VTOL concept and types of VTOL aircrafts

1. VTOL

2. • A vertical take-off and landing (VTOL) aircraft is one
that can hover, take off, and land vertically. This
classification includes fixed-wing aircraft as well
as helicopters and other aircraft with powered rotors,
such as cyclogyros/cyclocopters and tiltrotors. Some
VTOL aircraft can operate in other modes as well, such
as CTOL(conventional take-off and landing), STOL (short
take-off and landing), and/or STOVL(short take-off and
vertical landing). Others, such as some helicopters, can
only operate by VTOL, due to the aircraft
lacking landing gear that can handle horizontal motion.
VTOL is a subset of V/STOL (vertical and/or short take-
off and landing).

3. HELICOPTERS
• The helicopter's form of VTOL allows it to take off and land
vertically, to hover, and to fly forwards, backwards, and laterally.
These attributes allow helicopters to be used in congested or
isolated areas where fixed-wing aircraft would usually not be able
to take off or land. The capability to efficiently hover for extended
periods of time is due to the helicopter's relatively long, and hence
efficient rotor blades, and allows a helicopter to accomplish tasks
that fixed-wing aircraft and other forms of vertical takeoff and
landing aircraft could not perform at least as well until 2011.
• On the other hand, the long rotor blades restrict the maximum
speed to about 250 miles per hour (400 km/h) of at least
conventional helicopters, as retreating blade stall causes lateral
instability.

5. AUTOGYRO
• Autogyros are also known as gyroplanes or
gyrocopters. The rotor is unpowered and rotates
freely in the airflow as the craft travels forward,
so the craft needs a conventional powerplant to
provide thrust. An autogyro is not intrinsically
capable of VTOL: for VTO the rotor must be spun
up to speed by an auxiliary drive, and vertical
landing requires precise control of rotor
momentum and pitch.

7. GYRODYNE
• Gyrodynes are also known as compound
helicopters or compound gyroplanes. A
gyrodyne has the powered rotor of a
helicopter with a separate forward thrust
system of an autogyro. Apart from take-off
and landing the rotor may be unpowered and
autorotate. Designs may also include stub
wings for added lift.

9. CYCLOGYRO
• A cyclogyro or cyclocopter has a rotary wing
whose axis and surfaces remain sideways
across the airflow, as with a conventional wing

10. • Convertiplane
• A convertiplane takes off under rotor lift like a
helicopter, then transitions to fixed-wing lift in
forward flight.

11. • Tiltrotor
• A tiltrotor or proprotor tilts its propellers or
rotors vertically for VTOL and then tilts them
forwards for horizontal wing-borne flight,
while the main wing remains fixed in place.

12. • Tiltwing
• A tiltwing has its propellers or rotors fixed to a
conventional wing and tilts the whole
assembly to transition between vertical and
horizontal flight.

13. • Tail-sitter
• A tail-sitter sits vertically on its tail for takeoff
and landing, then tilts the whole aircraft
forward for horizontal flight.

14. FUNDAMENTAL PROBLEMS OF VTOL DESIGN
• A number of unique problems characterize the
design and operation of jet VTOL aircraft. Two
fundamental problems stand out because they
tend to have the greatest impact upon the
selection of a VTOL propulsion concept and
upon the design and sizing of the aircraft:
balance and thrust matching.