|COVERING AND FINISHING|
Don't skip covering the fuselage and tail just because they are solid wood. Painting them without covering first is not enough. They will be much more resistant to splitting and breaking on hard impacts if they are covered with something - Sig Silk, Silkspan, Sig Silray or iron-on covering material.
|The manufacturer's directions for applying iron-on coverings are packed with the material. Follow these closely, for different types of covering have
different iron-on temperatures and techniques of application.|
Whatever kind of covering you desire to use, it will not conceal a rough framework. Sand carefully with fine sandpaper before beginning to cover.
Covering With Silk, Silkspan, or Silray
Although we refer to silk in the directions, all of these coverings are applied wet in the same manner as follows:
Brush an unthinned or very lightly thinned coat of clear Sig Supercoat or Sig Lite-Coat Dope over all parts of the framework that will contact the covering. When dry, resand with fine sandpaper, to remove any fuzz or raised grain. Brush on a second coat and sand again.
The bottom of the wing is a good place to start covering. Cut a piece of material about 1/2" larger all around than half of the wing, with the grain running lengthwise. (The grain of woven materials runs parallel to the finished bias edge.) Some builders next dip the piece in water and apply it to the wing. I find that the silk sticks together and takes a lot of pulling and smoothing to get it in place so we do it a bit differently as shown in the photo.
Pin the dry covering in place and "paint" the water on with a brush.
Go around the edges, pulling out wrinkles and stretching the material smooth. You need not pull it up drum tight, in fact going to this extreme is not advisable. Just pull out all of the wrinkles. Use pins, if necessary, to hold the silk smooth, though wet silk usually stays in place without too much pinning. We like to fasten one end - in this case the center joint of the wing - pretty firmly with pins so that you can pull against this anchored end in stretching the silk the long way.
Brush around the outside edge of the stretched silk with clear dope. The dope will soak through the material and adhere to the dope already dried into the framework. Allow to dry.
|Trim off the edges with a sharp blade. We find that a thin double-edged razor blade is ideal for this, but a single-edged blade does okay and you can't cut your fingers on it. On the bottom, trim off flush with the wing all the way around. Go over any rough areas or places that have not stuck down properly with more dope and press the loose spots down as the dope is drying and getting stickier.|
|The top half is done in identical fashion except that the silk should be brought down over the edges instead of being trimmed off flush. On the front, lap the silk over the edge of
the bottom, over-lapping about 1/8". At the back, bring the material down over the back edge of the trailing edge but do not lap it over the bottom covering.
Use the same process on the tail section and fuselage.
|Allow the water to dry out of the wood before applying the first full coat of clear dope. Apply 3 or more coats of clear dope. Sand with 220 3M Tri-M-Ite or other no-load paper. Keep in mind that extra coats of dope will add weight. Sig Lite Coat clear dope may be used in place of Supercoat Clear if desired. It has low shrink characteristics and is less likely to warp.|
Three coats of clear should provide a good base for color. Sand lightly when dry with 220 grit 3-M Tri-M-Ite no-load paper. The color dope may be brushed or sprayed.
Supercoat Color Dope should be thinned with 10% or more Supercoat Thinner for brushing. This helps prevent brush marks and gives smoother coats. Flow on wet coats and avoid rebrushing back over an area already painted. For spraying, thin dope about 50 - 50. Add more thinner if the dope does not go on evenly.
If high humidity causes the dope to "blush" or turn white, the test way to handle this problem is to wait until the humidity situation improves and apply another coat of dope. This will eliminate the blush. If it is necessary to dope during high humidity, Sig Retarder may be used in place of part of the Supercoat Thinner (amount depends on the humidity) to reduce the tendency to blush.
Painting the entire model white is recommended for a good color base, particularly when white is part of the color scheme. Color coats can be sanded with 360 Tri-M-Ite or 400 or finer wet paper. When using masking tape for trimming, seal the edge with a coat of clear dope to prevent the color dope from bleeding under the edge. Don't leave the masking tape on any longer than necessary. The longer it is on, the harder it sticks.
Complete the job with several sprayed coats of clear over the color scheme. This seals the colors and adds gloss. For best results, it is not a good idea to try to mix different brands of paint. Use SIG products from the start.
Finishing The Plastic
The plastic parts should be sanded to remove the gloss before they are painted. Don't use coarse sandpaper, which can cut deep scratches. These scratches may open up during doping (which softens the plastic) and become more noticeable. Instead use something like 220 3-M Tri-M-Ite no load silicon paper to start and polish down with 360 Tri-M-Ite or 400 wet paper before color doping.
The plastic cowling and wheel covers may be painted with Sig Supercoat Dope. Care should be used not to apply heavy, wet coats of dope. Put on light coats and allow them to dry thoroughly before applying a second coat. A spray gun is a good method of getting a good finish with a minimum amount of dope. Be especially careful with spray cans not to wet the plastic too much. Spray several light dusting coats with adequate drying time allowed. Plastic may also be painted with Sig Plastinamel, Sig Skybrite, K&B Super Poxy, Hobbypoxy or DuPont Dulux Enamel.
CANOPY: We recommend Sig Plastinamel or Sig Skybrite for painting the framing outlines on the canopy. Dope is very difficult to use on canopy plastic because of its warping action. Epoxy paint can be used, but it does not stick on the plastic quite as well as Plastinamel or Skybrite. Sanding the gloss off the plastic will help adhesion. Other enamels and plastic paints can be used, but test in advance on scrap. Glue the canopy on right after the paint is dry.
Decals are not furnished in the kit. See Sig catalog for special Kougar decals. The water-slide type will not adhere well to plastic film covering. For plastic-film covered Kougars, get Stik-Tite pressure sensitive decals. Stik-Tites can be used on any surface but are slightly thicker than water-slide decals
Assemble the tank hardware as shown in the photo. Two vent pipes are used when your engine is equipped with a pressure tap. Run a line from one to the muffler tap. Put a piece of tubing on the other, running outside the cowl for filling. Pump fuel into this until it overflows into the muffler line. Then plug the filling hole with a 4-40 bolt. If pressure is not used, install only one vent. Fill by removing needle valve line, pumping into it until fuel runs out the vent. Bring it out the bottom of the cowl so raw fuel can't spray on the canopy. You can also use pressure on a single vent tank by filling through the needle valve line and letting the line to the muffler top be the overflow vent. See "TIPS ON TANKS" for more information.
|Clevises supplied in the kit may be metal or plastic. If the pins fit too tightly in the nylon horns, open up the hole with a No. 51 drill.|
Having the proper connector makes servo installation much easier. We show here a variety of ways to attach push rods to servos.
You should decide on which type of fittings you will use in the case of the cable pushrods and have them on hand during fitting construction because the type chosen will affect the location of the pushrod exit holes through the firewall, etc. The balsa pushrods to the rudder and elevator are not limited as to location and can be adapted to any of the types of connectors shown without preliminary planning of exact position.
|Some of the variety of detachable pushrod retainers for securing the push rod wires to the servo that are available are shown here. Or you can make a "Z" bend in the end of the wires to go into the servo. When a "Z" bend is used, the pushrod must be put onto the servo outside of the fuselage and then threaded through the fuselage, which is more difficult to manage than the pushrod alone, as is the case when a retainer fitting is used.|
|5/16" square balsa sticks are provided to make the fuselage pushrods that run to the elevator and rudder. Bind the fittings to each end with heavy thread and epoxy glue. Use threaded rods with HC links at the tail end of the pushrods so that trimming adjustments can be quickly made. Straight pieces of 1/16" diameter wire are provided for the other end of the pushrods to allow hookup with the servo arm.|
RADIO EQUIPMENT INSTALLATION
The most convenient method of installing servos is on the plastic mounts which most radio equipment makers offer with their outfits or as an accessory. These are screwed to hardwood mounting rails for fuselage servos or to hardwood blocks for mounting in the wings. Instructions for the use of these mounts are included with them.
A flexible cable pushrod with nylon outer tubing (not furnished) is recommended for hookup of the throttle to the motor control servo.
A variety of quickly detachable pushrod retainers are available from Sig Catalog for hooking the pushrods to the servos. SIGSH184 pushrod retainers are recommended, or a solder clevis (SIGSH527) may be used.
Servos, for which plastic mounts are not available can be screwed directly to the two 3/8" square hardwood rails placed across the cabin, three abreast, as shown in the accompanying drawing. With rubber grommets installed in the servo mounting holes, mark the spots for drilling the pilot holes for screws. Space the servos at least 1/8" apart and do not have then contacting the hardwood mounting rails except on the grommets. Using a washer on the wood screws, mount the servos to the rails. Do not tighten the screws down against the grommets since this will cause vibration to be transferred to the servos. The washer should just rest against the grommet without compressing.
The receiver battery pack should be wrapped in foam rubber sheet, held on with rubber bands. It is a good idea to put the package in a small plastic bag, taped shut around the battery cable to protect the battery from leakage.
The receiver should be similarly wrapped up in foam rubber to protect it from engine vibration. Cover it with a plastic bag also. Stow this package just in front of the servos. Make certain that the receiver will stay in place.
Radio installation in one of the prototype Kougars A UM-3 plastic mount on the 3/8" sq. crosspieces holds three EK-MM servos. The receiver is wrapped in a foam rubber package and stowed just ahead of the servos.
Some RC outfits have one or more reverse direction servos which are handy when it is found more convenient in a particular installation to have a pushrod hook to the servo on the opposite side.
In this installation, using Logictrol SM servos, the battery and receiver have been semi-permanently installed. WIth scrap balsa crosspieces holding the foam rubber wrapped packages in place. The motor and nose wheel pushrods are tacked to the crosspiece over the receiver with 5-minute epoxy. If necessary to remove the equipment, break out the battery retaining cross-piece and pull out the battery and the receiver, leaving the receiver retaining strip in place. (Some Kougars may need the battery in the nose under the tank for proper balance.)
Various brands of servos can give different control movement direction and amounts of travel. For this reason, follow the measurements below when setting the Kougar up for flight rather than any particular horn hole drawn in this book or visible in a Kougar picture. Shift the RC link to whatever horn hole will produce the amount of movement shown in the drawings below. Measurements are made at the trailing edge of the control surface.
The control measurements shown should give full aerobatic capability. Test flights may indicate a need for more or less movement, depending on individual model differences, C.G. location, your personal preferences, etc. (Flight Tests may determine that the neutral point should vary slightly from level but for purposes of illustration the neutral point is shown level.)
For training purposes, do not carry excessive elevator movement. Use only enough to properly perform a nice sized loop at full travel. Over control with excessive movement can get a novice in trouble. After you are more expert, additional movement can be used, if desired, for quick snaps and other violent maneuvers.
The recommended Center of Gravity locations are:
For the first test flight, balance the Kougar by suspending it on the finger tips placed on the bottom of the wing on the first mark. Balance with an empty fuel tank, but with all other equipment installed and the model completely finished and painted. Add lead to the nose, if necessary, to get the model to hang level. Be sure and fasten the weight securely. Do not attempt flight tail heavy.
The "Test Flying" position is on the nose heavy side. When slightly nose heavy, the model is more stable and less likely to stall or snap roll from over-elevating. It also cuts down reaction of the model to control movements and this is good during test and practice flights, to help prevent overcontrolling. After the model has been test flown and initial trimming accomplished you may want a little quicker response. Move the balance back slowly and check results in the air.
Some aerobatic capability is sacrificed with the forward C.G. positions, so for making deliberate snap rolls and spins a position farther back may be required. Move the C.G. back slowly and check results and control response in the air at a good altitude. Don't move the C.G. back any farther than necessary.
IMPORTANT: The Kougar is not a basic trainer. If you have no previous RC flying experience you cannot successfully fly a fast and responsive design like the Kougar, particularly on test flights. It is suggested that you not attempt flying without the assistance of a modeler with experience. Contact your local model club or ask your hobby dealer for the names of good fliers in your vicinity and a suitable location for flying.
Many hours of work are involved in the construction of a model and it can all be lost in a moment of beginner's indecision. A skilled flier can help you get past the first critical test and trimming flights without damage to the model and give instruction in proper control.
Be certain to carefully range check your radio equipment and see how it operates with the engine running before attempting test flights.
A lot of problems can be avoided if the engine has been well broken-in and the idle adjustment perfected on a test block or in another airplane before installation in the model.
Takeoffs with the Kougar from grass fields are easily made if the grass is not too long or the ground too rough. Generally a lot of elevator application is required for liftoff.
Be prepared to relax control pressure partially after becoming airborne so the climbout will not be too steep. On surfaced or smooth dirt runways less application of elevator will be needed.
If a good, smooth take-off surface is not available, the model can be hand launched by the pilot's assistant. (Do not attempt to hand launch by yourself --- instant action on the transmitter may be required.) Holding the front part of the fuselage with the left hand and under the tail with the right, run into the wind at a fast trot and thrust the model forward with the nose slightly up in a spear throwing motion. It is not necessary to achieve a lot of velocity in the launch-it is more important that it be released smoothly and with the wings level. The model may dip slightly and then should begin climbing at a slight angle. If it does not begin to climb after about fifty feet of flight, apply a small amount of up to lift the nose. Use hand launching only as a last resort.
Use the ailerons to keep the wings level and headed straight into the wind until about seventy-five feet of altitude is obtained. Keep first turns gentle and not steeply banked. Stay up wind of the transmitter. Use trim levers on your radio equipment where necessary to obtain straight and level flight with the control sticks in neutral position but don't attempt to make these adjustments until the model is at a good altitude. Throttle back at altitude to find out the model characteristics in a gliding condition so that some indication is seen of what to expect during the landing approach. It is a good idea to make several practice landing approaches at a good altitude to get the feel of the model for this approaching critical maneuver. Make your final and complete landing approach while your engine still has plenty of fuel remaining so that the engine is not liable to stop before completion of the flight. This will allow application of power if the approach is undershot. Notice the percentage of missed landings at an R/C flying field. Those undershot greatly outnumber those missed by overshooting. So, if an approach that looks a little high is maintained, chances are good that a spotlanding can be made.
|After each test flight, readjust the RC clevis links on the pushrods so that the trim levers on the transmitter can be returned to a neutral position. It will take several flights before exact trim is established on all axis of flight.|
Print, cut out and join the following pages together in order for the plans.
|© Copyright SIG Mfg. Co., Inc.|
SIG MFG. CO., INC.
Montezuma, Iowa 50171-0520
|LIMIT OF LIABILITY:|
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.