Transcript G -Force - FLY OSA

GRAVITATIONAL
FORCES
“G”
 The measure of gravity acting on a object.
 The normal force which acts on all bodies is
equal to 1 G.
 During freefall, an object will fall at 32.2 fps2
terminal velocity is reached
ACCELERATION
Change in velocity in either magnitude or direction
 The most common accelerative force is gravity
DECELERATION
Any reduction in the velocity of a moving body
INERTIAL FORCE
The resistance to a change in the state of rest
or motion
A body at rest tends to stay at rest, a body in
motion tends to stay in motion
TRI-AXIAL REFERENCE
SYSTEM
FACTORS AFFECTING
ACCELERATIVE FORCES
Intensity
Duration
Rate of onset
Body area and site
Impact direction
PHYSIOLOGICAL EFFECTS
OF LOW MAGNITUDE
ACCELERATION
+Gz Forces
Head to Foot
FACTORS MODIFYING +GZ
DECREMENTAL FACTORS
Any factor that reduces overall efficiency of the
body, especially the circulatory system
 Blood volume decrease
- varicose veins
- hemorrhage
 Blood pressure decrease
- hypotension
- fatigue/illness
- alcohol abuse
INCREMENTAL FACTORS
Any factor that increases overall efficiency of
the body, especially the circulatory system
 Hypertension
 Fear & excitement
 Tensing of muscles
 Short stocky build
 L-1 Maneuver
L-1 MANEUVER
Procedure:
Remain upright
Tense muscles
Exhale against a closed glottis at 2 to 3 second intervals
Note: Increases G-load tolerance by 4
Disadvantages:
Physically Exhausting
-Gz Forces
Foot to Head
+/- Gx FORCES
Mild transverse accelerations / decelerations during
landing and taking off
TRANSVERSE “G”
TOLERANCE
+Gx
15 G’s
5 seconds
-Gx
12 G’s
5 seconds
+/- Gy FORCES
Human body has minimal tolerance to right
or left accelerations
Most aircraft do not apply accelerative forces
in the lateral direction
PHYSIOLOGICAL EFFECTS
OF HIGH MAGNITUDE
ACCELERATION AND
DECELERATION
EFFECTS
Minor discomfort
Incapacitating
Minor injury
Irreversible injury
Lethal
SOURCES
 Aircraft
crashes
 Ejection seats
G’s
(Seconds)
AIRCREWMEMBER
SURVIVABILITY DURING
THE CRASH SEQUENCE
CRASH SURVIVABILITY
CRITERIA
Amount of decelerative forces transmitted to
the body
Occupiable living space
Human Tolerance Limits to
Whole Body Impact
-16 Gs
-Gz
(0.1 second
duration)
-40 Gs
+9 Gs
-Gx
+Gy
+Gx
- Gy
+80 Gs
-9 Gs
+Gz
+20 Gs
AIRCRAFT DESIGN
FEATURES
(CREEP)!
 Container
 Restraint
system
 Environment
 Energy absorption
 Post crash protection
QUESTIONS?