• Landing Gear should locate
near the center gravity (CG)
of the plane
3
Landing gear
Specifications landing gear:
• Comfortable shock absorption
• Short stopping distance (braking)
• High rolling stability during ground maneuvering
• Small storage volume
• Low drag (specially for fixed landing gears)
• High reliability and safety
• Low maintenance
• Low weight
4
Landing gear
Materials :
• Composites will be integrated into gear because they
are stronger and cheaper than the current used high
strength steels and titanium
• Ultra-High Tensile Steels are already being integrated
into the A400M and the B-787 landing gear, replacing
the low-alloy steels.
• Research into organic matrix composites and metal
matrix composites using titanium are promising, though
still very expensive.
Fixed and Retractable Landing Gear:
Fixed : gear is attached to the airframe
and
remains exposed to the slipstream as
the aircraft is flown.
Retractable : Retractable
landing gear stow in fuselage
or wing compartments while in
flight.
As the speed of the aircraft
increases,
the drag caused by the landing
gear becomes greater and a
means to retract the gear to
eliminate parasite drag is
required,
5
Landing gear
Shock Absorbing and Non-Shock
Absorbing Landing Gear :
• Shock Absorbing : the shock
energy is altered and transferred
throughout the airframe at a
different .rate and time than the
single strong pulse of impact,
• Non-Shock Absorbing : the
shock is absorbed by
converting the energy into
heat energy.
Constriction:
6
Landing gear
Landing Gear Alignment :
a) Parallel to the longitudinal axis (aligned)
b) Converge on the longitudinal axis (tow-in)
c) Veer away from the longitudinal axis (tow-out)
Landing Gear Support:
Aircraft landing gear are attached to the
wing spars or other structural members.
Retractable gear must be engineered in
such a way as to provide strong
attachment to the aircraft and still be
able to move into a recess or well when
stowed. The trunion is a fixed structural
extension of the upper strut cylinder
with bearing surfaces that allow the
entire gear assembly to move.
7
Landing gear
Landing Gear Retraction:
Retraction Systems
The simplest contains a lever in the flight deck mechanically
linked to the gear. Through mechanical advantage, the pilot
extends and retracts the landing gear by operating the lever. Use
of a roller chain, sprockets, and a hand crank to decrease the
required force.
To decrease drag in flight some undercarriages retract into the
wings and/or fuselage with wheels flush against them surface or
concealed behind doors; this is called retractable gear.
8
Landing gear
Hydraulic power system :
9
Landing gear
Emergency Extension Systems :
The emergency extension system lowers
the landing gear if the main power system
fails.
Some aircraft have an emergency
release handle in the flight deck that is
connected through a mechanical
linkage to the gear up locks.
When the handle is operated, it
releases the up locks and allows the
gear to free-fall to the extended
position under the force created by
gravity acting upon the gear.
Other aircraft use a non-mechanical
back-up, such as pneumatic power, to
unlatch the gear.
10
Landing gear
Reference:
•
•
•
•
•
•
http://www.slideshare.net/rishikeshims/aircraft-landing-gear-system
http://www.slideshare.net/partyrocka99/landing-gear-for-aircraft
http://www.aviationworld.me/vb/t41.html
http://army-tech.net/
https://en.wikipedia.org/wiki/Landing_gear
Book : Aircraft Landing Gear Systems ch 13
11
Landing gear
Note:
This dimension sheet is not the same as the S.W design.
( we got from the calculations "Non-Logic Piston diameter ",so we had to
change the dimension) .