Classic Tutorial...control systems in ARFs ailerons, elevator and rudder!

An often over-looked, area of a precision aerobatic model is the control system. Most spend enormous amounts of time and money on selecting the servos. What about the parts that connect the servos to the control surface? How many flights can you fly without maintenance? Is your control system as "tight" and slop free for hundreds of flights? If not read on!

Control systems in ARFs- Many of todays ARFs offer some combination of unique subject, value or time from box to flying field. Current offerings are containing more and more complete hardware packages. The following is how I UPGRADE ARFs. Please understand that these ideas are mine, have worked for me and can be consistently executed with my skills, tools and time availability...they may NOT work for you!

Subject: Great Planes Zlin 526

The Great Planes Zlin was designed by Great Planes R&D airplane designer Mark Hampe and builder/writer Steve Beros with George Rodriguez as the product manager. This same team developed the "Sequence", which I have flown extensively, written about on a RCU thread in the electric pattern section and just think is incredible!

Split Elevator set-up- Classic pattern airplanes typically had one elevator pushrod connected to one elevator half and a "u" shaped wire connecting the (2) elevator halves.

Most current ARFs use (2) wire pushrods guided by independent plastic tubes pre-installed in the fuselage. The wire works fine, is reasonably simple to install and align. My method saves at least (2) ounces (!!!), allows the use of titanium ends which save more precious grams and allows for VERY simple and accurate installation.

Dual Elevator retrofit- I use .060 or .070 carbon fiber rod from Midwest (#5800 for the .060 or 1.5mm carbon rod, weighs .081 grams per inch) and Central Hobbies pushrod ends, 3mm dual axis rod end for servo, Kraft-Hayes 4-40 nylon clevis with steel pin for rudder and the Central Hobbies new control horn.

Photo 3,4- The radio compartment shows the Futaba 9151 digital servo for the rudder (left side of model) and Futaba 3151 digital servo for the elevator. The rudder uses the Central Hobbies 3mm dual axis rod end threaded to a 3mm titanium fitting with a .070 hole for the carbon rod. The fitting is glued with JB Weld. The elevator .060 carbon rods are first glued (JB Weld) into a larger carbon tube (slotted to accept the angle of rods) with titanium fitting/3mm threaded end for 3mm dual axis rod end. Once this is dry (over night) I remove the assembly and wrap with 1/2a control line thread and coat the hole thing with a film of JB Weld to absolutely make the hole thing solid.

Photo 1,2- Alignment is absolutely critical!!! I attach sharpened carbon rods to the elevator halves (make sure the elevators are hinged and glued in the CENTER) with painters tape, aligning them as shown in the photos. Note I do not install the rudder until this is completed.

Photo 5,6- The titanium rod ends have been prepared by measuring and test fitting. The control horns were installed exactly like the ailerons (see previous post) BEFORE the elevators were glued in place. JB Weld is applied to the carbon rod, inside the titanium rod end with a pin and pushed in and out. Use a couple pieces of wood pinned to the rudder post to keep the stuff aligned and let cure overnight.

Photo 7+ The rudder end is handled the same except the carbon rod is exposed a little more...I add a telescoping tube for strength and speed alignment of the 4-40 titanium fitting/steel pin clevis.

The other photos show the completed model with wing #1 (stock version), YS 63 with Hatori header/muffler enclosed in cowl with exhause exiting out of the fuselage!

Wing #2 has independent aileron/flap (scale dimensions-larger than kit) modified landing gear with aluminum wheel, no wing tube and lots of lightening holes. The full scale airplane had interesting deflection angles of the aileron/flap...I am going to have 2-5 conditions for outside ailerons only and variable flap angle, aileron/flap coupled, outside ailerons with coupled elevator flaps and "crow" which will raise the ailerons and lower the flaps for super slow down-lines? I am just about done with this and will post as completed and discuss results of flight testing. The testing is a to sample the Hanno/Matt airbrake set-ups.

Finally, the "faux" landing gear detail was made with silver craft pen (hub) from Michael's for the wheels, holes were drilled in the hub, wheel collars covered with black heat shrink, white heat shrink for bottom of wire, a waterproof pushrod exit for a R/C boat for the shock absorber, bits of gasoline fuel tubing/carbon tube/dowel are the hard-points, white cover is paper tube for servo wires covered in white/silver trim monoKote...it made the ugly wires look better!

Rusty Dose
Team Futaba
SPA #213