PLT256: Effect Of Loading On Performance
What code PLT256 covers, why the FAA tests it, and how to study Effect Of Loading On Performance before your checkride.
Recall glider performance - effect of loading
What this means for your checkride
Added weight, whether from a heavier pilot or from water ballast, raises the wing loading and shifts the airspeeds at which the glider reaches its performance. The handbook shows that increasing weight moves the best L/D airspeed higher while the glide ratio itself stays about the same. A heavier glider can cruise faster between thermals through sinking air, and although it climbs a little less well, the cruise advantage can outweigh the climb penalty in strong lift. Pilots normally jettison water ballast before the traffic pattern to lower approach speed and reduce loads on the landing gear.
Knowing how added weight shifts performance speeds is central to deciding when ballast helps and when it hurts.
More weight does not worsen the glide ratio. It moves the same lift to drag ratio to a higher airspeed rather than shortening how far the glider can glide.
Where to study it
A code on your test report is an area of deficiency. An authorized instructor must review it with you and endorse that review before you take the practical test, and the examiner may revisit it during the oral. Study it until you can explain it out loud, not just recognize the answer.