As spinning is still involved in around 60% of all aircraft accidents (BFU, 1985 and Belcastro, 2009), this aerodynamic phenomenon is still not fully understood. As U.S. and European Certification Specifications do not require recoveries from fully developed spins of Normal Category aeroplanes, certification test flights will not discover aeroplane mass and centre of gravity combinations which may result in unrecoverable spins. This book aims to contribute to a better understanding of the spin phenomenon through investigating the spin regime for normal, utility and aerobatic aircraft, and to explain what happens to the aircraft in terms of the aerodynamics, flight mechanics and the aircraft stability. The approach used is to vary the main geometric parameters such as the centre of gravity position and the aeroplane’s mass across the flight envelope, and to investigate the subsequent effect on the main spin characteristic parameters such as the angle of attack, pitch angle, sideslip angle, rotational rates, and recovery time. First of all, a literature review sums up the range of technical aspects that affect the problem of spinning. It reviews the experimental measurement techniques used, theoretical methods developed and flight test results obtained by previous researchers. The published results have been studied to extract the effect on spinning of aircraft geometry, control surface effectiveness, flight operational parameters and atmospheric effects. Consideration is also made of the influence on human performance of spinning, the current spin regulations and the available training material for pilots. A conventional-geometry, single-engine low-wing aeroplane, the basic trainer Fuji FA-200-160, has been instrumented with a proven digital flight measurement system and 27 spins have been systematically conducted inside and outside the certified flight envelope. The accuracy of the flight measurements is ensured through effective calibration, and the choice of sensors has varied through the study, with earlier sensors suffering from more drift than the current sensors (Belcastro, 2009 and Schrader, 2013). In-flight parameter data collected includes left and right wing α and β-angles, roll-pitch-yaw angles and corresponding rates, all control surface deflections, vertical speeds, altitude losses and the aeroplane’s accelerations in all three directions. Such data have been statistically analysed. The pitch behaviour has been mathematically modelled on the basis of the gathered flight test data. Nine observations have been proposed. These mainly cover the effects of centre of gravity and aircraft mass variations on spin characteristic behaviour. They have all been proven as true through the results of this thesis. The final observation concerns the generalisation of the Fuji results, to the spin behaviour of other aircraft in the same category. These observations can be used to improve flight test programmes, aircraft design processes, flight training materials and hence contribute strongly to better flight safety.
Author(s): Steffen Haakon Schrader
Publisher: Springer Vieweg
Year: 2023
Language: English
Pages: 273
City: Berlin
About this book
Contents
1 Introduction
1.1 The Problem with Spinning
1.2 Scope of the Research
1.3 Reasoning for the Research and Its Relevance
1.4 Aim of the Study
1.5 Research Questions and Subsequent Observations
1.6 Preparation for the Flight Testing
1.7 Structure of the Work
1.8 Contributions to State of the Art/Research
2 Literature Review
2.1 Introduction into the Literature Review
2.2 Civil and Military Spin Training Material
2.3 The Phases of a Spin
2.4 Measurement Techniques for Spinning
2.4.1 Experimental Measurements
2.4.2 Theoretical Models
2.4.2.1 Force and Moment Models
2.4.2.2 Area Models for Spin Safety
2.4.2.3 Computational Programmes for Modelling High Angle of Attack Cases
2.4.3 Flight Tests
2.4.3.1 Low Wing Aircraft
2.4.3.2 High Wing Aircraft
2.5 Effect of Aeroplane Shape on Spin Behaviour
2.5.1 Wing Leading Edge Changes
2.5.2 Control Surface Effectiveness
2.5.3 Tail Effects
2.6 Spin Parameters
2.7 Spin Accident Statistics/Safety
2.8 Spin Related Regulations
2.9 Sources of Human Factors During Spinning
2.10 Conclusions of the Literature Review
3 Measurement System for Spin Test Data Acquisition
3.1 Introduction
3.2 System Requirements
3.2.1 What Needs to be Measured?
3.2.2 What Precision is Needed for the Parameters of Interest?
3.2.3 What Ranges are Needed for the Parameters of Interest?
3.2.4 What Resolution is Needed for the Parameters of Interest?
3.3 The Measurement System
3.4 Data Acquisition
3.5 Installation of the Measurement System in the Research Aeroplane
3.5.1 Installation of displacement sensor system
3.5.2 Installation of the Inertial Measurement Unit (IMU)
3.5.3 Installation of the Wing Booms and Wind Vanes
3.5.4 Installation of the Data Acquisition Computer, Pressure Sensors and Uninterrupted Power Supply (UPS)
3.5.5 Wiring of the Measurement System
3.6 Calibration and Data Validation of the Sensor System
3.6.1 IMU Data Calibration
3.6.2 Wind Vane Sensor Calibration
3.6.3 Static Pressure Sensor Calibration
3.6.4 Calibration of Fuel Gauges
3.7 Conclusions
4 Preparation of the Aeroplane and the Spin Trials
4.1 Introduction
4.2 Modification and Inspection of the Utilized Aeroplane
4.3 Suction System Modification
4.4 Wing Spar Inspection
4.5 Choice of the Relevant and Investigated Parameters
4.6 Flight Envelope Determination Regarding Masses and Centre of Gravity Positions, Limit of the Tests and Choice of the Test Points Within the Defined Flight Envelope
4.7 Legal Basis for Test Flights
4.8 Flight Trial Procedures and Conditions
4.9 Conclusions
5 Spin Description
5.1 Introduction
5.2 Spin Description on the Basis of the Measured Flight Test Data
5.3 Example of a Spin Entry
5.4 Example of a Developed Spin
5.4.1 Angle-of-Attack and Angle-of-Sideslip Behaviour
5.4.2 Acceleration Behaviour Around all Three Axes
5.4.3 Aeroplane’s Attitude and Turn Rate Behaviour (Φ with p, Θ with q, Ψ with r)
5.5 Example of a Spin Recovery
5.6 High Frequency Data Fluctuation
5.7 Conclusions of the Spin Description
6 Mathematical Spin Test Data Analysis
6.1 Introduction into the Mathematical Spin Test Data Analysis
6.2 Evaluation and Processing of the θ-Values
6.3 Pitch Angle Data Analysis
6.4 Observation 1: The Second Minimum Value of the Pitch Down (ln_Theta) Function Always Produces the Highest Negative Value.
6.5 Observation 2: Independent of the aeroplane’s Mass and CG Position, the Pitch Angle (ln_Theta) Approximates to a Characteristic Value
6.6 Observation 3: Maximum Yaw Rate (ln_r) Changes with CG Position and Mass
6.7 Observation 4: The Yaw Rate (ln_r) Oscillation Changes with CG Position or Mass
6.8 Observation 5: Maximum Difference in Angle of Attack Values Between Left and Right Wings Leads to a Maximum in Roll Rates (alpha_le_c—alpha_ri_c; ln_p)
6.9 Observation 6: Rate of Roll (ln_p) Changes with CG Position and Aeroplane’s Mass
6.10 Observation 7: Total Angular Velocity Ω Changes with CG Position and Mass
6.11 Observation 8: Recovery Time Becomes Shorter with CG Moving Backwards
6.12 Observation 9: The Spin Behaviour of the Fuji FA 200 – 160 Can Be Generalised for Single-Engine Low-Wing Aeroplanes
6.13 Conclusion of the Spin Test Data Analysis
6.13.1 Conclusions of the Observations
7 Flight Test Data Comparison
7.1 Introduction
7.2 Comparison of Angle-Of-Attack at the Centre of Gravity
7.3 Comparison of Angle-Of-Sideslip at the Centre of Gravity
7.4 Comparison of Pitch Rate
7.5 Comparison of Yaw Rate
7.6 Comparison of Roll Rate
7.7 Conclusions
8 Conclusion
8.1 Main Conclusions, Contributions and Impact
8.1.1 Observation 1: The Second Minimum Value of the Pitch Down (Θ) Function Always Produces the Highest Negative Value
8.1.2 Observation 2: Independent of the Aeroplane’s Mass and CG Position, the Pitch Angle (Θ) Approximates to a Characteristic Value
8.1.3 Observation 3: Maximum Yaw rate (ln_r) Changes with CG Position and Mass
8.1.4 Observation 4: The Yaw Rate (ln_r) Oscillation Changes with CG Position or Mass
8.1.5 Observation 5: Maximum Difference In AoA Values Between Left and Right Wings Leads to a Maximum in Roll Rates (alpha_le_c – alpha_ri_c; ln_p)
8.1.6 Observation 6: Rate of Roll (ln_p) Changes with CG Position and Aeroplane’s Mass
8.1.7 Observation 7: Total Angular Velocity Ω Changes with CG Position and Mass
8.1.8 Observation 8: Recovery Time Becomes Shorter with CG Moving Backwards
8.1.9 Observation 9: The Spin Behaviour of the Fuji FA 200—160 can be Generalised for Single-Engine Low-Wing Aeroplanes
8.2 Publications
9 Recommendations for Further Work
10 General Understanding of Spinning and Supporting Material
10.1 General Understanding of Spinning
10.1.1 Phases of a Spin
10.1.2 The Steady Erect Spin
10.1.3 Motion of the Aeroplane
10.1.4 Balance of Forces in the Spin
10.1.5 Effect of Attitude on Spin Radius
10.1.6 Angular Momentum
10.1.7 Moment of Inertia (I)
10.1.8 Inertia Moments in a Spin
10.1.9 Factor Contributions of Aerodynamic Moments
10.1.10 Balance of Moments
10.1.11 Effects of Controls in Recovery from a Spin
10.1.12 Effect of Ailerons
10.1.13 Effect of Elevator
10.1.14 Effect of Rudder
10.1.15 Inverted Spin
10.1.16 Oscillatory Spin
10.1.17 Conclusion (of Sect. )
10.2 Gyroscopic Cross-Coupling Between Axes
10.2.1 Introduction
10.2.2 Inertia Moments in a Spin
10.3 Example of a Certification Spin Test Planning
10.3.1 Introduction
10.3.2 References
10.3.3 Purpose and Test Description
10.3.4 Configuration
10.3.5 Conformity
10.3.6 Instrumentation and Data
10.3.7 Safety
10.3.8 Processing of a Spin Test Matrix
10.3.9 Envelope Range
10.3.10 Spin Test Matrix
10.3.11 Procedures and Acceptance Criteria
10.4 Excerpt from the Current Certification Specification EASA CS 23 on Spinning
10.5 Technical Data of the Research Aeroplanes
10.5.1 NASA Research Aeroplane, Piper PA 28 RT-201 T Turbo Arrow IV
10.5.2 Research Aeroplane of the Collaborating ATO, Fuji FA-200-160
10.6 Aeroplane Categories
10.7 Calibration Protocols
10.8 Mathematical Methods
10.8.1 General Methods
10.8.1.1 Gradient Descent
10.8.1.2 Smoothing, Detection of Relative Maximum/Minimum of a Time Series (yi)
10.8.1.3 Numerical Derivation
10.8.1.4 Periodic Linear Regression Model
10.8.1.5 Discrete Fourier Transformation (DFT)
10.8.1.6 Linear Homogenous Ordinary Differential Equation of Second Order
10.8.2 Statistical Methods
10.8.2.1 Multi-Linear Regression, Coefficient of Determination (Multiple Regression Coefficient)
10.8.2.2 Coefficient of Determination
10.8.2.3 Analysis of Variance (ANOVA)
10.8.2.4 Wilcoxon—Test
10.8.2.5 Confidence Interval for Values Predicted by Linear Regression
Glossar
References and Bibliography
