RADIO CONTROL AEROBATICS
Rick Allison, 15618 NE 56th Way, Redmond WA 98052
Introduction
Last month, in the midst of my diatribe on learning to fly straight and square, I mentioned passing on a few practice techniques for learning to use the rudder properly.
By "properly," I mean as something besides a ground-steering, stall-turning device that comes in handy for the occasional snap roll, spin, or tumble — which describes the skill level of the average, well-practiced RC pilot. Using the rudder properly for precision aerobatics means genuine three-axis control of the aircraft regardless of attitude, speed, altitude, or flight conditions.
I said mastering the rudder wasn't really a priority on the way to learning to fly straight, and that it could be done later. While that is true, now is later, and there is a very good reason for learning to use the rudder skillfully: pattern contests are held outdoors, and 99% of the time that means wind — more specifically, crosswind.
Wind, Rules, and Scoring
The rule book is explicit about wind correction. From the AMA Competition Regulations and the AMA RC Pattern Judge's Guide (Paragraph B, page 70, subheading (a) Precision):
"... All maneuvers in RC Aerobatics are required to be wind corrected in such a manner as to preserve the shape and symmetry of the maneuver and the track of the model. All straight lines, both horizontal and vertical, will be graded on the track projected by the model. Change in attitude of the model to maintain a straight track will not be reason for downgrading the maneuver."
Two major points:
- Wind correction is required; failure to correct will lead to downgrades.
- The proper attitude (fuselage angle) is the one that allows the model to fly a straight track.
Some confusion arises from a perceived conflict with the One-Point-Per-15-Degrees Rule. That rule refers to "defined maneuver geometry," and that geometry is always judged on track, not on attitude. If a stall-turn entry track is vertical (but yawed for correction) and the return track is vertical (also yawed), the track has shifted by exactly 180°, satisfying the turn requirement. The Guide even notes that "lines can and should be judged more critically than deviations in roll," which supports judging on track.
Bottom line: you must wind-correct. If you don't, you'll end up so far out of position that the rest of your pattern will be scored with poor marks.
The Crab Angle and Rudder Fundamentals
The set crab angle is the basic wind-correction maneuver for crosswind flying and is accepted in AMA and FAI competition. Basic instruction: apply and hold rudder into the wind to hold the ground track while maintaining zero roll and pitch deviation.
Practical notes on rudder use:
- Rudder is often the last control mastered. For right-handed Mode 2 pilots it’s the off-hand, its direction appears to reverse to a ground-based pilot as the plane goes from upright to inverted, and it produces yaw rather than roll or pitch.
- At significant speed, rudder deflection past about 15° adds mostly drag and can disrupt flow over the horizontal stabilizer, causing pitch problems.
- Use only the deflection needed — usually less than 5° — and never apply it abruptly.
- A small amount of exponential travel dialed into the rudder control helps modulation.
- If you still can't modulate well, consider using radio limits or a flight-condition switch to restrict total rudder travel at high throttle (set enough deflection to allow a slight climb in knife-edge flight).
One more important point: many rudder techniques are borrowed from full-scale aviation, but a key difference exists. A full-scale pilot picks a fixed ground point to measure drift; an RC pilot is the fixed point and judges measure the aircraft relative to the pilot and ground. What the aircraft appears to be doing is what it is doing relative to the ground — the plane doesn't "know" it's windy, but you and the judges do.
Practice Exercises (Rudder Building)
Learning the rudder is like building a muscle — exercise and repetition are key. Start with calm conditions and a well-trimmed airplane.
- Parallel pass crab corrections
- Begin with the parallel pass used in the Straight and Level exercise.
- Set up on the far side of the flags. Out of the turnaround, apply enough inboard rudder pressure to slide the model inbound toward the flight line.
- Use a gentle, smooth application and aim for about 25–30 meters of correction over the length of the pass.
- Counter any pitch or roll excursion with aileron or elevator and make the correction look seamless.
- At the end of the pass, release the rudder and use a deep cross-box turnaround (e.g., Humpty Bump or Top Hat) to reposition on the far side of the flags.
- Repeat in the opposite direction. Run back and forth until smooth and confident.
- Reverse-direction passes
- Repeat the exercise starting from inside the flags and correct as you come toward the judges.
- This builds feel for headwind vs. tailwind effects and forces you to learn where corrections should be applied so the model presents the correct track when it matters.
- Top-of-box practice
- Take the exercise to the top of the box and do more repetitions, both inbound and outbound.
- Inverted-flight practice
- Still at the top of the box, repeat the exercise with the model in inverted flight.
- Optionally bring the model down to box-middle height and reconstruct the exercise.
- Vertical-line slide corrections
- Use the same techniques to learn to slide-correct vertical lines, both at the box ends and in the center.
- Practice with the model both edge-on and on platform-form (quarter-rolled).
Do enough reps to make the process natural and automatic.
Tips and Warnings
- Modern precision designs and radio mixing help separate pitch, roll, and yaw axes, but almost any design will go divergent if enough rudder is applied, especially at full throttle.
- Avoid abrupt rudder inputs; smooth, measured inputs win.
- Think out there: the best tool on a windy day is the brain between your ears.
- Be patient — mastery takes a lot of fuel and time. Pilots who catch on immediately are rare.
Conclusion
You are now (theoretically) ready for a cross-windy day and some real-world practice with these rudder tools while flying your actual maneuver schedule. If you master these techniques, you'll be well on the way to becoming a master pilot.
Transcribed from original scans by AI. Minor OCR errors may remain.
