Hints & Tips

Hints & Tips

Questions & Answers

R_C Model Aircraft Questions and Answers

Battery Care

Another View on Batteries

How's your Nicads?

The Nicad batteries that we use in our Transmitters and Aircraft wear out with time. If you have a battery pack that is more than 3 years old you should be keeping a close check on it by cycling every month. If it is 5 years old or older you should replace it and be sure to properly dispose of the old cells. So - how do we tell the age of our batteries? Most Futaba battery packs and individual Sanyo battery cells (which most OEM radio manufactures use) have a 2 letter date code stamped somewhere on the pack or cell. The first letter of the code is the year of manufacture and the second letter is the month of manufacture. 1996 = "A", 1997 = "B", 1998 = "C", 1999 = "D", 2000 = "E", etc….. January = "A", February = "B", March = "C", etc…… So - if you have a battery or pack with a date code of "CB" it was manufactured in February of 1998 - probably still OK but keep a close check on it. The pack in my 8UAF transmitter was "ZF" or June of 1995 so I replaced it. I found one pack with a date code of "WC" which translates to 1992 - replace that one without question.

Happy flying

Ted Brindle

Battery Advice From America

Charge & Discharge
Written by: Dr. Bob Motazedi

If your batteries need to be cycled and you don’t have an automatic cycler, you will need a simple voltmeter and some time. An expanded scale voltmeter (ESV) can be purchased from most hobby shops and can be easily converted to accept plugs for your particular system. Now, get a full overnight charge on your batteries. Check the voltage of the receiver and transmitter batteries. They should both register into the green areas. If not, there is damage to at least one cell. Don’t even try to cycle any of these damaged cells because they are irreparable. Simply buy a new battery pack to replace the damaged pack. If both packs register into the green areas, turn on the entire system and allow it to discharge itself. You must keep track of the time during this phase. Put a good movie into the VCR; this will take some time. Intermittently move the controls to simulate in flight use. This causes the receiver battery to discharge at a believable rate. Every 15 minutes or so, check the voltage of both packs. Remember you don’t want the packs to completely discharge because you can damage your cells. You want the packs to discharge to a level of 1.1 volts per cell. A standard transmitter pack contains 8 cells so you will turn it off when the voltage drops to 8.8 volts. Receiver packs usually have 4 cells so stop the receiver discharging at 4.4 volts. Record the time it takes for these voltages to be reached. On average, properly conditioned packs should give you between 60-90 minutes of time. Of course, this value can change with different systems, servo types and other variables. If your time is shorter than this, you will need to complete the cycle and check the times again. Simply put the batteries back onto the charger for about 16 hours to bring them up to a full charge. After this, discharge the packs as before and keep track of the time. You should see an improvement in the times. If not and the time is still less than 60 minutes, it is time to replace your packs. Occasionally you will have to cycle you packs up to three times to restore their maximum capacity. Do what is necessary to protect you expensive investment; batteries cost a lot less than airplanes. All of your packs should be cycled at least once every three months or so in order to insure their reliability. For those of you that don’t have the time to cycle your batteries by hand, I would recommend that you buy an automatic battery cycler. The units that I personally use are the Accu-cycle and Accu-cycle Plus by Hobbico. These units can automatically discharge your receiver and transmitter batteries to the proper levels while keeping track of the time and the actual milliamp hours. The Accu-cycle Plus can also cycle your batteries one full cycle or up to three full cycles (deep conditioning) automatically, This is perfect for reconditioning your packs if they have been sitting around for awhile and have developed some memory. The original Accu-cycle charges your packs on a time determined basis only and works best if you use the discharge cycle every time. This is recommended to prevent over charging your packs. Both units also automatically switch to a trickle rate charge after the charging cycles. This trickle rate keeps your batteries fully charged without danger of over-charging and damaging your cells and keeps them at their peak for flying. A final note regarding batteries has to do with the ESV (expanded scale voltmeter). This should be a required component found in your flight box at all times. Use it regularly to check your batteries before you fly every time. You should get into the habit of checking all of your batteries prior to each flight. Battery cells can “go south” and die at any time. With proper care and with prudent pre flight checks, you can easily prevent a very expensive crash. These types of uncontrolled crashes can easily result in damage to people and property on the ground. I have seen this very type of problem happen needlessly many times over the last several years, fortunately, not with any of my ships. Get one of these units and play it safe.

Measuring Washout

Washout, the downward twist in wingtips that improves low-speed flight, is sometimes used in airplanes with flat-bottom wings. A good way to make sure each wingtip has the same amount of washout (or any at all) is to get two straight wood dowels or carbon rods. Tape each to the bottom of the wing near the tips. Set the wing on something so you can see both rods, and sight down the wing so you can see see each rod in relation to the other. The rods magnify any angle that might be present in the wing. Correct the wing twist until you have the angle you want. This doesn't work too well with wings that are rounded on the bottom, but is an excellent way of making sure flat-bottom wings are true.

4 Tips about Epoxy

1. Wax Paper: Take a sheet of wax paper, and mix your epoxy on half of the sheet. Then when done, fold the wax paper in half, trapping the epoxy residue inside. This way you can fold it up with no mess and throw it away, and it won't stick to the inside of the trash can.

2. Foam: When epoxying to styrofoam, such as attaching leading or trailing edges to a foam-core wing, once the parts are coated well with epoxy and put together, wiggle them around some to work the epoxy into the pores of the foam. Then let it dry normally. This results in a stronger bond.

3. Bed-Buddy: Ever been caught with cold epoxy? It's much more workable and mixes better when its just above room temperature (about 80-85 F). I use a "Bed-Buddy" to warm it and keep it warm. A Bed-Buddy is like a long sock with some kind of granular chemical in it that stays warm for hours after you microwave it for two minutes. They're designed to keep your feet warm at night, and you can wrap it around your epoxy bottles too between each use. You can also put the epoxy bottles directly in the microwave oven for a short time, but be careful doing it.

4. Inverter: When your epoxy bottles start getting low, it can take a while to get it out, especially when cold. Build a simple wooden "inverter" to hold both bottles upside down, and keep them in it between each use. This way your epoxy will always be ready for use.

Servo Blanks

Here's an easy way to make sure your servos will fit in your plane properly, especially helpful with scratch-built designs: Take the measurements of your servos, and make a few from wood, identical to the real ones. This may be easy if the manufacturer supplies full-size drawings of the servos. I made my servo blanks from pine blocks, a little plywood for the mounting hole piece, and a dowel for the motor shaft. These servo blanks will not only help in drilling the holes to mount servos, but will assure adequate clearance on all sides. In addition, the dowel is the correct size to press on an actual servo arm, which will help in aligning pushrods or cables. Using this method will help keep your real servos safe and clean during the building process.

Vertical Fin Alignment

To get a fin in correct alignment with a fuselage, try using thread. Make sure you have an accurate center mark near the top-front of the fuselage, and tack-glue a long piece of thread to the top near the nose, a distance from the centerline equal to half the thickness of the fin. Run the thread back to the tail, and hold it against the side of the fin. The thread should touch the side of the fin evenly overall. If it doesn't, then rotate the fin until it does, then tack glue the fin into place, reinforcing it later. Last, remove the thread you tack-glued.

Keeping Knives and Blades Safe in Storage

Get a small block of styrofoam and stick your hobby knife in it. This way the blade won't be exposed, and you won't cut your hand if you reach into a drawer or box for it. Always keep new blades in their original container, and throw away used blades into a closed can with a slot cut in the top, don't just throw them into the trash can by themselves.

Sharp Props

Most propellers have very sharp edges when new, especially at the trailing edge, which can cut your fingers. Always sand the edges smooth with fine sandpaper as soon as you buy them. Be extra careful when turning over someone else's motors by hand, because they might not have sanded the edges of their props.

Extra-Long Screws

If you need an extra-long screw or bolt for something, such as a wing tank or mid-mounted wing, make one by cutting the correct size threaded rod you need, then solder a wheel collar on one end. Next, using a cut-off wheel, cut a slot in the wheel collar for a screwdriver.

Engine Mount/Nosegear

If you have a small plane with a very tight engine installation (usually resulting from a very streamlined cowl), often there's no room for a nose gear assembly. Try drilling holes through the engine mount to accept the nose gear wire, and hold it in place with wheel collars. The steering arm can be placed below the engine, even on the outside of the plane. This will work with most engine mounts, even the two-piece ones as long as the engine is rotated 90 degrees.

Setscrew Gripping

Ever have wheel collars not hold on axles? Or maybe that nosegear keeps twisting because the steering arm won't tighten? Try grinding or filing a flat spot on the wire where the setscrew will go. This provides a better surface for the screw to tighten against. Better yet, grind a flat spot with a small diameter (worn out) cut-off wheel. The small diameter causes the flat spot to actually be concave, which helps the setscrew grip even more.

Parts From Plastic Soda Bottles

Several things for RC airplanes can be made from 1, 2, or 3-liter soda bottles.

Use the colored base that come with some bottles for cowls. They're sized about right for .15 to .25 engines.

On bottles that have the base molded into the bottom, cut the bottom off, and this can become a "stand-way-off" 5-cylinder radial dummy engine when painted properly.

The cylinder that's left after cutting off the top and bottom of bottles can be used to form canopies and other parts. This plastic shrinks easily with a heat gun and can be molded around wooden forms.

Take the colored base off of a 1-liter bottle, which should leave a hemisphere at the end. Glue fins on the other end, paint it, and you have a bomb for a large airplane. And if you want to drop it, it probably won't break.

NOTE: It's getting more and more difficult to find the "old style" soda bottles with the hemisphere and cap on the bottom, which look best for bombs. The "new style" soda bottles have lobes molded into the bottom which make up the base. This makes a lot more sense from a product processing standpoint, but they don't make near as good bombs!

Curving Balsa

Get some ammonia, found in the household section of the supermarket. Put some in a spray bottle, and spray both sides of balsa sheet liberally. Carefully bend the sheet to the right shape. You can even tape it to a form, such as aluminium soda cans, and let it dry. Once dry, it may be used as turtle-decks, etc.

Wing-Tail Alignment

Get an old (but straight) telescopic antenna, the same type as on transmitters. Use it as an adjustable-length measuring rod to compare critical measurements on planes during construction. I use this idea to compare the distance from one wingtip to the stabilizer, and to make sure this distance is equal on both sides of the plane. This ensures that the stabilizer is parallel to the wing.

New Pilot Tip

Something to pay attention to when learning to fly is control reversal. Control reversal is when the inputs on the transmitter sticks must be reversed when your plane is flying toward you, rather than away from you.

When flying away from you, there is no problem, just move the stick in the direction you want to turn.

Many new pilots become disoriented when their plane is approaching them. To help with this, move the stick in towards the low wingtip. This will level the wing when your plane is coming toward you, avoiding a sharp bank, and possibly a crash.

Example: Say your plane is coming toward you, and the right wingtip is low, as if banked to the right. Move the stick to your left, toward the low wingtip. This will bring the plane's right wingtip up, and level the wing.

Installing Triangle Stock

For me, triangle reinforcements have always been difficult to handle due to their shape, especially if they're coated with epoxy.

Try sticking your Xacto knife loosely into one end of the triangle. Then lay it on the bench so that the wide part of the triangle (the hypotenuse) is against the benchtop. Now apply the epoxy or other adhesive to the sides that will contact the airframe.

Next, by using the knife handle, insert the triangle into position in the airframe. Press down with your finger onto the wide side that has no glue, and carefully slide the knife out of the piece.

This way you can cleanly install triangle stock, and not get any glue on your fingers.

Rib Maker

Cut two ribs from 1/16-inch steel. Drill two holes along the center line, one near the leading edge, one near the trailing edge, for 1/4-inch bolts to pass through. Make sure both steel ribs are identical.

Use a steel rib as a template to draw ribs onto balsa sheet. Leave room around each rib. Cut each rib "block" out of the sheeting, and drill the holes in each.

Assemble all ribs on the correct length bolts, and sandwich all between the steel ribs. Using nuts, tighten the assembly down, making sure it's straight.

Now, using a belt sander (a disk sander will work too), remove the extra wood around the ribs down to when the steel begins touching the sander. Cut out the spar notches with a hand saw, and clean them out with a file.

This will make all the ribs for a wing at once, and they'll all be identical, resulting in a straight, uniform wing. It can also be used for a tapered wing (with all the ribs of different size), and bulkheads and formers can be made using this method too.

Sandbag Weights

Fill plastic zip-lock bags of various sizes about 3/4 full of fine sand, and seal each well.

Use these to hold down large parts while building, such as wings. The sand will conform to the shape of parts well. They also work good when gluing sheeting to foam.

Air-Bleed Screws

When adjusting air-bleed carburetors (the ones with the little hole in the front), a good rule to remember is the word "richen". Split this word in half (rich-en), and when you want the carburetor rich, turn the screw in. Of course leaning the carburetor would be turning the screw out.

Measuring Balsa Density

Knowing the density or weight of balsa pieces can be important. It's especially useful when making ailerons or wingtips, because you want the pieces to be "matched", which will result in a better balanced and better flying airplane. To do this, choose balsa that is similar in weight by weighing them on a gram scale. If you don't have a gram scale, use the deflection method: Take the balsa pieces, and using heavy weights or sandbags, hold down a few inches of one end of each balsa piece onto the edge of a table. Make sure that equal amounts of each piece of balsa overhang the edge. Place a smaller weight onto the other end of each piece, and measure how far each one bends from the floor. The one that bends the most generally is the lighter piece. Using this method, you can choose balsa that is similar in density. Keep in mind that if you build from kits, you don't have to use the supplied wood if you don't like it!

Cleaning Superglue (CA) Tips

After using a bottle of CA adhesive for a plane or two, the tip usually gets cured glue all over it. Remove the tip from the bottle and soak it in a closed jar of acetone. Nail polish remover also works, as long as it's the kind that contains acetone. After about an hour, the cured CA will gel, and is easily peeled off the tip.

Transmitter Neck Straps

If you use a neck strap on your transmitter, beware of getting it caught in a rotating propeller! Some people leave the strap around their neck and detach the transmitter while starting engines. This is a perfect way for it to get caught in the prop, especially if you start your planes on the ground rather than a stand or table. Also, having the transmitter nearby while starting an engine is potentially a hazard. When you pick up the transmitter make sure the strap or antenna doesn't swing into the prop.

3-Blade Props

3-blade propellers are useful when you have a scale plane that's modeled after a plane that uses them. However, since the engine has more mass to turn, the maximum RPM is lower. The general rule is to use a 3-bladed prop one inch smaller in diameter than the 2-blade you would normally use. This will allow close to the same maximum RPM as you would have with a 2-bladed prop. You may also increase the pitch by one inch, but experiment and see what works best with your engine and plane.

Firewall Fuelproofing

Firewalls of planes are normally coated with epoxy to help prevent fuel and oil damage to the wood. On planes with no cowling, apply a coat of epoxy on the firewall after you cover the plane with film covering. Make sure the film overlaps a little onto the firewall. This way the epoxy seals the edges of the film covering. Besides, most film adheres better to wood than epoxy, so that's another plus.

Ultracote Printing

Goldberg Ultracote film covering has a paper backing that you can print on. Cut a 8.5 X 11 inch sheet, put it in an inkjet printer, and print your design on the paper backing (don't use a laser printer or anything that uses heat - it'll destroy your covering). This works well for large lettering. Make sure your image is reversed, so that when it's printed on the backing you can cut it out and it'll be correct when ironed on your plane. If you want to use a piece of covering that's smaller, print the design onto paper first. Then carefully tape the Ultracote to the paper over the design. Then run the whole thing through your printer, and the design should print in the same place.

Cutting Dowels Straight

When cutting a dowel, it's easy to make the cut crooked. To help ensure a nice 90-degree end, especially on larger diameters, try rolling the dowel into the bandsaw or scrollsaw blade.

Picking up Glass Safely

After sweeping up broken glass off your shop floor, it's difficult to pick up tiny fragments. Try making a loop of duct tape, adhesive side out. Place the loop over your hand, and pat the fragments carefully so they stick to the tape. Then just throw the tape loop in the trash.

Antenna Holder

Here's a way to attach a receiver antenna to the back of your plane after it exits the fuselage. Take a short length of fuel tubing and make two cuts into it, dividing it into thirds, but make the cuts go through the tubing only halfway. Then pin the tubing to the top of the plane's fin. Thread the antenna through the tubing, lacing it through the cuts. This will keep the antenna somewhat taught and out of the way of control surfaces.

Converting Cubic Inches to cc's

Sometimes there's a need to convert cubic inches to cubic centimeters (cc) or vice-versa where engine displacement is concerned. One cubic inch is equivelent to 16.39 cubic centimeters. So to convert from in3 to cc's, just multiply the in3 by 16.39 to get cc's. To convert cc's to in3, divide the cc's by 16.39 to get in3. And remember, a 7.5cc engine is the same as a .46 (pretty close).

Repairing Dings & Dents

Have you ever had a dent in a balsa leading edge? Try fixing it with water! Get a small diabetic syringe and put water in it. Inject a little water into the balsa into and around the dent in the leading edge. Heat the area with your covering iron. When the water starts boiling, it will build pressure and push the balsa out to its original shape. (Courtesy Victor A.)

Film Covering Degreaser

Have you ever wanted to add more film covering (Monokote, Ultracote)to a plane you've already flown? It's difficult to get all the oil exhaust off the plane so the film will stick. Try using Cyanoacrylate (CA or superglue) kicker (catalyst). Just spray it on and wipe it off. I've been told it's a very good degreaser. (Courtesy Vince R.)

Pull Oil out of Wood

Sometimes firewalls and engine areas of older planes get soaked with oil from the fuel. This weakens glue joints to the point where a plane could fall apart in midair. Try using Cyanoacrylate (CA or superglue) kicker (catalyst). Just spray it on and wipe it off. I've been told it pulls the oil right out of the wood. Several treatments may be necessary. This also works if a fuel tank develops a leak and the fuselage gets soaked with fuel. (Courtesy Jevan F.)

Balancing Planes

Here's a good way to balance airplanes. While building your plane, insert a half-inch square piece of plywood where the balance point should be. For a low wing, this should be on the bottom of the wing, and for a high wing this would be on top of the wing (Note: sometimes something will be in the way, like a canopy, and you can't use this technique). When the plane is finished, put a small hook into the plywood and suspend the plane with wire or string. This way you can check the fore-aft balance AND the lateral balance at the same time (Note: a low wing will be suspended inverted).

Fiberglassing Wing Centers

Whenever I fiberglass a wing center section, I've found it's difficult to get the fiberglass cloth to lay flat after it's been folded in a bag. Here's two ways to make this easier: (1)Use thin CA to tack it down. You may saturate the whole cloth with thin CA, or apply epoxy. On foam wings, make sure you use CA safe for foam. (2)Give the cloth a light spraying of 3M Spray Adhesive, then apply it to the wing. I've found this method to work extremely well, and it's safe for foam. Then apply the epoxy as usual.

Control Horn Installation

When installing control horns onto control surfaces the screwdriver invariably slips. The result is a hole poked into the covering material or a gouge in the balsa. There is a simple tool you can make that will eliminate this damage. Take a small piece of thin plywood and cut a rectangular opening in it just slightly larger than the base of the control horn. Place this opening around the control horn base before tightening the mounting screws. Now when the screwdriver slips there will be no damage to your new aircraft! (Courtesy Fred H., Derby Radio Control Club, Derby Kansas)

Turning Wing Bolts

If you use nylon wing bolts on your plane that take a slot screwdriver, and you forget your screwdriver, try using a quarter. A quarter is actually easier to use than a screwdriver, since it won't slip off the bolt and damage your wing. What if you forget your quarter too? Usually you can get a quarter from loose change in your pocket, or your car.

Tail Wheel Strengthening

Tail wheels and their associated parts take a lot of punishment, especially on rough fields. Sometimes the "tiller" part of the wire that goes into the rudder breaks out. Here's two ways to strengthen it: 1. Put hardwood or plywood into the part of the rudder that the tiller goes into, a piece about half an inch square by the rudder thickness should do for most planes. 2. Position the tiller so that it goes in-between the rudder control horn.

Deburring Brass Tubes

I use 1/8" brass tubing for fuel lines through firewalls. Silicone fuel tubing is connected to the brass on both sides of the firewall. To provide a better fit and extend the life of the silicone fuel tubing, carefully debur the ends of the brass by running a hobby knife along the inside edge of the brass. Then use fine sandpaper to smooth the outside edges. Since brass is a soft metal, the fine sandpaper (about 220 grit) works very well.

Needle Valve Modification

On planes with cowlings, I modify the engine's needle valve so it can be adjusted inside while the engine is running. I grind the outside end of the needle valve flat. Then I cut off the head of a hex bolt (either size 6 or 8), and solder the head onto the end of the needle valve. Then you can stick a hex wrench through a small hole in the cowling to adjust the valve.

Foam Cutting

When I buy a large (4 x 8 ft.) piece of foam, I like to cut a smaller piece off before using the hot wire. My hot wire isn't big enough to use on a full sheet, so I use a reciprocating electric knife, the kind used for meat and bread. It works pretty well for cutting off a usable piece.

Wheel Axle Bushings

If you have a wheel that's too big for the axle, make bushings from brass or aluminum tubing to make up the space. If you get tubing of the correct size, you can also make multiple bushings that fit inside each other, if that is required. Don't let wheels wobble! They'll wear out quicker, and make ground handling difficult.

Cleaning Airplanes Well

If you have an airplane that you really want to take care of and look good for a long time, you have to occaisionally clean it really well. Do this by disassembling what you can (remove the wing and landing gear) and wipe it down with alcohol from the drug store. This will remove fuel oil residue well. This is also a good cleaning for film covering when you have to apply new film over old.

Empty Fuel Bottles

If you purchase fuel in plastic bottles, when they're empty, put it in an out of the way place with the cap off for about a day. This will allow the residual fuel to evaporate. If you place the cap on without airing it out, you have a potential bomb if an ignition source should ever penetrate the bottle. After the bottle is aired out, crush it, then replace the cap. Then recycle the plastic if you can at a recycling center. Many places don't take plastic, so if it does end up in a landfill, at least it will take up less space by being crushed. You should air out and crush metal fuel cans too.

Wheel Collar Tightening

If you use wheel collars with the tiny hex setscrews (I think most of us do), sometimes while tightening them the hex wrench rounds off a little, causing it to stick in the setscrew. So you end up turning the hex wrench to loosen the wheel collar just to get the wrench out. But now the setscrew may not be tight anymore. To check it, just turn it with your fingers. If it doesn't turn, it's tight enough. If you can turn it, try to tighten it more.

Drill Depth Gage

Sometimes I carve foam with a drill bit in my rotary tool, but I need a certain depth. I measure the depth I need on the bit, and wrap a piece of masking tape around the bit above the mark. Then when the bit is spinning, I know not to go past the edge of the tape. This will work if you need a not-all-the-way-through hole in almost any material.

Antenna Tubes

Need an antenna tube inside that long fuselage? Next time you go to your favorite restaurant, grab five or six extra straws. At home, cut each with scissors lengthwise, colapse it in on itself and add a little tape. This colapse make the straw a smaller diameter, which works best for receiver antennas. Then make a small cut in one end, colapse it a little, and stick it into the next straw, and apply tape. You can chain several of these together, then put into the fuselage for holding the antenna.

Smoking While Fueling

There's no smoking signs at gas stations, as it could be dangerous to smoke while filling your gas tank. So why smoke while you fuel your airplane?

Fuel and Battery Separation

In your field box, keep the fuel storage, and starting battery, at opposite ends. If they're next to each other, and the battery or power panel shorts, it could ignite fuel vapors. I have two separate boxes, one has the fuel and pump, the other has the battery and tools. When I want to fuel, I just plug the fuel pump into the power panel on the other box. And even though there's two field boxes, they're easier for me to carry instead of one big heavy box.

Arrow Shaft Drill

Need a long straight hole through solid foam or several pieces of balsa, either in a fuselage or wing? Take an aluminum arrow shaft, and cut small notches on one end, as if to make it a saw. Put the shaft in a drill, and it will cut long straight holes for cables, pushrods, antennas, etc.

Clothespeg Clamp

Have you ever tried soldering clevises or other small parts and didn't have anything to hold it with? Try a plain old wood clothespin. They work great for holding small hot parts while soldering, and they have many other modeling uses too.

Cleaning Epoxy from hands

After holding parts together attached with epoxy, you notice some epoxy got on your fingers. Before it's fully cured, just remove the epoxy with isopropyl alcohol (rubbing alcohol) and a rag. It does a good job of removing epoxy.

Paul's Model Cleaner Formula

Here is a great model cleaner formula. It works better than Windex or similar cleaners and is inexpensive. 1/2 Gallon Model Cleaner: 1/4 cup ammonia, 1/2 pint denatured alcohol (not isopropyl alcohol), 1/2 teaspoon liquid detergent, and water as required to make 1/2 gallon total. (Courtesy Paul)

Shortening Bolts

Sometimes it's necessary to cut off a bolt that is too long, especially on a firewall where the excess bolt might puncture the fuel tank. Wrap a piece of tape around the bolt with the edge of the tape even with the end of the bolt, making a "flag". Use a pen to mark on the tape where to cut the bolt. Using your Dremel or other rotary tool, cut the bolt at the mark. Since you don't cut through all of the tape, the excess bolt is captured, and will not fly away. This prevents it from hitting you, and keeps your workshop cleaner.

Antenna Pull-Thru

I like putting receiver antennas through tubes in fuselages or wings. The more flexible antennas (such as JR) are very difficult to stuff through the tubes. Put a cable in the tube, and tack-glue the end of the antenna to the cable, then carefully pull the cable out, which pulls the antenna through.

Temperature-Sensitive Items

In warm summer months, keep in mind several RC items that deserve a temperature-controlled environment. Batteries left in airplanes that are hung in the garage can get too hot. Fuel can evaporate quicker. Monokote and other film coverings can separate from their backing. CA glues can age quicker. Try to keep these things cool so they'll be ready to use in good condition when you need them.

Tack Cloth

Make an inexpensive tack cloth by lightly misting a paper towel with water, then wipe your balsa plane before covering. This will remove balsa dust, even dust that vacuuming doesn't get. This should result in a better covering finish.

Plan Transfer

If you're building a plane from a plan, and you need to trace unusual shapes like formers, try this: Make a photocopy of the parts on the plan you need. Place the photocopy upside down onto balsa sheet, then iron it on high heat. Some of the toner from the copy will transfer onto the balsa sheet, so you can cut the part out. Be careful though, because this process reverses the image, so it's good for symmetrical shapes only.

Easy Hinging

For control surface hinges I usually use the Sig or Dubro mylar hinge material, so I can economically cut hinges to the size I want. Before installation, I sand each with about 220-grit sandpaper, so thin CA will adhere better. I also cut the corners off, making them "dog-eared". This makes it easier to put them into the slot in the balsa.

Epoxy Curing

Next time you mix epoxy on something and use it on your plane, you can check the cure rate by checking the residual leftover from mixing. This way you don't have to mess with the parts you epoxied, possibly bumping them out of position. And if you're impatient like me, ALWAYS use 5-minute epoxy!

6 Firewall Tips

1. Use a "hole pencil" or other device to accurately mark where to drill holes for the engine mount.

2. Check blind nuts before you install them in a firewall. Sometimes the threads aren't quite right and it's better to know before you use them.

3. When possible, it's easier to install blind nuts to the firewall before the firewall is attached to the fuselage.

4. Always use traiangle stock in the corners near a firewall, these add a lot of strength to the corners.

5. After the blind nuts are in the firewall, use a little thick CA or epoxy around the outside flange to secure them, but make sure you don't get glue on any threads.

6. Use hex bolts for engine mounts, and use the little hex wrenches. The 90-degree bend in the tool allows better leverage when tightening engine bolts.

Engine Break-In

When breaking in (Running In UK) a new engine, always follow the manufacturer's instructions, and use the correct propeller. Never break-in an engine as a pusher! Pushers don't have as much airflow over them as tractors and can overheat when breaking-in. If you have your new engine going onto a pusher plane, break-in the engine on a test stand first.

Refrigerate CA

You can extend the shelf life of cyanoacrylate adhesive (CA) by keeping it cool in the refrigerator. What this is really doing is keeping it dry, as CA reacts with moisture to cure.

Alternate Materials

Balsa, plywood, and a film covering is not the only stuff available! Try using EPS foam, EPP foam, BluCor foam, Coroplast, paint, and hot glue. Of course these less-expensive and more versatile materials are more appropriate for electric-powered planes (hint...hint)

Hot Glue

Forget CA and epoxy! I've been using nothing but hot glue exclusively, even in places where you'd think epoxy is the only answer. Hot glue is much less expensive than other adhesives (especially CA). Of course hot glue is used on electric-powered foam planes (hint...hint).

CG Beads

Here's a quick way to check center of gravity location - mark where the CG should be on the bottom of each wing half. Then put a small bead of hot glue over the mark. Now you can hold up the plane by your fingertips, feeling for the bead, and check the balance point quicker.

Dual Tank Setup

1) Engine draws from tank #1 clunk.

2) Overflow on tank #1 is connected to tank #2 clunk.

3) Tank #2 overflow goes to open air or muffler pressure.

4) With this setup, tank #2 completely empties before tank #1 drains at all.

One advantage of this setup is that for the first half of your flight time flat spins etc are much safer since you're very unlikely to suck up any air bubbles.

Barry A. Boes

Any Old Bikes Lying Around?

A good thing to use for pushrods are bicycle spokes. You can find

old used wheels for next to nothing andtake out the spokes.

They are threaded and come in different sizes.

Littlewing

Remedy for A Scratched Canopy

Scratched canopys? Theres a great product made by Meguiar Co. Their clear plastic cleaner... it works... and polishes your canopy at the same time... The product is sold by NAPA auto parts stores..... Meguiar's inc. irvine ca. 92713 usa.... i hope you try this, i was truely amazed......

Happy flying

Chris Allen

Remedy for Poor Idle

You can get the idle problem solved simply. Put a one way in line choke valve (a couple of $ in any hobby store) between the muffler and the tank. That way, when the engine is at full throttle and there is good back pressure in the muffler, that pressure is also in the tank. When you idle, the choke prevents the air from the tank to go back to the muffler, therefore maintaining the same high pressure in the tank as before. This WILL solve any fuel draw problems at idle.

Happy flying

George Brod

Installing Control Horns

Mark Hinges

When using CA hinges use a marker to draw a black line across the middle of the hinge. This way you can tell if the hinge is being pushed into

the wing when you put on the aileron. I have had some hinges do this and end up with a sixteenth of an inch in the aileron and the rest in the

wing, not very strong. If you can't keep the hinge from being pushed into the wing stick a pin through the middle of the hinge it will not

weaken the hinge at all.

Fiberglass Hint

How do you get the creases or lumps out of the fiberglass cloth we use to reinforce the center section of the wing? This method will probably eliminate them. Prior to applying the fiberglass cloth to the center section of the wing, take the time to iron it flat with your clothes iron. This will make it soooooo much easier to achieve a FLAT surface. Next, place the glass cloth on the center of the wing and tack it down to the surface with one drop of CyA (each corner, top and bottom).

This may require that you have to pull the cloth taught, but don't overdo it! Now you should have the cloth resting smoothly on the top of the wing. Now apply the resins (or CyA) over the cloth. You may find that after 3/4 of the cloth is attached that you now have puckers along one edge or the other, but this is easy to fix. Lift the material where you tacked it to the wing (remember I said to tack it down, not permanently attach it), pull taught, and tack it

down again. there you have it!

Vertical Fin Alignment

Balancing Planes

Fiberglass Wing Centers

Whenever I fiberglass a wing center section, I've found it's difficult to get the fiberglass cloth to lay flat after it's been folded in a bag. Here's two ways to make this easier: (1) Use thin CA to tack it down. You may saturate the whole cloth with thin CA, or apply epoxy. On foam wings, make sure you use CA safe for foam. (2) Give the cloth a light spraying of 3M Spray Adhesive, then apply it to the wing. I've found this method to work extremely well, and it's safe for foam. Then apply the epoxy as usual.

Control Horn Installation

Cutting Dowels Straight

When cutting a dowel, it's easy to make the cut crooked. To help ensure a nice 90-degree end, especially on larger diameters, try rolling the dowel into the bandsaw or scrollsaw blade.

Firewall Fuelproofing

Installing Triangle Stock

For me, triangle reinforcements have always been difficult to handle due to their shape, especially if they're coated with epoxy.

Next, by using the knife handle, insert the triangle into position in the airframe. Press down with your finger onto the wide side that has no glue, and carefully slide the knife out of the piece.

This way you can cleanly install triangle stock, and not get any glue on your fingers.

Rib Maker

Use a steel rib as a template to draw ribs onto balsa sheet. Leave room around each rib. Cut each rib "block" out of the sheeting, and drill the holes in each.

Assemble all ribs on the correct length bolts, and sandwich all between the steel ribs. Using nuts, tighten the assembly down, making sure it's straight.

Curving Balsa

Get some ammonia, found in the household section of the supermarket. Put some in a spray bottle, and spray both sides of balsa sheet liberally. Carefully bend the sheet to the right shape. You can even tape it to a form, such as aluminum soda cans, and let it dry. Once dry, it may be used as turtle-decks, etc.

Addendum:

To soak wood, get a piece of PVC pipe the wood sheet will fit in. Cap one end, and stand upright. Fill with water (You can't buy pure ammonia, the stuff on the shelf is low grade, water works fine) and drop in the sheet and cap the top if it floats out.

Wing-Tail Alignment

Engine Mount/Nosegear

Servo Blanks

Poke a Hole in You Covering

Gee why would anyone want to make a hole in your nice new covering job. Well holes for wing bolts, switches, hatch screw holes, pushrod openings, etc come to mind. Sure you could cut the hole/opening with a Xacto, or razor blade, but then you have to adhere the fresh cut covering to the surrounding wood. The solution; get an old soldering iron tip (pointed preferably) and cut the hole/opening with it. I use a 25 Watt Weller, and it cuts through the covering with ease, and makes a perfect seal. Once you try this you won't want to do it any other way. One word of caution, clean the tip after each cut. I use a wet sponge like that used for soldering, but use a different sponge as to not foul the clean tip used for soldering. If you don't clean the tip regularly the burned covering will cake on, and not only smell really bad, but will inhibit the cut, as you will not have maximum heat. I thoroughly clean the tip with a wire wheel after each use. After it completely cools of course.

Hardening Mounting Holes In Balsa

To harden small holes in balsa in order to better retain wood screws or threads, use thin CA. Sometimes the CA will get on a finished surface doing this step. To prevent getting CA on the outside surface, use MicroBrushes. If you do not have MicroBrushes handy in the shop, you can also use one of the plastic coffee stirrers cut at a sharp diagonal to form a thin point. A drop of CA in the cavity at the sharp tip can be used to place a small amount almost anywhere.

Alignment Of Wings And Tail Surfaces

A very important task in building an RC model is alignment of the flying surfaces with respect to the fuselage. Most of the time there is no absolute reference which will allow you to measure the mounting angle and be certain that it is square. One method is to mark a point at the nose or tail (depending on whether you need a reference for the horizontal stabilizer or the wing) at the center of the fuse and measure to the tips of the respective flying surface until it is properly centered. If your aircraft model is in the "bare-bones" stage, using a large heavy straight-edge can easily create hangar rash even before you have done the finishing. Here are a couple suggestions to avoid the large metal straightedge problem.

One is to use a length of ordinary lamp cord. If you get a piece of it fresh off a roll and hang it in your shop, with a small weight at the bottom end, for several days it will be straight enough to ensure accurate measurements. Put a piece of heavy tape around one end (about the last 3/4" or so) and use a pin immediately in front of the tape and through the center of the cord to locate the reference point on the aircraft fuselage. Then hold the other end at a reference point on each end of the stab or wing to compare the two measurements. A small piece of duct or masking tape will mark your measurement on the lamp cord while you make adjustments to the mounting location of the airframe component.

Another trick is to use what home builders refer to as a "story stick". This is merely a small piece of wood (carpenters use a 2 x 4 but that could be as dangerous as the metal straight edge) possibly a long, 1/2" dowel or similar sized piece. Drill a hole about 1/2" from one end which accepts a heavy building pin to use as the locator. Use the other end to mark wing and stab locations. This can be a good reference tool to ensure your wing mounting is secure. Mark the dowel with the name of the plane next to the final dimension to the wing tip and check your model after several flights.

Locating Engine Mounting Holes

Engine thrust angle can be affected by small errors in the location of the mounting holes. To ensure the mounting holes are properly located on the engine mount, the most important task is marking the holes to match the engine case lugs. One good way to mark these holes is with a machine screw of just the right size to pass through the hole in the mounting lug. Cut the screw so it is just a few thousandths of and inch longer than the thickness of the lug, and, cut it on an angle so there is a sharp edge which extends just through the lug. Now, use two small pieces of double sided tape to hold the engine temporarily in place while you rotate the cutoff screw in each of the four mounting lug holes. This will leave a mark which is the exact diameter of, and in the proper location for, the mounting screws.

The next part is to get a true center mark for this mounting hole. If you have an automatic center punch, you may be aware that some of them come with replaceable tips. Buy an extra tip or two and grind them so they just fit through the mounting lugs and use them to center punch the holes.

Dust collector

Next time your wife yells about the balsa dust from sanding steal one of her large fluffy bath towels and use it to sand on. It not only protects the airplane from dings, but it will trap a huge amount of dust. When done sanding fold it carefully then take it outside and shake it out.

Note: see disclaimer above, I am not responsible for what happens when your wife catches you doing this!

Cutting covering

When cutting sheets of plastic shrink covering nothing beats glass for a surface to cut on, it will not dull the knife or slow it down when cutting. The covering material will kind of stick to the glass if the backing is removed all by itself for easy cutting. You can also use low heat to make it stick even better for critical cutting. You can use solvent to put together large panels of covering without it sticking to the work surface. The best place to find a suitable piece of glass is at the flea market. Look for an old glass top coffee table. The rectangle ones work super if you have the room. Stay away from non-safety glass it breaks too easy…Saw this one somewhere….

Holding Canopies

Use electrical tape to secure the canopy on airplanes. {Striping tape that will hold a canopy on surprisingly well however the oil always gets under it and loosens it in time.}

Rib Holder

Get a piece of aluminum 1 or 2 inch right angle that can be found at most hardware stores. Make sure it is really square (90%) then cut off 1/2 inch wide pieces.

Next drill small holes in each end about the size of a push pin or T pin.

Use the angles to hold ribs perpendicular to the building board by putting one on each side of the rib and then pinning it to the board.

Rotary Cutter

A good way to cut thin balsa sheets is with a rotary cutter made for cutting fabric. This also works well to cut plastic covering .

Better Holes

IF you have to drill a hole in thin balsa do not try to use a common wood drill it will usually leave a ragged hole that is the wrong size. Go to the hobby store and get a piece of thin wall brass tubing the same outside diameter as the hole you want to drill. Mount the tubing in an electric drill (preferably a drill press) then hold a piece of sand paper or a file against the end while turning to sharpen it. Use this to drill your holes it will cut perfect holes. After cutting several holes you may have to push out the wood that collects inside the tube with a stiff wire. If you can find a drill the same size as the inside of the tube stick in in the top part so the drill chuck does not crush the tube. Also watch that the tube does not flare out at the bottom and change the size of the hole. From the instructions for the Great Planes Wing Jig.

Better Plans Cover

Waxed paper is the standard covering for plans when building an airplane on top of them I find that waxed paper does not come in large enough sheets and tends to stick to the airplane. Last time I built I used some left over plastic that is used to cover windows. This stuff is made by 3M Scotch and comes in large 3X5 foot sheets this is just the size of the plans I was using. the covering will shrink if heated but this is not necessary as it lays very flat. CA and other glues will not stick to this stuff at all and it is crystal clear unlike waxed paper. There was even a roll of double stick tape in the box. The price on the box (Which was several years old) was $5 this is cheaper then the Great planes plan protector stuff but I don't think you get as much.

Better Screw Holes

When you have to use screws that will be removed often drill the holes for the screws large enough to allow you to insert a small piece of Sullivan Gold-N-Rod glue the rod in the hole. The screws can then be removed and reinserted with out weakening the wood. John does not recommend this for high stress areas.

Mixing Epoxy

When mixing epoxy use an old coffee can lid, after the epoxy hardens just flex the lid and the epoxy will pop off.

Easier Plastic Bolting

After you cut a plastic wing bolt stick it in one of those cheep plastic pencil sharpeners and give it a beveled tip this makes it much easier to insert the bolt and cleans up the start threads .

Bending Wood

Use 409 spray cleaner to bend balsa wood. It also makes a good airplane cleaner for you and the airplane.

T-bar Sanders

If you use T bars for sanding, gluing sand paper on them can be a mess and the stick on paper at the hobby stores is expensive. I find that stick on sandpaper made for electric sanders at hardware stores works just as well, or even better. The only problem is you need to cut it to size.

If you use the old style T bars the kind that have a thin vertical handle, you will find putting a piece of masking tape on where you hold it makes it much easier to hold on to.

Take a file and round the corners of your T bars you will be much less likely to gouge what you are sanding.

Mark Hinges

When using CA hinges use a marker to draw a black line across the middle of the hinge. This way you can tell if the hinge is being pushed into the wing when you put on the aileron. I have had some hinges do this and end up with a sixteenth of an inch in the aileron and the rest in the wing, not very strong. If you can't keep the hinge from being pushed into the wing stick a pin through the middle of the hinge it will not weaken the hinge at all.

Use for an Old Sheet

A handy thing to have around when covering a airplane is a old folded king size bed sheet. It is soft and heavy enough to hold down a wing when stretching the covering over the ends or use it to prop up a fuse upside down when working on it.

Fiberglass Wing Centers

FORMULA's

I have wrote down all kind of rules that I have used in the past, I don't even know where I got them, but here they are !

ENGINE SIZE ---- DX12=W and W/12=D ---- What the heck is that?

Lets say that D is Engine size like an OS 40 is .40 of a cubic inch

Lets say that W is aircraft weight like 5 lbs.

an example? a .40 engine would be happy pushing around a 4.8 lb. airplane or .40X12=4.8

or example, a 6 lb. airplane would like a .50 size engine or 6/12=.50.

What can I tell you, It works for me !

Other rules that I use are size of Ailerons, Rudder, Elevator

Ailerons ------------------ 10% of wing area.

Rudder -------------------- 25% of Stab. area.

Elevator ------------------ 25% of Stab. area.

CG ------------------------ 25 to 30% of wing chord

Barn Door Ailerons should be 1/4 of the chord, and 1/4 of the Span.

Strip Ailerons should be 1/8th of the chord.

Distance from the CG to the prop should be about 30%.

Distance from the CG to the rudder post should be about 70%.

Engine Size -------------- Wing Area sq. in.

.10 ------------------------------ 200-250

.25 ------------------------------ 400-500

.40 ------------------------------ 500-700

.60 ------------------------------ 600-850

Gas -------------------------- 1000 - up

( CANARD Center of Gravity ) Thought I would pass on some information on the CG of Canard type Aircraft. This is what a viewer had to say. --

This is written in general terms:

1. Both canard (forward wing) and wing should be of high aspect ratio. Better than seven. The canard should have the higher ratio than the wing.

2. The airfoil section of the canard should stall before the wing.

3. The area of the canard should be 20% to 40 % of the wing.

4. The angle of incidence of the canard should be 2 to 6 greater than the wing. In some cases even greater.

5. Keep the distance between the canard and the wing as long as possible.

6. The balance or center of gravity should be just ahead of the wing. In general if the area of the canard is 30% of the wing area. The center of gravity should fall 30% of the distance ahead of the center of lift of the wing. 100% would be the distance between the centers of lift of both lifting surfaces. Measurement is taken from the center of lift of the wing forward.

7. The center of lateral area of the aircraft is back of the center of gravity. Extent the fuselage back of the wing so that the vertical stabilizer can be effective.

8. In the case of swept back wings the centers of lift will be further back than a straight platform wing. The centers of lift can de determine graphically. The Gentle Lady is a good subject for the conversion into a Canard. However, a new canard has to be built. Hope this answers your questions. The same for powered aircraft.

More Thoughts on locating your CANARD's CG.

These design notes are from R/C Model Builder December 1980 page 18 written and contributed by Col Bob Thacker. These are the details on the design of the OMAC-1 a 63" canard model of a proposed full size aircraft.

The C.G. is very hard to discuss because we have no common reference points. Let's establish them right now. The first thing you are going to have to do on any canard is figure out where the centre of lift is for both wings. The simplest and easiest way of doing this is to take the plan form right off the plan in the magazine. Stick this onto card and cut out. Now you are going to balance that half of the wing in two 90 degree planes, so balance in one plane, mark a line on it, turn the wing 90 degrees balance and mark another line on it. Where they intersect, draw a straight line along the airflow (chord) of the wing from front to back. The line you have drawn on the wing (and we do not care how much sweep or whether it is a double delta or whatever plan form) is going to be your Mean Chord.

Now 25% back from the leading edge of that chord (mean chord) mark and draw a line at right angles so it intersects the centre line of the fuselage and mark, this is the centre of lift on that wing. Repeat the procedure for the fore plane (canard wing) Now you have two lifting points, one forward and one aft. Now you are going to figure out where to put the C.G. First establish the area of the main wing and the canard wing. Let us assume that the areas work out as 20% for the canard and 80% for the main wing, this will give us some numbers to work with. Now measure 20% back from the forward Centre of lift or 80% forward of the aft Centre of lift (that is 20% or 80% of the distance between the two Centres of lift. This establishes the mean lifting point of the entire aircraft.

On conventional aircraft, we always have the C.G. forward of the Mean lifting point, 10% of the distance between the two Centres of lift forward of the mean lifting point will give you a starting point for your C.G. IMPORTANT. When you are calculating the wing area do not forget it is the lifting area you are after, so the part of the wing either on the bottom of or buried in the fuselage will be of no interest because it is part of the fuselage now and contributes no lift and therefore should not be a part of your calculations of the wing area." CENTRE OF LATERAL AREA.

How this fits into the picture I am not sure, Bob Thacker in his article has this to say about it. "Now we are not exactly sure why we have a Dutch roll, but there is one sure way to correct this, start adding more lateral area aft of the C.G. Our thanks to Sitting Bull who said "if your arrow flies poorly, just add bigger tail feathers". What are we talking about when we talk about this centre of lateral area ? If it is so important how do you figure it out so that you stay out of trouble ? Back to the trace and card as you did for the wing and canard wing, trace around the side view or your aircraft and cut out (if you have two rudders cut out another rudder and glue it right over the first rudder) Balance the fuselage (you have cut from card) two ways and draw lines through where these two balance points meet. The is your CENTRE OF LATERAL AREA.

The further aft on a canard that you can get your lateral area, the more stability you are going to have. It must be aft of the C.G. and very close to the aircraft's CENTRE OF LIFT. To get rid of Dutch roll we increased the lateral area aft of the C.G. and lowered the centre of lateral area by going under the wing with a large sub-rudder". Please credit RC Model Builder and Col Bob Thacker for the above information. I found the following info on the net but was unable to locate a photograph so the model was developed into a full sized aircraft.

OMAC 1977: OMAC Inc ("Old Man's Aircraft Company"; fdr: Carl Parise and Larry Heuberger), Reno NV. 1985: Albany GA. Laser 300 1988 = 7pChwM rg; 750hp P&W Canada PT6A-135A [N301L]; span: 41'6" length: 29'7" load: 3250# v: 291/230/71; ff: 7/29/88. Production version of OMAC 1. OMAC I 1981 = 6-8pChwM rg canard. Prototype 1: 700hp Avco Lycoming LTP 101-700A-1 pusher; ff: Dec 11, 1981. Prototype 2 [N81PH]: 700hp Garett TPE331-9 pusher; span: 35'0" length: 30'0" load: 2500# v: 299/250/63 range: 2950; ff: 2/19/83.

A special Thanks to Michael Walsh

Dave Spiller sent in this tip on how to make tapered wings. Ribs that are dimentionally smaller from station 0 ( center of plane ) to station X ( 1/2 the wings overall span) case in point a 40" wing having a rib in the center of 6" cord would be 20" long on each side .

At 2" spacing there would be 10 ribs on each side. The tip could be 4" for argument sake giving you a different size ribe each 2" span along the wing. make a hard rib pattern for the center and a hard rib for the tip with alignment holes for some music wire to keep the bottom of the ribs flat to the bottom of the wing. Insert ten pieces of material to shape the ribs from ( foam , balsa , bass etc.) poke the alignment wires through the holes and straight line sand from the tip rib to the center rib and it will produce a perfect tapered rib pattern at that spacing,

Next put ten more rib pieces and put the tip pattern on the other side and produce the opposite wing. Good luck and happy flying.

Canopy forming using a sealant gun