Before adding aircraft, measure where the waiting happens.
Plan beyond advertised endurance
Purdue’s field guide explains that load, battery condition, route, terrain and weather affect endurance. Refill and recharge logistics matter; long loaded transit can consume capacity before useful work begins.
Separate parallel and sequential tasks
Measure landing-to-relaunch activities. Tasks performed by one person cannot be counted as concurrent. Separate clean battery handling from chemical handling, using manufacturer procedures, appropriate protection and hygiene rules.
Model the whole energy supply
Check cooling and charging time, available power, sustained generator output, cables and ambient conditions. More aircraft can create charging and water queues. Include tools, spare parts, shade, cleaning water and approved waste handling in the staging plan.
Read effective capacity
The calculator uses area per sortie × 60 / (flight minutes + ground minutes). This is a simplified single-aircraft estimate without queues; travel and weather reduce it further. Its battery count is a theoretical minimum, not an operational recommendation.
Ground time includes controllers and positioning equipment
Ufes records preparation, travel, energy use and charging for the aircraft, controller and positioning equipment when assessing real costs. Counting only flight batteries misses other causes of interruption.
Track individual batteries and their release state
Our proposed workflow records each battery’s ID and state: in use, awaiting cooling or inspection, charging, released, or isolated. Preserve who changed the state and when. A full-charge display alone must not authorize another flight. Apply manufacturer procedures and aircraft conditions to temperature, appearance and connection checks, removing suspect units from the normal queue. An unreadable ID prevents reconciliation and should not silently bypass recordkeeping. Linking aircraft and battery records also supports investigation when one battery repeatedly returns early, separating operating conditions from possible unit-specific problems.
| State | Record for the next stage |
|---|---|
| Awaiting cooling or inspection | Return time / battery ID / pending checks |
| Charging | Charger ID / start time / fault indications |
| Released | Reviewer / time / applicable procedure |
| Isolated | Reason / identification / reassessment owner |
Compare return demand with release capacity
Consider a planning model in which A batteries return per hour and B complete inspection and charging for release. If A persistently exceeds B, extra spares only postpone a growing queue. This is a capacity diagnostic, not an instruction to accelerate charging. Record charger availability, power constraints and reviewer availability as separate waiting causes. If water supply, material preparation and batteries share one worker, include that person as a shared resource. Before adding an aircraft, identify what current equipment and procedures can support. Evaluate changes using maximum waits and whole-day accepted area.
Use one clock to distinguish overlap from waiting
An illustrative event log might show landing at 10:00, battery handover at 10:02, refill confirmation at 10:05, release at 10:07 and takeoff at 10:10. Recording the reason for the three-minute post-release wait makes it actionable. Do not add simultaneous activities twice when calculating elapsed time; both workers’ labor time still belongs in cost. Review causes of long stops as well as averages. Faster flying accompanied by missed checks or rework is not success. Assess total time and cost per safely completed, accepted area.