Hubert Hajduk
Flight Dynamics Engineer · Flight Dynamics & Aeroelasticity
Warsaw, Poland
Flight Dynamics Engineer responsible for developing and maintaining the 6-DOF flight dynamics model for new aircraft variants. Analyzes stability and control characteristics, extracts aerodynamic derivatives from CFD and wind tunnel data, and performs handling qualities assessments against CS-25 requirements. Experienced in pilot-in-the-loop simulation for upset recovery and unusual attitude evaluation.
Expertise
- 6-DOF flight dynamics modeling
- handling qualities analysis
- stability and control derivatives
- pilot-in-the-loop simulation
- CS-25 handling qualities compliance
Technologies
Work History
2025-01
Pilot-in-the-loop simulation for unusual attitude recovery assessment — conducted 40 evaluation sessions with 4 pilots using the engineering flight simulator. Quantified recovery times and control inputs for CS-25.143 normal control category assessment.
Challenge: Simulator visual system latency (60ms) affected pilot perception of the aircraft response, biasing recovery time statistics. Required applying a latency correction factor to extrapolate from simulator to aircraft results — a correction that needed justification in the compliance documentation.
Learned: Pilot-in-the-loop simulator evaluations for certification compliance must account for and document simulator fidelity limitations. Latency corrections must be explicitly justified and agreed with the DER before the evaluation — applying post-hoc corrections to certification test data is not acceptable.
2024-06
Handling qualities assessment vs. CS-25 — computed short period and phugoid mode characteristics, roll and spiral mode time constants, and Dutch roll damping ratio across the flight envelope. Identified 3 handling qualities non-compliances at aft CG.
Challenge: Dutch roll damping at aft CG and high altitude fell below the CS-25.181 limit of 0.05. Required active yaw damper authority increase, which cascaded into a yaw damper system safety assessment update and new FCS software requirements.
Learned: Handling qualities non-compliances discovered late in the flight dynamics analysis cascade into FCS architecture changes, system safety updates, and software requirements changes. Run handling qualities compliance checks iteratively throughout aircraft design, not as a single late analysis activity.
2023-10
Stability and control derivatives extraction from CFD data — processed 180 RANS CFD solutions at varying AoA, sideslip, and control surface deflections to build aerodynamic coefficient tables for the flight dynamics model.
Challenge: CFD-derived control effectiveness (dCl/dda, dCn/ddr) at high AoA differed significantly from low-AoA linear panel method predictions. The aileron roll effectiveness reversed at AoA > 18° due to leading edge separation — not captured by the panel method used for initial sizing.
Learned: Control effectiveness reversal at high AoA is a critical flight dynamics risk that linear aerodynamic tools will miss. CFD analysis at the full AoA range is mandatory for any handling qualities assessment that includes unusual attitude or upset recovery.
2023-03
6-DOF flight dynamics model development for a new aircraft variant — built the complete equations of motion model in MATLAB/Simulink with aerodynamic coefficient tables from CFD and the reference model's wind tunnel database.
Challenge: Aerodynamic database from CFD covered ±25° AoA but the model was needed for ±60° (upset recovery envelope). Extrapolation beyond CFD data range using high-AoA Newtonian aerodynamics caused discontinuities at the database boundaries. Required blending functions to smooth the transition.
Learned: Flight dynamics models for upset recovery certification must address the full high-AoA envelope well beyond CFD coverage. Build explicit blending functions at database boundaries from the start — discontinuities at boundaries create false breakpoints in the simulation that mislead pilot handling quality evaluations.