SMITH MINIPLANE RC38 FINISHING AND FLYING

The photo of Glen's Smith was constructed in 1967 by Billy Simpson of Jerseyville, ILL. His expert workmanship is evident by the dazzling, high gloss red, white, and black paint job. The Miniplane's construction is typical of many home-built designs - with steel tube, fabric covered fuselage and tail surfaces; wood and fabric wings; metal cowl; and fiberglass wheel pants.


16.

Sanding And Painting Plastic Parts

All of the ABS plastic parts should be sanded to remove the gloss on the surface of the plastic before they are painted. Avoid using coarse sandpaper which can deeply scratch the plastic.

Deep scratches can open up during doping and become prominent. Use something like 220 grit 3M Tri-M-Ite Free Cut Finishing Paper (See Sig Catalog). Polish down the first sanding with 360 grit Free Cut Tri-M-Ite or 400 grit Wet-Or-Dry paper before color doping.

The plastic parts may be brushed or sprayed with Sig Supercoat color dope. Care should be taken not to apply heavy, wet coats of color dope to the plastic. Put on light coats and allow them to dry thoroughly before applying a second coat.

The ABS plastic parts may also be painted with K&B Super Poxy, Hobbypoxy, or DuPont Dulux Enamel. Do not use other paints, dopes or finishes without first testing on scrap plastic to make certain they are compatible with the plastic.

NOTE: Do not try to cover any of the plastic parts with monokote or other iron-on types of covering material. The heat can damage the plastic parts.


17.

Covering And Painting

The Miniplane should be covered with silk, or other cloth material, rather than silkspan, due to the large unplanked areas. Remember that covering and paint won't cover up poor workmanship - Be sure all surfaces are smooth. After the final sanding of the finished framework give it two coats of unthinned dope wherever you want the silk to adhere to the framework. Give these areas another final, light sanding. Apply the silk wet but do not stretch too tightly, as it will only encourage warping later on. Pull the silk up just enough to get out all the slack and wrinkles. Paint dope around the edges. This will soak through and adhere to the pre-doped framework. Let dry before trimming with a sharp razor blade. Check for any spots that are not stuck down and apply more dope.

Next give the entire airplane three coats of Supercoat Clear Dope or Lite-Coat Low Shrink Clear Dope. Thin the dope until it brushes on easily and flows out smoothly. Brush on the first coat over the open areas sparingly. As the brush rubs across the ribs, dope is rubbed off the brush and through the silk and will run down the ribs inside. As excessive amount will run completely through the framework and puddle against the covering surface on the other side. When these puddles dry, the large amounts of dope solids in them causes more shrinkage than in the rest of the covering and a scarred area results. So apply dope very lightly the first time over. A second coat should seal most of the pores of the silk and from this point, running through will not be a serious problem.


A fourth or fifth coat of dope may be necessary, depending on how heavy a coat is applied, to completely fill the silk grain. The ideal is a completely smooth and even base.

Keep in mind that weight can build up fast in finishing and restraint must be used in application. Sand lightly with 220 grit Tri-M-Ite paper between the later coats of dope. Don't bear down on the edges of the balsa structure or the silk fibers will be cut.

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If possible, best results can usually be obtained by spraying on the color finish coats. Reduce the dope for spraying fifty-fifty with Supercoat Thinner. Two or three coats of your base color should give good coverage if the surface preparation was sufficient. The following steps outline the finishing coats that were used on the prototype models to duplicate the color scheme of Glen Sig's Smith.

Spray three coats of Brilliant White Supercoat Dope on the entire airplane including the plastic parts. Refer to previous section for notes on painting the plastic parts.

When dry, mask off the edges of the red trim color areas with Drafting Tape (3M Scotch brand is available at most office and art supply stores). Completely cover with paper and tape all areas that should remain white. Use heavy, close grained paper (not newsprint, etc.). Brush or spray the edges of the drafting tape with clear dope. This seals the tape, preventing leakage of the red trim color underneath the tape. Spray on two coats of Light Red Supercoat Dope. When dry, carefully remove the tape.

Spray on a coat of clear dope to protect the colors from scuffing and to give the entire color scheme a uniform gloss.

The black pin stripes along the red and white color separation lines were put on at this point using a #5 technical drafting pen (Rapid-a-Graph or Castell) and black drawing ink. You must spray several more light coats of clear dope over the ink lines, after they are dry, in order to make them fuel proof and permanent.

18.

Completing The Cockpit

a.

Trim the cockpit opening to final shape using the full size pattern provided below as a guide. A piece of black rubber tubing is provided for simulating the cockpit edging. With a sharp single edge razor blade, slit the tubing lengthwise along one side so that it can be opened and slipped over the edge of the 1/8" balsa cockpit rim. Use epoxy glue to permanently fasten the tubing in place.

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b. Sand the bottom of the ABS plastic headrest as necessary to get a good fit on the top of the fuselage. Glue it in place on the top of the fuselage. Glue it in place with Sig-Ment, used sparingly. Paint the headrest Brilliant White - refer to Sanding and Painting Plastic Parts section.

c.

Cut the windshield from clear plastic sheet, using the pattern on the plan. Fasten it to the model with SigMent glue. The cyanoacrylate adhesives (Hot Stuff, Jet, Zap, etc.) also work well for attaching the windshield since they bond almost instantly. Cover the glue seam with a strip of vinyl plastic to simulate the windshield attachment strip of the full size airplane.

Cockpit of the Prototype Model

Cockpit of the Full-Size Miniplane

Williams Brothers 2-5/8" Scale Standard Pilot is recommended for the Smith Miniplane.

19.

Decals

Instructions For Dry Application:
Cut the decal from the sheet with scissors or a sharp modeling knife. Trim close to the image, leaving about 1/32" to 1/16" of clear edge. Peel the backing sheet from about half of the decal because after it is in place it is very difficult to move. Once it is in place, press down on the edge and carefully work toward the half which does not have the backing sheet removed. Continue to peel off the backing sheet as you press the decal into place, being careful not to trap air under the decal. If an air bubble is trapped under the surface, puncture it with a pin and press the decal down on the surface. Rub with a soft, dry cloth to make certain it is sealed to the surface.

Instructions For Wet Application:
Cut out the decals with a pair of sharp scissors. Leave about 1/32" to 1/16" of clear edge around the decal. Round the comers as you are cutting. Wet the surface on which the decal will be placed with soapy water (use dishwater detergent). Peel the decal film from the backing sheet. Place the decal on the model and squeegee the water from underneath with a balsa paddle. Allow to dry. This procedure will prevent air from being trapped underneath as is possible when the decals are applied dry. It also permits shifting it to exact position during application. Decals applied dry cannot be moved after they are pressed on.

20.

Tank Installation

Use a 8 or 10 ounce rectangular plastic clunk tank. A side mounted engine installation is recommended. The plan shows the- correct position of the tank for proper fuel draw and idle characteristics. Assemble your tank as shown in the photo with three outlet tubes - 1 fuel feed and-2 vents to allow refueling without removing the fuel feed line at the carburetor. Both vent tubes should curve upwards inside the tank. Drill a group of three holes in the firewall large enough in diameter to pass the tank outlet tubes with fuel line tubing installed.


Install the tank semi-permanently with cross-pieces of plywood or balsa to hold it in place. If the tank is equipped with an internal fuel line cut from Sig Heat Proof tubing it can be left in the fuselage indefinitely since this line -will not harden when immersed in fuel. Seal the outlet holes in the firewall against leakage of exhaust oil into the fuselage with G.E. Silicone Seal or equivalent silicone rubber sealer. Should the need arise to remove the tank, break away the wood supports and bathtub seal and pull the tank out through the lower wing opening.


21.

Radio Installation Notes

NOTE: No servo Mounting Material or Hardware is supplied in this kit.
The most convenient method of installing servos is on the plastic mounts which most of the 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 wing. Instructions for the use of these mounts are included with them.

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Servos for which plastic mounts are not available can be screwed directly to at least 3/8" square hardwood rails placed across the cabin 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 them 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 trasferred to the servos. The washer should just rest against the grommet without compressing it.

The receiver battery pack should be wrapped in foam rubber sheet, held on with rubber bands or masking tape. Place in as far forward in the fuselage as possible, preferably under the tank. 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 accidental fuel 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 completed package in front of the servos. Make certain that the receiver will stay in place during aerobatic maneuvers.

The switch may be mounted wherever it is convenient on the side of the model, preferably the side away from the engine oil. Another good spot is inside of the cockpit where it may be reached easily. (See photo in "Completing The Cockpit" section 18.)

"Brick" type receiver and servo combinations will have to be mounted on rails as specified by the manufacturer of the radio equipment.


"A model, engine or radio that is not prepared and working properly on the ground before takeoff will not improve in the air---IT WILL GET WORSE! 'There is no point in attempting to fly until everything is 100% correct."

The output arms of some servos will take 1/16" wire or the pin in a RC link clevis without it being necessary to enlarge the hole. The fit will be snug but usually will not be tight enough to cause too much friction and put a load on the servos, Should it appear to be too tight, drill the holes out with number size drills only, selected carefully. A No. 51 is about right, no larger than' a No. 50. An overly large hole will cause control surface slop and flutter. After installation is complete, operate all controls to full movement and listen to the servos. If overloaded, they will probably buzz or hum.

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Another sign of excess load on the servo is a pushrod that sticks or reaches the end of its travel before the servo does and bends or arches up 'or down from the servo pushing it against a deadend. Locate the cause of overloads and eliminate them. Overloaded servos will cause high battery drain, .with loss of control when the batteries run down. Servos may be damaged by continual overload.

Double check all Control Hookups - No Binding, Rubbing, or Sticking
NOTE: Some RC sets have one reverse direction servo that will require an opposite hookup than that shown shown here for logictrol radios.

22.

Pushrods

A flexible steel cable pushrod with nylon outer tubing (SIGSH559 or DuBro No. 165) is recommended for hookup of the throttle to the motor servo.

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 RC 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. A variety of quickly detachable pushrod retainers (Rocket City #07, SIGSH84, or solder clevises) are available from the Sig Catalog for securing the pushrod wires to the servos. Or you can make a "Z" bend in the end of the wires as shown.

The aileron pushrods are threaded rods with RC links - cut off and connected to the servo output arm by one of the methods described above for the servo end of the fuselage pushrods. DuBro No. 103 or Rocket City No, 05 strip aileron horn wire connectors are suggested to link the aileron pushrods to the wire torque rods.




23.

Muffler Installation Notes

The prototype models of the Miniplane used the Tatone Side Mounted Manifold #EM-SS. If fits completely inside the cowl and neatly directs the exhaust out two rubber tubes exiting thru the bottom of the cowl. It muffles adaquately and doesn't detract from the scale appearance of the model. Since the construction of the prototypes, Tatone has introduced the #EM-40S, a slightly smaller version manifold for .40 size engines. If you are using a .40 engine, the #EM-40S would be our first recommendation. If you've got a .45 engine, you should get the #EM-SS.

Large expansion chamber, flow-thru, or stack (DuBro MuffL-Aire) mufflers will require an extension to locate completely outside of the cowl.

PROTOTYPE INSTAllATION
Enya .45 and Tatone #EM-SS Manifold.

24.

Pre-Flight

Balance the model at the C.G. point indicated on the plan. If it balances further back, add lead to the nose as necessary. Trying to fly with the C.G. too far back is much more dangerous than the slight increase in wing loading caused by adding lead to the nose. Balance with an empty fuel tank. When slightly nose heavy the model is much more stable and less likely to snap roll or stall. The reaction to control movements is less sensitive so its not as easy to over control.

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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.

A properly balanced and aligned model with a reliable engine and radio is assured of successful flights.

25.

Flying

If you are a newcomer to model flying it is suggested that you not attempt flying without the assistance of a modeler with experience. Contact your local club or ask your hobby dealer for the names of good fliers in the 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.



Hold a small amount of up elevator during the first part of the takeoff to keep the tailwheel steering effective until air speed is high enough for the rudder to take over. The model will drift to the left from torque during takeoff. Feed in some right rudder as soon as the tail wheel clears the ground, earlier if required. The model is not difficult to manage in the air and can be flown by anyone who is capable of handling a multi-channel model.

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© 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.