.
Start your radio installation with the receiver. All of our prototypes had the receiver installed just behind the fuel tank in the
opening in F-3. Wrap the receiver in 1/4" foam rubber for protection.
With the receiver in place, now you can install the aileron servo. Measure carefully for the cutout in the wing so that the
aileron servo will clear the receiver. Glue the two die-cut 3/32" plywood aileron servo mounts (ASM) to the balsa sheeting,
and screw the servo in place. Make the aileron pushrods from threaded rod and nylon clevises then hook them up to the
nylon aileron connectors (which should be threaded onto the torque rods). You can use an extension wire from the
receiver to the servo, but we typically plug the aileron servo wire directly into the receiver just before bolting on the wing.
This saves weight and keeps loose wires to a minimum. You may have to make a small notch in the stabilizer leading
edge to clear the torque rods during wing installation.
Now you need to do some decision making. The battery, switch, and remaining servos should be positioned as necessary
to achieve the proper balance point on the finished model without having to add weight to the nose or tail. If you're using a
very lightweight engine, the battery will probably need to go under the fuel tank and receiver. Heavier engines will dictate a
more rearward battery position, possibly behind F-4. Assemble the Wonder , place it on a balancing stand, then shift the
components around on the outside of the model until you find the best arrangement.
BALANCING
IMPORTANT: It is vitally important that your Wonder is balanced properly. The correct balance point for first flights is 2-
3/8" (plus or minus 1/16") behind the wing leading edge. This is a short-coupled airplane and the balance range is very
small. Our prototypes all flew well with the balance point between 2-5/16" and 2-7/16" behind the leading edge. If the
balance point is too far forward, the Wonder flies well under power but you can run out of "up" elevator during the
landing flare. If the balance is too far back, the plane can become unstable and eventually, uncontrollable.
Oh, and don't use your fingertips for balancing! Build yourself a quick and
dirty balancing stand like the one shown in the diagram. Mark the balance
point on the bottom of the wing with tiny lengths of striping tape. Shift the
radio gear or add weight as necessary to bring the balance point into the
proper range. Trying to fly with the balance point too far forward or too far aft
is much more dangerous than the slight increase in wing loading caused by
adding nose or tail weight. Always balance the model with an empty fuel tank
so that it sits level on the balancing stand.
In addition to the fore/aft balance, it's important that you balance the model
spanwise. A "heavy wing" on one side can result in poor loop tracking. To
check for this, pick up the assembled model by the spinner at the front and
under the center of the stabilizer at the rear. Insert weight (small finishing
nails work well) into the lighter wingtip until the model is balanced.
The battery should be wrapped in foam rubber and secured inside the fuselage with balsa sticks to keep it from moving.
The sticks can be broken away later when you need to remove the battery from the plane.
The throttle servo and the elevator servo on most of our prototypes were installed using servo tape, which works very well
on a small model like the Wonder. Here are a few tips for using servo tape:
Coat the area of the fuselage where you plan to install the servo with glue, either epoxy or CA, and allow it to dry.
The tape will stick much better to this than it will to bare balsa.
Clean the servo with alchohol before applying the tape.
Cover the entire side of the servo with tape. You want as much bonding as possible.
Make certain the servo arm and screw are installed before taping the the throttle servo in position. You won't be
able to get at the screw once the servo is taped in place!
The throttle pushrod is a 1/16" steel cable which moves inside a nylon tube. The hole in F-1 has already been drilled for
the tubing, but you need another hole in F-3 to route the tubing so that it's pointed directly at the servo arm. Solder the
clevis (included in the kit) to the steel cable, route the cable through the nylon tube and into the pushrod connector located
on the engine's throttle control arm. Snap the solder clevis on the servo arm and adjust the cable at the pushrod connector
end.
The elevator servo is very easy to install through the hatch. Bend a pushrod to suit from a 2-56 threaded rod. At the field,
adjustments to the clevis can be made at the rear fuselage opening, if necessary.