|KADET MARK II RC49 COVERING AND FINISHING|
There is a variety of covering and finishing methods available that are well suited to the Kadet Mark II. The final choice should be made after reading through each part of this section so that you can make an informed decision. Plastic iron-on coverings are popular because they are fast and easy to apply. Sig Koverall will give the model the strongest and most durable finish; while materials like silk, silkspan, and silray will appeal to the more traditional modeler
IMPORTANT! If you plan on using a finishing method that requires painting (Koverall, silk etc.) 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 covered, than painted.
Regardless of which covering you decide to use, it will not conceal a rough framework. Take the time to sand the model carefully with fine sandpaper (360-400 grit) 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 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. We 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 upper 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.
Trim off the edges with a sharp blade. We find 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 area 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 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. On the open framework area on the wing, brush the dope on sparingly. If too much is applied, the dope will be rubbed through the material and will run down the the surface on the inside and form a puddle. When these puddles dry, the large amounts of dope solids in them cause more shrinkage than the rest of the covering and a scarred area results. So apply dope very lightly the first time over. A second coat will seal most of the pores of the material and from this point, running through will not be a problem.
Use one or two coats of regular Supercoat clear on the wing to shrink the covering. After that, unless the covering is still not tight and unwrinkled, Sig Lite-Coat low shrink dope is recommended to help prevent warping. The solid wood fuselage and tail can have Sig Lite-Coat from the beginning if desired. Sig Supercoat Color Dope has low shrinkage qualities.
A third coat of clear should provide a good base for color. Sand lightly when dry with 360 grit 3M Tri-M-Ite no-load paper. Don't bear down on the edges of the ribs or the silk fibers will be cut through. The color dope may be brushed or sprayed.
Supercoat Color Dope should be thinned with 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. If brush marks show, you need more thinner. 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 best 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.
The original Kadet Mark II was given 2 coats of sprayed Sig Supercoat white. The windows and decoration scheme was then traced on with a soft pencil and the design covered with masking tape. Two coats of Sig Supercoat light Red were then sprayed on. When the masking tape is pulled off, the design will probably not have perfectly even edges. if you do not wish to pin stripe it with a ruling pen and dope, as described in the next paragraph, use the pen to touch up the edges.
The pin striping was applied with a mechanical drawing ruling pen. Thin the dope slightly with blush retarder to slow the drying process and aid the flow of dope through the pen points. Clean the pen frequently with dope thinner and wipe on a cloth before reloading with fresh dope. Don't try to draw a thick line with the dope and pen but instead draw a thin line on each side of the desired pin stripe (about 1/8" wide were used on the original) and fill in between the lines using the pen free hand and opened up for a wider flow. If you have a steady hand, use a small brush. Use a French curve to outline curved parts of the decorations. The cabin windows were painted silver.
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 COWL|
The plastic cowling 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 Superpoxy, Hobbypoxy or Du Pont Dulux Enamel. Don't use other paints without testing first on scrap plastic.
CAUTION: Do not try to cover the cowl with any type of iron-on covering. The heat may melt or distort the plastic.
DECALS - Stik-Tite Pressure Sensitive
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 corners as you are cutting. Wet the surface on which the decal will be placed with soapy water (use dishwasher detergent). 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.
COVERING WITH SIG KOVERALL
Sig Koverall is a relatively inexpensive, synthetic polyester-base, heat shrinkable fabric much like the covering used on full-scale aircraft. It is the strongest and most durable finish you can use on your Kadet - it will actually add strength and rigidity to the model's framework. If you are careful in cutting the material, one medium sized package (SIGKV002, 48"x72") is enough to cover all the parts of your Kadet. It can be applied to the model using dope or ironed on using Stix-It, a heat-activated adhesive.
Whichever application method is used, you should first brush two coats of clear dope onto the framework wherever the covering material makes contact. Lightly sand after each coat to remove any raised grain or fuzz.
Applying Koverall With Dope
Start with the bottom of the wing by cutting out a piece of material about 1/2" larger all around the panel, with the grain running spanwise. (The grain of Koverall runs parallel to the finished bias edge.) Lay the Koverall on the wing, pulling out any major wrinkles. Unlike silk, which uses water to shrink it tight, Koverall uses heat. In fact Koverall shrinks so well that there is no need to worry about such things as packaging folds or creases because they will come out easily with the iron. Brush clear dope around the edges. This will soak through the fabric and adhere it to the dope already dried into the framework. Allow dope to dry before trimming off the excess material with a sharp razor blade. Check for any rough edges or places that are not stuck down properly and apply more dope. Let dry.
Applying Koverall With Stix-It
Directions for applying Koverall with Stix-It are on the can. The basic procedure is to apply Stix-It around the edges of the framework where you want the covering to attach. When dry, the fabric can be ironed-on around the edges where the Stix-It was applied.
Shrinking and Sealing Koverall
After both sides of the surface are covered (such as the top and bottom of the wing), shrink the Koverall evenly with an iron or hot air gun. (Be sure to read the Koverall package instructions.) The fabric can now be sealed with three or four coats of clear dope. Since Koverall has such a tight weave, fewer coats of dope are necessary to fill it than silk. Thin the dope until it brushes on easily and flows out smooth (about 25% to 30% thinner). The first coat should be applied sparingly to avoid puddles underneath the fabric. The second coat will seal most of the pores of the Koverall and from then on, running through will not be a problem. Sand the model VERY LIGHTLY with FINE sandpaper after the second coat is dry. The next two coats will completely seal and begin to fill the weave of the fabric. When dry, sand again. Your Kadet should now be ready for its colored paint scheme.
Apply the colored dope to the Koverall exactly as described in the "COVERING WITH SilK, SllKSPAN, OR SllRAY" section, starting with the white base coats.
COVERING WITH SIG SUPERCOAT IRON-PLASTIC COVERING
Many modelers prefer to use an iron-on plastic covering on their models for several reasons. Some modelers simply don't like to paint or have workshops located where paint fumes can't be tolerated. Others like the speed and ease of application afforded by plastic coverings.
|You can generally finish a model much faster using an iron-on covering rather than a painted finish. However, plastic coverings are less durable and do not
add nearly as much strength to the structure as fabric covering. On the plus side, plastic coverings are fairly easy to apply and result in a glossy, smooth finish. Plastic coverings tend to be susceptible to
punctures and tears, but they are easily repaired.|
If you decide to cover your model with this type of material, we recommend Sig Supercoat Iron-On Plastic Covering for it's low cost, light weight, and ease of application. To cover the Kadet, you will need at least four rolls of Supercoat. You can use one color for the wing and another for the fuselage, or go with all one color. Two pages of photo illustrated instructions are supplied with each roll of Supercoat, so only a quick outline will be presented here.
Like any other type of finish, Supercoat will not hide poor workmanship. The entire framework should be given a final sanding with 360 or 400 grit sandpaper before application of the material. Wipe the surface with tack rag or cloth dampened with alcohol to remove all excess dust.
Covering The Wing
Cut a piece of material slightly oversize, remove the protective plastic backing sheet, and lay the adhesive side of the covering material against the structure. Tack the material in place around the edges using and iron to activate the adhesive. Seal the entire edge, then trim off the excess. Repeat this process for the top of the wing, being sure to overlap the material about 3/16" to 1/4". Always plan your covering sequence so that seams are on the bottom surface or at corners so they aren't so easy to see. Once both top and bottom have been covered, shrink the material with an iron or heat gun, heating evenly from one side to the other.
Once your model has been covered, you can add trim decorations using Sig SuperTrim Self Adhesive Trim Sheets. SuperTrim is made of the same material as Supercoat, but it has a sticky backing. Simply cut out your design and stick it in place. Thin strips can be cut from SuperTrim sheets or you can use one of the many brands of striping tape (such as Sig SuperStripe) which come in various colors and widths. Be certain to add some kind of stripe or decoration to the top of the wing so that while you are flying it is easy to distinguish the top of the airplane from the bottom.
NOTE: The remainder of these instructions concerning Pre-Flight Checkout and Flying contains information specifically concerning the Kadet Mark II. At this point, you should refer to the booklet "Basics of Radio Control" included with your kit for more information on balancing, control throws, and other items that are important to the success of your model. In particular, go through the "Pre-Flight Checklist" in Chapter 7 carefully before attempting to fly.
Kadets will be okay for test flying if their balance is somewhere within the indicated range. Our own Kadets are balanced in the forward position and seemed quite happy that way. It is probably safer for beginners to have the balance point forward, at least on test flights. Tail heavy Kadets have a tendency to not react quickly to aileron movements in slow speed and/or nose-up situations.
|Do not fly with the balance point behind the range shown unless you are an expert flier with a definite purpose (such as extreme aerobatics) for doing so.
SUGGESTION: For test flights, put a piece of masking tape on the bottom of each wing tip and mark the Balance Point range on the tape. This will make it convenient to check the actual balance point location and adjust it as desired.
The balance point range is measured from the leading edge of the wing. Suspend the model on finger tips placed on the bottom of the wing on the marks. Balance with an empty fuel tank, but with all other equipment installed and the model completely finished and painted. It should hang from the finger tips approximately level.
If the tail hangs down, it is tail heavy. Add lead or weight to the nose as necessary to get it to hang level. Be sure and fasten the weight securely. Do not attempt flight in tail heavy condition.
If the nose hangs down below level, the model is nose heavy. If it is only a little nose heavy, don't do anything about it, it will be okay to go ahead and test fly. If it is more than a little nose heavy, correct by moving the radio batteries out of the nose and as far back in the cabin as is necessary to achieve balance.
Control measurements below are suggested as a beginning. Test flights may indicate a need for more or less movement, depending on individual model differences, center of gravity (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.)
It is not uncommon for the best Kadet elevator neutral position to test out to be slightly drooped down from level. This introduces some nose down trim to keep the model from climbing when the transmitter stick is in the center. The exact best neutral elevator position for each particular model must be determined during flight testing.
With the model flying at about 3/4 throttle, feed in down trim with the transmitter lever until the model flies level. Land and observe the position of the elevator. Adjust the elevator push rod as required to keep this flight checked "neutral" position when the transmitter trim lever is returned to the center.
Aileron movements are approximate. Differential between up and down movement may vary in individual installations but it is not a critical matter, as long as you have more up than down movement with at least as much difference between the two as shown in the table.
If the ailerons should need offsetting from neutral to correct wing warp, try setting the neutral point of the ailerons slightly above level and use the "up" side of the movement for required corrections more than the "down" side of the movement. It is not a good idea to have the aileron drooped down below level for adjustment of trim in either aileron if it can be avoided.
|Optional Aileron Gap Seal|
Too wide a gap at the aileron hinge line can cut down on their effectiveness due to pressure leakage through the gap. Sealing the gap with plastic tape or a strip of plastic film covering material will make the ailerons more effective, even on a model with a small gap. (The factory Kadets were flown with unsealed gaps to establish the recommended control movements listed here.) While this suggestion will help insure that the ailerons are effective, the primary means of controlling roll response is still by adjustment of the aileron movement. If your Kadet will not turn or roll to your satisfaction, it is most likely due to an inadequate amount of up and down movement of the ailerons.
The adjustable nylon fittings on the aileron horns (supplied with the kit) provide a fairly good range of aileron movement adjustment. Screw the nylon fitting in toward the wing for increased movement of the ailerons; out away from the wing for decreased movement. After raising or lowering the fittings, chances are you will need to readjust the neutral point of the ailerons using the adjustable RIC links on the aileron push rods.
Optional Aileron Servo Hookup
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. A method of getting a better differential - the alternate neutral position is described above and this helps the situation. However, the best way to increase differential is by offsetting the pickup point on the servo for the pushrods as shown in the accompanying drawings. Any amount desired can be obtained in this manner. The farther up the wheels the push rods are attached, the greater the differential, i.e., more up, less down movement.
We suggest the use of DuBro Ball Link fittings on the servo wheel but they are not shown on the drawing for clarity. Kadet fliers who are using this approach suggest starting with about twice as much up as down. For example, 1/2" up would be accompanied by 1/4" down. This exact proportion of this relationship is not critical, since the Kadet flies very well without any differential at all, but improved turn characteristics are said to be had by this setup of the servo.
If your fin should be glued on slightly crooked and thus causes the model to turn one way or the other, use offset of the rudder to correct the tendency. Do not use aileron offset to correct turns caused by the fin. Aileron offset should only be used to correct wing mis-alignments.
Flying the Kadet MK II on Three Channels when using a Four-Channel Radio
Plug the rudder servo in the fuselage into the receiver outlet marked aileron. If an aileron servo is installed in the wing, leave it unplugged and tape the ailerons in place so that they cannot be bumped and moved off of center. Use of the aileron stick on your radio equipment to operate the rudder will enable you to develop the proper left and right reactions that will later be needed when advancing to aileron control, using the same hand. If you plugged the rudder into the rudder socket when only using 3 channels you would have to make a difficult transition from one hand to the other at the time you advanced to aileron control, just about the same as starting over. The most important thing you are learning in the early stages is an automatic left and right reaction on a particular transmitter stick with a particular hand. Forget which control surface is doing the turning on a 3 channel Kadet MK II, assume that the rudder is an aileron.
|Flying the Kadet MK II on Four Channels|
Plug all controls into the receiver outlets as marked. The rudder is now on the left hand stick and, on an aileron model, will only be used for ground steering and certain aerobatic maneuvers. If you started flying on 3 channels, practice taxiing the model around on the ground to help make the transition from the right hand operation easier. In the air of course, you will be using the same turn motion you have practiced as a 3 channel flier.
Flying the Kadet MK II on Two Channels
3 or 4 channels are best, but the Kadet can be flown on 2 channels when this is necessary. We recommend use of rudder and elevator control for the two channels. Motors above .25 cu. in. in size should be run throttled back to about 3/4 power by tying down the throttle arm at the desired speed. .25 cu. in. motors can be run wide open. Altitude gain on two channels is controlled by use of elevator down trim or application of down elevator stick movement when required. On first test flights with a 2 channel Kadet, fill tank 1/2 full. This will help keep the model from gaining too much altitude if the trim is not set properly at first and the rate of climb is excessive.
General Flying Tips
Test flying and flight trimming are covered thoroughly in the "Basics of Radio Control" booklet. Read those sections carefully, especially if you are a first-time pilot. No amount of reading material or pre-flight discussion can totally prepare you for the actual experience of handling your model in the air, but knowing what to expect will make it much easier.
We highly recommend that you try to find an experienced R/C pilot to help with your first flights and serve as an instructor while you are learning to fly. Have the instructor make the first flight on the model to get it trimmed out and to make sure everything is working okay.
The Kadet MK II can takeoff from paved runways or smooth grass, but these aren't always available. If a good, smooth takeoff surface isn't 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 with the wings level. The model may dip slightly and then 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 elevator to lift the nose.
Don't Wallow Around The Sky!
A common mistake made by beginners is to fly around with the model having too much up trim. It climbs out steeply under full power in this condition (and is probably a safety factor for a rank beginner) and you can level it off by throttling back on the motor. However, in this over-up condition, it wallows around with the nose high, it is hard to turn properly and it will not fly into the wind because of low airspeed. The solution is to apply some down trim to the elevator to bring the nose down and make the model fly more nearly level at cruising power. it may be necessary to droop the elevator a bit from level by screwing in the RC link on the elevator pushrod to get enough down. The way to learn how to do this trimming process is to experiment with the model in the air and note it's reaction to increased down trim or other changes. Moving the center of gravity in combination with trim changes can also alter the flying characteristics. For example, you may find that the balance point specified for test flights will be okay for the first few flights but when the model is trimmed down to fly more level under cruising power you may find that moving the balance point back will give you better performance. Or you may find reactions to aileron movements improved by keeping the balance point forward and using more aileron movement.
It is impossible to give exact directions for every case, since individually built models vary slightly and the engine used also affects results. But if the model is not flying in a satisfactory manner, the chances are it is not trimmed properly and should be adjusted accordingly. Do a little tinkering, a bit at a time. This is an instructive way to fathom the mysteries of perfect trim and in the process you can improve your flying performance considerably.
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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.