Final Setup: I covered setting up the control surfaces, throttle, and trim settings in detail in the second part of this series of articles. To recap, all control surfaces must first be in the neutral, centered position. Turn on the transmitter and center all the trim tabs. All servo output arms must be in the center position.

    Since our servos move in a curve, any offset from center will result in "differential" control-surface movement. An elevator will move more up than down if the servo arm were offset. This is true of all control surfaces and can make for a difficult-to-understand flight experience.

    Once the servo arms are centered, disconnect the pushrods at the control surface. Clamp the control surface in neutral using two straight pieces of wood and two modeling clamps. Align and clamp the ailerons with the wing's TE. Adjust the clevis until it can easily be inserted into the control horn without pressure.

    The control surfaces are now in neutral. This is the time to set movement direction and travel amounts.

    Most instructions specify the amount of movement in inches of travel. The Hobbistar 60's elevator should move 7/8 inch in either direction. Set the fuselage on a flat surface and adjust the amount of movement.

    In this example if the elevator moves too far, relocate the pushrod clevis into the next hole away from the control surface. Or you could move the servo connection inward toward the center of the servo arm. Reverse these operations if there is too little movement.

    Sometimes relocating both connections is required to get the proper amount of control-surface travel. On a computer radio leave the connections alone and set the amount of travel using the transmitter.

    Experience has shown that changing the amount of travel on the transmitter by more than 30% sets up a problem. In these situations transitions from left to right aileron or up- to down-elevator become somewhat "sudden," making smooth transitions difficult. Use a combination of transmitter and mechanical clevis adjustments to eliminate excessive transmitter settings.

    I also previously covered setting the throttle in detail. The basic idea is to fly with the throttle trim lever set on "high," then lower it to "half" to land, and have engine shutoff set for full low trim. The reason for the "high" trim flight setting is that many analog, noncomputer transmitters require maximum throttle trim to achieve complete throttle-arm movement.

    Although various engines and installations may differ, a good starting point is usually 2,800 rpm at high throttle trim, 2,300 at the middle trim setting, and 0 rpm at low trim. This usually means the throttle barrel should be open approximately 1/16 inch at the middle trim setting.

    After completing all the assembly work and setting control-surface travel, step back from the assembled aircraft, take a deep breath, and concentrate. Think of nothing but the control surfaces and move the aileron transmitter stick all the way to the right. The right aileron should move upward, and the left aileron travels downward. If not, fix it.

    It is always surprising how these settings somehow just change during the building process. Give all the control surfaces, and the nose wheel, this final check to ensure proper movement.  

Click on photo to view large image with caption

On the Flightline: All the checks and settings were done on the Hobbistar 60, so I loaded the airplane, all the field gear, and Frank Costello—one of the best in-air photographers around—into my Suburban and headed out to the field to see if all the extra work was worth it. At the field we unloaded everything and assembled the airplane. The bolt-on wing paid for itself right then.

    I switched on the transmitter and then the onboard radio system. Always turn on the transmitter before the flight radio, and turn it off last when shutting down. This prevents possible servo damage and jitters from stray signals.

    We took a short walk (roughly 100 feet) with the antenna collapsed and tested the radio connection. After that test was passed, we checked control-surface movement again to make sure everything was connected during assembly.

    The flight data we obtained tells the performance story and is detailed in the sidebar, but there is a great deal the data does not accurately portray. Piloting the modified Hobbistar 60 left some strong impressions.

    The stock Hobbistar 60 is a fine advanced trainer; it's stable yet responsive, with a maneuver repertoire that is well above average for its class. The modified version feels more solid, flies faster, has more positive responses, and has an even wider maneuver envelope than the unmodified version.

    The O.S. Max .61 FSR is a fairly powerful engine, even by today's standards, and takeoff required less than a 100-foot ground roll. Climbout was steady, with just a touch of right rudder, at approximately 1,900 feet per minute despite a strong crosswind. At that climb rate the airplane reached "fun time" altitude quickly.

    We left the throttle at maximum and quickly noticed one performance difference in comparison to the stock Hobbistar 60s that we have flown. The modified model was faster at full speed, yet it was extremely steady.

    RealTree Systems' Flight Data Recorder was set for testing low-speed aircraft, and the modified Hobbistar 60 quickly passed its 70 mph maximum reading. My guess would be a top speed near 75 mph. This is roughly 10 mph faster than most stock Hobbistar 60s can reach.

    Lowering the flaperons reduced the top speed to 67 mph. Although the airplane remained steady at this rate, it did feel "loose" and required constant small corrections to maintain heading. Pitch control became more sensitive as well. But then, flaperons are not meant for high-speed flight. Their advantages are best used in the slower speed spectrum.

    We slowed the airplane, and the flaperons started to perform their magic. Yes, they lowered approach and landing speeds, but the real difference was in the model's stability and control responsiveness at low airspeeds. Even at less than 30 mph, the modified Hobbistar 60 remained steady and responsive, especially to aileron inputs.

    The ailerons remained almost as effective during the approach as they did at higher airspeeds. The sluggishness that is so common at low speed was greatly reduced when the flaperons were down.

    Altitude control during the landing approach was improved, and spot landings became predictable. The entire approach could be flown more slowly, but it was rock steady. With flaperons it was possible to start the approach as much as 75 feet higher than normal, yet land the aircraft at runway center without increasing speed during the steeper approach.

    The flaperons allowed this advanced airplane to fly and land at basic-trainer airspeeds. Not bad for a few hours' work.