By York R/C Club
Introduction
A well-trimmed RC airplane flies straight and level, so you aren’t constantly fighting the controls. In this guide, we’ll explain mechanical and digital trim, walk through a step-by-step trim flight, cover essential ground checks, and troubleshoot the most common trim issues. Because summer weather can affect your trim, we’ll also discuss why it’s important to re-check every season. We’ve gathered the best practices from AMA, Horizon Hobby, and our own club instructors. Therefore, whether you’re a beginner or a veteran, you’ll find useful tips here. For even more discussion, see Trimming a plane by Flite Test Forums.
TL;DR — Proper trim makes flying easier, safer, and much more enjoyable. First, fix any issues with hardware. Then, finish fine-tuning using your radio. As a result, you’ll fly with confidence every time you go to the field. Watch this YouTube video on RC trimming basics for a step-by-step demonstration.
1 — Why Trimming Matters
- Trimming reduces battery draw and pilot fatigue. As a result, you get longer flights and more enjoyment.
- It also improves flight performance and servo life.
- Furthermore, trimming prevents you from “fighting the sticks” on every lap. Because of this, you’ll feel more relaxed and in control.
- For more on the risks of poor trim, read our Top 5 Mistakes New RC Pilots Make.
2 — Mechanical vs. Digital Trim
- Mechanical trim: Adjust pushrods, servo arms, and clevises on the bench to get control surfaces neutral with transmitter trims centered. First, always start with mechanical trim before you fly.
- Digital trim: Use transmitter trim levers or buttons for small, in-flight adjustments once airborne. Then, fine-tune for perfect flight.
- In summary, always get as close as possible mechanically before making digital trim tweaks.
3 — The Trim Flight: Step-by-Step
- Pre-flight: Confirm CG (center of gravity) and check that wings and tail are symmetrical. This step is essential before every trim flight.
- Take off, then fly straight and level at 60–70% throttle.
- Release the sticks:
- If the airplane banks or pitches, add the appropriate trim (start with aileron, then elevator, and finally rudder) until it flies level and straight.
- Make small adjustments—usually a few clicks at a time. This way, you avoid over-correcting.
- After landing, adjust the pushrods or clevises to physically re-center your control surfaces. As a result, you can reset your trims on the transmitter back to zero.
4 — Ground Checks Before You Fly
- All control surfaces should be neutral with trims centered. Before every flight, always double-check this.
- Also, make sure there is no binding, warps, or unequal servo travel.
- In addition, check that all linkages are tight and secure.
- If you find warps or breakages, see our Field Repairs guide. As a result, your plane will remain reliable.
5 — Common Trim Problems and Fixes
- Constant roll: Check aileron linkage length and look for wing warps. For example, even a small twist can cause rolling.
- Pitch up/down: Check CG, elevator horn, or linkage. If the plane constantly climbs or dives, you’ll often find the problem here.
- Trim drifts during flight: This may be caused by a faulty servo or loose hardware. Therefore, always inspect for mechanical problems.
- Mushy elevator: Inspect for flex, loose hinges, or servo slop. Otherwise, you might struggle with consistent pitch control.
6 — Why Summer Air Changes Trim
- Foam and balsa expand or contract with temperature and humidity. As a result, your trim may change even if nothing else does.
- In addition, covering and tape may loosen, and warps can appear.
- Therefore, always re-trim after storage, major repairs, or big weather swings.
7 — Pro Tips for Digital Flyers
- Use sub-trim for minor tweaks, but not for big corrections. In other words, save big changes for mechanical adjustments.
- Also, save separate setups for summer/winter or after major repairs. This way, your plane is always ready for changing conditions.
- Consider elevator-aileron mixing for truly hands-off turns, especially for trainers and sport planes.
Conclusion & Next Steps
A perfectly trimmed airplane is a joy to fly and much safer for everyone at the field. Because trimming is a quick process, you’ll save time and reduce stress later. Take a few minutes each new season or after repairs to re-check your trim. As a result, your plane—and your nerves—will thank you!
Happy flying! — York R/C Club
Published July 25, 2025
Internal links: Top 5 Mistakes New RC Pilots Make • Field Repairs
External (no-follow): Trimming a plane by Flite Test Forums • YouTube: RC Trimming Basics