This thesis presents the design, testing and analysis of an autonomous autorotative payload delivery system called the Autobody. The Autobody must passively deploy a payload on ground from an aircraft by means of an autorotative rotor. The system must achieve the steady state autorotation quickly to minimize its impact upon landing. A hub design incorporating negative pitch-flap coupling, negative blade pitch and a negative precone is implemented to passively achieve the transition to a state of steady autorotation. An analytical model is developed to predict the Autobody behavior in steady state autorotation. Wind tunnel…
Author: Brindejonc, Anne Marie
Source: University of Maryland
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Contents
1 Introduction
1.1 Objectives
1.2 Why an autorotative rotor?
1.3 Operational requirements
1.4 State-Of-The-Art
1.4.1 Autorotation flight regime
1.4.2 Autogyro
1.4.3 Autorotative vehicle dropped from an aircraft
1.4.4 Re-entry vehicles
1.5 Contribution of the present work
1.6 Thesis outline
2 Physical Principles
2.1 State of autorotation
2.2 The Autobody case
3 Analytical models
3.1 Time marching study
3.1.1 Step 1 : Inputs
3.1.2 Step 2 : Initial conditions
3.1.3 Step 3 : Calculation of aerodynamic forces
3.1.4 Step 4 : Check for autorotation
3.2 RPM Sweep Study
3.2.1 Step 1 : Inputs
3.2.2 Step 2 : Initial conditions
3.2.3 Step 3 : Inflow, λ
iv3.2.4 Step 4 : Aerodynamic angles and forces
3.2.5 Step 5 : Definition of Autorotation
4 Wind tunnel tests
4.1 Goal
4.2 Prototype construction
4.3 Bench-top tests
4.3.1 Bench-top test set-up
4.3.2 Results
4.4 Wind tunnel test set-up
4.5 Instrumentation
4.6 Range of test conditions
4.7 Experimental results
4.7.1 Curve fit
4.7.2 Discussion of experimental trends
4.7.3 Change in pitch θ0
4.7.4 Change in precone βp
4.7.5 Change in pitch-flap coupling angle δ3
4.8 Correlation with analysis
4.9 Parametric study
4.9.1 Influence of the pitch angle,θ0
4.9.2 Influence of the pitch-flap coupling angle, δ3
4.9.3 Influence of the precone angle, βp
4.9.4 Influence of the blade mass, mb
5 Flight tests
5.1 Prototype construction
5.1.1 Hub and grips
5.1.2 Blades
5.1.3 Rotor/fuselage assembly
5.2 Full scale flight tests
5.2.1 Goal
5.2.2 Test platform
5.2.3 Instrumentation
5.2.4 Test settings
5.2.5 Flight test results
5.2.6 Landing impacts
5.2.7 Correlation with analysis
6 Conclusions and Future work
6.1 Summary and conclusions
6.2 Future Work
A Technical Drawings
A.1 Model scale rotor assembly
A.2 Rotor stand used in the wind tunnel
A.3 Load balance
A.4 Full scale rigid hub
A.5 Full scale gimballed hub
A.6 Full scale blade grip
Bibliography