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The Finch is a light weight, easy to build and fun to fly RC micro plane made from free CAD airplane plans. The Finch employs the popular and affordable ParkZone aircraft line of radio control gear. The Finch sports a 20 inch wingspan, weighs 1.1 ounces and uses three channels of control for throttle, rudder and elevator. The Finch is made from common building materials (balsa and some plywood), and can be constructed in a weekend using supplies you likely already have in your wood bin.
And best of all, Finch plan can be downloaded here as free, full size plans. The Finch’s eight sheet Microsoft Word plan file simply needs to be downloaded, printed out at your home computer and taped together as instructed on the plan's cover sheet. There is no need to go to a copy center and enlarge the plans. Print out your Finch full size free model airplane plans and let’s get started building.
By the way, if you have TurboCAD installed on your computer, download the TurboCAD Finch plan here.
Building the wing
The Finch’s wings use 1/8” square balsa, sanded to a round dowel shape, for the wing leading and trailing edges. Cut out five 1/16” balsa wing ribs for each wing. Pin the 1/8” balsa dowel wing leading and trailing edges over the plan on your building board.
Note that I sanded down the 1/8” square balsa main spar a bit to save weight. Cut out 3-4 scrap wood jigs to elevate the 1/8” square balsa main spar, and pin the spar to the top of the jigs. Glue in the front and aft wing ribs as shown on the Finch’s free model airplane plan.
Ensure you make the three 1/32” plywood wing dihedral braces, and install these braces in slits cut into the wing’s leading and trailing edge dowels as well as the 1/8” square balsa main spar. The dihedral braces have 2” dihedral built in. I pinned down one wing panel to the building board, raised the other wing tip 2”, and glued in the three dihedral braces.
Building the fuselage
The fuselage is built primarily from 3/32” square balsa. You can use a lighter grade of balsa for the fuselage which will provide plenty of strength for this micro model.
Build the fuselage frame directly over the full size free model airplane plan. Add the 3/32” square balsa fore and aft wing posts. The wing post length is important, as this will set the all important incidence for the Finch’s wing. Add the 1/16” balsa sheet for the Finch’s motor mount and RC equipment tray to the fuselage frame. Install the fuselage side 3/32”square balsa and 1/32” sheet cowling, as well as the decorative 1/16” square balsa tail stringers as desired.
The landing gear is made from 0.032” music wire bent to shape per the plans. Use scrap balsa to secure the fore and aft (L-1 and L-2) landing gear sections to the fuselage underside, and bind L-1 and L-2 with thread at the main axle. Use a pair of lightweight wheels. I used a set of wheels from the ParkZone Cessna 210 on my Finch prototype.
The tail surfaces are made from 3/32” square balsa. Make the elevator and rudder control horns from 1/32” plywood.
Drill the hole in the control horn as per the plan. If the control wire hole in the horn is too far out, you will have reduced control throw, as there is no way to adjust for control throw with the linear servo arm of the ParkZone control brick.
The ParkZone aircraft electronics are installed as per the plan, and should permit for the correct center of gravity. Be certain to use the ParkZone electronics for the P-51 aircraft. Do not use the electronics for their Cessna 210 as the C-210’s smaller motor will not provide enough thrust for the Finch to fly.
The electronics part list follows: The receiver/electronic speed control/servos brick is part PKZ3351. The motor and gearbox is ParkZone part PKZ3624. Install the E-Flite Ultra Micro Propeller 130mm x 70mm, part PKZ3601 to the motor. Finally, use the E-Flite 120 mAh 1 cell 3.7V lipo battery, PKZ1035.
All these items are available on the Horizon Hobby website, and will ensure plenty of thrust for flying success with your Finch built from free model airplane plans.
You will have to cut off the alignment posts on the motor’s plastic mount, and glue the motor directly to the Finch’s balsa engine tray. I used double sided foam tape for installing the electronics brick. The control rods for the elevator and rudder are from 0.025” music wire with Z-bends are each end. I used two pieces of 0.025” music wire, centered the rudder and elevator, and applied a small piece of electrical tape to fix the control rod at the proper length. A piece of Velcro will keep the lipo battery securely attached to the fuselage. You can move the battery forward and aft to adjust for the center of gravity.
For the final finish details of your Finch, 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 1/16” balsa tail skid such that the rudder does not drag on the ground.
Cover your Finch with lightweight covering such as Coverite Coverlight. You can also use plastic Saran Wrap as covering for a model aircraft this small. To save weight I covered just the top of the wing and tail surfaces. Use clear hinge tape to attach the rudder and elevator. The wing is glued in place.
Finch is a gentle flyer
The Finch is a slow flyer that handles very well. The geared motor provides plenty of power. Your ground run for takeoff is just a few feet. I have flown the Finch outdoors, but the winds need to be calm. The Finch flies best indoors. Give this fun RC micro flyer a try - I know you will enjoy it!
Author: Gordon McKay