In this step you need to cover all the parts of your model with the covering material of your choice, before proceeding on to Final Assembly of the model.

General Notes

There are many different covering materials available for finishing model airplanes. They range from raw coverings that must be bonded to the structure with adhesive and then painted; to iron-on plastic materials that have the color and finish built right in.

The choice of which type of covering material to use on your KADET LT-25 is a matter of personal choice. However, if this is your first model airplane, we recommend that you chose one of the popular pre-finished iron-on plastic film coverings. This type of covering material provides a high gloss, durable finish that is easy to apply and repair. It goes on relatively quick and is not near as messy or smelly as using a covering material that must be painted. All of the KADET LT-25 prototypes built here at the SIG factory were finished with SIG SUPERCOAT IRON-ON PLASTIC COVERING.

Since all iron-on plastic covering materials come with detailed step-by-step instructions on how they should be applied, we will not go into a repetitive step-by-step sequence here. We will instead outline some ideas that are specific to the KADET LT-25. Be sure to read all the instructions that come with your covering material and follow them carefully. NOTE: There are also complete books and video tapes available on applying iron-on covering materials. These sources can be very helpful, providing a lot more tips than we can cover in these instructions. Often times, the video tapes can be rented or borrowed from your local hobby shop or model airplane club.

Choice Of Color Scheme

One of modelingís pleasures is the chance to decorate your model to suit your own taste. There are a huge variety of after-market items available in the hobby shops to dress up your airplane. Striping tapes and trim sheets in every color of the rainbow, stick-on decals and markings, are all available and easy to apply.

You can go for a military look, a Cessna-like civil aviation look, or something totally wild in vivid neon colors. Your imagination is the only limit!

If this is your first model, our advice is to keep the color scheme simple and visible. The most economical way to go is to choose one primary color for the entire model. Choose a light color! Covering the entire model in black, dark blue, gray, etc., is not a good choice. In the air a dark colored model will quickly turn into a black silhouette, and it will be difficult to distinguish which way the airplane is going. A light color is more visible at greater distances! White, yellow, orange, cream, and neon colors are excellent choices for a trainer model.

The LT-25 kit includes one sheet of stick-on decals to duplicate the windows on the fuselage and fin. On our kit box model, we covered the back part of the wing with white covering material, and then covered the front part of the wing with blue covering. The blue covering overlaps approximetely 3/8" onto the white covering material, at the main spar. The fuselage is done the same way. If you want to make your LT-25 the same as ours, it will take 2 rolls of White and 1 roll of Medium Blue. This 2-color scheme will take a little more time than if you make the wing and fuselage all one color. The choice is yours!

Surface Preparation

A good covering job starts with good surface preparation! Regardless of what type of covering material you use it wonít hide poor workmanship. Finish sand the entire model with 220 grit sandpaper. Fill any holes, gaps, nicks or dents on the surface of your model with lite-weight filler. After the filler dries, sand off any excess flush with the surface.


Fuel Proofing

Since itís very difficult to apply iron-on covering material inside the engine compartment, this area should be fuel proofed by painting it with a fuel-proof hobby paint, before the covering material is applied. We prefer to use SIG SUPERCOAT BUTYRATE DOPE. Itís an excellent fuel proofer. Choose a color of paint that closely matches the color of the covering you will be using. Use a small (1/2") wide brush to apply 2-3 coats of paint to the engine compartment, letting it dry between coats. Paint the entire front surface of the Firewall plus the inside of the engine compartment "cheeks". Run the paint around the edges onto the outside of the fuselage sides, far enough that the iron-on covering material will overlap the painted areas at least 1/8" when applied. Also paint the edges of the hatch area, the wing saddle, and partway inside the tank compartment.

Cover The Rudder

First cover both ends of the Rudder with small pieces of scrap covering material before covering the sides. Run the end covering "around the corner" about 1/8" onto the sides and the front of the Rudder. Trim off the excess.
NOTE: Always be careful when trimming excess covering material off of the wood parts. Donít "score" or cut into the wood. Scoring a critical structural component of the airplane could seriously weaken its strength and possibly cause an in-flight failure.
Cover the left side of the Rudder with a separate piece of covering material. Run the left side covering completely around the leading and trailing edges, far enough so that there will be at least 1/8" overlap with the right side covering when it is applied. Trim the side covering flush with the top and bottom ends of the Rudder.

Cover the right side of the Rudder in the same manner you did the left side, making sure that it overlaps all other pieces of the covering material at least 1/8". No areas of wood should be exposed.

Cover The Fin

Cover the top end of the Fin with a small piece of scrap covering material before covering the sides. Run the top covering aroung the corners about 1/8" onto the sides, front, and back of the Fin. Now, cover the left and right sides of the Fin with separate pieces of covering material like you did the Rudder. Do not cover the bottom of the Fin, where it will be glued onto the fuselage.

Cover The Ailerons, Elevator, And Stabilizer

Covering these parts is virtually the same as covering as covering the Rudder. First cover the ends of the part with small pieces of scrap covering material. Now cover the top and bottom with separate pieces of covering material. Overlap all seams at least 1/8".

Cover The Fuselage

The fuselage should be covered with several pieces of covering material (bottom, top rear, windshield, left side front and rear, right side front and rear). Start by covering with one or two colors, the entire bottom of the fuselage. Run the sides of the covering up around the corners about 1/8" onto the sides of the fuselage. Trim the front of the covering flush with the Fuselage Bottom Front. Trim the rear end of the covering flush with the tail end of the Fuselage Bottom. Now, go back and seal the covering to the fuselage bottom. Cut the exit slots in the covering for the tailwheel cables.

Now is the best time to install the Tiller Bar Assembly.

TILLER BAR ASSEMBLY - Assemble the laser-cut plywood Tiller Bar and plywood Tiller Bar Mount using a 4-40 x 3/4 Mounting Bolt, 4-40 Aircraft Lock Nut, 2 Flat Metal Washers, 3 Nylon Washers, and Nylon Bushing- as shown by the drawing on Plan Sheet #1.


Cut the .027 x 6í steel cable provided into two equal length pieces. Attach one end of each cable to each end of the plywood Tiller Bar as shown in this photo. First pass the end of the wire through the hole in the end of the Tiller Bar. Loop approximately 1" of the end of the wire back to lay alongside the rest of the wire. Slide a 3/32"o.d. x 1/2" Aluminum Tube over both wires and smash the tube tightly to crimp both wires securely together.

Glue the Tiller Bar assembly in place in the Fuselage. Feed the cables through the Fuselage formers and out through the nylon exit tubes in the bottom of the Fuselage. Tape the loose ends of the cables to the bottom of the fuselage so they wonít be in the way while you do the rest of the covering.

Finish Covering The Fuselage

Next cover the top rear of the fuselage with one piece of material. Run the sides of the covering down over the corners about 1/8" onto the sides of the fuselage. Trim the front and rear ends of the top covering flush with the ends of the Fuselage Top Rear. Cut open the holes where the rudder pushrod and Fin leading edge go through.

Using the fuselage plan as a guide cut the angle on the Fuselage side rear covering. Seal it as you did before with overlapping 1/8" over the top and bottom. Repeat this step for the other Fuselage rear side.

Cut the angle on the front Fuselage right and left sides covering and seal them to the Fuselage Front. Overlap all seams 1/8" onto other covering material or onto the pre-painted areas. At the engine compartment, try to work the covering around the first corner of every edge, and then trim off the excess covering flush with the inside corners. Do the same for the wing saddle area. Do not apply any covering on the Stab Mount, where the Stabilizer will be glued on! When youíve finished, cut the holes in the fuselage sides for the wing dowels.

Cover the windshield with a single piece of covering. Run the sides of the covering down over the corners 1/8" onto the sides of the fuselage. Tuck and iron the front and rear edges of the covering around the ends of the windshield.

Cover The Hatch

There are so many corners and edges, that it takes some time to get all of the Hatch covered. And because the Hatch will be directly exposed to a lot of engine exhaust, it is very important to get it all covered. Do not leave any exposed wood! Start by applying an overside piece of covering to the top of the hatch. Then turn it over and cut out the corners of the excess covering to make it easier to wrap and seal the covering around the edges. Continue wrapping and sealing the covering around the edges and onto the bottom.

Cover The Wing

Begin by covering the ends of the Center Section Trailing Edge with scrap covering. Run the covering around onto the top and bottom. Slit the covering to lay down smoothly around the torque rods.

Next cover the bottom of one panel with one piece of covering material. Like all open structures, you should seal the covering down all along the outside edges of the structure first. (Do not shrink the center of the covering tight at this time). At the root of the wing panel, seal the covering down about 1/4" past the center joint. Cut a hole in the covering to allow the aileron torque rod to stick through. Also, itís not necessary to cover over the Aileron Servo Mount - merely cover up to it. At the back of the wing panel, slit the excess covering at the end of the Center Section Trailing Edge, then run it around the corner and seal it onto the back of the Trailing Edge. Trim off flush with the top rear corner of the Trailing edge.


At the tip end of the wing panel, seal the bottom covering to the last W-5 wing rib. Then continue on, working the covering bown smoothly onto the bottom of the wing tip. Wrap and seal the covering completely around the edges of the Wingtip. Trim off flush with the top surface of the Wingtip.

Now cover the top of the wing panel in the same manner you just did the bottom. Remember to overlap all seams at least 1/4" onto the other pieces of covering material.
Then cover the other wing panel in the same manner.

Wait until all pieces of the wing covering have been completely sealed down around their edges before shrinking the middle areas of the covering. When shrinking the middle, do not completely tighten one side of the wing first. Itís best to alternate between the top and bottom wing surface, shrinking each side a little at a time, to avoid uneven shrinking which could case a warp.

Installing Easy Hinges

WARNING: SIG EASY HINGES are designed to be used in conjunction with THIN CA glue. Thin CA (any brand) is the ONLY type of glue that can be used on EASY HINGES - do not use any other type of glue on EASY HINGES!


Mark the locations for the Easy Hinges on the model parts, using the full-size plans as a guide.


Begin by carefully cutting a very shallow slit at the hinge location using a sharp #11 blade in your modeling knife. This first slit should be very shallow so you can better control the direction of the knife. Itís main purpose is to establish your hinge slot in the right place, so concentrate on staying on the hinge line and donít try to cut too deep. NOTE: Make the slit slightly wider than the actual hinge.


Now make 3 or 4 more cuts in the exact same line, going slightly deeper each time. As you make these additional cuts, concentrate on staying in the slit and keeping the headed straight into the center of the wood so that it wonít come out the side of the part. You will find that as the blade gets deeper into the wood, it will become harder to move it along the slot. Try "wiggling" the knife handle in the slot to make it cut, instead of trying to "slice" the blade along in one continuous motion. Continue making additional cuts until the slot is approximately 1/2" deep.
CAUTION: You must use extreme care to avoid cutting yourself while cutting the hinge slots. If the balsa breaks while you are pushing on the knife, the blade could go into your hand before you can stop it. A good precaution is to wear a leather glove on the hand that is holding the model part while you are cutting the slots.


After all the slots have been cut, insert a single Easy Hinge halfway into each hinge slot in the fin (or rudder, stab, elevator, aileron, wing, as the case may be). If the hinge is difficult to push in, re-insert the knife and move it back and forth in the slot a few more times and then try again.



Now carefully slide the mating part onto the exposed half of the Easy Hinges. You will find it easiest to slide the part onto the hinges at an angle, one hinge at a time, instead of trying to push it straight onto the hinge at once. Donít be overly concerned if the hinges donít end up perfectly straight or centered in the slots - they do not have a center line.


To set the proper amount of gap between the model parts, simply deflect the control surface to the maximum amount of travel needed. This will automatically set the proper hinge gap! Keep in mind that for best control response the gap should be kept as small as possible, but big enough to allow full movement of the control surface. If everything appears to function properly, move on to the next step.


7. Place three or four drops of Thin CA glue directly onto the Easy Hinge in the gap. You will notice that the glue is quickly wicked into the slot as it penetrates both the wood and the hinge. Turn the part over and glue the other side of the Easy Hinge. Continue this process until you have glued both sides of all the Easy Hinges! Keep a rag handy to wipe off any excess glue. (CA glue residue can be cleaned from most iron-on plastic covering materials with CA Debonder).
VERY IMPORTANT: Make only one application of glue to each side of an Easy Hinge! If you apply additional glue to the hinge after the first application of glue is already cured, the second application of glue will merely puddle in the hinge gap and make the hinge too stiff to operate properly. The excess glue could also weaken the hinge! When properly glued, the portion of the Easy Hinge that you can see in the hinge gap should have a dry appearance, not wet. A dry appearance indicates that almost all of the glue has properly soaked into the hinge slot. A wet appearance indicates that excess glue is puddled in the hinge gap. Three to four good size drops of Thin CA should be about the right amount. NEVER USE CA ACCELERATOR ON EASY HINGES!


Let the glue cure a minimum of 3-5 minutes before flexing the hinges. At first you might notice a little stiffness in the joint. This will go away after the hinges have been flexed back and forth a couple dozen times.


SPECIAL INSTRUCTIONS FOR HINGING THE AILERONS - The ailerons will be hinged exactly like the tail surfaces, except that the torque rods must be glued in before the Easy Hinges are glued. Start by completely re-assembling the ailerons and Easy Hinges back onto the wing without any glue. Next, working with one aileron at a time, pull the root end of the aileron back away from the wing until the first Easy Hinge is just barely still in its slot and the torque rod is exposed as shown in the photo. Slide a small piece of wax paper between the front of the torque rod slot and the wing trailing edge. Apply glue, then quickly slide the aileron back into position against the back of the wing.Remove the wax paper and wipe off any excess glue that oozes out of the slot with a rag. If any glue remains between the front of the torque rod and the trailing edge, slide a piece of paper through there to mop up the excess. Let dry!



The following sequence is recommended for applying the window decals.


First stick the front windshield decal in place on the model. Note in the picture that the bottom edge of the windshield decal should be approximately 7/16" up from the bottom of the balsa windshield. Wrap the overhanging sides of the decal down onto the sides of the fuselage.


Apply the decals of the left and right side windows next. Leave the 3 side windows in one piece. Do not cut them apart! Applying them as a single piece will guarentee that they will end up perfectly lined up with each other.
HELPFUL HINT - When applying the side window decals (or any large decal for that matter) it is best to first squirt some type of soapy water solution (window cleaner, SIG Pure Magic Cleaner, etc.) onto the model before laying down the decal. The soapy water will allow you to slide the decal into exact position before it sticks permanently in place. Once you have the decal properly positioned, use a small piece of scrap sheet balsa or stiff cardboard to squeegee the soapy water out from underneath the side window decal. Any residual soapy water will evaporate out from under the decal within 24 hours, and at that point the decal will be permamently bonded to the model.


The decals for both sides of the fin should also be applied wet because of their large size. We recommend that the fin decals be applied in one piece - without cutting apart the orange and blue sections.
WARNING: Do not try to paint over the kit decals! Butyrate dope, lacquer, enamel, and many other paints will dissolve the decals. If you wish to top coat your decals, be sure to test for compatibility on a scrap decal before applying the paint. Frankly, SIG MFG. CO. does not recommend top coating the decals in this kit. They are already fuel-proof!


Final Assembly


Insert the two 1/4" x 4-3/4" hardwood dowels through the holes in the fuselage. The dowels should protrude 11/16" from each side of the fuselage. Glue the dowels in place.

Paint the exposed portion of the dowels with a couple coats of fuelproof paint. Let dry.


Mount the wing on the fuselage with two #67 rubber bands. Using a tape measure, carefully measure from the fuselage sides out to the wing tips (measurement A ) to be sure that the wing is centered on the fuselage. Now, measure from the wing tips back to the tail end of the fuselage (measurement B ) to make sure the wing is square with the fuselage. Once the wing is properly located, put some line-up marks on both the wing and fuselage so that you can easily re-locate the wing the next time you put it back on the fuselage.


Put a center mark on the top of the fuselage, right above former F-6. Also put a center mark on the front of the Stabilizer. Using no glue, trial fit the Stabilizer onto the fuselage. Line up the center marks at the front and use one T-Pin to secure the front of the stab, as shown. Push the pin completely through the stab and into the fuselage, to secure it in position.


Carefully measure from the stab tips to the fuselage front (measurement C ), to make sure the Stabilizer is square with the fuselage. Pivot the back of the stab until both measurements are exactly the same! Now, push another T-Pin through the stab, into the fuselage, to secure it in position.


Lift the rear of the fuselage up, without jarring the stab loose, to enable you to mark the location of both fuselage sides on the bottom of the stab with a pencil.


Remove the stabilizer from the fuselage and very carefully strip away the covering material on the bottom, between the two lines, where the stab will be glued to the fuselage. CUT THE COVERING LIGHTLY ALONG THE LINES! AVOID CUTTING THE WOOD UNDERNEATH THE COVERING MATERIAL! HINT: For a better finished appearance, cut about 1/32 inside the lines so that the stab covering will appear to tbuec ked inside the glue joint.


Gluing the Stabilizer to the Fuselage: First apply a coat of SIG Epoxy or Thick CA glue to the area of the fuselage where the Stabilizer will go. Use enough glue to completely wet the entire surface of the joint. Quickly remount the stab onto the fuselage, using the edges of the cutaway covering on the bottom to get the stab back into correct alignment on the fuselage. Press the Stab down firmly into contact with the fuse while you wipe off any excess glue that oozes out of the joint with a rag. Hold tight until the glue cures.


Draw a center-line on top of the stab, running from the center mark above F-6 to a point above the rear of the fuselage. NOTE: In the photo you ll see that we have temporarily stuck a T-Pin through the hinge gap to give us a visual alignment with the middle of the end of the fuselage. Use a straight edge to draw the line from the mark above F-6 to the pin.


91. Place the Fin/Rudder assembly on the fuselage, sticking the leading edge of the fin through the hole in the top of the fuse. Carefully line up the trailing edge of the fin using the center-line on top of the stab as a guide. Draw along both sides of the fin, marking its location on the top of the fuselage and stab. Take the Fin/Rudder assembly off the fuse and strip away the covering material inside the lines.


Gluing the Fin to the Fuselage: Apply a coat of Thick CA glue to the area where the Fin will go. Remount the Fin onto the fuselage, line it up as before, and hold it firmly in place until the glue dries. Hold a 90 degree triangle against the Fin to insure that it cures perpendicular to the stab.

Radio Installation

NOTE: The receivers and servos of different brand radios are not all the same size! Consequently, it is practically impossible for us to guarantee that every word and picture in this next sequence will pertain exactly to your installation. As you go along, you may notice some differences between your radio equipment and ours! Nonetheless, most of the radio system components will be close enough in size and appearance that you should be able to figure out for yourself how to handle any minor differences. Follow the instructions as closely as possible. If you have any questions, seek the advice of an experienced modeler. The installation of the control system in your new model is very important! It must be done correctly in order for your airplane to fly successfully and safely.



Locate the laser-cut plywood servo tray. Mount your throttle, elevator, and rudder servos in the tray using the screws, washers, and rubber grommets that came with your radio system. Be sure to orient the servos in the tray as shown in the fuselage top view.

CAUTION: The rubber grommets act as shock absorbers and prevent engine vibration from damaging the electronics in the servos. Do not over tighten the servo mounting screws to the point where they compress the rubber grommets so far that all shock absorbing ability is lost. Tighten the screws just enough to make contact with the grommets and keep the servos in place.


Set the servo tray in place inside the fuselage, on the "shelf" made by the fuselage doublers. Slide the servo tray as far forward as you can. Flow Medium CA glue into the joints between the edges of servo tray and the fuselage sides. Be careful to not get any glue on the servos or servo wires.



Locate the Small Nylon Control Horn (the one with 4 holes) and two #2 x 1/2" Sheet Metal Screws for the Rudder. Cut the Control Horn and the Retainer Plate apart. Hold the Control Horn in exact position (see plan) on the right side of the rudder and mark the location of the mounting holes. Drill pilot holes through the rudder with a 1/16" dia. drill bit (turn the bit with your fingers, a drill is not necessary). Mount the Control Horn onto the rudder with the Sheet Metal Screws and Retainer Plate.
NOTE: Turn the screws down until both the control horn and retainer plate make firm contact with the balsa. Then, turn each screw in 1/2 turn further. By tightening the screws in this manner, the control horn will not crush the balsa.


Cut one of the 10" Threaded Steel Rods to 7" overall length. Cut off the plain end of the rod, not the threaded end!


Locate one piece of Small Nylon Pushrod Tubing (1/8" O.D. x 36" long). Slide the plain end of the 7" long threaded steel rod inside the tubing up to the beginning of the threads. Now get a good grip on the threaded portion of the steel rod on the nylon tube and start screwing the threads into the tubing. Keep turning the rod until a MINIMUM of 1/8" of threads are inside the nylon tubing (3/16" is even better).


98. Screw one of the Nylon R/C Links onto the threads remaining outside the nylon pushrod tube. Screw it halfway onto the exposed threads - until there are the same amount of exposed threads in front and in back of the R/C Link.


Slide the rudder pushrod (from the rudder end) inside the larger nylon pushrod tube that is already in the fuselage. Slide it in until the nylon R/C link is even with the rudder control horn. Pry open the R/C link, clip it into the outermost hole of the control horn, and then snap it shut. Now reach into the fuselage and try operating the rudder pushrod from the servo end. It should work smooth and easy. If not, figure out why and fix it.


Set the rudder in neutral position. Mark the servo end of the Small (inner) Nylon Pushrod Tubing exactly 2-3/8" from the hole in the rudder servo arm. Cut off the nylon tube at the mark.


Cut another 10" Threaded Steel Rod to 2-1/2" overall length. Cut off the plain end of the rod, not the threaded end! Solder a 2-56 Solder Clevis to the smooth end of the rod. Screw the threaded end of the rod completely into the end of the inner Nylon Pushrod Tube. Then connect the Solder Clevis to the servo arm.


Using the leftover cutoff wire from the previous step, make a pushrod to run from the opposite side of the rudder servo arm back to the plywood Tiller Bar. Bend the wire according to the full-size pattern shown at the bottom left corner of this page.



Assemble a Pushrod Connector in the innermost hole of the rudder servo control arm.

NOTE: A Pushrod Connector consists of a brass Connector body, a 4-40 Set Screw, and a Nylon Retainer .

Install the Tiller Bar Pushrod in the Pushrod Connector and Tiller Bar (see full-size plan). Put the 90į bend of the pushrod in the hole in the plywood Tiller Bar - the other end in the Pushrod Connector on the rudder servo arm.


Temporarily plug the rudder servo into the receiver and testthe operation of the rudder. If you sense any binding in the rudder movement, find the cause and fix it now. With full right and left movement of the transmitterís rudder control stick, the rudder should move approximately 1" right and 1" left.

NOTE: If you are not getting the correct amount of rudder travel, try moving the nylon R/C link to a different hole in the servo arm. Also, fine tune the overall length of the rudder pushrod, by screwing one or both of the nylon R/C links further in or out, until the rudder is exactly neutral when the transmitter stick (and trim lever) is neutral.


Complete the installation of the steerable tailwheel by assemblying the Tailwheel Wire (w/Wheel), the Tailwheel Steering Arm, and two 1/16" Wheel Collars into the Tailwheel Bracket as shown on the plan. After the parts are secured, turn on the radio, center the rudder servo and the tailwheel, and then crimp the ends of the steering cables to the tailwheel steering arm with the aluminum tubes provided.



Construct and install the Elevator Pushrod, using previous Steps 95 thru 101 as a guide (simply subsitute the word "elevator" whenever the word "rudder" is used in those steps).


108. When finished, temporarily plug the elevator servo into the receiver and test the operation of the elevator. If you sense any binding in the elevator movement, find the cause and fix it now. With full up and down movement of the transmitterís elevator control stick, the elevator should move approximately 9/16" up and 9/16" down.

NOTE: If you are not getting the correct amount of elevator travel, try moving the nylon R/C link to a different hole in the servo arm. Also, fine tune the overall length of the elevator pushrod, by screwing one or both of the nylon R/C links further in or out, until the elevator is exactly neutral when the transmitter stick (and trim lever) is neutral.



Mount your aileron servo in plywood tray which is already installed on the bottom of the wing. REMEMBER: Do not over tighten the servo mounting screws to the point where they compress the rubber grommets too far.


Locate the Nylon Aileron Connectors and cut them apart. Thread one Nylon Aileron Connector onto the end of each Aileron Torque Rod. Screw the connectors on until they are about 1/8" past the tip of the torque rods (see Plan Sheet 1, Fuselage Side View).


The aileron pushrods are made from two 10" Threaded Steel Rods. Screw a Nylon R/C Link halfway onto the threaded end of each rod. Then clip the R/C Links into the holes in the Nylon Aileron Connectors and line up the pushrods with the servo arms.


Tape the ailerons in neutral position (the bottom of the ailerons and the wing should be flush). Mark and cut the plain end of the pushrod wires 5/8" short of the holes in the aileron servo arm.


Solder an R/C Solder Link onto the end of each pushrod wire. NOTE: Itís best to take the pushrods off for soldering. You wouldnít want to drop a piece of hot solder and burn a hole through the wing. Also, make sure the pushrod wire sticks completely inside the barrel of the solder link.


When done soldering, untape the ailerons and install the aileron pushrods between the servo and the torque rods. It will probably be necessary to re-adjust the overall length of the aileron pushrods. Screw the Nylon R/C Links further in or out, to get both ailerons into neutral position at the same time make sure the aileron servo is neutral while doing this.


Temporarily plug the aileron servo into the receiver and test the operation of the ailerons. If you sense any binding in the aileron movement, find the cause and fix it now. With full right and left movement of the transmitterís aileron control stick, the ailerons should move approximately 3/8" up and 3/8" down.

NOTE: If you are not getting the correct amount of aileron travel, try moving the nylon R/C links to a different hole in the servo arm. You can also screw the Aileron Connectors up or down on the Torque Rods to increase or decrease the amount of travel.



Materials are provided for making a "flex-cable type" throttle pushrod. This type of pushrod is semi-flexible, which means it can be bent in gradual flowing curves if necessary to make its ends line up with both the engineís throttle arm and the throttle servo. The Throttle Pushrod consists of: one 1/8" o.d. piece of Small Nylon Pushrod Tubing (already glued into the firewall back in Step 70); one 1/16" dia. x 18" Steel Cable; and two Pushrod Connectors.


117. Assemble one Pushrod Connector into the engineís throttle arm, and the other Pushrod Connector into the throttle servo arm.


Stiffen one end of the 1/16" dia. Steel Cable by flowing solder into it. Start by first coating the end of the Cable with "soldering paste". Then heat the end of the Cable with a good hot soldering iron. When you think youíve got the Cable hot enough to melt the solder, touch the solder to the hot Cable (do not touch the solder to the soldering iron). The solder should melt imediately and flow into the Cable. If it doesnít, it means you didnít get the Cable hot enough. Continue to heat the Cable with the soldering iron until the Cable is hot enough to melt the solder. When you have approximately the first 2"-3" of the Cable filled with solder, let it cool completely. Then sand the soldered end smooth if necassary to remove any lumps of solder.


From the front of the airplane, slide the soldered end of the Cable into the Nylon Pushrod Tube that is glued in the firewall. Slide it in until you can slip the soldered end of the Cable into the Pushrod Connector on the engine.


Inside the fuselage, grab the end of the Steel Cable that is sticking out of the Nylon Pushrod Tube and try to work the throttle. If it sticks or binds at the engine end, find the cause and fix it before going on to the next step. You may have to put some slight bend(s) in the soldered portion of the cable to make it operate smoothly.


Back inside the fuselage, mark the appropriate spot for cutting off the ends of both the Nylon Pushrod Tube and the Steel Cable. Note that the Nyon Pushrod Tube should end in front of the throttle servo, while the Steel Cable should be long enough to pass thru the Pushrod Connector on the throttle servo arm (see top view of full-size plan). Remove the Steel Cable from the Nylon Pushrod Tube while you cut them both to length.


Before sticking the Steel Cable back inside the Nylon Pushrod Tube, stiffen the servo end of the Cable in the same manner you did the throttle end (Step 118). When cool, install the Cable inside the Nylon Tube for the final time, and tighten down the Pushrod Connectors at both ends.



Wrap the battery pack with a single layer of 1/4" thick soft foam rubber to insulate it from engine vibration and shock. Use tape or rubber bands to hold the foam around the battery. Install the wrapped battery pack inside the nose of the model, under the fuel tank floor, in the position shown on the plan (fuselage side view).



Drill a 1/16" dia. hole completely through the bottom of the fuselage in the area where the receiver will be located. This hole is for the receiver antenna wire to exit the fuselage. Put a single drop of Thin CA glue around the edges of the hole to keep the covering from coming loose. Let cure completely!
NOTE: These instructions describe running the antenna outside along the bottom of the fuselage. There are a lot of other ways to handle the routing of a receiver antenna. If you prefer a different method, by all means use it. The main thing to keep in mind is that you should always strive to keep the antenna as far away as possible from all the servo and battery wires.


Wrap the receiver with a single layer of 1/4" thick soft foam rubber to insulate it from engine vibration and shock. Use tape or rubber bands to hold the foam around the receiver.


Following the radio manufacturerís instructions, plug all the wires for the servos, battery pack, and switch harness into the receiver so the radio system is fully operational. Double check to be sure that each servo is plugged into its correct receiver terminal and that it is responding properly.
NOTE: Since the receiver will be hard to get at, you should use a short "extension" wire (available from the radio manufacturer) for the ailerons. Plug the extension wire into the receiverís aileron terminal. Whenever you take the wing on/off the model, you can connect/disconnect the ailerons at the plug-in between the extension wire and the servo wire, leaving the extension wire itself permanently plugged into the receiver.


Install the wrapped receiver inside the nose of the model, right behind the battery pack. Before you get the receiver completely in place, poke the antenna wire down through the hole in the bottom of the fuselage (use an "antenna strain relief" fitting if one came with your radio). Make sure the antenna wire is not tangled up in the servo and battery wires! Continue pulling the antenna out the bottom of the fuselage as you slide the receiver forward against the battery pack. If the receiver seems loose in the nose of the model, pack additional pieces of foam rubber around it to make sure it cannot move around in flight.


128. Anchor the loose end of the antenna on the outside of the model near the rear of the fuselage using a small rubber band and a T-Pin (an "antenna hook" is also handy if one came with your radio). Stick the T-Pin into the bottom of the fuselage at an angle, as shown. Put a drop or two of Slow CA glue on the pin to keep it in place. Tie the rubber band to the antenna (or the antenna hook) and then loop it over the T-Pin. The antenna should be just taut, not tight! The rubber band allows a certain amount of give in case the antenna is snagged by accident.


Cut an opening in the left side of the fuselage (the side away from the exhaust) to accommodate the radioís on/off switch. Use the switch cover plate as a guide to mark the location and size of the opening and the two holes for the mounting screws. Install switch.

CAUTION: Make sure the opening you cut for the switchís on/off lever is just slightly bigger than the lever, so that the switch will operate safely, without catching or binding on the wood.

Control Horn Basics

  • Sometimes the holes in molded plastic control horns and servo arms end up being a little undersize, making it very hard to install the R/C Links and Pushrod Connectors that attach to them. All of the R/C Links and Pushrod Connectors in this kit have a pin size of 1/16" dia. If you have difficulty getting the pins to go into the holes in the control horns or servo arms, open up the holes with a 1/16" dia. drill bit. DO NOT USE A BIT LARGER THAN 1/16" DIAMETER!

  • Nylon control horns should always be mounted so that the adjustment holes in the control arm line up with the hinge line of the control surfaces! If not, the control surface will have unequal travel in one direction.

  • Some radios have a feature called "End Point Adjustment" (sometimes called "Adjustable Travel Volume") that allows the user to electronically adjust the total travel of the servos, and thus, the total travel of the control surfaces. This is a very handy feature! If you do not have this radio feature, you can still make control surface travel adjustments by mechanical means. Move the linkages in the directions shown to get more or less travel.

Why Solder Links

You may be wondering why we provided R/C Solder Links for the servo ends of the aileron, elevator, and rudder pushrods, when all the rest of the control system installation is solderless! Why didn t we use more Pushrod Connectors, or maybe just a Z bend in the wire?

Well first off, Z bends are a good alternative, but we felt that they are too difficult for a beginner to make correctly on his first try. Second, Pushrod Connectors are great, but not in all situations. They are more than adequate for non-aerodynamic controls like the throttle and nose gear. However the set screw in a Pushrod Connector can come loose! If that happens to the throttle or nose gear, it most likely won t cause any serious problem. But if it happens to the ailerons, elevator, or rudder, the airplane will most likely crash! That s why you don t see any Pushrod Connectors on the ailerons, elevator, or rudder pushrods of the KADET LT-40!

If you have never soldered before, don t worry, it s not difficult. The hardest part will probably be coming up with a soldering iron (or gun). If you don t want to purchase one at this time, seek the assistance of someone who already has one and knows how to use it. The secret to easy soldering is to use plenty of heat! You need a heavy-duty soldering iron to do this job, not one of the little pencil style irons that are only intended for soldering small electrical wires and components. It will take a soldering iron of at least 75 watts (100w or 200w is better) to solder the R/C Solder Links and pushrod wires in this kit. Use ROSIN CORE SOLDER (60% tin, 40% lead) and a good brand of SOLDERING PASTE FLUX. Put the wire in a vise. Coat the end of the wire with soldering paste flux.


Slide on the R/C Solder Link. Press the tip of the soldering iron firmly to the outside of the barrel of the R/C Solder Link. Let it heat! Keep the iron against the barrel while you touch the tip of your solder to the joint (not to the soldering iron). When the two parts get hot enough, the solder will melt and flow into the joint. Continue flowing solder into the joint until it is full. Let cool. Wipe the solder joint clean with a rag.

Landing Gear


Bolt the aluminum Main Landing Gear in place on the fuselage with two 4-40 x 1/2" bolts.


Assemble the wheels to the main landing gear as shown in this drawing. First slide the 3" dia. wheel (not provided) onto a 6-32 x 1-1/2" Mounting Bolt. Thread on two 6-32 hex nuts, side by side. Run both hex nuts up close to the wheel hub, but not too close - make sure that the wheel can still turn freely on the axle. Tighten the hex nuts up against each other. Stick the end of the bolt thru the aluminum gear leg and thread on 6-32 aircraft locking nut. Tighten securely.


Because of the tiny size of the tailwheel wire, we prefer to use soldered washers to mount the tailwheel instead of wheel collars. First solder a #2 flat metal washer at the inner bend of the tailwheel wire as shown. Helpful Hint: Slide a small piece of small diameter silicone fuel line tubing onto the axle wire to hold the washer in position while you solder. After the solder joint has cooled, remove the fuel tubing.


Slip the tailwheel onto the axle, and then put a small piece of thin cardstock or paper (the paper serves two purposes - to protect the wheel hub from the solder, and serves as a spacer to insure that the wheel will turn freely after the soldering). Next slide a #2 flat metal washer on the wire and solder it place.
A Soldering Tip: The secret to easy soldering is cleanliness. Sand the washers and the wire where the washers are to be soldered and then wipe everything clean with alcohol before attempting to solder.


Lay the Nylon Tailwheel Bracket in position on the bottom of the fuselage, aligning the rear hole in the bracket with the hole in the fuselage. Drill three 1/16" dia. pilot holes in the bottom of the fuselage, and attach the Tailwheel Bracket using three #2 x 3/8" Sheet Metal Screws.

Fuel Tank
The following instructions and photos pertain specifically to a 6 oz. Du-Bro Fuel Tank, although the proceedure for assemblying other brands of plastic "clunk" tanks should be basically the same.


Pull the stopper cap out of the front of the fuel tank. Inside the tank there should be two brass tubes, one brass clunk weight, and a short piece of fuel line tubing. Shake the tank to get these parts out through the hole. You may have to reach inside the tank with a tweezers or needle nose pliers to get a hold of the fuel line tubing and pull it out . (CAUTION: Donít squeeze too hard and put a hole in the tubing). Now shake the tank a few more times to make sure there is no dirt or plastic shavings inside!


Take a look at the stopper cap. Rotate the front plastic cap, the middle rubber stopper, and the rear plastic cap until the holes line up. You should be able to see daylight through two of the three holes. NOTE: We will only be using two of the holes. Leave the third hole closed.


Cut one of the brass tubes to 1-1/2" long - this will be the Fuel Feed Tube. Cut the other brass tube to 2" long - this will be the Vent Tube. A razor saw works well for cutting the brass tubing. Clean up the sawn end of the tubing with 220 grit sandpaper to remove any burrs or sharp edges that might cut the fuel line tubing later.


138. Put the plain end of a 3/32" dia. drill bit about 1/4" inside the back end of the vent tube. Using the drill bit for leverage, slowly bend the back end of the vent tube upwards about 45ļ, or until the end of the tube is even with the top of the stopper cap.


Carefully push the brass tubes through the two open holes in the stopper cap. Keep pushing the tubes in until 3/8" of tube sticks out in front of the stopper cap. (PLAN AHEAD: The two brass tubes should end up horizontally opposed to each other at the bottom of the stopper cap. The short fuel feed tube should be on the left side, and the long vent tube on the right.)


Cut the piece of fuel line tubing. Slide one end of the tubing onto the brass clunk weight. Slide the other end of the tubing over the back end of the fuel feed tube.


Insert the completed assembly into the neck of the fuel tank. Rotate the stopper cap so the brass tubes are horizontal at the bottom of the stopper. Hold the tank up to a strong light and look inside to see if the vent tube is close to the top of the tank. Also check to see if the brass clunk weight inside the tank swings freely from side-to-side, whether the tank is right side up or upside down. If the clunk weight is hitting the back wall of the tank, take the stopper cap back out, shorten the length of the fuel line tubing a little, and then test again. When everything is right, tighten the screw in the stopper cap until the cap is snug in the neck of the tank.


Test the fuel tank for leaks! Fill your kitchen sink with water. Slip the 12" long piece of Fuel Line Tubing onto the tankís vent tube. Submerge the tank in the water, holding your thumb firmly over the fuel feed tube. Blow air into the other end of the fuel line tubing and watch for air bubbles coming around the cap of the tank. If itís leaking, tighten the screw in the cap a little at a time until the leaking stops.


Cut two pieces of fuel tubing, approximately 6" long. Slip one piece onto the tankís fuel feed tube and the other onto the vent tube. Run the loose ends of the fuel line tubing through the hole in the firewall at the same time that you are placing the tank in the fuselage.


Slide the fuel tank up against the back of the firewall. Cut a piece of scrap wood (can be stick or sheet, balsa or plywood) to use as a rear tank brace. Reach in through the servo area and wedge the brace between the fuselage sides, right up tight against the back end of the tank. Spread some Slow CA glue on the ends of the brace to glue it to the fuselage sides. (HINT: Put some glue on the end of a long stick or nail, then reach in and dab the glue on the ends of the brace.) This brace will insure that the tank cannot shift backwards in flight.


Cut two strips of 1/4" thick soft foam rubber to fit along the sides of the fuel tank, between the tank and the fuselage sides. This packing keeps the tank from shifting sideways in flight.


Attach the fuel feed line to the engineís carburetor and the vent line to the pressure fitting on the muffler. (NOTE: Trim off any excess length of fuel line tubing. The fuel lines should be kept as short as possible for best fuel draw, but not so short that there is danger of them coming off in flight. Leave a little slack in the lines.)


To fill a fuel tank with this vent arrangement, first remove the fuel lines from the carburetor and the muffler pressure fitting. Pump the fuel into the tank through the fuel feed line (carb line). When the tank is full, fuel will begin to run out the vent line (muffler line). Stop pumping when you see the fuel start to come out the vent line! Re-connect the fuel lines and you are ready to start the engine.

Balance Your Airplane

Yes, we know your KADET LT-25 looks done and youíre real anxious to go out and fly it, BUT WAIT A MINUTE - ITíS NOT REALLY DONE YET! It must be balanced! All airplanes, model or full-size, must be accurately balanced in order to fly successfully. An airplane that is not properly balanced will be unstable and will most likely crash!


PRELIMINARY: To balance your KADET LT-25, all of the parts and components must be installed in their correct positions on the model. The battery pack and receiver must be installed in their correct locations; the propeller, spinner, and muffler must be installed on the engine; the fuel tank and fuel lines must be installed and connected; and every other piece of essential equipment must be installed, ready for flight. ALWAYS BALANCE THE KADET LT-25 WITH THE FUEL TANK EMPTY!


Attach the wing to the fuselage with twelve #67 rubber bands (at least 6 per side).

BALANCE POINT = 30%, or 3-1/2" Aft of The Leading Edge of the Wing


Familiarize yourself with the balance point shown on fuselage side view plan.

Using a ruler, measure back 3-1/2" from the leading edge of the wing and make a pencil mark at this point, on the bottom surface of the wing next to the fuselage. Make the same mark on the other side of the fuselage. Next place a fingertip on each pencil mark and lift the airplane up in the air. No part of the model should be touching anything except your fingertips!

If the KADET LT-25 will sit on your fingertips in a LEVEL ATTITUDE, then it is PROPERLY BALANCED and ready to fly.
If the airplane sits on your fingertips in a NOSE DOWN ATTITUDE, then it is NOSE HEAVY!

You will have to add weight to the rear of the airplane to get it to balance. NOTE: Before adding additional weight to the tail of your model, try simply moving the battery pack to a further aft location. The battery pack is relatively heavy and therefore makes a good balancing tool. You might try switching places between the battery and receiver; or move the battery right in front of the servos; or in extreme situations, move it behind the servos. If you canít get your model balanced simply by re-locating the battery pack, then you will have to glue lead weights into the tail end of the fuselage.

If the airplane sits on your fingertips with the TAIL DOWN, it is TAIL HEAVY! DO NOT ATTEMPT TO FLY IT!
A tail heavy model is very dangerous and will most likely crash!! Lead weight will have to be added to the nose of the model to bring it into balance. The weights can be glued to the inside of the fuselage "cheeks" in front of the firewall; or inside the fuselage alongside the fuel tank. There are also "spinner weights" available for tail heavy models. Wherever you put the balancing weight, make sure it cannot be lost in flight!

Pre-Flight Checkout

Be certain to range check your radio equipment according to the manufacturerís instructions before attempting to fly.

A lot of problems can be avoided if your new engine has been "broken in" on a test stand per the manufacturerís instructions before you attempt to fly.

Double check the alignment and movement of all the controls one more time! Make sure the control surfaces move in the proper direction when you move the sticks. Youíd be amazed to know how many models have been destroyed on takeoff with one of the controls reversed. If youíre in this hobby for very long, you will see it happen. Donít let it happen to you! Itís a good idea to get into the habit of checking for proper control response every time you get ready to fly.

Adjust all of your pushrod linkages so that the control surfaces are in their neutral position when the transmitter sticks and trim levers are centered. When you get to the flying field, donít be surprised is the elevator and rudder are suddenly misaligned after you had them perfect at home. Temperature and humidity changes can cause nylon pushrods, like those on the KADET LT-25ís elevator and rudder, to shrink or expand slightly. If they are just slightly out of neutral, use the trim levers on the transmitter to neutralize them before flying.

Adjust your pushrod linkages as necessary to provide the prescribed amount of control surface travel. Make sure all of the R/C Links are securely snapped shut.


ELEVATOR9/16" up, 9/16" down
RUDDER1" left, 1" right
AILERONS3/8" up, 3/8" down


Find A Safe Place To Fly

Donít try to fly your KADET LT-25 in your backyard, at the local school yard, or in any other heavily populated area! If you have never seen an R/C airplane fly before, you probably donít realize how much room you really need. Itís more than most people think! A school yard may look inviting, but it is too close to people, houses, power lines, and possible radio interference.

The best place to fly your model is at a designated model airplane club flying field. Ask your hobby shop dealer if there is a model club in your area and join. Not only will you have access to a large, safe place to fly, but you will enjoy being around all types of R/C model airplanes and talking to their builders.

The KADET LT-25 is designed to give you the best possible chance to succeed in learning to fly R/C. However, learning to fly model airplanes is not a skill you can learn overnight. Itís very similar to learning to fly a real airplane in that you should go through a learning phase with an instructor before you try to pilot the airplane yourself. A lot of things can go wrong with these machines, and if you are not prepared to deal with them instantly, you will loose your new airplane in a crash. To reduce the chance that your first flight will end in disaster, we strongly recommend that you seek the assistance of a competent R/C pilot to help you with your first flights.


© Copyright SIG Mfg. Co., Inc.

SIG MFG. CO., INC............Montezuma, Iowa 50171-0520

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.