cone with the provided #4 x 7/16-inch screws.
Step 2 Slide a CA hinge into each of the pre-cut hinge slots in the rudder leading edge. Step 3 Slide the rudder hinges into the slots in the fin and align the rudder with the top and bottom of the fin. Twin Otter ARF Assembly Manual Step 4 Remove the T-pins and apply 3–4 drops of thin CA to each of the hinges. Allow the CA to cure without using accelerator so it can penetrate the hinges completely.
Step 2 Use sidecutter to trim two arms from a large 4-way servo arm, leaving two arms opposite each other. Center the servo using your radio, then use a #1 Phillips screwdriver to install the arm as shown. Step 4 Place the servo in the radio tray in the upper fuselage and mark the mounting hole locations with a pencil. Step 6 Use a #1 Phillips screwdriver and the hardware provided with the servo to secure it to the radio tray with the output shaft forward.
Step 8 Remove the pushrod. Place a small control horn on the rudder at the marked location and use a felt-tipped pen to mark the mounting holes. Step 9 Use a 1/16-inch drill bit in a pin vise to drill the mounting holes for the control horn. Apply a drop of thin CA to strengthen the wood and help retain the screws. Allow the CA to cure without using accelerator. Twin Otter ARF Assembly Manual Step 10 Use a #1 Phillips screwdriver to install the control horn with two #2 x 1/2-inch screws.
Step 14 Use pliers to crimp the sleeves and secure them to the cable ends. Step 16 Slide a copper sleeve onto each of the cables then pass them through the second hole from the base of the rudder control horns. Insert the ends of the cables back through the sleeves.
Step 2 Prepare the nosewheel steering servo with grommets and bushings. Note that the bushings are installed from the bottom of the servo. Step 4 Set the servo in place and mark the mounting holes with a pencil. Step 3 Use sidecutters to remove three arms from a standard 4-way servo arm, leaving one long arm. The required servo arm length is 1/2 inch (13mm). Center the servo using your radio then use a #1 Phillips screwdriver to install the arm as shown.
Step 8 Use sidecutters to trim the bent portion of the wire to a length of 3/8 inch (9mm). Step 10 Use a 5/64-inch drill bit in a pin vise to enlarge the center hole in the nose gear steering arm. Step 9 From inside the fuselage, pass the bent end of the pushrod through the slot in the bulkhead then connect the clevis to the outer hole of the servo arm and secure it with the silicone keeper.
Step 14 Set the hatch in place and mark the mounting hole locations with a pencil. Step 16 Use a #1 Phillips screwdriver to install the hatch with four #2 x 1/4-inch woodscrews.
Step 2 Prepare two 8-32 x 1-inch screws by applying a drop of threadlock to the end of the threads. Step 3 Slide the landing gear and fairing into the fuselage. Insert an 8-32 x 1-inch screw into the inboard and aft holes and use a 1/8-inch hex wrench to secure the gear to the fuselage. 36 Step 4 Insert the wing strut into the gear fairing and align the hole in the strut with the forward landing gear mounting hole.
Nose Cone Installation Parts Required Fuselage Nose cone #4 x 7/16-inch woodscrews (3) Step 2 Slide the nose cone into place over the screws then turn it counterclockwise to engage the screw heads in the keyhole slots in the nose cone bulkhead.
Step 2 Use double-sided foam tape to attach the battery to the left-hand side of the radio tray in the upper fuselage. You may choose to mount the battery in the nose section if required for balancing. Step 4 Mount the remote receiver in your desired location using double-sided foam tape. It is shown here on the right-hand fuselage side below the wing tube.
Step 2 Use a 1/16-inch drill bit in a pin vise to drill the mounting holes. Apply a small drop of thin CA to each of the holes to strengthen the wood. Allow the CA to cure without using accelerator. Step 4 Invert the fuselage and slide the stabilizer tube into place. Slide each stabilizer half onto the tube and connect the servo leads. Engage the alignment pin in the leading edge and slide the stabilizer into place.
Step 8 Use a 3/32-inch hex wrench to secure the wing strut to the wing with a 4-40 x 3/4-inch Allen head machine screw. Step 10 Set the top hatch in place on the fuselage and mark the mounting hole locations with a pencil. Step 9 Thread a 1/4-20 x 2-inch nylon bolt into the wing panels to secure them to the fuselage. Step 11 Use a 1/16-inch drill bit in a pin vise to drill the mounting holes in the fuselage. Apply a small drop of thin CA to each of the holes to strengthen the wood.
Center of Gravity An important part of preparing the aircraft for flight is properly balancing the model. Caution: Do not inadvertently skip this step! The recommended Center of Gravity (CG) location for your model is 2 1/2 (64mm) to 3 inches (76mm) behind the leading edge of the wing. Mark the location for the Center of Gravity on a piece of low-tack tape on the top of the wing next to the fuselage as shown.
Flight Preparations Maintaining Your Model Flight preparations should be performed each time you travel to the flying field. Because your model will encounter a variety of situations, it is best to keep an eye on the various components of your model to keep it in the best flying condition. The following is a check list you should follow every time you have completed a flying session with your model. Doing so will keep your aircraft in the best flying condition.
Safety Do’s and Don’ts for Pilots ● Ensure that your batteries have been properly charged prior to your initial flight. ● Keep track of the time the system is turned on so you will know how long you can safely operate your system. ● Perform a ground range check prior to the initial flight of the day. See the “Daily Flight Checks Section” for information. ● Check all control surfaces prior to each takeoff.
Flying Tips You will find the Twin Otter to be a very docile model in the air and on the ground. Takeoff’s are a easy. Landings are slow and gentle and very predictable. This aircraft has a very light wing loading and will be a fun, perhaps even your first, twin engine model. With the Otter’s gentle flying characteristics and excellent single engine performance you will have hours of fun flying this wonderful model. Begin by placing the model on the ground.
Warranty Information Warranty Period Exclusive Warranty- Horizon Hobby, Inc., (Horizon) warranties that the Products purchased (the “Product”) will be free from defects in materials and workmanship at the date of purchase by the Purchaser. Limited Warranty Horizon reserves the right to change or modify this warranty without notice and disclaims all other warranties, express or implied. (a) This warranty is limited to the original Purchaser (“Purchaser”) and is not transferable.
Non-Warranty Repairs Should your repair not be covered by warranty the repair will be completed and payment will be required without notification or estimate of the expense unless the expense exceeds 50% of the retail purchase cost. By submitting the item for repair you are agreeing to payment of the repair without notification. Repair estimates are available upon request. You must include this request with your repair. Non-warranty repair estimates will be billed a minimum of ½ hour of labor.
Academy of Model Aeronautics National Model Aircraft Safety Code Effective January 1, 2010 GENERAL A model aircraft shall be defined as a non-humancarrying aircraft capable of sustained flight in the atmosphere. It may not exceed limitations established in this code and is intended to be used exclusively for sport, recreation, and/or competition. 1.
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