Why Didn't I Think Of That? - Top Tips Part 2

Top Tips, some you may know some you won't, but they all come in useful, especially if you're new to the hobby!

If you have any great tips that you want to share with other modellers, then send them to us at editor@flyingsites.co.uk or to the address listed on our 'Contacts' page.

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.

Four 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 rubbish bin.

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.

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 centre 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 rubbish bin 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 Pop Bottles

Several things for RC airplanes can be made from 1, 2, or 3-litre pop 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 formers.
  • Take the colored base off of a 1-litre 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" pop 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!

This page has been contributed by Jeff's R/C Airplanes