Build the Finch – Download Free Plans Here!

The Finch is an indoor radio controlled model plane I designed that uses the popular ParkZone line of RC gear and compact geared electric motor.

Front view of the Finch covered with silkspan

Front view of the Finch covered with silkspan

The Finch has a 20 inch wingspan, weighs a little over one ounce and uses three channels of control for throttle, rudder and elevator. The Finch is easy to construct and is made from normal building materials of balsa and some plywood. You can build your Finch in few days using supplies likely already in your workshop.

Top view of the Finch fuselage forward section

Top view of the Finch fuselage forward section

Free CAD plans for the Finch are available for download Finch Plans on Word. I drew the original Finch plans in TurboCAD. The problem with this approach is that you require a copy of TurboCAD on your computer to view these files.

Detail of Finch motor and ParkZone electronics installation

Detail of Finch motor and ParkZone electronics installation

To assist folks who do not have a CAD program installed on their computer, I’ve pasted the full size Finch plans from TurboCAD into a Microsoft Word document. Simply download

Three channel radio control Finch in a fly by

Three channel radio control Finch in a fly by

this plan file and (assuming you have Word installed on your computer) print out the eight sheets with your home printer on regular 8.5” by 11” paper. Tape the page tiles together as shown on the cover sheet and you’ll quickly have a full size set of Finch CAD plans.

Let’s get started building . . . you should be able to complete your Finch in a weekend!

Nose section of the Finch showing landing gear, motor and RC electronic arrangement

Nose section of the Finch showing landing gear, motor and RC electronic arrangement

The wings employ 1/8” square balsa sanded to a round dowel shape for the leading and trailing edges. Cut out five 1/16” balsa wing ribs for each wing. Pin the leading and trailing edges over the plan. Cut out 3-4 scrap wood building jig supports to elevate the 1/8” square balsa main spar and pin the spar to the top of the jigs. Note that these elevation jigs are used only to elevate the spar during construction, and are not part of the finished wing. Glue in the front and aft wing ribs to the leading and trailing edge as shown on the plans.

Close up of the Finch nose section and fuselage underside

Close up of the Finch nose section and fuselage underside

Cut out three 1/32” plywood wing dihedral braces and insert them into slits cut into the wing’s leading and trailing edge as well as the 1/8” square balsa main spar. Note that the dihedral braces have the two inches of dihedral (one inch of dihedral on each side of the wing) built in. I pinned down one wing panel to the building board and raised the other wing panel two inches at the tip. Glue the three dihedral braces into their slots to create the finished wing frame.

The fuselage is made primarily from 3/32” square balsa. Build the fuselage frame directly over the plan. Add the vertical 3/32” square balsa fore and aft wing posts. The wing post length is important as this elevation will set the positive incidence for the Finch’s wing. Glue the 1/16” balsa sheet for the motor mount and RC equipment tray to the fuselage frame. Install the fuselage side 3/32”square balsa and 1/32” sheet cowling. Add the decorative 1/16” square balsa tail stringers as desired.

Detail of the Finch fin and rudder assembly

Detail of the Finch fin and rudder assembly

The landing gear is made from 0.032” music wire. Use scrap balsa to secure the fore and aft (L-1 and L-2) landing gear sections to the fuselage underside. Bind the landing gear with thread at the axle. Use your choice of lightweight wheels.

The tail surfaces are constructed from 3/32” square balsa. You can make the elevator and rudder control horns from 1/32” plywood. An alternate plan is to harvest some plastic control horns from an older ready to fly model.

Detail of ParkZone electronics in the Finch

Detail of ParkZone electronics in the Finch

Drill the hole in the elevator and rudder control horns as shown on the plan. Note that if the hole in the horn is too far away from the control surface you will have reduced throw. On the other hand, if you desire more control throw, locate the hole in the horn closer to the control surface. There is no way to adjust the amount of control throw with the linear servo arm setup of the ParkZone control brick. Thus the distance out of the hole on the control rod is important for the resulting control surface throw and the Finch’s flight characteristics.

Following are some part numbers for the electronics. Stevens Aero is a good place to purchase the electronics as well as Horizon Hobby. Google can provide other sources. The receiver/electronic speed control/servos brick is part PKZ3351, and the motor/gearbox is ParkZone part PKZ3624. I used the E-Flite Ultra Micro Propeller 130mm x 70mm, part PKZ3601. Use a 120 mAh or greater 1 cell 3.7V lipo battery.

Mike's Finch with clear yellow heat shrink covering

Mike’s Finch with clear yellow heat shrink covering

I cut off the plastic alignment posts on the motor’s supplied mount and epoxied the motor directly to the balsa engine tray. I employed double sided foam tape for installing the electronics brick. The control rods for the elevator and rudder are made from 0.025” music wire with Z-bends for trim adjustment at each end.

To connect the servos to the elevator and rudder I overlapped two pieces of 0.025” music wire and centered the control surfaces. I then applied a small piece of heat shrink tubing at the overlap to hold the control rods at the proper length. A piece of Velcro will hold the lipo battery securely attached to the fuselage.

For the final finish details install 1/16” balsa control rod guides midway between the cockpit area and the tail surfaces. I cut a small opening in the balsa guide, and glued thread on the top. The idea is to keep the control rods from flexing as they move the rudder and elevator. Install a tail skid such that the rudder does not drag on the ground.

Finch showing 1/32" balsa cowling

Finch showing 1/32″ balsa cowling

Cover your Finch with lightweight covering. I used Coverite Coverlight. To save weight I covered just the top of the wing and tail surfaces. Be sure that whatever covering you use is not shrunk so as to induce a wing warp. Use clear hinge tape to attach the rudder and elevator. I recommend gluing the wing in place as there is no need to make it removable.

The Finch is a slow flyer that handles very well. The ParkZone motor provides plenty of power and the takeoff run is just a few feet. I have flown the Finch outdoors, but the wind needs to be calm.

Keep in mind that you can easily “bash” (i.e. change) this plan to make a unique model. Try experimenting by increasing the wingspan for slower flights, changing the outline of the tail surfaces or creating a unique variant of the cowl.

The Finch is a great first step to making a plan built indoor model airplane. Slight mods are the first step to creating your own model airplane design some day!

Author: Gordon McKay