Developing Vertiport Safety Areas: A Data-Driven Approach to Downwash and Outwash Dynamics
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Abstract
The integration of electric vertical takeoff and landing (eVTOL) aircraft into urban transportation networks requires empirically validated safety area guidelines that account for their unique aerodynamic characteristics. This study analyzed Federal Aviation Administration flight test data to quantify the effects of downwash and outwash (DWOW) on eVTOL aircraft and develop evidence-based safety zones for vertiport operations. Traditional momentum theory consistently underestimated eVTOL wake velocities by factors of 2 to 4, necessitating enhanced modeling approaches that incorporated multi-rotor wake interactions and disc loading effects. An enhanced semi-empirical model, incorporating geometric amplification factors, ground effects, and jet entrainment, achieved exceptional predictive accuracy, with mean absolute errors ranging from 0.498 to 1.568 m/s and correlation coefficients of 0.949 to 0.991 across validation datasets. Medium eVTOL aircraft (1,000-2,500 kg) exhibited the highest wake amplification factors (2.0-3.2), creating the most challenging operational conditions. Based on established rotorwash hazard criteria and validated model predictions, a three-zone safety framework was developed: Danger Zone (0-50 feet) with complete evacuation required during operations, Caution Zone (50-150 feet) permitting controlled access with protective measures, and Buffer Zone (150-200 feet) with minimal operational restrictions. The empirically validated 150-foot minimum safety radius provides scientifically defensible guidelines that balance rigorous safety requirements with operational feasibility for urban air mobility integration, supporting regulatory frameworks and vertiport design standards worldwide.
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