Effects of Epistemic Uncertainty on Empennage Loads During Dynamic Maneuvers

Abstract

The Federal Aviation Regulations contain descriptions of a number of dynamic maneuvers that may lead to the development of critical loads for aircraft structural components. The structural members must be sized and designed to withstand such loads, and this must be demonstrated as part of the certification process. Given the high costs of aircraft certification and the programmatic risk associated with design modifications necessitated during later design stages, there is currently a trend towards certification by analysis. Towards this end, from the structural loads perspective, there is a need for a framework that can simulate maneuvers and evaluate the structural loads thus developed. However, in the earlier phases of design, significant epistemic uncertainty may exist with regard to the aircraft mass properties and aerodynamic characteristics, which in turn lead to uncertainty in the maneuver loads. This work demonstrates a methodology that employs sensitivity and Monte Carlo analyses to assess how maneuvering structural loads are affected by uncertainty factors. These analyses are applied to a dynamic simulation model created to simulate a representative business jet performing a checked pitch maneuver. The resultant variability of critical structural loads provides insight into the areas where epistemic uncertainty should be reduced.

Evaluation of Off-Nominal Performance and Reliability of a Distributed Electric Propulsion Aircraft during Early Design

“…The flight dynamics simulation environment used in this work is the Dynamic Environment for Loads Prediction and Handling Investigation (DELPHI) [59][60][61] framework developed at the Aerospace Systems Design Lab. DELPHI is developed as an object-oriented python code which can accept any aircraft model, any desired maneuver, and simulate the flight dynamics.…”

Framework to Assess Effects of Structural Flexibility on Dynamic Loads Developed in Maneuvering Aircraft

“…The closed-loop simulation of the aircraft and structural dynamics is done through suitable extensions to a MATLAB/Simulink flight simulation capability [5,6], which is described in the following sections.…”

“…In prior work by the authors [5], a three degree-of-freedom (3-DoF) aircraft simulation capability was developed in order to assess dynamic loads developed on the horizontal stabilizer during the Checked Pitch Maneuver, in accordance with the pilot actions and test envelope specified in FAR $ 25.331(c) (2). In followon work [6], the sensitivity of these loads to uncertainties in the aircraft aerodynamic characteristics and mass properties was assessed.…”

A Certification-Driven Platform for Multidisciplinary Design Space Exploration in Airframe Early Preliminary Design

“…A framework named Dynamic Environment for Loads Prediction and Handling Investigation (DELPHI) is under development at ASDL following prior work in [25][26][27]. An aircraft in DELPHI is defined by 1) mass properties (Section A), 2) aerodynamic characteristics (Section B) which describe the total forces and moments at a reference point as a function of aircraft states and control surface deflections, and 3) propulsive performance (engine deck) which define the propulsive loads at the reference point as a function of altitude, Mach number and throttle.…”