Why added weight reduces reserve thrust for climb

Remote Pilot (Part 107) practice question 19 of 25 on Loading and Performance. ACS element UA.IV.A.K2 · difficulty: applied. Want to answer it in a timed quiz? Use the Remote Pilot (Part 107) practice mode.

Question bank updated 2026-09-22

QUESTIONAdding weight to an aircraft reduces the reserve thrust available for climbing. According to the Remote Pilot study guide, what chain of effects explains this?

  1. AA lower angle of attack is needed, which reduces lift and forces the engine to run at lower power
  2. BThe added weight increases the air density around the wing, which lowers thrust
  3. CA higher angle of attack is needed, which raises drag and requires more thrust to overcome it
Show the answer and explanation

Correct answer: C. A higher angle of attack is needed, which raises drag and requires more thrust to overcome it

  • A — incorrect Added weight requires a higher, not lower, angle of attack, and the guide describes more thrust being consumed by drag rather than less power being produced.
  • B — incorrect Aircraft weight has no effect on air density; the mechanism is increased drag from a higher angle of attack.
  • C — correct The guide explains that added weight forces a higher angle of attack to hold altitude and speed, which increases induced and parasite drag, so more thrust is needed to overcome drag and less reserve thrust remains for climbing.

BACKGROUND

The Remote Pilot study guide states that weight has a very pronounced effect on aircraft performance. If weight is added, the aircraft must fly at a higher angle of attack to maintain a given altitude and speed. This increases the induced drag of the wings as well as the parasite drag of the aircraft. Increased drag means additional thrust is needed to overcome it, which leaves less reserve thrust available for climbing. Designers therefore go to great lengths to minimize weight.

STUDY TIP

Follow the chain: more weight, higher angle of attack, more drag, more thrust consumed, less thrust left to climb.

KEY POINTS

  • Added weight requires a higher angle of attack.
  • Higher angle of attack increases induced and parasite drag.
  • More thrust goes to overcoming drag, so less is available for climb.

SOURCES

  • remote_pilot_study_guide.txt ch3b "Climb Performance Factors"
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SkyDrill is not affiliated with the FAA. This is an original practice item based on 14 CFR part 107, 14 CFR part 89, and the FAA Remote Pilot – Small UAS Study Guide (FAA-G-8082-22). Regulations and handbooks are revised; confirm details against the current edition.