GT AE 3310 - Vertical Take Off & Landing (18 pages)

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Vertical Take Off & Landing



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Vertical Take Off & Landing

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Pages:
18
School:
Georgia Tech
Course:
Ae 3310 - AE Vehicle Performance
Unformatted text preview:

Vertical Take Off Landing VTOL Aircraft A Comparison Lift Propulsion Control Approaches For VTOL Aircraft General For Shaft Driven VTOL Aircraft Need At Least Two Thrusters Fixed Thrusters One Main One Anti Torque Two Equal Size Opposite Rotation Vectored Thrusters Thruster Tilting Exhaust Deflection Methods of Transition for Various V STOL Concepts VTOL Concepts PURE HELICOPTER ADVANTAGES Most Efficient Hover Loiter Low Downwash Good Low Speed Maneuverability Symmetrical Yaw Control Low Empty Weight DISADVANTAGES Low Max Speed Lowest Cruise Efficiency Range Limited High Speed Maneuverability Attitude Depends on Speed Acceleration Rotating Component RCS Highest Vibration Environment Complexity 2 Fixed Thrusters THERE ARE MAJOR PROBLEMS WITH ADDING A WING Thrust Thrust Wing Lift Velocity Velocity Wing Needs Aircraft to be Nose Up to Get Lift Wing Lift Download Main Rotor Needs Aircraft to be Nose Down to Get Propulsion Need to Get Propulsion from Someplace Other than Main Rotor SOLUTION Add a Third Fixed Thruster Propulsive Thruster or Use Vectored Thrust COMPOUND HELICOPTER Fixed Thruster ADVANTAGES Good Hover Loiter Efficiency Low Downwash Faster Than Pure Helicopter Good Maneuverability All Speeds Attitude Independent of Speed Acceleration Symmetrical Yaw Control Reverse Prop Thrust All Speeds DISADVANTAGES Low Cruise Efficiency Range Rotating Component RCS High Vibration Environment Increased Empty Weight Complexity 3 Fixed Thrusters COMPOUND HELICOPTER Advancing Blade Concept ADVANTAGES Good Hover Loiter Efficiency Low Downwash Faster Than Pure Helicopter Good Maneuverability All Speeds Attitude Independent of Speed Acceleration Symmetrical Yaw Control No Anti Torque Rotor Required Reverse Prop Thrust All Speeds DISADVANTAGES Low Cruise Efficiency Range Rotating Component RCS High Vibration Environment Increased Empty Weight Complexity 3 Fixed Thrusters COMPOUND HELICOPTER Vectored Thruster Open Prop ADVANTAGES Good Hover Loiter Efficiency Low Downwash Faster Than Pure Helicopter Good Maneuverability Except Conversion Reverse Prop Thrust at High Speed DISADVANTAGES Low Cruise Efficiency Range Conversion Limited Agility Attitude Depends on Acceleration at Low Speed Unprotected Vectored Thruster Rotating Component RCS High Vibration Environment Increased Empty Weight Complexity 1 Fixed 1 Vectored Thruster COMPOUND HELICOPTER Vectored Thruster Ducted Prop ADVANTAGES Good Hover Loiter Efficiency Low Downwash Faster Than Pure Helicopter Good Maneuverability Except Conversion Reverse Prop Thrust at High Speed Ground Safety Damage Ducted Prop DISADVANTAGES Low Cruise Efficiency Range Conversion Limited Agility Limited Unsymmetrical Yaw Control Attitude Depends on Acceleration at Low Speed Rotating Component RCS High Vibration Environment Complexity 1 Fixed 1 Vectored Thruster CANARD ROTOR WING ADVANTAGES Good Hover Loiter Efficiency Low Downwash Potential for High Subsonic Cruise Good Maneuverability Except in Conversion No Anti Torque Rotor Reduced RCS in High Speed Mode Low Vibration Environment in High Speed Mode DISADVANTAGES Limited Maneuverability in Conversion Power for Yaw Control Near Hover Moderate Vibration Environment in Low Speed Conversion Modes Rotating Component RCS in Low Speed Mode Complexity Rotor Stopping Convertible Engine TILT ROTOR ADVANTAGES Good Hover Loiter Efficiency Moderate Downwash Good Max Speed Good Cruise Efficiency Range Good Maneuverability All Speeds Attitude Independent of Speed Acceleration Ground Safety Damage No Tail Rotor DISADVANTAGES Greater Operating Width Conversion Benign Rotating Component RCS Moderate Vibration Environment Increased Empty Weight Complexity 2 Vectored Thrusters TILT WING ADVANTAGES Fair Hover Loiter Efficiency Faster Than Tilt Rotor Good Cruise Efficiency Range Good High Speed Maneuverability Attitude Independent of Speed Acceleration Symmetrical Yaw Control DISADVANTAGES Marginal Downwash Conversion Limited Corridor Rotating Component RCS Increased Empty Weight Complexity 1 Fixed 2 Vectored Thrusters TILTING DUCTED FANS ADVANTAGES DISADVANTAGES Enclosed Thrusters Safety Symmetrical Yaw Control Low Hover Loiter Efficiency Limited Low Speed Maneuverability Conversion Limited Corridor High Empty Weight Complexity 1 Fixed 2 Vectored Thrusters FAN IN WING ADVANTAGES High Max Speed Good Cruise Efficiency Range Attitude Independent of Speed Acceleration Good RCS High Speed Mode Low Vibration Environment DISADVANTAGES Low Hover Loiter Efficiency High Downwash Temperature Limited Low Speed Maneuverability Conversion Limited Corridor High Empty Weight Complexity 3 Vectored Thrusters VECTORED JET LIFT ADVANTAGES Highest Max Speed Highest Cruise Efficiency Range Excellent High Speed Maneuverability Attitude Independent of Speed Acceleration Symmetrical Yaw Control Low Vibration Environment Moderate Empty Weight DISADVANTAGES Poor Hover Loiter Efficiency Extreme Downwash Temperature Limited Low Speed Maneuverability Conversion Benign Rotating Component RCS Forward Jet Exhaust IR Complexity 1 Thruster 8 Nozzles Summary VTOL Aircraft Are Inherently More Complex Than Conventional Take Off and Landing CTOL Aircraft Mechanization Required to Change Direction of Thrust With Respect to Aircraft Additional Controllers e g Collective Stick Conversion Best VTOL Concept Only Has Meaning in the Context of the Mission to be Performed What Do You Need Most Hover Time Fast Cruise Long Range What Do You Have Available Runway Comparison of Different Types of V STOL Platforms VTOL Concept Helicopter Tail Rotor Aux Prop Features Examples Compound Compound Compound Advancing Vectrd Thrst Blade Concept Open Prop Compound Tilt Rotor Tilt Wing Canard Rotor Fan in Wing Wing Jet Lift Vectrd Thrst Ducted Prop AH 64 RAH 66 AH 56 Sikorsky XH 59 Sikorsky AAFSS Piasecki VTDP XV 3 XV 15 V 22 CL 84 TW 68 Boeing CRW XC 142 Best Good Good Good Good Good Fair XV 5 Grumman ACAS AV 8B Low Low Poor Hover Loiter Ground Ops Efficiency Endurance Downwash Temperature Low Low Low Low Low Moderate Marginal Marginal High Extreme Optional Open Prop No Anti Torque Open Prop Ducted Prop Optional No Anti Torque Jet Exhaust Low Helicopter Helicopter Helicopter Helicopter Good Tilt Rotor High High Highest Lowest Low Low Low Low Good Good Good Good Highest Low Speed Good Good Good Good Good Good Fair Limited Limited Limited High Speed Limited Good Good Good Good Good Good Good Good Excellent Ground Ops Protection Cruise Dash Max Speed Dash Cruise Efficiency Range Maneuverability


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