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SOAPY THREADS
If you are trying to thread a screw into a plywood or hardwood block—for example, for a landing-gear strap—it is often hard to thread the screw into place without wearing out the screw head. The best way to make the screw go into the tight-fitting hole is to apply some bar soap to the threads.  The soap lubricates the threads and makes the job much easier. It also helps when it is time to remove the screw.

MAGNETIC SCREWDRIVER
High-powered magnets are available everywhere, from online to most home-improvement stores. They are strong and compact, and if you attach one to a metal screwdriver, you’ve just made a magnetic screwdriver that will hold a screw in place. This makes feeding the screw into place in your airplane (like for servo mounts) a piece of cake. As an added bonus, they make it easy to pick up loose screws, pins, and nuts on the workbench.

PAINT DRIPS
An easy way to avoid messy paint drips around the workshop is to take a rubber band and slip it over the paint can as shown. You can now dip in the brush and wipe the excess paint off the bristles by pulling them over the rubber band, which is stretched over the can’s opening. This tip is great for all brush-on paints, including dope and epoxy paints.

THINK SMALL
When you are custom-mixing paints, such as when you are trying to match a camouflage color, think in small amounts. By mixing up small batches using glass jars and measuring cups, you can fine-tune your mixtures without wasting too much paint. If you get it wrong, you throw out an ounce at a time, not pints or quarts. When you do get the ratios correct, write them down and then you can multiply the ratios to mix larger quantities.

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CUTTING BRAIDED CABLES
When you cut braided metal cables for pull-pull control setups, like rudder and nose-wheel
steering, the ends will often unravel and become frayed. Simply wrap the cable where you want to cut with paper masking tape and the ends will stay orderly and neat.

BALSA DENT REMOVAL
If you notice small dents and dings in the soft balsa before covering, fill a small dish with water and use a Q-tip to apply a drop of water on the dent. Lightly heat the area with a sealing iron and the dents will literally disappear in a puff of steam. As long as the balsa is merely dented and not torn or cracked, this will work perfectly.

HOMEMADE FUEL-LINE BARBS
Don’t you hate it when the fuel line comes off inside the fuel tank? It usually causes a dead stick and damage to the model. To avoid this, wind copper wire onto the brass fuel tube and cut the wire with pliers to produce one ring of copper wire near the end. Clean the joint, and solder the ring to the tube. Use just enough solder to form a small fillet around the wire and ring, and let it cool off. Slide your silicone or Tygon gas fuel line in place, and secure with a tie wrap.

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Let’s face it! Accidents are bound happen, and when it comes to flying RC airplanes, the chances are that you’re going to suffer some damage to your airplane. There’s no reason, however, to trash your crash. With today’s beautiful molded foam fliers, you can get back into the air with very little effort. You also can save some bucks by repairing your bent bird instead of buying new parts or an entirely new airplane.

What’s Needed

The supplies needed for any model repair are a hobby knife with sharp replacement blades, some masking tape, a sanding bar with medium sandpaper (100 to 150 grit), and some fine 220-grit sandpaper. The glue needed is 15-minute two-part epoxy, foam-safe CA adhesive, and foam-safe accelerator. Denatured alcohol is good for cleaning the surface of the foam and for cleaning up excess epoxy from repairs. We used an assortment of glue, including those by Bob Smith Industries and Flash Adhesives.

Removing Dents

Step 1: The leading edge of a foam wing can really take a beating, but dents are really only cosmetic issues. If you have a minor dent, simply apply a wet paper towel to it and heat with a covering iron. Most of the time, the steam will expand the foam and your dent will disappear.

Step 2: If the dent is more pronounced, you can quickly cut away a section of the damaged material with a razor saw and glue in some new foam.

Step 3: Cut some new foam to length, and glue it in place with foam-safe CA. The best way to do this is to cut the foam a bit oversize, and spray foam-safe accelerator to the new material. Apply the CA glue to the cutout area, and insert the repair piece. Hold it in place until the glue sets. Use your saw to remove most of the unwanted material, then use a sanding block to smooth the replacement piece.

Step 4: Apply a little hobby filler around the edges to fill in any gaps (Hobbico HobbyLite Filler is great for this).

Step 5: Once the filler has dried, use fine sandpaper to smooth the repair. If you need to, apply more filler around the repair area to feather out the repair area.

Step 6: Apply some matching foam-safe paint to complete the leading-edge wing repair. The hardest part of this repair really is finding matching paint. Usually, the instructions that come with your airplane will call out the colors used. If not, go to the hobby shop and check out the Master Modeler and Tamiya brands of acrylic foam-safe paints. You’ll be able to match the color chips and then lighten or darken the colors slightly to match. In real life, warbird repairs seldom matched the rest of the airframe, so welcome to scale weathering!

Mending Broken Wings

Step 1: In extreme cases, you might break a foam wing in two (or more!) pieces. A great trait of foam is that it is usually very easy to piece back together. Mix up a small batch of 15-minute epoxy on a plastic can lid. Run two or three lengths of each part as shown and then mix together.

Step 2: Place some waxed paper or food wrap under the wing pieces and then apply just enough mixed epoxy to cover the exposed ends of the break. Use some masking tape to hold the parts together while they rest flat against your work surface. Be sure to wipe away any excess epoxy that oozes from the repair using a paper towel and some denatured alcohol.

Step 3: After the epoxy has set, remove the tape. Using a sanding bar, smooth out the repair area.

Step 4: If your wing is more than 36 inches in span, use a piece of thin plywood that is 4 to 6 inches long and ½ inch wide as an internal brace. Using a hobby knife and a razor saw, cut a straight line all the way through the wing, as shown. Test-fit the plywood, then apply foam-safe CA and insert it into the wing. Apply some accelerator, and let the glue set.

Step 5: After the glue sets, apply model filler to the repair and let the filler dry.

Step 6: Using fine sandpaper, sand the filler smooth and flush with the rest of the wing surface.

Step 7: Apply matching foam-safe paint, and let it dry. The repair is complete, but you can also apply some decals over the repair area, if you like, to completely cover the mended area.

Repairing Foam Hinges

Step 1: It is not possible to repair a live-foam hinge, where the hinge is molded in as part of the control surface. It is best to install new hinges in the damaged surfaces. Before removing the surface, mark the locations for the new hinges. For this rudder, three 1/8-inch Robart Hinge Points will be installed.

Step 2: After marking the hinge locations, take a sharp hobby knife and slice through the molded hinge to separate the rudder from the fin. Use some sandpaper to smooth the mating surfaces.

Step 3: Sharpen the end of a 1/8-inch brass tube, and use it as a drill to produce the holes for the Hinge Points. This produces much neater holes than a wood drill bit.

Step 4: Mix up some 15-minute epoxy, and use a toothpick to apply the adhesive into each of the holes in the rudder.

Step 5: Insert the Hinge Points into the holes, and set aside until the epoxy cures. Make sure that no epoxy gets into the pivot pins. If it does, quickly remove the hinge and install a new one. You have about 20 minutes before the epoxy starts to thicken and set.

Step 6: Apply more glue inside the holes in the vertical fin, and slide the hinges in the rudder into place. Again, wipe away any adhesive that oozes out of the holes with paper towels and alcohol. Set aside until the epoxy sets.

That’s it! Let the glue set and get your pride and joy back in the air.

Please share your easy repair tips in the comments below!

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Dedicated Location
First off, you’ll enjoy your build more if you have a dedicated space. Whether it’s a basic table in the guest room or a full garage with custom shelving and a workbench – you need the freedom to spread out and stay organized. It will make a big difference when you don’t have to clean up in the middle of your project (or worry about the family pup getting into your small-parts pile).
If you have a spare room you have the perfect space and an old table is all you really need. You can also use plywood and sawhorses if they are sturdy. Once you find the perfect spot with a solid and flat work surface, you’re ready to start adding tools. This is where utility benches or extra tables to store larger tools keeps your immediate work area cleaner and less crowded.

Building Boards
Most modelers don’t build directly on their work table. They often use “building boards” with a cork top surface, called a Wright Building Board. These soft-top building boards allow modeling pins to be pushed into their surface so you can hold all the parts of a build kit safely in place.

Pro Tip – You can use insulation foam boards and ceiling tiles too! Just use 3M spray adhesive to affix it to the top of your workbench and keep it from moving.

You won’t want to cut things on your building board due to the soft surface so leave yourself enough room on your table to have a clear hard surface that can double as a cutting and work area.

Organization
Stay organized! With so many moving parts, it’s important that everything has a designated location as you progress through a project. Organize all your hardware to make it easy to find. This saves building time and prevents cosmetic damages to the parts you’re working with. RTL Fasteners has lots of excellent hardware and handy organizer boxes for this, check them out!

Pro Tip – As you work, we suggest dividing your project into sessions so you have only the parts and tools you need for the task at hand, reducing clutter or the chance of losing a part.

Lighting
With so many small pieces of hardware and minute details to get right, make sure you have ideal lighting in your work area. Optimally, you should have overhead lighting as well as a moveable spot or task light that allows you to direct the lighting exactly where you need it.

Basic Tools
The old saying that “you can do anything with the right tools” is particularly true in modeling; the proper tools will simplify any job. Whether it’s a quick-assembly ARF or a complete scratch-build, there are basic hand tools that every modeler needs.

Pro Tip – We suggest starting with the basic RC tool kit before moving on to bigger power tools such as a sander or drill press. That way, you can get started with the smallest up-front investment and get a feel for a simple build.

Any modeling project can be completed with a simple workshop as described above.
Once you have your workshop situated, it’ll be time to select your first build kit and get started, knowing that you already have everything you need!

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INSTALLATION 101

1 First, check that your servos are properly installed. Unless you’re flying a foamie or small electric in which the servos are glued into place, use the rubber grommets and brass eyelets that come with your servos. Install them so the wide brim of the eyelets are under the grommets (between them and the servo tray). Tighten the screws until their heads meet the brass bushing’s top edge. The rubber grommet will be compressed a bit, but that’s OK. The object is to have a secure, shock-mounted servo installation that won’t move when the servo arm is deflected. If the eyelet is installed with the wide end up, the grommets will be compressed so much that they won’t isolate the servo from the source of vibration.

DIRECTION CORRECTION

2 This is a crucial setup check and should be done before any linkages are hooked up. Does the control surface move in the correct direction relative to the transmitter’s stick input? Start with one servo and place the servo arm on the spline. Don’t concern yourself with whether it is exactly 90 degrees to the case. Turn on your transmitter and receiver and move the stick (top) that corresponds with that channel. If you see that the arm is moving in the wrong direction required for the correct control surface movement (middle), use the servo reversing menu and hit select “norm” to “rev” so the servo responds in the correct direction (bottom). Now go one by one through the remaining servos and correct their directions if necessary.

CENTERING THE ARM

3 First, all servos should be centered with the transmitter sticks and the control trim levers centered, then place the servo arm on the spline (mechanical portion). Move the arm’s position on the spline to get it as close to 90 degrees to the servo case as possible then, if necessary, use the sub-trim menu to adjust the arm’s position. Do the mechanical adjustments first; don’t rely on the subtrim function only. This can affect the servo’s overall control throws and end points.

For most elevator, rudder and aileron servos, the servo arm should be at a 90-degree angle to the case.

MECHANICAL HELP

4 Because the servo placement is usually pre-determined in an ARF, you need to mechanically (i.e. no programming) set the control linkage at 90 degrees to the servo arm. Determining which hole to use in the servo arm is simple: if you want more throw on the control linkage, place it in the hole farthest from the servo’s center; closer if less throw is desired. Different size models will have various linkage setup requirements, so consult the instruction manual for the proper linkage setup. With the linkage disconnected to the servo’s arm, there shouldn’t be any binding when you move it by hand.

SURFACE CONNECTION

5 The control surface’s linkage connection depends on the type and size model you’re flying. If you want to achieve maximum surface deflection, connect the clevis to the control horn using the hole closest to the surface. For large-scale and 3D airplanes, connect the linkage to the outermost hole (farthest from the surface) for maximum leverage; this also helps to prevent flutter. This photo (below left) shows threaded rods for control horns with plastic connectors to which the clevises attach. Note that they are at the end of the rod rather than close to the surface. It is usually best to have a straight line from the pushrod linkage’s fuselage exit to the hole in the surface’s control arm/horn. Sometimes a slight bend in the rod (top right) after it exits the fuselage is needed to relieve servo and linkage binding.

END POINTS

6 Depending on your brand of transmitter, you’ll see EPA, ATV or Trav. Adj. in your radio’s menu. EPA means end-point adjustment; Trav. Adj. is travel adjustment, and ATV is adjustable travel volume. These programs adjust how far the servo arm will move in either direction. Their default settings are usually 100 percent but can often be increased or decreased using the increase/+ or decrease/-keys. Use this menu when you have either too much or not enough control-surface travel when you try to match the manufacturer’s recommended settings.

Here’s an example. Your model’s elevator travel should be only 1 inch up or down, but when you move the radio’s elevator stick to its most forward and aft positions, the elevator moves 2 inches each way. While in this menu and on the channel you need to limit (in this case, elevator), pull the stick all the way back, hold it there and keep pressing the decrease/- key (lower left) until the deflection matches the 1-inch mark. Push the stick forward and do the same to achieve the correct amount. Note: if you had to reverse your servo’s direction, you might have to hit the increase key (lower right) to decrease the throw. If you need to increase travel, hold the stick in the mentioned positions and hit the increase key. Repeat this for your aileron and rudder deflections using side-to-side stick movements.

TWO POSITIONS

7 With the flip of a switch, dual rate commands two different amounts of surface deflection when you move a transmitter stick. Generally limited to the elevator, rudder and ailerons, dual rate is great for test flights, takeoffs and landings. The first amount of high-rate deflection was set when you adjusted the control-surface travel to the manufacturer’s recommendations. On your transmitter, dual-rate switches correspond with the mentioned channels. When you set your travel volume/high rates, the switches were either up or down. How you set them is up to you; some folks like to flip the switches up for high rates and down for low. Others prefer the opposite. Go to the dual-rate menu in your transmitter and note the switch position; these are marked with either a 0 and 1 or a 1 and 2. These examples show 1 and 2. The factory-set percentages for each position is 100 (top left), so leave your preferred high-rate switch position at 100 and flip the switch to the low-rate position. Using the decrease/- key, lower the percentage rate until the surface deflection measurement matches the recommended low-rate amount (middle left). As you do this, hold the corresponding transmitter stick to its fullest forward or back, left or right position and watch the surface deflection decrease down the markings on the ruler held in your other hand (bottom left) to measure the deflection amount. Sometimes, a third hand helps with setting the low rate. Now hold the stick fully deflected and flip the corresponding channel dual-rate switch back and forth. You should see the control surface move to two different positions (top right).

STOP OVERCONTROLLING

8 Exponential (aka expo) decreases the sensitivity of the stick inputs around the center of its movement. Whether you’re flying 3D or just taking off or landing, this function is extremely helpful for the over-controlling pilot and I highly recommend that you use it until you perfect your technique. On some radios, this feature is found in the dual-rate menu. In others, you have to go to the non-basic menu to find it. It’s best to consult your radio’s manual if you can’t find it. Once found, the screen shows “expo” and a percentage amount, usually factory-set at 0 (top left). Select a specific channel on the screen and press the increase/+ key to dial in the amount of required expo (top right). Sometimes, manufacturers have it listed in the instructions (you see this especially in 3D airplanes), or the amount is left up to you. Before you decide, it is best to note the amount of stick movement with which you fly. For example, if you’re flying a trainer and move the sticks all over the place, you want to set those percentages on the high side-usually around 30 to 40. If you have a finite control of the sticks, 15 to 20 seems to work well. High-performance 3D aerobats can require 50 to 60 percent or higher.

Some surfaces may require a different percentage than others, which is fine. Note that expo is set for each dual-rate position, so you may need to adjust the expo percent for the low dual-rate setting as well (lower left and right).

TURNING HELP

9 What is aileron differential? Simply this: when you move the aileron stick, one aileron deflects at a higher amount of travel while the other one deflects at a lower amount. This helps to prevent adverse yaw, which is the airplane’s nose initially turning in the opposite direction of the turn input, thus resulting in a slip during the turn. Who should use it? Pilots whose left thumbs are not quite adapted to adding rudder input when initiating turns. It is particular useful when flying high-wing scale aircraft and trainers, as it visually smoothes out the turn. As with expo, aileron differential is either in the regular menu or the non-basic and is also based on a percentage amount. When you bring up the aileron differential screen, you see a 0 as the factory-set percentage. Use the increase/+ key to add the differential to your aileron’s deflection. A good starting amount is 25 percent. Try that for a flight or two; if you discover it needs to go higher, increase by increments of 5 until you achieve the desired results: a smooth, coordinated turn when you only use the ailerons to bank the model.

THROTTLE SETUP

10 First and foremost, you want the throttle linkage to run in as close to a straight line as possible from where the linkage attaches to the throttle servo’s arm to its connection on the carburetor barrel’s control horn. Sometimes, a straight line is not possible and the linkage might need a Z-bend, usually within the fuselage’s radio compartment. There shouldn’t be any binding in the linkage’s movement. If there is, you need to mechanically fix it before you set your throttle travel on your radio. Now go to radio’s endpoint adjustment menu and dial up the throttle channel. You’ll note that it reads 100 percent in either the throttle-up or -down position (top right). Here’s one way to achieve the correct high- and low-throttle settings. When connecting the throttle linkage to the servo arm, usually with an EZ connector or Kwik Link, push the linkage in the direction that fully opens the carburetor barrel. Remove the servo arm from the throttle servo, slide the connector onto the wire and reattach the arm so it is in the full-throttle position when the transmitter stick and trim are set as such (above). Tighten the small hex-head bolt and your high-throttle travel position should be set. If you hear the servo binding, lower the percentage on this position using the decrease/- key until the buzzing disappears. You may only need to drop a few percentages to achieve this. Next, lower the throttle stick all the way to see how far the carburetor barrel closes (top right). If it closes all the way, decrease the travel throw until there is an opening that will allow air into the carburetor (above right). Lower the throttle trim and note the position where the barrel completely closes. If it doesn’t, adjust this by decreasing the travel throw (left). Your engine should completely shut off when you lower the stick and then the throttle trim. The throttle trim need not go to its max lower limit to stop the engine from running. Your engine’s travel limits are now set.

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Covering a wing panel with film covering is fairly simple and easy to do, even for those with little skill; that is, until you get to the wingtip. Of course, all wingtips are different shapes, and not all fall in the category of difficult to cover. Some have a gentle taper to a rounded tip with very few compound curves, making covering a simple process. Others can be more difficult. The wingtip I describe here is one of those that can’t be covered along with the wing. The better way is to cover it separately. Although you will end up with a seam on the final wing rib, you will find it a more reasonable approach to success.

I went through this covering process with UltraCote film covering several times and noticed that it makes a difference how the film covering is cut from the roll. I found it best to leave extra material when covering the length of the wing, and then use the piece trimmed off at the end to cover the tip. Using a piece of film cut parallel to the edge of the roll will cause it to sag severely in the shrinking process. The secret for success is to make sure the piece you cut is perpendicular to the roll edge. Oh, yes, this tip will also work with MonoKote.

So, heat up your covering iron and trim iron, grab a sharp knife and follow along in the photos my process for covering that pesky wingtip.

Tools required for covering and covering the wingtip. (DSC9749) Typical problem wingtip, with the covering problem occurring between the gusset and the leading edge. Cover the wing panel and trim off at the last rib, leaving a generous overlap ironed down against the rib. The rib thickness is not enough surface area to retain the film when shrinking. Note: Black marks indicate the amount of overlap covering fore and aft.

On the piece of covering to be applied, develop a contour to fit the rib for an even overlap seam, generally to the shape of the rib contour. The overlap should be approximately 1/4 inch.

Using the trim iron, tack the covering at one end to the rib just inside the black mark. Later, you can remove the black mark with alcohol. Grabbing the loose end, pull it across the top of the rib for an even-width seam, and iron in place. You are now ready to tack and iron down the opposite side.

Before you start to tack down the covering, place the wing on the workbench with the wingtip extending over the edge. Use a sandbag to hold it down, so you’ll have two hands to work with. Starting near the front, pull the covering straight down and tack it in place. Work along in small increments toward the trailing edge. Now, move to where you started, and do the same thing going forward. Try and get the covering as tight as you can. Lift and retack, if necessary, as you go along. The covering should lay flat and tight without gathering and bunching up.

Trim off the excess covering, and seal it in place with the covering iron. Using the trim iron, shrink the covering staying away from the seams on both sides. Gently glide the iron over the surface until the covering is wrinkle-free. You will have to do this four times, on each side of each tip, to complete the wing.

What a beautiful wingtip, and not a wrinkle to be seen. A covering job you can be proud of!

TEXT & PHOTOS BY JERRY SMITH

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THE BASICS

Fuel tanks come in all shapes and sizes.

Fuel filters are worth their weight in gold! Clean fuel means no trash in the tanks.

Whenever possible, pad your fuel tank with foam rubber-it helps prevent “foaming.”

Just like the family car, the fuel tank contains the engine’s fuel supply. The tank is connected to the engine’s carburetor with flexible fuel line (plastic tubing), and a rubber stopper seals it. For a tank to operate properly, it must have a vent line that allows air to enter the tank as fuel is drawn out. It relieves the vacuum left in the tank. Model airplanes don’t always fly straight and level. To allow the fuel to flow at different attitudes, the tank has a flexible internal pick-up tube. A heavy “clunk” fitting is attached to the end of the pick-up tube to always keep the end of the tube at the lowest part of the tank. If the pick-up tube wasn’t flexible, once the fuel level dropped below the pick-up tube, the supply of fuel would stop and the engine would die.

Lengths of brass tube pass through the tank’s rubber stopper, and the fuel lines that carry the fuel to the engine slip over the ends brass tubes. The rest of the fittings and accessories help the fuel system work properly and make it easier to maintain and operate.

BAD VIBES

Making your fuel tank easy to get to makes maintenance of your fuel system easier to do.

The removable fuel tank tray can also secure your battery packs.

One common problem that can lead to your engine running lean is fuel foaming in the tank. Vibration causes this and it forms tiny bubbles in the fuel. The bubbles cause erratic fuel flow and the air in the bubbles causes the fuel mixture to lean out. The simple solution to this is to make sure to properly pad your fuel tank with soft foam rubber. Also, make sure that after time, you check the padding to see if any part of the unprotected tank is coming in contact with the model’s inner structure like a former or engine mount bolt or nut. I prefer to use rubber bands to hold the foam padding in place but you can also use tape. Make sure you don’t compress the foam too much as this will lessen its ability to isolate the tank from the vibration.

Regular maintenance is key to keeping your entire model in top condition. One way to keep a better eye on your fuel system is to make the tank removable. When there is no fuel tank compartment hatch, I make a slide-in tank tray from lite-ply and a matching set of rails inside the fuselage. This way, I can slide the tank into place and secure it with a couple of small screws. You can save more space by attaching your battery pack to the tray as well.

This system works extremely well, especially with large airplanes.

To choose the correct size fuel tank for your airplane, check your kit’s directions or check the engine manufacturer’s recommendations. You’ll want a tank that can hold enough fuel for a 15 to 20 minute flight.

TWO-LINE SETUP

Adding a fuel filter to your fuel supply line gives you double protection.

A two-line fuel system is the simplest and almost foolproof way to go. The setup requires only two pieces of brass tube, a clunk, a rubber stopper and a short length of silicone tubing. Bend one tube 90 degrees to form the vent and insert it through the stopper. The vent lets outside air in as the fuel is drained out, and it acts as an overflow indicator when you fill the tank. The second tube is the fuel-supply for the engine and the interior pick-up tube and clunk are attached to it. To fill the tank, the fuel supply tubing is removed from the carburetor and attached to your filler pump line. When the tank is full, you simply reattach the line to your carburetor. The vent line is often attached to a pressure fitting on the engine’s muffler. This arrangement helps pressurize the tank to enhance fuel flow to the engine.

2-line setup

The simplest and most trouble-free setup is a two-line tank.

THREE-LINE SETUP

In a three-line tank, the setup is just like for a two-line arrangement, but a third line is added and used to fill the tank. The third line doesn’t need an interior pick-up line and clunk, but many do add them to allow the removal of fuel at the end of the day. Before running your engine, you must seal off or cap the third line to prevent fuel from leaking out. Fuel line plugs called “Fuel Dots” are available commercially to do this, but you can also use a tight-fitting machine screw or a short piece of ?-inch-diameter brass rod material as well. In a pinch, you can use a one-inch length of ?-inch dowel.

3-LINE SETUP

Three-line tank setups allow convenient tank filling without removing the fuel line from the engine.

ILLUSTRATIONS BY FX MODELS

TROUBLESHOOTING

Properly installed, your glow engine fuel system will last a very long time and may never need to be changed. In a hard landing, however, some of its parts may be dislodged or a line can become kinked or pinched. Here are some common fuel-flow problems and fixes.

After a hard landing, the flexible pickup tube and clunk inside the fuel tank can be forced all the way forward. This can go unnoticed until the next flight when the tank stops delivering fuel to the engine in a nose-high attitude. To prevent this, solder a short piece of brass tube to your clunk. This decreases the pick-up tube’s flexibility a bit but still allows it to draw fuel in normal flying attitudes.

If your engine starts to run lean for no apparent reason, check for small pinholes in the fuel-supply lines. Check closely where ever there is a tight bend or where the fuel or line comes into contact with the firewall. To help prevent chafing at the fire-wall pass-through, drill a small hole in the firewall and use a length of brass tube in the holes. Slip the fuel lines over the brass tubes to complete the system.

If your engine begins to run erratically, debris may have gotten into your fuel system. It usually finds its way into the model’s fuel tank from your fuel storage jug, and if it blocks fuel flow, your engine will die. To prevent this, use an in-line fuel filter in the fuel supply line just before the carburetor. Install another filter in your fuel-pump line so you fill your tank with clean filtered glow fuel. Add a combination fuel clunk/filter, and you have a triple defense against dead-sticks.

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Foamies have led us to new ways of building and flying model airplanes. They allow us to assemble a plane in hours rather than days or weeks. Because they involve very little investment in terms of money and labor, we no longer need to fear pushing our flying skills to the limit.

The procedures followed for building with foam differ from those used when working with balsa. For example, there are various ways to hinge the control surfaces, and the method you choose will depend on the type and thickness of the foam. Let’s look at a few hinging techniques.

MAKE THE HINGE LINE

The Dremel tool is perfect for drilling holes in the control surface for Robart Hinge Points.

The first step when hinging any surface is to bevel the edges to be joined. If you use thin foam for your plane, you might not need to do this; simply hinge the surfaces.

Most foamies need beveled edges at the hinge line. Use a sharp hobby knife and a metal ruler to do the cutting. Put the ruler along the edge of the foam surface and, holding the knife at a 45-degree angle to the ruler, make one continuous cut; draw the blade from one end of the surface to the other. Have some type of cutting mat underneath the foam so that your cut is clean. A sharp knife is very important for producing a clean edge that’s ready to be hinged. A dull knife will leave a jagged edge that you’ll have to sand smooth.

You could also use a sanding block to bevel the edge. I like Great Planes’ Easy-Touch Bar sander with 150-grit sandpaper. I put the edge to be beveled at the edge of the workbench and then drag the bar sander across it at a 45-degree angle. Work across the edge until the entire surface is beveled correctly.

Charger RC’s Super Beveller (introductory price: $5.99) can handle foam of up to 5/16-inch thickness. Pull it along the edge of the surface to be beveled from one end to the other; the result will be a perfect cut every time.

SURFACE PREPARATION

Make a bevel in the control surface by using a metal ruler and a hobby knife.

Clean surfaces ensure that the hinge material will bond solidly and last for the life of the plane. Foam is sometimes slightly oily or dirty, so clean it to guarantee a secure bond. A quick wipe of rubbing alcohol cleans foam without destroying it.

Then be sure to let the foam dry completely before you hinge it-especially if you use tape as a hinge material.

Another way to ensure a good bonding surface for tape hinges is to dab thick, foam-safe CA onto the surface where the tape will go. Wrap plastic wrap around your finger and spread the CA over the surface. Then lightly spray on CA accelerator, clean off the excess accelerator with alcohol, and allow the surface to dry. It will then be ready for the tape hinge.

HINGE MATERIALS & HOW TO USE THEM

The Super Beveller is a new tool from Charger RC. It makes beveling the edge very easy to do.

Use foam-safe CA to make a thin layer of glue on the foam where the hinge tape will go. This makes for a smooth, solid surface for the tape to bond to.

Clear packing tape seems to be the most popular hinge material. It’s readily available, it sticks to surfaces very well, and it’s inexpensive. Also good is clear first-aid tape; it’s quite flexible and sticks well to control surfaces.

I put the two pieces to be hinged on a flat surface and line them up in their proper positions. I keep them in place with small weights such as beanbags. I like to keep a small gap (1/16 inch or less) between the two surfaces at the hinge line to allow complete 3D movement. I put the tape across the two surfaces with the hinge line along the tape’s center. After attaching the tape, I use a balsa stick to press out all the air bubbles and further strengthen the hinge bond. I flip the piece over, weight it down again and put tape on the other side; I make sure that the top and bottom pieces of tape stick together at the 1/16-inch hinge-line gap.

You can use CA hinges on foamies as long as you meet certain conditions. The foam should be thick enough for you to bevel a 45-degree angle on both the top and the bottom edges of the control surface and still have a 1/16- to ?-inch-thick flat edge. Cut your hinge slots with a sharp hobby knife, and insert the hinges just as you do when you hinge a balsa plane. Put five or six drops of foam-safe, thin CA on both sides of the hinge at the hinge line. Foam does not have the same moisture content as balsa, so it will take the CA a while to cure; let it do so overnight.

Robart Hinge Points are also good for thicker foam. Start by measuring the positions of and drilling the holes for the hinge points. I drill holes in foam with a Dremel tool. A Dremel spins the bit faster and is easier to control than a regular drill gun.

Epoxy works well for the hinges, and polyurethane glue is another good choice because it expands around the hinge as it dries. This glue requires moisture to cure, so wet the hinge point before you push it into the glue-lined hole. Whether you use epoxy or polyurethane glue, you should protect the hinge “knuckle” with oil or petroleum jelly. Polyurethane glue will expand out of the glue joint and onto the hinge “knuckle,” so let it dry before you attempt to remove the overflow.

SUMMING UP

Check out these hints, and you’ll have a strong, durable hinge joint. Foamies might not last forever, but there’s no reason why their hinges can’t.

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