Is vibration spoiling your next flight?
A vibrating RC heli is telling you something. The trick is to work out whether the problem comes from blade tracking, blade balance, a bent shaft or somewhere else in the drivetrain, before making adjustments at random.
Tracking and balancing are related, but they are not the same. Tracking means both main blades fly in the same plane. Balancing means their mass and centre of gravity are matched closely enough to rotate smoothly. A rotor can be balanced but out of track, or track cleanly while still being unbalanced.
This guide gives you a safe, systematic way to investigate. If vibration persists after careful checks, stop flying and ask an experienced modeller for help. At AT Models, our dedicated heli specialists can offer expert advice and ongoing after-sales support.
What does the vibration tell you?
Is it a buzz, a wobble, or a helicopter trying to walk away? The movement and the speed at which it occurs can help narrow down the fault.
- A slow, low-frequency wobble often points towards a rotating part that is bent or out of true: think rotor imbalance, a bent main shaft or feathering shaft, loose head hardware or excessive play.
- A higher-frequency buzz may be linked to motor or gear speed rather than the main rotor. Inspect the motor shaft, bearings, pinion mesh, main gear and belt or tail-drive system. Tracking adjustments won’t cure a drivetrain fault.
- A once-per-rotation shake can indicate that the blades are generating uneven lift or that their mass or centre of gravity differs.
- The classic “helicopter walks on its skids” (a repeating shake or shimmy while the model is on the ground) can be a sign of out-of-track main blades. It is a clue, not a diagnosis: a bent shaft, loose head or other fault can produce similar symptoms.
Vibration frequencies can overlap, so don’t rely on sound alone. Notice where the shake is most obvious, whether it changes with rotor speed, and whether anything has changed since the last smooth flight. Never use a flight controller’s settings to mask a mechanical fault.
Start with a safe inspection
Before reaching for a linkage, have you ruled out damage and looseness? Remove the LiPo (lithium-polymer battery) or disconnect the power source before inspecting, tightening or adjusting anything. Follow your model’s manual for safe handling and assembly.
Work through this checklist with the helicopter switched off:
- Main blades: confirm the blades are a correct, matched pair and fitted in the right direction. Look closely for chips, cracks, delamination or other visible damage.
- Blade grips: check for looseness, uneven movement, worn bearings and secure fasteners.
- Spindle or feathering shaft: inspect for a bend; this is the short shaft through the blade grips.
- Main shaft and head: check for runout, loose hardware, worn bearings and excess play.
- Links and balls: look for a bent or damaged pitch link, a loose ball link or a link that binds.
- Tail blades and tail rotor: check blade condition, matching, secure mounting and shaft or hub runout.
- Motor and gears: inspect for a loose pinion, damaged teeth, uneven or incorrect gear mesh, rough bearings and shaft play.
- Swashplate and frames: look for slop, cracks, damaged mounts and loose fasteners.
Pro tip: Change one thing at a time and keep a short note of what you checked. If the vibration changes after a single adjustment, you have a much better diagnostic clue.
What is blade tracking?
Are both blades following the same path through the air? On a two-blade head, they should rotate in the same plane. If one blade sits higher or lower than the other, it produces lift on a different path. That mismatch can make the rotor pull unevenly and shake the airframe.
Tracking is not corrected by adding weight. It is generally corrected by adjusting the relevant pitch linkage in small increments, following the model manufacturer’s instructions. If the linkage adjustment seems to have little effect, or the setting changes unexpectedly, stop and check for a bent shaft, damaged link, loose grip or head slop before going further.
The contrasting-tape tracking check
Can you tell one blade’s path from the other? A small piece of contrasting tape can help identify which blade is running high or low. Treat this as a powered-rotor procedure: spinning blades can cause severe injury.
- Switch off and inspect first. Confirm that the blades and head are sound, and check that all fasteners are secure.
- Mark one blade. Apply a small, firmly secured piece of contrasting, lightweight tape near its tip. Don’t use loose, bulky tape, and never put your hands or tools near a powered rotor.
- Arrange a safe observation. Follow the manufacturer’s procedure. If you are not experienced with powered checks, ask an experienced pilot to help. Keep everyone well clear of the rotor disc and do not lean over the model.
- Observe from the side. When it is safe to do so, view the rotor disc edge-on from a safe distance. If the two blade paths appear as one line, tracking is close. If you can distinguish two separate paths, the blades are out of track.
- Shut down completely before adjusting. Make a very small change to the appropriate pitch linkage, as directed by the model manual, then recheck. Never adjust a linkage with the rotor turning.
A controlled, light hover check may be appropriate for an experienced pilot in a clear area, but it is not a beginner’s shortcut. Do not hold the model down by hand or use an improvised restraint for a ground run. If you cannot make the observation safely, don’t attempt it.
How to balance the main blades
Do the blades weigh the same, and is their mass in the same place? A pair-matched set is the best starting point. Two blades can show the same reading on a scale yet still have different centres of gravity, so compare more than total weight.
- Check each blade’s spanwise centre of gravity. This is the balance point along the blade, from root to tip. Support each blade on a suitable balancing edge or tool and mark the point where it balances. Compare the marks with the blade mounting holes aligned. If the marks differ, the blades’ mass is distributed differently along their length.
- Check chordwise balance. This means the balance from leading edge to trailing edge. Use a blade balancer or the manufacturer’s recommended method to compare the pair. Avoid improvising a test that could scratch or damage the blade.
- Compare blade weight. Use a suitable scale to weigh each blade and note the difference. A scale is useful, but it does not replace checking the balance point.
- Use a blade balancer. Mount the blades securely on the balancer as its instructions specify. If one side consistently drops, make only small adjustments with appropriate balancing tape, then test again.
- Secure any tape carefully. Keep it smooth, firmly attached and in a suitable position, often near the root or balance point, depending on the blade and balancer instructions. Do not add tape at random or sand, drill or modify a blade unless its manufacturer explicitly permits it.
Once balanced, check tracking again. Balance and tracking are separate adjustments, and one does not automatically correct the other.
Don’t overlook the tail rotor
Is the tail boom or tail area where the shake is strongest? Tail blades are smaller, but a damaged blade, loose hub, bent tail shaft or poorly matched pair can still contribute to vibration.
With power disconnected, check that the tail blades are the correct type and size, matched, undamaged and securely fitted. Turn the tail rotor by hand and watch for obvious runout, rubbing or roughness. Check the tail shaft, hub, bearings and drive system, too. A tail rotor that wobbles on its shaft cannot be corrected by balancing the blades alone.
Tail-rotor tracking and inspection depend on the helicopter’s design. If the blades do not appear to follow the same path, or the tail assembly has been damaged, use the model manual or ask a heli specialist before running it. Never inspect a powered tail rotor from close range.
Check the spindle and feathering shaft
Could a bent shaft be tricking you into adjusting the wrong thing? The feathering shaft, also called the spindle, runs through the blade grips. If it bends, it can create runout and imitate a tracking fault.
Remove the shaft according to the manual and roll it gently on a piece of known-flat glass. Watch for a visible lift or rocking motion. If it does not roll true, replace it, do not try to straighten it. A bent spindle counteracts nothing; it worsens vibration and can make linkage adjustments misleading. Check the main shaft in the same way if you suspect it is bent.
Rebalance, or replace?
Is the problem a small mismatch, or damage to the blade itself? A simple difference in weight or balance point may be corrected by carefully balancing a sound, suitable pair. If the blades are not a compatible pair, replace or pair-sort them rather than trying to make a poor match work.
Always replace blades that are chipped, delaminating, cracked or visibly damaged. Do not rely on tape or balancing to make a damaged blade safe. If a blade has taken a hard impact, inspect it closely and follow its manufacturer’s guidance even if the damage is not immediately obvious.
Main-blade options to explore
Check the blade length and fitment against your exact model before ordering. The categories below cover different makes and blade types; the product listing provides the relevant details for each option.
Browse all RC helicopter blades
View Align 550mm carbon-fibre main blades
Key Takeaways
- Tracking is about both blades flying in the same plane; balancing is about matching their mass and centre of gravity.
- A helicopter that “walks on its skids” may have a tracking issue, but check shafts, grips, bearings and drivetrain parts before adjusting links.
- Use contrasting tip tape only for a carefully controlled observation, and shut down fully before making any adjustment.
- Match blades using their weight and balance points; replace any blade that is chipped, cracked, delaminating or visibly damaged.
- Check the tail rotor and drivetrain, too. A blade adjustment cannot fix a bent shaft or loose pinion.
Still feeling a shake?
Don’t keep flying and hope it disappears. Work through the checks methodically, replace damaged parts, and confirm that the mechanical system is sound before considering electronic setup. Vibration problems are fixable, and getting the diagnosis right protects both your helicopter and your confidence at the sticks.
If you’re unsure which blades fit your RC helicopter uk setup, or the cause is still unclear, bring your questions to AT Models’ heli specialists. Our technical expertise, extensive stock and long-term after-sales support are here to help you get back to smooth, confident flying, and soar to new heights.
