Preparing For Covering

Regardless of what type of covering material you elect to use, a good covering job starts with good surface preparation. You can't hide poor workmanship with covering material! Fill any small surface gaps with a light-weight filler or spackling paste. Sand the entire model including the ailerons and tail surfaces, with 220 grit sandpaper, then again with 360 or 400 grit sandpaper.


The structure that is to be covered must be clean, dry, and dust free. Wipe the entire surface with a tack rag or a cloth dampened with alcohol to remove all excess dust.

Before starting the actual application of the covering material, use your wife's or mom's (ask first) favorite vacuum cleaner with the soft brush attachment and vacuum the entire model and the work bench. This greatly helps eliminate the dust particles tnat get under the covering.

Select A Covering

All of the Ninja prototypes were covered with Sig Supercoat Iron-on Plastic Covering. Supercoat is ideal for slope soarers because of its light weight and ease of application.

The color scheme that is pictured on the label is quite easy to duplicate and only requires two rolls of Sig Supercoat Covering. The colors needed are two rolls of Black. In addition you will need one roll of Sig Supertrim Cub Yellow, one roll Dark Orange, and one roll Waco Red. The canopy was covered in Silver, however any contrasting color can be used and still have the same effect.

You will notice in the following photos of the covering process, that we prefer to use a "sock" on our sealing iron. This is not necessary, but is a personal preference. A sock helps eliminate the unsightly small scratches that can be caused from the dragging the iron across the surface of the covering material. We also highly recommend that you use a temperature gauge to set the temperature of your iron to the exact setting the covering manufacturer recommends.

Covering The Wing


Start by covering the back of the trailing edges, including the insides of the wing tip and torque rod assembly, with 1/2" strips of covering material cut from the roll.


Cover the ends of the wing tips making sure to run the covering material "around the corner" about 1/8".


Cover the bottom of the wing first and then the top of the wing. This leaves the front seam overlapped on the bottom where it is less visible. Cut the covering to size, allowing approximately 1" excess around the edges. Lay it down and smooth out as many wrinkles as possible.

Using your hot sealing iron, carefully iron the covering material from the center of the wing panel out towards the wing tip, and then out towards the wing root. This is to help avoid trapping air bubbles under the covering. Work slowly and allow the iron to shrink the covering as you go along. Trim the covering off flush with leading edge and reseal it with the iron.


77. Trim off the excess covering material leaving a 1/8" overlap at the trailing edge. Seal the overlap down with an iron.


Cover the top of the wing in the same manner as described in the above steps 74 through 76. Leave a 3/16" overlap of covering material on the leading edge of the wing and seal it down with an iron.

Repeat the process from steps 74 through 78 to finish covering the other wing panel.

Covering The Fuselage


Cover the bottom of the fuselage first. When cutting the material for the bottom allow enough extra material around the nose, or any other area with compound curves, so you can get a good grip on it with your hand. Start by sealing the covering to the model at the tail. Work slowly forward with the sealing iron, sealing the covering smoothly to the bottom of the fuse. When you get to the nose area, work the iron over the covering with one hand while you pull on it with the other. As the covering becomes pliable from the heat, you can pull it gently around the curve. Work slowly, allowing the heat to do the work. Do not pull too hard or the covering might tear.


Trim off the excess covering material with a sharp single-edge razor blade and reseal the edges with the iron.


Repeat this procedure for covering both sides of the fuselage. Allow about 1/8" to 1/4" overlap onto the top and bottom of the fuse.


Cover the fuselage top in the same manner as the bottom and sides. Remember to reseal the edges after trimming.

Covering The Tail Surfaces And Ailerons


The stabilizer, elevator, ailerons, and fin should each be covered with two pieces of material - cover each side separately. Iron the material from the center out to avoid trapping air bubbles. Once the ailerons have been covered, cut away the material to expose the slot and hole for the torque rods.


Installing Easy Hinges

Sig's famous EASY HINGES have been included in your kit to hinge all the control surfaces. Each ultra-thin hinge is actually a three-part laminate, a tough plastic inner core sandwiched by an absorbant wicking material on each side. They are specially designed to be installed with thin C/A glue. The hinges have been chemically treated to slow down the set time of the glue to allow it to soak all the way to the ends of the hinge and into the wood surrounding it, for a super strong bond. Once the glue has dried, the hinge cannot be pulled from the structure without tearing wood out with it! We recommend that all surfaces be completely covered before installing the EASY HINGES.


Use a #11 X-Acto blade (or similar) to cut slots in the stabilizer trailing edge and elevator leading edge to accept the EASY HINGES. Make the slots approximately 1/2" in depth and slightly wider than the hinges. Refer to the full-size plan for the exact hinge locations.


After all of the slots have been cut, insert EASY HINGES halfway into the stabilizer slots. DO NOT GLUE THE HINGES YET! Next, carefully slide the elevator onto the hinges. You'll find it easiest to slide the elevators onto the hinges at an angle, one at a time, instead of trying to push it straight onto all the hinges at once. Don't be concerned if the hinges aren't perfectly straight or centered in the slots - they don't have a center line.


To set the hinge gap, deflect the elevator to the maximum amount needed. For best control response, the gap should be as small as possible but big enough to allow full movement of the control surface.


Place three or four drops of thin C/A directly onto the hinges in the gap. The glue will wick into the slot as it penetrates both the wood and the hinge. Continue this process, gluing the same side of all the EASY HINGES. Then turn the stabilizer over and repeat the gluing process on the other side of each hinge.


After the glue has cured (3 to 5 minutes) the joint should be flexed to full deflection in each direction a couple of dozen times to reduce the stiffness. Don't worry about shortening the life of the hinges, as they are almost indestructible.


The ailerons are hinged exactly like the tail surfaces, except that the torque rods must be glued in at the same time the hinges are put in the slots. Start by cutting the slots in the wing and the ailerons (three per aileron) and slide the EASY HINGES halfway into the ailerons only. DO NOT GLUE THE HINGES YET!


Next slide a small piece of wax paper between the torque rods and the wing. Working with only one wing at a time, apply Kwik-Set epoxy glue to the slot and hole in the aileron leading edge, and then slide the aileron onto the torque rod, working the EASY HINGES into the wing slots at the same time. Try not to get any epoxy on the brass tubing! Before the glue sets, be sure to deflect the aileron back and forth to set the proper hinge gap.

Once the epoxy has dried, remove the wax paper and apply thin C/A to the EASY HINGES, in the same manner as you did earlier for the elevator.


Bolt the wing in place and then position the stabilizer on the stab support at the back of the fuselage. Carefully align the stab with the wing. Refer to the alignment drawing and carefully align the stab with the wing. When satisfied with the alignment, draw cut lines on the bottom of the stabilizer at the fuselage sides. Cut away the covering on the bottom of the stab where it will be glued to the fuselage (there must be wood to wood contact in the glue joints). Use a sharp modeling knife or a single-edged razor blade and don't cut too deep into the wood.


91. Glue the stab in place onto the fuselage. Use slow drying epoxy (SIGEG001) to allow you ample time to carefully realign the stabilizer with the fuse and wing. Check and double check the final alignment of the stab to the wing from the front and top before the glue dries. Step back about 10 feet and view the model from the front. Tilt the stab for proper alignment if necessary. Use a tape measure to make sure the stabilizer tips are at equal distances from the trailing edge of the wing. Use pins to hold the stab securely in position until dry.


Cut away a 1/8" strip of covering material from the center of the stabilizer where the fin is to be glued. Epoxy glue the fin onto the stab and into the die-cut slot in the fuselage top at the same time. Use a 90 deg. triangle to align the fin with the stabilizer, pin securely in place, and allow to dry.


A 1/2"x12" strip of ABS plastic is provided for a landing skid. Round the two front corners of the strip with a sanding block. Apply double-coated foam servo mounting tape to the plastic skid, remove the paper backing from the tape, and press the skid into place.
NOTE: The ABS plastic skid can be painted a matching color with either enamel or dope.

Completing The Elevator Pushrod


A small nylon control horn has been supplied for the elevator. Install the control horn onto the elevator with #2 x 1/2" sheet metal screws.


To complete the installation of the nylon elevator pusnrod, first cut one of the 2-56 x 10" threaded rods provided to 3-1/2" overall length, measuring from the threaded end. Slip the rod completely into the inner pushrod tube and then screw in about 1/4" of the threaded portion. Screw the nylon R/C link onto the rod leaving a gap of about 1/8" from the end of the inner pushrod.


Slide the 1/8" o.d. nylon inner push rod tubing into the outer tubing from the elevator end of the fuselage and attach it to the nylon control horn. With the elevator level, cut off the protruding end of the inner pushrod 3/8" from the end of the other pushrod tubing. Unhook the nylon R/C link from the control horn, and push the inner pushrod forward towards the servo.


Locate and cut one of the 2-56 x10" threaded rods provided to 1-1/2" overall length, measuring from the threaded end. Then put a "Z" bend (or a ''L" bend if you are going to use a pushrod keeper) in the non-threaded end of the rod.


Screw the threaded end of the wire approximately 1/4" into the 1/8" o.d. nylon inner push rod tubing. Install the "Z" bend through the servo arm and hook it up to the servo and reconnect the R/C link to the elevator control horn. NOTE: It may be necessary to trim the servo arm down to prevent it from rubbing on the side of the fuselage.


Aileron Pushrods


Mount the aileron servo to the hardwood rails in the manner recommended by the radio manufacturer.


The aileron pushrods are made from two 2-56 x10" threaded rods. Screw a nylon R/C link onto the threaded end of each rod. Next screw the self-threading nylon aileron connectors that are provided 1/4 of the way down the aileron torque rods that are sticking out of the wing. Snap the R/C links into the aileron connectors and line up the pushrods with the servo arms. With the aileron servo neutralized and the ailerons level, measure 1/2" past the servo arm and cut off the wire. Put a "Z" bend in the end of the rods and install them in the outside end of the servo arm.

The aileron horns are offset for differential movement as much as is practical without striking the fuselage structure during movement. Some of this offset is cancelled out when the adjustable nylon fittings are added. The best way to increase the amount of differential in the ailerons is by offsetting the pickup points on the servo for the push rods as shown in the accompanying drawings. Any amount desired can be obtained in this manner. The farther up the wheels the pushrods are attached, the greater the differential, ie., more up. less down movement.

Radio Installation


A typical 2 channel radio installation is shown in the photo. The battery pack and the receiver are lightly packed in foam rubber and positioned just forward of the elevator servo. The switch harness is servo taped to the fuselage side just opposite the elevator servo. This allows the radio system to be easily turned on and off by removing the quick release hatch.

Recommended Control Surface Movements

The following control surface movements are recommended for initial flight tests and for newcomers to the sport of R/C slope soaring. For the accomplished pilot and for all out aerobatic performance the following movements are suggested.
ELEVATOR 3/8" UP and 3/8" DOWN ELEVATOR 1/2" UP and 1/2" DOWN
AILERONS 1/2" UP and 7/16" DOWN AILERONS 9/16" UP and 1/2" DOWN

Optional Rudder

There may be some of you, especially veteran slope fliers, who will want to modify the Ninja from two channels (aileron and elevator) to three channels (aileron, elevator, and rudder) for increased aerobatic performance. The hardware that is provided in the kit is for the two channel version only.

To convert the Ninja to three channel operation you will need the following items, (1) SIGSH568 30" nylon pushrod assembly, (1) SIGSH220 short nylon control horn, and (2) EASY HINGES.


102. Drill an additional 3/16" hole in the opposite side of fuselage former F-2 to accept the outer nylon push rod for the rudder.
NOTE: The fuselage construction must be completed through step 66 before proceeding.


Cut a slot 3/16"x1-1/8" in the fuselage top for the outer nylon push rod tubing to exit through, as shown in the diagram.


Install the 3/16" o.d. outer nylon push rod tubing (SIGSH568) for the rudder by passing it through the pre-drilled hole in former F-2 and the diecut notches in formers F-3, F-4, and the push rod exit hole in the fuse top. Epoxy glue the outer push rod tubing in place at each of the fuse formers and to the fuse top.

NOTE: Make sure that the outer push rod extends out in front of former F-2 for 3/16". Cut the outer push rod tubing oft flush with the top of the fuse.


Hinge the fin and rudder with EASY HINGES.


After the fin/rudder assembly is glued in place on the fuselage and properly aligned, install a small molded nylon control horn (SIGSH220) onto the rudder with two #2 sheet metal screws.


Refer to the elevator servo and pushrod installation procedures elsewhere in this book for guidelines on completing the rudder servo and pushrod installation on the opposite side of the fuse.


Adjust the control throw of the rudder so that you have minimum of 3/4" left and 3/4" right of movement.


Make a balancer from a block of wood and two pencils that are tipped with erasers. Drill two holes in the block of wood about 3" apart and install the pencils. To check the fore and aft balance of your model, mount the wing on the fuselage and place the model in the balancer. The fuselage side view plan shows two locations for balancing the Ninja. The forward C.G. location is best suited for the first test flights and newcomers to the sport of R/C slope soaring. The rearward location is for more experienced pilots. The rearward C.G. makes the Ninja more sensitive to control movements, improving it's aerobatic ability. Balance the Ninja within the recommended C.G. range to suit your needs. Do not attempt to fly the model with the balance point any further back than the rearward C.G. limit.

The spanwise balance of the wing is an often overlooked but essential part of balancing a model. Check the spanwise balance of the wing by placing the wing upside down on the balancer. Hold the wing level and then release it, observe which wing panel falls. Add very small amounts of weight to the opposite wing tip until it will balance. NOTE: Small finishing nails pushed into the end of the wing tip are ideal for this.



Make sure the servos are securely mounted, the servo arms have their retaining screws in place, and all screws are tight. Range check the radio as per the manufacturer's instructions and make sure it is fully charged. If there are any problems, send the radio in for repairs.

DOUBLE CHECK EVERYTHING YOU CAN THINK OF! A model and radio that is not prepared and working properly on the ground before take-off will not improve in the air - IT WILL GET WORSE! There is no point in attempting to fly until everything is 100% correct.

First Test Flight

Choose an area that is free of obstructions such as buildings and trees, and pick a day when there is little or no wind. If your flying site is occupied by other fliers, check with them to be sure that your frequency won't interfere with theirs, and vice-versa.

Gently hand toss the glider into the wind with the nose pointed slightly down and the wings level. Start by running a couple of steps with.the model, then release it with a smooth spear-throwing action. Aim for a spot on the ground about 50 yards out ahead of you. The Ninja should glide smooth and flat with no veering to the left or right. After each test flight, readjust the R/C links on the push rods so that the trim levers on the transmitter can be returned to a neutral position. It may take several flights to completely trim out the model.

Introduction To Slope Soaring

Slope soaring offers a unique brand of flying excitement not found in other types of R/C model flying. From flying lazily along with a floater, to breathtaking high speed beach runs, slope racing, and aerobatics, there is something for every skill level of pilot. Besides being a lot of fun, how many other model pilots do you know who want the wind to blow?

It is easy to see why slope soaring is fast becoming one of the most popular parts of R/C soaring. Slope soaring is no longer limited to just the east and west coasts. As the popularity of slope soaring grows, more flying sites are turning up throughout the country.

Finding a Hill

Wherever you can find a respectable-sized hill with a 10-20 m.p.h. wind blowing straight into the slope, you can slope soar. The wind is deflected upward by the slope of the hill creating the lift we soar on. The amount of lift generated by a particular hill is regulated by the wind velocity and the amount of slope in the hill. Also a hill that has a smooth approach to it (free of trees, buildings and etc.) will almost always produce stronger lift. Don't overlook places like dams, reservoirs, bluffs overlooking lakes and river valleys. They all make good flying sites. The ideal slope site is one in which there is a "bowl" created by either a curved hill or by a series of hills.

Flying Tips For The Novice Slope Soarer

Launch the Ninja into the wind out over the crest of the hill by throwing it with the wings level and nose pointed slightly down. Let the model travel out a little ways to build up speed and then make a turn that brings the flight path of the model parallel to the slope. When you need to turn the model around, make your turn into the wind away from the slope and again fly parallel to the slope. Repeat the above procedure when it is time to turn again. Flying this flattened figure eight coarse back and forth across the face of the slope is standard procedure. This helps keep the model in the maximum lift zone which yields the most altitude gain.



The clean lines and the low frontal area of the Ninja allow it to penetrate winds in the 10-20 m.p.h. range without ballast. However, when flying in winds of excess of 20 m.p.h. some ballast may be needed. Stick-on lead weights are ideal for adding ballast. Simply press them in place inside the fuselage directly over the C.G.


Slope soarers don't have engines to pull them through aerobatic maneuvers like power models do, so we have to rely on the lift and the speed of the model to perform aerobatics. Always pick up speed by diving the model before entering a maneuver. The amount of speed required, depends on the maneuver and the available lift. If you are new to slope soaring make your maneuvers into the wind at first until you feel comfortable. Aerobatics with the Ninja are a snap. It will do any maneuver in the book and then some.

When the Sig Factory Fliers go to the slope, we have a blast making up new aerobatic "maneuvers" on the spot. For instance, how about our death defying "Chicken Immelman" - start by diving straight at the hill, wait until the last possible second, then pull up into a quick half loop and roll out at the top. Crazy, but not boring! Or how about a "Reverse Corkscrew" start real high, dive straight down (We mean straight!!!), performing two aileron rolls on the way down. Then quickly pull the airplane straight up! Try to get in two more rolls before running out of airspeed. Tons of fun!!! If you come up with any, new ones, let us know.


To make a landing approach, start with a fair amount of altitude, then fly the model slightly behind the crest of the slope, and try to fly a steady descending path right down to a landing on top of the hill. If you are too high on your landing approach, make S-turns to lose altitude or go around and try it again. Most slope soaring sites create an air turbulence on the back side of the hill. Avoid getting caught in this turbulence as it might cause you to lose control of your model and crash.

NOTE: When flying at established sites, check with the local flyers to determine what is the best approach for landing at this site.

Flying Off A High Start Or Winch

Launching the Ninja from a high start or winch is as simple and straight forward as launching any sailplane. Although most of the flights are short in duration, they can be quite exciting while doing loops, rolls, inverted flight, and other aerobatic maneuvers. Install a tow hook in the bottom of the fuselage 3-1/2" back from the fuselage former F-2. During periods of strong lift, it is possible to thermal the Ninja with flights lasting over 15 minutes.


It will take a little practice to master the art of slope soaring, but it is well worth the effort and a lot of fun. So, next time the wind blows, grab your Ninja and head for your favorite slope.

In use of our products, Sig Mfg. Co.'s only obligation shall be to replace such quantity of the product proven to be defective. User shall determine the suitability of the product for his or her intended use and shall assume all risk and liability in connection therewith.
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SIG MFG. CO., INC............Montezuma, Iowa 50171-0520