Vertical Take Off & Landing
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Vertical Take Off & Landing (VTOL) Aircraft -- A Comparison PowerPoint PPT Presentation


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Vertical Take Off & Landing (VTOL) Aircraft -- A Comparison. Fixed Thrusters. l. Vectored Thrusters. l. Lift / Propulsion / Control Approaches For VTOL Aircraft (General). For Shaft-Driven VTOL Aircraft, Need At Least Two Thrusters:. > One Main, One Anti-Torque.

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Vertical Take Off & Landing (VTOL) Aircraft -- A Comparison

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Vertical take off landing vtol aircraft a comparison

Vertical Take Off & Landing

(VTOL)

Aircraft

--

A Comparison


Vertical take off landing vtol aircraft a comparison

Fixed Thrusters

l

Vectored Thrusters

l

Lift / Propulsion / Control Approaches

For VTOL Aircraft(General)

For Shaft-Driven VTOL Aircraft, Need At Least Two Thrusters:

> One Main, One Anti-Torque

> Two Equal Size (Opposite Rotation)

> Thruster Tilting

> Exhaust Deflection


Methods of transition for various v stol concepts

Methods of Transition for Various V/STOL Concepts


Vertical take off landing vtol aircraft a comparison

VTOL Concepts


Vertical take off landing vtol aircraft a comparison

  • 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)

PURE HELICOPTER


Vertical take off landing vtol aircraft a comparison

Thrust

Thrust

Wing Lift

Velocity

Wing "Lift"

Velocity

(Download)

Wing Needs Aircraft to be Nose Up to Get Lift

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

THERE ARE MAJOR PROBLEMS WITH ADDING A WING


Vertical take off landing vtol aircraft a comparison

  • 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

(Fixed Thruster)


Vertical take off landing vtol aircraft a comparison

  • 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

(Advancing Blade Concept)


Vertical take off landing vtol aircraft a comparison

  • 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)

  • ADVANTAGES

  • Good Hover/Loiter Efficiency

  • Low Downwash

  • Faster Than Pure Helicopter

  • Good Maneuverability (Except Conversion)

  • Reverse Prop Thrust at High Speed

COMPOUND HELICOPTER

(Vectored Thruster - Open Prop)


Vertical take off landing vtol aircraft a comparison

  • 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)

COMPOUND HELICOPTER

(Vectored Thruster - Ducted Prop)


Vertical take off landing vtol aircraft a comparison

  • 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)

CANARD ROTOR WING


Vertical take off landing vtol aircraft a comparison

  • 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 ROTOR


Vertical take off landing vtol aircraft a comparison

  • 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)

TILT WING


Vertical take off landing vtol aircraft a comparison

  • ADVANTAGES

  • Enclosed Thrusters (Safety)

  • Symmetrical Yaw Control

  • DISADVANTAGES

  • Low Hover/Loiter Efficiency

  • Limited Low Speed Maneuverability

  • Conversion (Limited Corridor)

  • High Empty Weight

  • Complexity (1 Fixed + 2 Vectored Thrusters)

TILTING DUCTED FANS


Vertical take off landing vtol aircraft a comparison

  • 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)

FAN-IN-WING


Vertical take off landing vtol aircraft a comparison

  • 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)

VECTORED JET LIFT


Summary

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, . . . ?


Vertical take off landing vtol aircraft a comparison

Comparison of Different Types of V/STOL Platforms


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