RPC UAS Loading, Performance & Emergency Procedures 2 — Questions and Answers
Question 1: How does high density altitude affect a multirotor UAS's performance?
- It increases lift efficiency and extends flight time
- It reduces rotor thrust output, requiring higher RPM for the same lift (Correct answer)
- It has no measurable effect on small UAS operations
- It improves battery efficiency due to cooler air temperatures
Correct answer: It reduces rotor thrust output, requiring higher RPM for the same lift
High density altitude means thinner air, so rotors generate less thrust per revolution and must spin faster, drawing more power and reducing hover efficiency.
Question 2: A remote pilot notices the sUAS is consistently drifting to the left during hover. This is MOST likely caused by:
- Excessive battery voltage
- An unbalanced payload shifting the center of gravity left (Correct answer)
- Flying above the maximum altitude limit
- A firmware update that changed control sensitivity
Correct answer: An unbalanced payload shifting the center of gravity left
A payload that shifts the CG laterally causes the flight controller to continuously compensate, resulting in persistent drift toward the heavier side.
Question 3: Which factor has the GREATEST influence on a fixed-wing UAS's takeoff roll distance?
- Airframe color and surface finish
- Gross weight and headwind component (Correct answer)
- Remote pilot's control input frequency
- Battery brand and cell chemistry
Correct answer: Gross weight and headwind component
A heavier aircraft requires more lift to become airborne, and a headwind reduces the ground speed needed to achieve flying speed, both directly affecting takeoff distance.
Question 4: During flight, a pilot observes the UAS climbing unexpectedly without control input. The MOST probable cause is:
- The GPS signal has been lost
- An updraft or thermal lifting the aircraft (Correct answer)
- The remote ID module is transmitting
- The battery percentage dropped below 50%
Correct answer: An updraft or thermal lifting the aircraft
Thermals and updrafts can exert significant vertical lift on a UAS, causing unexpected altitude gain independent of pilot commands.
Question 5: When calculating payload capacity, a remote pilot must ensure the total weight including payload does NOT exceed the:
- Weight of the battery pack alone
- Manufacturer's maximum gross takeoff weight (Correct answer)
- Empty weight of the airframe
- Regulatory 55-pound small UAS definition limit only
Correct answer: Manufacturer's maximum gross takeoff weight
The manufacturer's maximum gross takeoff weight is the structural and performance limit; exceeding it risks structural failure and degraded flight characteristics.
Question 6: A sUAS experiences a loss of GPS signal mid-flight. In 'Attitude Mode' the aircraft will:
- Automatically land at the last known GPS position
- Maintain altitude and heading without position hold (Correct answer)
- Shut down motors immediately for safety
- Transmit an emergency signal to ATC
Correct answer: Maintain altitude and heading without position hold
Without GPS, the flight controller switches to attitude mode, stabilizing pitch and roll but no longer holding position, requiring the pilot to manually control drift.
Question 7: Which condition would MOST likely cause a lithium-polymer battery to deliver reduced flight time on a warm day?
- The battery was stored at room temperature overnight
- The battery was charged to 100% capacity before flight
- The battery was used for three consecutive flights without cooling time (Correct answer)
- The battery connections were cleaned before installation
Correct answer: The battery was used for three consecutive flights without cooling time
Consecutive flights without cooling cause LiPo battery temperature to rise excessively, which degrades internal resistance and reduces usable capacity.
RPC UAS Loading, Performance & Emergency Procedures 2
How does high density altitude affect a multirotor UAS's performance?