Crash Dynamics

Question 1

Define short acceleration

Answer 1

< 0.5 sec

Question 2

Effects of short duration acceleration on body tissues

Answer 2

Magnitude of force
Duration
Rate of onset (Jolt)
Direction of applied force - Gx>Gx>Gy
Anatomical site of application

Question 3

Factors of crashworthiness - EXAM

Answer 3

CREEP
Container
- rigid protection - roll cage
Restraint
- Comfortable, efficient, easy to use, minimal restriction (harnesses and seat)
Environment - in cockpit
Energy attenuation - collapsible seats
Post-crash factors and escape

Question 4

Differences between harness

Answer 4

Lap belt

• advantages: easy to use, minimal restriction. Improve with brace position
• disadvantages: No upper body restriction, submaring

3 Point harness

• Advantages: better upper body restraint
• Disadvantages: minimal lateral restraint, submaring

4 point Harness

• Advantage: good upper and later restraint
• Disadvantages: submarining still possible. No negative G restraint

5 Point harness

• Advantages: best, negative G protection, no submarining.
• Disadvantages: no head and limb restraint

Question 5

Problems with restraints

Answer 5

Low take-off point - possible thoracic #
Dynamic overshoot - harnesses not securely tightened. Due to air gap and elasticity of materials and body tissue. Exaggerated high-peak deceleration means increase injury risk

Question 6

Characteristics of ideal Helmet

Answer 6

Optimum weight, size, shape, balance C of G
Smooth
Comfortable
Good fit
Easy to use
Good visibility
Other functions
- eye protection
- face/wind blast protection
- Hearing protection
- fire protection
- mounting ancillary equip

Question 7

For a helmet to work it needs to

Answer 7

Attenuate and absorb energy
- cracking of the shell
- deformable foam
Resist rotary forces
Avoid dynamic overshoot
Protect against penetration
Stay on during impact
Be fitted and worn correctly

Question 8

Types of helmets

Answer 8

HGU 55P - fixed wind
HGU 56P - Rotary wing
JHMCS (F/A-18F)
Topowl HMSD - MRH-90, ARH tiger (EC665)
F35 Gen III HMDS - F35

Question 9

The best negative G restraint is provide by which harness type
A. 2 point
B. 3 point
C. 4 point
D. 5 point

Answer 9

D.. 5 point harness