Why does my aircraft bounce on the ground in FSX?

An aircraft usually bounces on the ground in FSX because its landing-gear contact points, spring compression or damping are wrong for its weight. If every aircraft bounces, suspect uneven scenery, excessive simulation rate, unstable performance or a control input instead. One brief settling movement after loading is normal; repeated oscillation is not.

Is the aircraft or FSX causing the bounce?

A problem confined to one add-on aircraft usually comes from that aircraft's configuration, while bouncing across several aircraft points to scenery, controls or simulator conditions. Test a default FSX aircraft at the same location, then test the affected aircraft at a stock airport with a flat hard runway.

How do I stop an FSX aircraft bouncing on the ground?

The safest fix is to remove external causes first and edit the aircraft only after proving that its configuration is responsible.

1. Return to normal simulation conditions. Set the simulation rate to normal, leave slew mode, select calm weather and start a new flight. Gusts can move a light aircraft, while an accelerated simulation rate can exaggerate ground-contact oscillations.
2. Check weight and balance. Remove unusual payload and reduce fuel to a normal amount. An overloaded aircraft, or one whose configured empty weight has been altered, may compress its landing gear beyond the range for which the contact points were designed.
3. Eliminate unwanted control input. Bring the throttle to idle, release the parking brake and centre the rudder and elevator. Temporarily disconnect controllers if necessary; duplicate assignments or noisy brake and rudder axes are common causes of ground hopping.
4. Test performance. Reduce demanding display and scenery settings long enough to obtain a steadier frame rate. Very irregular performance can make FSX's ground-contact calculations appear unstable, although it is less commonly the root cause when only one aircraft is affected.
5. Restore the original add-on. If the bouncing began after an edit, repaint installation or file replacement, restore your backup. When a clean copy is needed, use the standard FSX add-on aircraft installation procedure rather than merging folders from different versions.

Which aircraft.cfg settings cause ground bouncing?

The main configuration causes are in the [contact_points] section of aircraft.cfg. You will find it inside the aircraft's folder under SimObjects\Airplanes; see our explanation of where FSX stores aircraft folders if the boxed and Steam Edition locations are causing confusion.

• Wheel position: Incorrect longitudinal, lateral or vertical coordinates make FSX place the physical wheels somewhere other than the visible wheels.
• Static compression: A value unsuitable for the aircraft's weight can make the undercarriage behave like an excessively stiff or soft spring.
• Damping ratio: Too little damping allows the gear to rebound repeatedly instead of settling after compression.
• Compression ratio and wheel radius: Implausible values can destabilise the ground contact or make the aircraft sit at the wrong height.
• static_pitch and static_cg_height: These affect how FSX initially places the aircraft on the ground. Bad values often cause a drop and bounce as soon as the flight loads.

Close FSX and back up aircraft.cfg before editing it. Each point.n entry contains comma-separated fields, so one missing comma shifts every value that follows into the wrong role. Change one value at a time, restart FSX and retest under identical conditions.

Do not copy contact-point lines from an unrelated aircraft merely because it has the same number of wheels. Gear geometry, centre of gravity and loaded weight all differ. Restoring the add-on author's original file is usually safer than guessing at damping values.

Why does the aircraft bounce only while taxiing or braking?

Nose-wheel hopping during taxi is commonly caused by excessive speed, abrupt braking or a brake axis that never fully releases. Taxi straight at idle thrust with the controls page open, then confirm that both differential brake axes return completely to zero and that rudder or nose-wheel steering is not receiving duplicate inputs.

High thrust against the parking brake can also make an aircraft rock or hop. If the bouncing stops when the brakes are released, correct the control assignment or taxi technique before changing the landing-gear configuration.

What if the bounce begins at touchdown?

A bounce that starts at touchdown but settles as the aircraft slows is usually a landing bounce rather than a stationary ground-contact fault. Excessive descent rate, excess airspeed, an early flare or forcing the nose down can send the aircraft airborne again.

Use the approach speed and landing technique specified for that aircraft. After a severe or escalating bounce, apply power and go around rather than trying to pin the aircraft onto the runway. Suspect contact-point data only when the add-on bounces during an otherwise controlled landing while comparable default aircraft behave normally.

Could the runway scenery be responsible?

If several aircraft bounce at one airport but work elsewhere, the runway surface or an elevation conflict is responsible. Disable duplicate airport scenery or conflicting elevation corrections and check the scenery-library priority; changing an aircraft's gear height to suit one faulty runway will make it wrong at every other airport.

If the aircraft remains partly below the pavement rather than oscillating above it, follow our separate checks for an FSX aircraft sinking into the runway. That symptom is more strongly associated with wheel-position or airport-elevation errors than damping.