FREQUENTLY ASKED QUESTIONS The present document is illustrated with some
net-references found in the literature. For an A4(.pdf) reference, its page number might
follow a letter attributed to this reference. Webpage reference got only a letter :
QUESTIONS I. Could
our system realize savings of life, and interest Air Forces & Civil
matters/means? Regarding the 10% ejection lethality rate & the Rockwell
crash rapport information (m)? II. Is spinal injury still today a high
preoccupation after the 1990s enhancements? Notably in the Navy & for
women crew (after B. Shinder)? III. In what pre-tension &tension is
an advantage facing the current forced compression distribution & facing GLOC? (Over 1700 pounds) IV. What loads (maximum) could support
the chest & armpits (discharge & fatigue counter measure)? V. May our system be active partially
at parachute opening shock? VI. How retention for loading above 1G
can be expected/forwarded & be positively comforted (After Madsen p.
3, After (f) thesis)? VII. If one can really want it, can
engineering be found/developed to permit additional space at the buttock
rotation? VIII. In what particular phase (how) can the
system act during the push-pull effect? IX. Is the head of a tall pilot so much
higher that our retention can’t be placed for their shoulders? IX bis. Might
dynamic overshoot be reduced at catapult ignition? X. Could
our design/system be complementary and act together with the current one? XI. Is
a blanket approach, from a white paper constructive? (Also see question VI, last terms)
GLOBAL
RESPONSE IN REGARD OF ALL QUESTIONS
REFERENCED IN MARGIN, & IN REGARD OF THE WEB LITTERATURE, AS SHOWN IN 1ST
PAGE
ABSTRACT
INTERIM TEXT BEFORE COMPLETE TRANSLATION AND DEFINITIVE VERSION
SUBJECT TO EVOLUTION
III.
1.1) Par le harnais de torse actuel. Il ne peut y avoir de
(re)distribution des forces en soulagement notamment parce que le harnais est
aussi solidaire du support fessier. La pre-compression conduit à une
concentration supplémentaire :
Ancré verticalement en bas à l’avant du siège et
rétracté derrière les épaules dans le plan horizontal [avec des tolérances -5°,
+30°] ce harnais transmet, dans ces deux attaches, deux forces dont la
résultante dirige le buste vers le bas et l’arrière.
Si une faible partie du poids du buste est
transférée par friction au dossier, la composante verticale occasionne, elle,
une surcharge vertébrale d’autant plus forte que diminue l’angle de tolérance et,
pour un angle donné, d’autant plus forte que le buste est en flexion (pilote
non adossé, de son fait, ou suite à une résistance à l’avancement, par impact).
Initialement la composante horizontale naît d’une
force non dosable (o, L6).
Si la pre-compression
« soude » les vertèbres et le fessier au support, option contre
l’overshoot (l’ensemble veut atteindre plus rapidement la vitesse du support
quand elle n’est pas encore trop grande), elle augmente par contre la
compression/fragilité sur les lombaires [et sur les facettes qui en supportent
10% si les disques sont sains ( J )]
d’un supplément non dosable (o, L6) [rétractation par ’’inertial reel’’] et propre à chaque composante
verticale suivant l’angle propre du vecteur rétraction, pour chaque hauteur de buste.
(o) “During ejection, a cartridge is fired to retract the shoulder
harness” Rappelons encore que
cette configuration avec composante sub-horizontale du restraint, en deçà des
[–5°], est fortement déconseillée en cas d’impact combinant les axes verticaux
et horizontaux..
(L6) “Known torso restraint retraction systems do not fulfil this need
because they are not adapted to respond to in flight accelerations
conditions.”(1987)
Considérons que par principe
cette rétraction est permanente jusqu’à la séparation du siège/pilote et que
cette force reste constante appliquée au contact du buste quelque soit son
affaissement, force possiblement aidée par des fonctions airbag entre les
sangles et le harnais :
Si cette pre-compression est
de 50 à 100 pounds (e76), cela peut représenter 5 à 10% de la charge en plus à
l’éjection (moyenne 15G). On rajoute du poids aux G sur les lombaires, c’est
dangereux.
1.2) En tirant la poignée
basse d’éjection (entre les jambes). 45 pounds minimum est requis pour la
sortir du logement mais les études prouvent que jusqu’en butée ou en butée, le
pilote dans l’urgence ne dose pas toujours exactement son effort et peut
appliquer considérablement plus de forces (crispation en butée) en prenant
appui avec les avant-bras sur les jambes et avec les jambes/cuisses sur le
support : jusqu’à 300 pounds (= limite technique/instrumentale lors des
essais/ simulations)*.
(*) www.google.com/search?q=cache:8_05xjugOjoJ:iac.dtic.mil/hsiac/GW-docs/gw_ix_2.pdf+handle+ejection+pull&hl=fr&ct=clnk&cd=13 (En cache. Pdf non dispo)
Là encore la pre-compression
est inconstante et peut dépasser son cadre opératoire : la charge augmente
de 5 à 25% sur les lombaires. Il y a distribution des forces dans le sens d’une
concentration, cumulative avec le
harnais actuel s’il agit sub-horizontalement.
|
VI. XI. |
2.1) Voir les effets
bénéfiques du recours à la ’’face curtain’’ dans les notes jointes (see
our website) : 60 pounds et plus, du poids
de la ceinture des épaules sont absorbés par ce point d’ancrage.
IX bis.
Cela fait [10%] + [10%
pre-compression (poignée basse)] soit 20%
en moins par rapport à la charge sur les lombaires avec pre-compression. Ce
recours à la face curtain démontre qu’une pre-tension est donc préférable.
D’autant plus que l’on flirt
avec les limites de la résistance spinale en compression (a27).
(a27-f°20)
“crushing resistance of the spiral column”
II. XI.
[(f) prone position with restraint harness + frontal impact] = [our
system sitting posture + Gz impact]
(q) « Future G protection: In order to
extend much beyond
II.
__”spinal compression may be prevented”
www.freepatentsonline.com/6422513.pdf Abstract lignes 5-6, et colonne 4, lignes 51-54.
III. IV. VI.
__ ”…pelvic restraint in the prone position would provide the advantage
of tension rather than compression loading of the lumbar spine…” (f56)
III. IV. VI.
ET A CONCLUSION QUE CECI EST
TRANSPOSABLE, A L’IMPACT VERTICAL, AU SOULAGEMENT DE LA COMPRESSION LOMBAIRE
SOUS LE POIDS DU BUSTE, EN MODE ASSIS NORMAL.
III. VI.
TOUT
COMME LE HARNAIS ACTUEL NE RETIENT PAS LE THORAX DE DESCENDRE, SES SANGLES
D’EPAULES, N’ETIRENT PAS AXIALEMENT LA COLONNE ET FONT UNE ROTATION AUTOUR DE
LEUR FIXATION, ENTRAINEES PAR LE POIDS APPARENT DU THORAX
III. VI.
“best results were obtained with restraint concept 3 (test 2 with
frontal impact)” (f96)
[Figure E4 : Prone concept 3, +7000N tension (green curve) –5000N
compression] (f136)
III. VI.
III. VI.
“Compression
of the spinal column by… shoulder harnesses should be avoided.” (f116)
2.3) Il est clairement dit et
répété dans nos courriers :
__Espace nominal maintenu
entre les vertèbres « as in supine
position » (cad 0G) « par exemple ». (o) « The erect or hyper extended
posture is ideal for ejections »
(ou ’’as in sitting
posture’’ soit 1G). Avec comme corollaire ce qui suit.
IV.
“The buttock supports the apparent pelvis weight” (0G).
La colonne, sa souplesse
sont donc préservées.
Par le soulagement du poids du
thorax, l’avantage immédiat est de préserver la jonction vertébrale très sensible entre la
base du thorax et au sommet des lombaires* (o,p,f)
I. II.
(o) “One of the most vulnerable
sites for injury of the spinal column is the region around the eleventh and
twelfth thoracic vertebrae (T11-T12). From the eighth thoracic to the first
lumbar vertebrae is the region of greatest frequency”
(p915) cap 22, f°39 : “T10 to L2”
(f30) ”upper lumbar
&lower thoracic segments”
VI.
VII. IX.
=> Le pilote n’est pas
plus haut (que au neutre : ’’sitting’’ sous 1G) ou à peine plus haut ( ’’as
in supine position’’ 0G, écart négligeable). Comme le support peut s’affaisser,
il peut même être légèrement plus bas (travail résistant des sangles). Cet
espace d’affaissement devrait être minime, le pilote conservant sa grandeur de
buste comme en position neutre (sitting ou supine).
=> facteur avantageux
pour l’adaptation (en encombrement) à tous les cockpits.
X.
IV.
Il est évident et du ressort
des constructeurs de prévoir que cette retenue s’efface instantanément ou
rapidement dès le stop fusée siège. Elle s’adapte donc aux poids apparents.
IV. V.
VIII.
la retenue effective dès la
« low Gz baseline » (<1G)
n’est qu’une hypothèse de travail et accessoire ; le terme
« perhaps » a été employé et dans un temps au conditionnel dans notre
document.
Elle pourrait cependant
s’appliquer dès (+0Gz)* qui correspond à l’espace vertébral optimal** de
repos (supine position), ou bien même dès –1Gz en travail résistant vers 0Gz+.
(*) www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ43410.pdf pages
19-20 : “During F15 &F16 US Air Force operations, it
was found that 17 to 66% (varying with mission profile) of engagements include
the push-pull component with a typically hypogravity exposure [from 0G to 0.5G]
for 3.5 to 5 seconds” (reduce drag &increase airspeed notably). This low Gz
baseline (push) precedes hypergravity [1G to 10G+] (pull).
Michaud VJ, Lyons TJ. The ’’push-pull effect’’ and G-induced loss of consciousness accidents
in the
(**) Pour le navigant, même s’il est retenu au support fessier
par des sangles et par le harnais actuel, lors de la course en hypogravité sa
colonne veut se mettre a) en décompression [plage des 0<Gz<1] ou b) en
tension [plage des Gz <0] par rapport :
1.
A
son niveau de compression maxi à l’éjection ou en high sustained +Gz
2.
A
la sollicitation nulle : 0G as in supine posture.
Notons encore que
during « inverted or negative G flight conditions at the time of
ejection…DANGEREUSE SUITE » (o), l’accompagnement résistant, d’une
substantielle retenue, pourrait amortir la course d’effacement/ réduction de
l’étirement spinal en captant l’énergie emmagasinée dans l’étirement naturel
(hypogravité) afin qu’elle n’aille pas augmenter quelque overshoot (résiduel ou
bien celui inhérent à la technique passée) et le risque de blessures.
2.4) Voir spécialement source
(u) [existe
aussi en html] :
II.
__Page 1 : See the “Chairman ‘s Message… 2001 International Acceleration Research Workshop. This year’s program is a blend of
both oral laboratory reports, as well as a number of special presentations on
“works-in-progress.” In keeping with last year’s workshop, I have chosen a discussion
topic that will (hopefully) form the basis of spirited discussion during the
workshop. I am grateful to Barry Shender for submitting this topic.”
__Page 10 : “Discussion Topic… the
occurrence of soft and hard tissue
injury during every day flight has become a greater and greater operational
problem.”
Vœux pieux aux vues des
dégâts et des menaces sur la santé des navigants au long terme. Nombreux
rapports rappelés.
See also (g,h,i,j,q31-32,37-38,s). (q31-32) : b) Disc Degeneration,
Lifetime Incidence.
XI.
Le spécialiste Mr Barry
Shender intervient dans ce document sous l’égide du Naval Air Warfare Center.
Trésorier du Safe Association, il est également l’un des signataires d’une
publication sur la résistance physique demandée aux femmes au niveau de leur
buste, à l’éjection ou sous hypergravité :
“Female Upper
Body Dynamic Strength Requirements in High Performance Aircraft…” www.stormingmedia.us/20/2089/A208903.html
3) AUTRES APPLICATIONS
III.
Voir (b30-32/f°21-23 After Madsen:
harness double strop suspension)
__Sous 1G c’est le mode de suspension le plus
durable (1 heure+) sans blessures. See
syncope phenomenon in “Horizontal Tilt Table” (Capter title). Il se rapproche de notre system de “fatigue
counter measure” lors de son initialisation : notre support
s’affaissant les genoux sont plus haut que le pelvis + traction aux
épaules. Alors que tous les autres (full-body, chest harnesses, waist
belts…) sont dangereux beaucoup plus vite : Le full body ne tire pas sous les bras et les jambes
pendent. Le waist belt + sit harness n’élève pas les genoux. Le
chest harness occasionne du venous pooling dans les jambes qui pendent.
__Sous forts “G ” nos sangles dépaules
soulagent la sitting posture, mieux que sans traction. Les genoux
sont plus au dessus du bassin qui s’enfonce dans le support
ammovible : « venous return is secured »
=> flux au cerveau maintenu + longtemps => G-LOC
retardé VI.
Voir encore (g) (q) et
document IAW2001Newsletter.PDF (u) précité, pages 5-6 et 8 :
“Increase aircrew G &GLOC tolerance”
“Techniques for releasing the total incapacitation period associated
with GLOC”
Si les pilotes étaient moins
fatigués, il y aurait moins de situations à risques d’éjection (m5 Rockwell).
3.2)
Pain Counter-Measure. Arm pain: voir même document
ci-dessous en IV et (q37-38).
I.
(*) Michaud VJ,
Lyons TJ. The ’’push-pull effect’’ and G-induced loss of
consciousness accidents in the
Michaud VJ, Lyons TJ, Hansen CM. Frequency of the ’’push-pull effect’’
in the USAF figther operations. Aviation, Space, &Environmental Medecine
1998;69(3) :201.
collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ43410.pdf pages
19-20 : “During F15 &F16 US Air Force operations,
it was found that 17 to 66% (varies with mission profile) of engagements
include the push-pull component with a typically hypogravity exposure from 0G
to 0.5G for 3.5 to 5 seconds (reduce drag &increase airspeed notably).”
COMPLEMENTS TO ABSTRACT & RECALL OF OUR WEBSITE ARGUMENTS :
ANSWERING QUESTIONS ONE BY ONE
I. Could our system realize savings of life,
and interest Air Forces & Civil matters/means? Regarding the 10% ejection
lethality rate & the Rocwell crash rapport information (m5) ?
__(c52) f°45 “Hearon, et al
: …Vertebral Fracture in the F/FB-111
Ejection Experience 1967 to 1980… Spinal injuries occurred in 23 of the 78
cases investigated (axial compression & flexion)”
__(c57) f°50 “Schall D. G.
: Non Ejection Cervical Spines
Injuries Due to +Gz in High Performance Aircraft.”
__(e92) “Acceleration-induced
injuries are due to the body’s inertial response to crash forces. An example of
an acceleration injury is rupture of the aorta in a high sink rate
rotorcraft crash. Here the application of the force occurs through the
individual’s thighs, buttocks and back, where he is contact with the seat. The
injury mechanism itself is due to tensile/shearing forces generated from the
heart’s inertial response to the resulting upward acceleration of the body.
Other examples of acceleration injuries include atlanto-occipital shearing [lethal],
vertebral fractures and contrecoup brain injuries.” Also concerning
#III below.
__(e95) “The most predominant
impact direction for a helicopter occupant is vertical (i.e., eyeballs
downward). A shoulder harness increases human tolerance without injury
for the vertical direction from 4-G’s to 25-G’s, an improvement factor of
six. A shoulder harness occupant survivability in the vertical impact
scenario because it retains the occupant’s pre-crash position (i.e., upper
torso remains essentially upright), keeping the spinal column aligned properly
and allowing it to carry much higher crash loads… Laterally, the shoulder
harness increases tolerance by a factor of two.” [more tolerance
improvements can be expected with our method by a new factor, because of
reduced compression]. See also (f34).
__(f25) “serious injury in
general aviation accident… frequently sustained at the head (overshoot)…
attributed to the lack of adequate torso restraint… shoulders provide a
sufficient attachment point for torso restraint… Special attention should also
be given to the angle of position of attachment of the shoulder belts to the
structure. Incorrect belts angle… could result in spinal injury due to the
compressive load introduced by the shoulder strap angle.
“webbing with a large width is desirable to decrease injury due to the
restraint system.”
__(f34) “shoulder harnesses in
aircraft might have prevented 76% of the fatalities &79% of the serious
injuries.”
“2% of fatalities may have been prevented & 38% of the serious
injuries may have been prevented by the use of energy absorbing seats.” [See also III. (e95) below]
__(f38) “compression of the
lower lumbar spine during high impact emergency landings often resulted
in back injury”
“Additional injury due to arrestment by the webbing (&buckles)
restraint system with little distribution of impact pressure is also a
disadvantage.”
__(g21) f°10 “Les plateaux cartilagineux sont souples et
les 1er à subir une déformation lorsqu’un segment vertébral est sous
charge. Leur porosité permet à l’eau expulsée d’un disque comprimé de circuler. ”
__(g23-24) f° 12-13 “Comportement mécanique… Le disque augmente
son rayon de 0.75mm pour une force de compression de 1000N. Sous une
compression prolongée, le nucléus peut perdre jusqu’à 20% d’eau. Inversement
lorsque la charge est réduite, le disque réabsorbe le liquide pour atteindre un
nouvel équilibre osmotique… phénomène
de déformation croissante lorsqu’une contrainte constante est appliquée… Le
fluage sous charge compressive s’explique par l’exsudation du fluide qui a
lieu en réponse au dépassement de la pression nucléaire admissible.”
__(g24-25) f°13-14
“Dégénérescence du disque intervertébral… La pathologie du disque
intervertébral est un problème épidémiologique majeur. Mécanismes responsables… problèmes de
nutrition du nucléus… mutations de protéines … accumulations de
produits dégradés dans la matrice… fracture par
fatigue de la matrice fibreuse… nombre d’artère (vascularisation)
diminue… plateaux cartilagineux se calcifient, perdant leur porosité…”
__(g34-35) f° 23-24 “Les disques dégénérés se caractérisent par
une réponse en déplacement plus grande que les disques sains : le nucleus
perd en incompressibilité et le réseau fibreux de l’annulus est endommagé.
Hirsh et Nachemson… ont été les premiers à déterminer que la dissection des
arcs postérieurs avait peu d’influence sur le comportement en compression. ”
__(g153-f°142) “Finally, disc degeneration effects on
creep properties have been demonstrated, notably stating higher creep rates for
more degenerated IVDs (Kazarian, 1975; Keller, et al., 1987; Li, et al., 1995).
__(g161) “Though able to sustain
high load magnitudes in various directions according to the individual posture…
better understanding of the mechanisms implied in degeneration &their
consequences on IDVs load-carrying performance is therefore of high clinical
significance”
__( j ) “…la dégénérescence discale
entraîne une augmentation de la charge sur les facettes articulaires, et en
conséquence, une dégénérescence des facettes articulaires… Les facettes, en
présence de disques sains, supportent environ 10% de la compression du poids du
corps, et le complexe corps vertébral-disque-corps vertébral supporte 90% du
poids. Dans le cas d’une dégénérescence discale, les facettes doivent supporter
un poids de plus en plus important, pouvant aller jusqu’à 50-70% du poids
total.”
__(k10) Ligne 23 “Apart from the immediate dangers of
involuntary movements occurring during a high speed manoeuvre the cumulative
effects of G-force on the pilot’s head &body cause pilot fatigue which
also impairs pilot performance. It would therefore be to a pilot’s
advantage if the effect of high G-forces could be compensated for or reduced in
some way.”
__(m5) lignes 9-17 “…improved aircraft manoeuverability is counterproductive
if the resulting forces imposed on the unprotected pilot are beyond human
tolerances. One can only speculate as to the number of fighter aircraft lost
as a result of pilot blackout…”
__(n1) “Abstract… Protecting
the head &neck &spinal cord from injuries resulting from rapid forward
deceleration &ejection… neck of human beings is at risk from lethal spinal
cord injury with rupture of the atlanto-occipital membrane which holds the base
of the skull to first cervical vertebra…”
__(n3) lignes 50-64 &
(n4) [Défaut des restraint
harnesses qui augmentent le whiplash de la tête : létal… idem in Formula racing
=> nécessité de soutenir la
tête.]
__(p896) cap 22-20 “We can demonstrate a clear relationship between through-the-canopy ejection
with higher peak G catapults and the incidence of vertebral fracture. We
"know" that improper body position (including a loose harness)
increases the risk of injury.”
__(q1) “Ut Secure Volent” [Tronc Ailé en
suspension du blason 2005 de : RAF Centre of Aviation Medecine]
__(q13) “USAF GLOC (G-induced
Loss of Consciousness) Accident : Lyons, TJ et al. Aviat Space Environ Med 2004 ;75 :479-48 ”
__(q32) “Current &next
generation of agile aircraft have the following properties:
Rapid G onset rate of over 10 Gs-1 (therefore no
visual symptoms prior to G-LOC…)”
II. Is
spinal injury still today a high preoccupation after the 1990s enhancements?
Notably in the Navy & for women crew (after B. ShEnder)?
__(u4) “Human Tolerance to Acceleration-Induced Spinal
Injury” est un programme de l’US Naval Air Systems. En
mai 2001. Soit bien après (plusieurs années) les dernières
avancées des années 90. Le problème des blessures spinales est donc crucial
encore postérieurement, au point d’y consacrer un programme toujours
d’actualité.
“US Navy Acceleration Research Programs. Barry Shender, PhD. Naval
Air Warfare Center Patuxent River MD,
__(u1) “Chairman ‘s
Message… 2001
International Acceleration Research Workshop. This year’s program is a blend of both oral laboratory
reports, as well as a number of special presentations on “works-in-progress.”
In keeping with last year’s workshop, I have chosen a discussion topic that
will (hopefully) form the basis of spirited discussion during the workshop.
I am grateful to Barry Shender for submitting this topic.”
__(u10) "Head/neck injury
during high performance flight in both fast jets and attack helicopters. The
discussion topic for this year’s Workshop was submitted by Dr Barry Shender…
Historically, research into head/neck injury tolerance has focused on the response
to impact acceleration, crash, parachute opening shock, etc. Designs for
protective systems have similarly stressed these areas and have, for the most
part, relied on automotive data. With the expansion of the anthropometric
range of pilots, male and female, and the increased use of
helmet-mounted devices (HMD), the occurrence of soft and hard tissue
injury during every day flight has become a greater and greater operational
problem. There have been a several reports by
[Vœux pieux aux vues des
dégâts et des menaces sur la santé des navigants au long terme. Nombreux
rapports rappelés. See also
(g,h,i,j,q31-32,37-38,s). (q31-32) : b)
Disc Degeneration, Lifetime Incidence]
“Chairman’s Note : This is an important
topic for us as a research
community to address. It goes to the very heart of issues surrounding the
protection and long-term health and safety of pilots flying high performance
aircraft. I would like to thank Barry for submitting this topic, and urge
all participants to carefully consider the issues involved and the questions
that Barry has raised. I hope that this topic provokes a lively and
constructive debate, and provides the impetus for many ongoing collaborative
research efforts.”
__(c47-48) f°40-41 Degeneration
of the intervertebral discs : “with age
the nucleous gradually loses its ability to bind water under mechanical
pressure and becomes fibrocartilaginous… butterfly swimmers… sports injuries”
“Burton et al. : Cervical
spinal Injury from Repeated Exposures to Sustained Acceleration, Research
&Technology Organisation of NATO (RO-TR-4)… Caused by manoeuvres in the
range 4G to 9G. Several pilots suffered bulging cervical discs.”
“Higher G levels may be an issue for flyers with relatively low density
of vertebrae.” [& low cross sectional vertebrae as with women crew]
“Review of the Vertebral Column Pain Problems in Polish Pilots
–Tatar et al… caused by rapid jolt & high acceleration values.”
__(c49) f° 42 Military Aircrew
Head Support System (MAHSS) : “Neck
injuries… during violent manoeuvres such as 8G turns… added weight of sophisticated
flying helmets… leading to incapacitating… (permanent physiological damage).
The problem is compounded if the airman has to eject at 16G, hence the
introduction of the MAHSS.”
__(c52) f°45 Hearon, et al. “…Vertebral Fracture in the F/FB-111
Ejection Experience 1967 to 1980… Spinal injuries occurred in 23 of the 78
cases investigated (axial compression & flexion).”
__(c57)
f°50 Schall D. G. “Non Ejection
Cervical Spines Injuries Due to +Gz in High Performance Aircraft.”
__(e93) “hazards associated with
the operational environment of military wheeled-ground vehicle also place a vertical
(z-axis) response requirement on the vehicle’s occupant protection system.
Occupant inertial response to mine blast forces and rough terrain maneuvers
requires that the energy associated with these hazards be managed to
preclude spinal injuries.”
“The Air force’s dynamic response index (DRI) provides a spinal injury
criterion based on this principle, that has been used to
qualify ejection seats and has also been used to comparatively assess crash
resistant energy absorbing seat systems.” [The dynamic amplification
factor =dynamic overshoot]
__(f25) “serious injury in
general aviation accident… frequently sustained at the head (overshoot)…
attributed to the lack of adequate torso restraint… shoulders provide a
sufficient attachment point for torso restraint… Special attention should also
be given to the angle of position of attachment of the shoulder belts to the
structure. Incorrect belts angle… could result in spinal injury due to the
compressive load introduced by the shoulder strap angle.
“webbing with a large width is desirable to decrease injury due to the
restraint system.”
__(g16) f°4 “Le tissus discal n’est pas vascularisé il dépend en cela de la porosité
des plateaux cartilagineux qui le surfacent.”
__(g19) f°8 Nucleus pulposus “Son liquide constamment sous pression absorbe et répartit
les charges et les chocs… doté d’un métabolisme actif, assurant un
renouvellement des protéoglycanes et du collagène…essentiellement de
type II… La matrice extra cellulaire du nucleus est biochimiquement équivalente
à celle du cartilage… avec des fibres de collagène entremêlées à de large
molécules de protéoglycanes. » (80%
d’eau chez l’adulte de 20ans).”
__(g21) f°10 “Les plateaux cartilagineux sont souples et
les 1er à subir une déformation lorsqu’un segment vertébral est sous
charge. Leur porosité permet à l’eau expulsée d’un disque comprimé de
circuler. ”
__(g23-24) f° 12-13 “Le disque augmente son rayon de 0.75mm
pour une force de compression de 1000N. Sous une compression prolongée, le
nucléus peut perdre jusqu’à 20% d’eau… phénomène de déformation croissante lorsqu’une
contrainte constante est appliquée… Le fluage sous charge compressive
s’explique par l’exsudation du fluide qui a lieu en réponse au dépassement de
la pression nucléaire admissible.”
__(g24-25) f°13-14
“Dégénérescence du disque intervertébral… La pathologie du disque
intervertébral est un problème épidémiologique majeur. Mécanismes responsables… problèmes de
nutrition du nucléus… mutations de protéines … accumulations de
produits dégradés dans la matrice… fracture par fatigue de la matrice fibreuse…
nombre d’artère (vascularisation) diminue… plateaux cartilagineux se
calcifient, perdant leur porosité…”
__(g34-35) f° 23-24 “Les disques dégénérés se caractérisent par
une réponse en déplacement plus grande que les disques sains : le nucleus
perd en incompressibilité et le réseau fibreux de l’annulus est endommagé.”
TRADUCTION PARTIELLE
__(g153-f°142) “Finally, disc degeneration effects on creep properties
have been demonstrated, notably stating higher creep rates for more degenerated
IVDs (Kazarian, 1975; Keller, et al., 1987; Li, et al., 1995).
__(g47-48)
f°36-37 “Avec les multiples sollicitations
qu’il doit quotidiennement subir, le DIV est progressivement soumis à des
dégradations liées en partie au vieillissement, plus qu’aucun autre tissu mou
du système musculo-squelettique… Ce phénomène, appelé dégénérescence
discale…s’exprime au travers de modifications biochimiques principalement
localisées dans le nucléus pulposus (baisse de la teneur en eau et en
protéoglicanes) qui perd son aspect gélatineux. Ces altérations imposent au
réseau de collagène de résister à des charges plus importantes, ce qui engendre
des initiations de ruptures menant à des fissures radiales ou
circonférentielles macroscopiques dans l’annulus fibrosus… à terme des
modifications de volume et de forme, notamment une perte de hauteur. A ces
endommagements intra-discaux peuvent s’associer une arthrose des facettes
articulaires et la formation d’ostéophytes sur les corps vertébraux.”
TRADUCTION CI-DESSOUS
VERIFIER
__(g144) f°133 “…better
understand low back pain factor… Aging &large daily loadings progressively
damage the IVD… Disc Degeneration (DD)… biomechanical changes mainly localized
in the nucleus pulposus (decrease of water content &proteoglycans), which
loses its gelatinous aspect. These alterations enforce the collagen network to
sustain higher stress, hence initiating macroscopic radial or circumferential
tears in the annulus fibrosus. Over a long period, these sequential events lead
to volume &shape modifications, such as a loss of disc height. Extra discal
damage (osteoarthritis, ostheophytes) can also appear… influence he mechanical
properties of he functional spinal unit… (FSU…).”
__(g157) “…The presence of tears in the collagen network influenced
instantaneous deformation; Hirsch &Nachemson (1954) demonstrated that his
phenomenon was more evident with a higher load (1000N).
… more dehydrated discs… had less damping capabilities than the other.”
__(g161) “better understanding
of the mechanisms implied in degeneration &their consequences on IDVs
load-carrying performance is therefore of high clinical significance.”
__( j ) “…la dégénérescence discale
entraîne une augmentation de la charge sur les facettes articulaires, et en
conséquence, une dégénérescence des facettes articulaires… Les facettes, en
présence de disques sains, supportent environ 10% de la compression du poids du
corps, et le complexe corps vertébral-disque-corps vertébral supporte 90% du
poids. Dans le cas d’une dégénérescence discale, les facettes doivent supporter
un poids de plus en plus important, pouvant aller jusqu’à 50-70% du poids
total.”
__(l6) lignes 33-45 “Tactical aircraft currently being developed
has increasing maneuvering capability with accompanying increasingly high
acceleration loads on the crewmembers. Resisting such high accelerations or “G”
force loads can cause excessive crew fatigue & a decrease in a crewmember’s
peak operating capability. Therefore, there is a need to assist crewmembers
in resisting the g loads experienced in high accelerations maneuvers in order
to prevent excessice fatigue & loss of operating capability. Known
torso restraint retraction systems do not fulfil this need because they are not
adapted to respond to in flight accelerations conditions.”
D’APRES LEUR ANGLE, LES SANGLES NE PASSENT PAS SOUS
ARMPITS, PAS DE TRACTION DU BUSTE NI DE SUPPORT FESSIER AMMOVIBLE
__(n1) “Abstract… Protecting
the head &neck &spinal cord from injuries resulting from rapid forward
deceleration &ejection… neck of human beings is at risk from lethal spinal
cord injury with rupture of the atlanto-occipital membrane which holds the base
of the skull to first cervical vertebra…”
__(n3) lignes 50-64 &
(n4) [Défaut des restraint
harnesses qui augmentent le whiplash de la tête : létal… idem in Formula racing
=> nécessité de soutenir la
tête.]
__(o) “Spinal impact associated with
ejection may result in vertebral compression fractures. The most common
fracture sites are T-12 and L-1, although other sites may be involved due
to poor body position (Rotondo, 1975).”
“One of the most vulnerable sites for injury of the spinal column
is the region around the eleventh and twelfth thoracic vertebrae (T11-T12).
From the eighth thoracic to the first lumbar vertebrae is the region of
greatest frequency due to the convergence of a multitude of factors. The
forward bending movement during ejection is accentuated because the center of
gravity of the head and torso is considerably anterior to the spinal plane
(Nuttal, 1971).”
__(q31-32) “Neck Pain
predisposing factors : /High +Gz
acceleration /High +Gz sustained for
long periods /High G onset rate /Helmet weight /Age /Flight
hours /Unprepared for manoeuvre.
Mechabnism of neck pain
a) Acute in-flight pain: /Ligamentous injury--muscle strain /cervical disk bulge , annular tear, C3-4
(Hämäläinen 1993) /compression
fracture (Andersen 1991)
/Fractured spinous process
/Facet joint dislocation
b) Degenerative disease: /Disk degeneration /Osteophytes…
Lifetime incidence of neck pain has beeb reported in the following
studies:
60% USN (Knudson 1988) 48% FAF
(Hämäläinen 1993) 63.6% 1 year
prevalence USAF (Vanderbeek 1988)
89.1% ‘checking 6’ in Japanese F15 (Kikukawa 1995)…
Some studies noted increased incidence with increased aircraft agility…
meta-analysis has now demonstrated a high level of probability that degenerative
spinal disease occurs more commonly in fighter pilots than age-matched
controls.
G related neck injury may become more prevalent over the next few years.
Unfortunately aircrew helmets are tending to become heavier rather than
lighter, with the addition of night vision equipment, FLIR cameras &helmet
mounted display systems. The centre of gravity of helmets & optics is a
major determinant of neck strain.”
__(s4-5) “neurological sequelae
of spinal injury, KS Mani, vol 17, summer 1974, N°1”
III. In
what pre-tension &tension is an advantage facing the current forced
compression distribution & facing
GLOC? (Over 1700 pounds)
__(a27) f°20 “Parachute opening & ejection shocks…
crushing resistance of the spiral column”
__(a94-97-101) f°87-90-94 [Studying prevention of ejection or
crash accident injuries]
“APPENDIX. FREE FALL ARREST NEW BODY CONTAINMENT DEVICE”
[Fall arrest “life jacket harness” [chest upper torso harness without
legs straps] preferred to waist belt & even to ejection seat
harness with leg straps: “straps around the legs… would have increased the
arrest load.” Note that our collapsing buttock support
advantageously replaces these legs straps.]
“A garment enveloping the whole of the upper torso. The principle
configuration of the straps was as such to encircle the torso & arm holes
of the lifejacket, and to provide a self-tightening feature… When a
fall-generated impact force was applied via the strop which connected the
harness to the aircraft, the loops of webbing around each arm hole would
tighten. This would hold the lifejacket closely around the upper torso, and
would offer two main advantages: …distributing the arrest load over
the whole upper torso. During testing, it was noted that the tension
around the chest… did not prevent breathing.”
__(a109) f°102 “Conclusion. This findings in this appendix
generally support & reinforce the conclusions in the main report (section
5) and the future research directions & recommendations for further
work (section6).”
“…close correlation between body harness design, energy absorbing
design and parachute opening testing practice… and that of corresponding
practices within the fall arrest industry.”
__(b19) f°8 “Harness
suspension: review & evaluation of existing information, by Paul
Seddon. Amphoux studied 5 subjects …ages of 18 & 59 during passive
suspension, using a torso harness, a parachute harness, a waist belt
with shoulder straps and a thoracic belt… The longest suspension time for
the torso harness was 43.25 minutes. The parachute harness was
tolerated for 28.17 minutes (Full body harness => compression); the thoracic
belt for one minute… 2 subjects… using the waist belt with shoulder straps
lasted one minute &3 minutes… (1982)
__(b30-32) f°21-23 “TILT
TABLE & DOUBLE –STROP SUSPENSION TESTS,
[P Madsen et al. 1996/97, Aviation, Space &Environment Medecine, 1998].
Although low blood pressure caused by
being in a vertical plane ¬ moving is usually not a problem, some
patients faint (which can lead to
death)…
Test 2 :
…subject to be suspended in a double padded strop arrangement. One strop
was placed around the thorax & connected to a rope, and the other strop was
passed under the legs just behind the knees &connected to the rope in the
same place as the first strop. On lifting the subject into a suspended
position, a sitting position was assumed, so that the upper part of the legs
was roughly just above horizontal:
Figure 2 : Suspension with a double-strop device (after Madsen). Thorax is
upright & venous return is secured by elevation of the legs…
subjects remained suspended without moving for one hour or until
pre-syncopal symptoms or signs appeared… only the female subject
…was taken down after 50 minutes.
__Sous 1G c’est le mode de suspension le plus
durable (1 heure+) sans blessures. See
syncope phenomenon in “Horizontal Tilt Table” (Capter title). Il se rapproche de notre system de
“fatigue counter measure” lors de son initialisation : notre support
s’affaissant les genoux sont plus haut que le pelvis + traction aux
épaules. Alors que tous les autres (full-body, chest harnesses, waist
belts…) sont dangereux beaucoup plus vite : Le full body ne tire pas sous les bras et les jambes
pendent. Le waist belt + sit harness n’élève pas les genoux. Le
chest harness occasionne du venous pooling dans les jambes qui pendent.
__Sous forts “G ” nos sangles dépaules
soulagent la sitting posture, mieux que sans traction. Les genoux
sont plus au dessus du bassin qui s’enfonce dans le support
ammovible : « venous return is
secured » => flux au cerveau maintenu + longtemps =>
G-LOC retardé
__(b43) f° 32 “If the legs
& arms aren’t moving, there is no pumping action, & blood tends
to stagnate in the arms &legs… there is less blood return to the heart… to
the head… what leads to the faintness.” (pre-syncope =pre-LOC)
__(b51) f°40 “interest of ‘muscle pumping’ …
legs in a substantially horizontal position or with the knees elevated (note
35).”
[Our system adds more movement liberties to the pelvis-legs & chest-arms
regions.]
__(b60) f°49 “[FALL ARREST,
Amphoux 1983 Toronto Fall Protection Seminar]… Amphoux considered the point of
attachment to the (full body) harness. He explained that whatever the place of
attachment, the cervical column (i.e. the spine at the neck) would always be
compressed. Tests carried out notably by the Japanese & the Americans on
dead bodies had indicated that the resistance of the vertebrae to
compression was less than to tension (idem P. 66, f°55)… especially true in
the most fragile part… the neck…”
See : www.dodsbir.net/sitis/view_pdf.asp?id=96-6.PDF Evaluation of an Energy
Absorbing Truck Seat for Increased Protection from Landmine Blasts, Alem & Strawn, Aircrew Protection Division, USAARL MINE CENTER BLAST EA (Energy
Absorber) SEATS :
_page 17 f°14 fig 1,
neck tension force : 750 to
250 LB
_page 28 f°25 fig 12, lumbar spine forces (100HZ
filter) : tension +700 LB to
-1329 compression
_page 20 f°17 fig 4,
Passenger EA seat acceleration : tension +22.76 LB to -42.76 compression.
(b60) f°49 continuation : “It
would be better for the compression to be localised on the body of the
vertebrae and not on the posterior joint, which were too fragile… Attachment
point would be better on the back than pre-sternal… 1800 pounds (8KN) is considered the appropriate maximum
arrest force… harnesses are to be used in arresting falls… (12 KN =
2,700 pounds threshold of significant injury incidence as for parachutists).”
__(b80) f°69 “Recommendations
for further work… As the majority of the body weight is usually taken by
the sub-pelvic &pelvic parts of the body, both during the arrest of a fall
& in suspension, research could be undertaken to examine the most
ergonomic designs for leg loops/thigh/waist support straps. In addition, similar
work could be undertaken for the chest &shoulder sections of
full body harnesses, as these also play a part in taking some of the load
in a fall & in providing support after the fall.”
__(c20) f°13 “center gravity of the trunk is in front
of the spinal column so that considerable muscular effort is required to keep
he spine in ‘optimum alignment’. The muscular effort thus induces disc
forces that are much higher than would be expected from the weight of trunk
above the disc… lumbar spine… intervertebral discs in this region of the
spine are 3 times stronger than the vertebrae… the apparent strengh of the
lumbar spine at these accelerations is the support given by the surrounding
muscular wall and other body tissue.”
[=> les vertèbres lombaires se fracturent plus
que leurs disques alors que les blessures cervicales concernent les 2 en même
temps (résistances avec ‘Compression Breaking Load’ proches. More, tension alleviates posture in profit of straining manoeuvers &
as a fatigue counter-measure]
__(c47-48) f°40-41 “Burton et
al. : Cervical spinal Injury
from Repeated Exposures to Sustained Acceleration, Research &Technology
Organisation of NATO (RO-TR-4)… Caused by manoeuvres in the range 4G to 9G.
Several pilots suffered bulging cervical discs.”
“Higher G levels may be an issue for flyers with relatively low density
of vertebrae.” [& low cross sectional vertebrae as with women crew]
“Review of the Vertebral Column Pain Problems in Polish Pilots
–Tatar et al… caused by rapid jolt & high acceleration values.”
__(c49) f° 42 Military Aircrew
Head Support System (MAHSS) : “Neck
injuries… during violent manoeuvres such as 8G turns… added weight of sophisticated
flying helmets… leading to incapacitating… (permanent physiological damage).
The problem is compounded if the airman has to eject at 16G, hence the
introduction of the MAHSS.” [Our
inflatable collar reduces neck compression and transmits head & helmet’s
weight in the tensioning shoulder & harness belts, thus discharging
spinal loads.]
__(c56) f°49 “Sances et al 1981 : Bioengineering Analysis of Head &Spine
Injuries… Spinal injuries from blows through the head to the spine
__(c57) f°50 “Schall D G : Non Ejection Cervical Spines
Injuries Due to +Gz in High Performance Aircraft.”
__(c59) f°52 “Snyder RG 1963 : Aerospace Medecine
Volume 34, N°.8, August 1963. When discussing +Gz seated impacts, (he)
states that “pelvic & vertebral trauma are prevalent… particularly
in the L-4 to T-12 area… supporting tissue structures… are
often damaged in impact but are not diagnosed due to more painful
complications masking such injuries.”
__(c61) f°54
“Swearingen JJ et al December 1960… Severe
organic pain :
stomach…”
__(c63) f°56 “edge-damage to the vertebrae (flexion or lateral bending)…” [See also
(a25) f°18 “adjacent spinal vertebrae…
square to each other. (Martin Baker)”]
__(e76) “slack in the restraint system can cause problems, including
‘submarining’…”
__(e87) Pretensioners
: “Crash sensors detect a crash pulse
that exceeds the predetermined initiation threshold…”
__(e92) Already mentioned
higher, in #I : “Acceleration-induced injuries are due to the body’s inertial
response to crash forces. An example of an acceleration injury is rupture of
the aorta in a high sink rate rotorcraft crash. Here the application of the
force occurs through the individual’s thighs, buttocks and back, where he is
contact with the seat. The injury mechanism itself is due to
tensile/shearing forces generated from the heart’s inertial response to the
resulting upward acceleration of the body. Other examples of acceleration
injuries include atlanto-occipital shearing [lethal],
vertebral fractures and contrecoup brain injuries.”
__(e96) “Restraint effectiveness with a SBS
(Integrated Seat Belt System, front crashes, BMW cars) : “Essentially a horizontal
belt run onto the shoulder, coupling the occupant more rapidly to the seat
and participating in the crash event as early as possible.” (Chest
acceleration drops from 48G to 34G with 29%
reduction). [With our device, same earlier participation during vertical
impact, & less dynamic overshoot]
__(f30)
Frontal impact: “When dual straps are
used the total strap loads may not exceed 8900N [(f36): 2000 pounds] …however
influenced by belt geometry, a factor not represented in the analysis.” [tolerances
should be improved by the prehensile harness around chest &armpits: wider
webbing/ webbing with a large width. See our system, & (f25) mentioned at #
I and II]
Abdominal
Injury “Considering the potential
severity of abdominal loading, it is recommended to avoid loading of the
abdominal area.”
“Compression loads on the spine frequently causes damage to the
vertebral column, particularly to the upper lumbar and lower thoracic
segment. This is especially true in aircrafts accidents when the impact
load normally involves a high magnitude vertical component.”
__(f49) “restraining methods
that will not contribute to injuries during a crash. Restraints should be
applied to portions of the body best able to withstand high impact
forces &accelerations like the shoulders… &pelvis.”
__(f50)
“provide energy absorbing mechanisms &materials in the structural design
that would attenuate crash forces…”
__(f52) “No seat structure
behind the pilot that would apply a dangerous compressive force to the spine
during a crash.”
__(f56) “…pelvic restraint in
the prone position would provide the advantage of tension rather than
compression loading of the lumbar spine… upper torso would displace forward
during a crash.”
__(f82) Test 2, frontal impact
“Spinal
compression loads were however induced by wedging of the upper body between the
angled shoulder straps &the seat base…” (but the LLC was not exceeded)
§
1st restraint concept of the Prone pilot
as indicated in Figure 4.22 (f76).
“…massive
spinal compression force was induced by the mass of the upper body &pelvis
impacting into the shoulders straps. This led to the conclusion that
sufficient pelvic restraint was vital to avoid high compression loads to
the spine in a frontal impact scenario.”
ET A CONCLUSION QUE CECI EST TRANSPOSABLE, A L’IMPACT
VERTICAL, AU SOULAGEMENT DE LA COMPRESSION LOMBAIRE SOUS LE POIDS DU BUSTE, EN
MODE ASSIS NORMAL
“The
hip belts did not restraint the pelvis from displacing forward because
the attachment angle was of such nature that the belts were not
elongated but only rotated around the seat attachment points by the pull
of the pelvis.”
TOUT COMME LE HARNAIS ACTUEL NE RETIENT PAS LE
THORAX DE DESCENDRE, SES SANGLES D’EPAULES, N’ETIRENT PAS AXIALEMENT LA COLONNE
ET FONT UNE ROTATION AUTOUR DE LEUR FIXATION, ENTRAINEES PAR LE POIDS APPARENT
DU THORAX
§
”In the proposal of the 2nd restraint
concept indicated in Figure 4.23… attachments of the hip belts were
moved backwards to offer more resistance to the forward pull of the pelvis...
two back straps achieved additional pelvic restraint.” [2nd restraint concept in Figure 4.23,
(f77)] ********BUT HUGE
TENSION*******
§
“From this exercise it was however
realised that there would exist a combination of belt slack &pretention
between the pelvic restraints &shoulder straps that would result in an
acceptable spinal loading scenario between the extreme tension
&compression cases :
In
the 3rd restraint concept in Figure 4.24, (f77)… “
“(Test
2, frontal impact) The lumbar spine load &head acceleration results for the
three prone concepts are contained in Figure E4 &E5…” (f 136).
[Figure
E4 :
Prone concept 3, +7000N extension
(green curve) –5000N compression]
(Figure
E4 : Prone concept 1, only compression,
blue curve. Prone concept 2, huge tension, red curve)
__(f85) “Conclusion : Although compression of he spine in the conventional pilot
position can be limited by following
the recommended shoulder harness &safety belt installations, it will
always be present due to the resultant force caused by the angle of the
shoulder straps & the seat structure below the pilot”. [cf. JAR 23 562 spec. (f123-124)]
__(f94) “Conclusion : …In comparison with the normal seated &supine seated
positions a pilot in the prone position would be exposed to much lower
spinal compression forces due to the orientation of the body with respect
to a crash load with both vertical &horizontal components… The
results of the different prone concepts indicated that spinal compression
during frontal impact case could be limited if adequate pelvic restraint was
provided. On the contrary, if the pelvis was restrained adequately but not with
sufficient upper body restraint a huge tension force was induced in the spine.
When analysing the final prone support-restraint proposal, it was however
discovered that a good balance between the two restraint systems could result
in acceptable spinal loads.”
__(f95) “…dynamic overshoot of the head …in
the prone position was limited by the inclusion of a chin rest…” [justify our
airbag collar in conventional position]
“Connecting
the helmet to the existing harness system of the prone positioned pilot will go
a long way to alleviate these problems without restricting the head’ freedom of
movement…
A
similar system called Head and Neck Support HANS in Formula 1 racing :
…
helmet is loosely connected to yoke through several tethers ensuring free
movement of the head. The yoke is on its turn fixed to the torso by belts thus
providing helmet restraint relative to the torso.
According
to Wright (2000) frontal impact tests with a Hybrid III ATD wearing the HANS
system produced similar results as that with an airbag system.”
__(f96) “…best results were obtained with restraint
concept 3…” (test 2 with frontal impact)
__(f116) “Compression of the spinal column
by… shoulder harnesses should be avoided.”
“The resultant restraint force shown in Figure B13 will place the spinal
column under compression, which will add to the stress on the vertebrae due to
the vertical deceleration in an accident.” [See (e77) at # IV below]
__(g16-f°4)
"…7 ligaments entre 2 vertèbres dont le rôle est uniquement de résister
au forces de tractions [tension/étirement de la colonne]." [ne s’opposent pas aux forces de
compression]
__(g19-f°8) “Nucleus pulposus : …Son liquide constamment sous pression
absorbe et répartit les charges et les chocs… doté d’un métabolisme actif,
assurant un renouvellement des protéoglycanes et du collagène… essentiellement
de type II… La matrice extra cellulaire du nucleus est biochimiquement
équivalente à celle du cartilage… avec des fibres de collagène entremêlées à de
large molécules de protéoglycanes (80% d’eau chez l’adulte de
20ans)."
__(g20-f°9)
Figure 3 : "Orientées à
+/-30°, les fibres de collagènes (type I) de l’annulus fibrosus entourent le
nucleus pulposus (aquaphile, 2 fois moins de collagène) [view figure 4
(g22-f°11)] en lamelles concentriques où l’orientation du collagène
s’inverse entre chacune d’elles."
Annulus
fibrosus
Nucleus
pulposus
[Cette orientation, à mi chemin entre l’horizontale
et la verticale, favorise la résistance de la colonne en tension/étirement
(axe longitudinal/vertical et aidée en cela par les ligaments), et aussi celle
du disque en tension circulaire d’évasement (axe transversal/horizontal) quand
la colonne est en compression]
"L’annulus externe est
lié aux vertèbres par les fibres de Sharpey tandis que l’interne l’est par les
plateaux cartilagineux."
__(g23-24, f° 12-13) "Comportement mécanique : Le nucleus transmet les charges compressives
à l’annulus sous forme de contraintes radiales ou tangentielles. En position
debout… DIV… contraintes compressives… transmission radiale de la charge, le
nucleus et l’annulus interne subissent une compression, tandis que les fibres
de l’annulus externe se trouvent en tension. Le disque augmente son rayon de
0.75mm pour une force de compression de 1000N. Sous une compression
prolongée, le nucléus peut perdre jusqu’à 20% d’eau. Inversement lorsque la
charge est réduite, le disque réabsorbe le liquide pour atteindre un nouvel
équilibre osmotique… processus menant au comportement viscoélastique… concerne
les matériaux biphasiques se comportant comme un fluide visqueux et un solide
élastique.
>> Le fluage, ou phénomène de déformation
croissante lorsqu’une contrainte constante est appliquée
>> La relaxation des contraintes, ou phénomène
de diminution des contraintes lorsqu’une déformation constante est appliquée.
Le fluage sous charge compressive s’explique par l’exsudation
du fluide qui a lieu en réponse au dépassement de la pression nucléaire
admissible. Si l’on applique au disque une contrainte constante, la déformation
augmente progressivement tant que le fluide continue à s’écouler. Lorsque l’ensemble
collagène-proteoglicanes est parvenu à équilibrer la charge externe,
l’exsudation tend à devenir constante.
L’origine de la relaxation de contraintes
provient également de l’exsudation de fluide.
Durant l’application d’un déplacement à une certaine
vitesse, une augmentation de la contrainte interne est générée par l’exsudation
forcée du fluide interstitiel et la compression de la matrice solide aux
environs de la surface. Lorsque le déplacement est maintenu, la relaxation de
la contrainte est en retour engendrée par la redistribution progressive du
fluide dans la matrice."
__(g24-25, f°13-14) "Dégénérescence du
disque intervertébral : La pathologie du disque intervertébral est un
problème épidémiologique majeur. Mécanismes responsables… problèmes de nutrition
du nucléus… mutations de protéines … accumulations de produits dégradés
dans la matrice… fracture par fatigue de la matrice fibreuse… nombre
d’artère (vascularisation) diminue… plateaux cartilagineux se calcifient,
perdant leur porosité…"
__(g34-35, f°23-24)
"Les disques dégénérés se caractérisent par une réponse en
déplacement plus grande que les disques sains : le nucleus perd en
incompressibilité et le réseau fibreux de l’annulus est endommagé.
__(g153-f°142) “Finally, disc degeneration effects on creep properties
have been demonstrated, notably stating higher creep rates for more degenerated
IVDs (Kazarian, 1975; Keller, et al., 1987; Li, et al., 1995).
Hirsh et Nachemson… ont été les premiers à
déterminer que la dissection des arcs postérieurs avait peu d’influence sur le
comportement en compression…
Le fluage… se traduit par la diminution de la hauteur du
disque au cours du temps sous l’application d’une charge compressive constante…
traduit la dualité de la composition tissulaire, à savoir la présence
d’un liquide visqueux et d’un solide élastique. En rhéologie, le premier peut
être assimilé à un amortisseur et le second à un ressort. L’association
en série ou en parallèle de 2 ou plusieurs de ces deux unités complémentaires
peut parvenir à traduire la réponse viscoélastique…
TRADUCTION
PARTIELLE
__(g152,
f°141) “IVD owes its viscoelastic behaviour to the combination of a liquid
phase (interstitial fluid composed of water, dissolved gas and small proteins)
and a solid phase (collagen fibres and proteoglycans) (Mow, et al., 1990). In
rheology, the first one can be related to a dashpot, and the second to a
spring. Series and/or parallel association of several of these units can
succeed in render the viscoelastic response of the connective tissue.”
L’unité Kelvin est un modèle rhéologique à 2
éléments, avec un ressort et un amortisseur en parallèle.
Keller et al. Réalisent un fluage de 30 minutes sous
un charge de 27 KG, en conservant les arcs postérieurs. Ils n’analysent que le
modèle à 3 paramètres, car lui seul peut être physiquement interprété. En
effet, le premier ressort E2 représente la déformation instantanée du disque
sous l’application soudaine de la charge ; l’unité Kelvin agit ensuite
pour progressivement diminuer la hauteur discale jusqu’à un état d’équilibre.,
mais à vitesse décroissante (appelée taux de fluage). Keller et al… notent
également, comme l’a fait Kazarian… avant eux, que le taux de fluage augmente
de façon très importante (facteur 2) dans le cas de disques dégénérés :
ceux-ci deviennent moins visco-élastiques. Le fluage (charge
constante) est responsable d’une perte de hauteur globale des individus entre
le matin et le soir… 18mm en moyenne pour une personne jeune… 13mm pour une
personne plus âgée."
__(g47-48, f°36-37) "Chapitre 3, Imagerie et Evaluation de la
Mobilité : …Avec les multiples sollicitations qu’il doit
quotidiennement subir, le DIV est progressivement soumis à des dégradations
liées en partie au vieillissement, plus qu’aucun autre tissu mou du système
musculo-squelettique… Ce phénomène, appelé dégénérescence discale…s’exprime au
travers de modifications biochimiques principalement localisées dans le nucléus
pulposus (baisse de la teneur en eau et en protéoglicanes) qui perd son aspect
gélatineux. Ces altérations imposent au réseau de collagène de résister à des
charges plus importantes, ce qui engendre des initiations de ruptures menant à
des fissures radiales ou circonférentielles macroscopiques dans l’annulus
fibrosus… à terme des modifications de volume et de forme, notamment une perte
de hauteur. A ces endommagements intra-discaux peuvent s’associer une arthrose
des facettes articulaires et la formation d’ostéophytes sur les corps
vertébraux."
TRADUCTION CI-DESSOUS
A VERIFIER
__(g144) f°133 “…better
understand low back pain factor… Aging &large daily loadings progressively
damage the IVD… Disc Degeneration (DD)… biomechanical changes mainly localized
in the nucleus pulposus (decrease of water content &proteoglycans), which
loses its gelatinous aspect. These alterations enforce the collagen network to
sustain higher stress, hence initiating macroscopic radial or circumferential
tears in the annulus fibrosus. Over a long period, these sequential events lead
to volume &shape modifications, such as a loss of disc height. Extra discal
damage (osteoarthritis, ostheophytes) can also appear… influence he mechanical
properties of he functional spinal unit… (FSU…).”
__(g69-f°58)
"Finalement, l’effet de la dégénérescence de DIV sur ses propriétés
en fluage a été mis en évidence à plusieurs reprise, faisant état notamment
d’un taux de fluage plus élevé dans le cas des DD [Disk Degeneration]."
__(g83-f°72)
"D’après Mow… une charge appliquée sur le DIV donne un gradient
pression, un mouvement de fluide dont une grande partie est extrudée. Le
frottement oppose une résistance au passage dans la matrice solide, d’où
dissipation visqueuse (chaleur), d’où une réponse fonction du temps mais réversible,
d’où l’amortissement du DIV, soit la capacité à dissiper l’énergie mécanique en
chaleur qui s’exprime dans les courbes d’hystérésis. La déformation élastique
instantanée est le réarrangement immédiat du réseau de collagène dans la
structure. Il y a corrélations entre hystérésis, déformation fluée et
pourcentage de charge relaxée ; logique cohérente pour la physique."
TRADUCTION
CI DESSOUS
__(g145) “When a load is maintained on an IVD, a pressure gradient appears
that initiates fluid motion (Mow, et al., 1990); a large amount of this fluid
is extruded. However, resistance is opposed to the flow due to the friction
forces through the solid matrix, resulting in a viscous dissipation. Since delayed,
mechanical responses are therefore timedependent. Damping is the result of
IVD’s ability to dissipate mechanical energy into heat, a phenomenon that is
directly responsible for hysteresis. The instantaneous elastic deformation is
caused by a rearrangement of collagen fibres network (Hickey and Hukins, 1980).
Correlations revealed between hysteresis, creep strain and percentage of load
relaxed, between creep damping and hysteresis, and independence of E2 with regard to E1 and ç hence
followed logical physical coherence.”
__(g157) “…The presence of tears in the collagen
network influenced instantaneous deformation; Hirsch &Nachemson (1954)
demonstrated that his phenomenon was more evident with a higher load (1000N).
…more
dehydrated discs… had less damping capabilities than the other.”
__(g161) “Though able to sustain high load magnitudes
in various directions according to the individual posture… better understanding
of the mechanisms implied in degeneration &their consequences on IDVs load-carrying
performance is therefore of high clinical significance.”
__(h) [Traction] “Tissu cortical : l'os compact peut être considéré comme
transversalement isotrope ce qui signifie que dans le plan perpendiculaire à la
direction longitudinale les propriétés sont les mêmes dans toutes les
directions… Tissu discal : les résultats de Markolf… en
1972 montrent que le disque lombaire et dorsal est plus souple en traction
qu'en compression…”
__(i) “En effet, l’application d’une traction
pendant la phase de dépériostage permet non seulement de stabiliser la colonne
vertébrale pendant ce temps opératoire mais surtout d’assouplir le rachis en
profitant de son comportement viscoélastique. ”
__( j ) “… la dégénérescence discale
entraîne une augmentation de la charge sur les facettes articulaires, et en
conséquence, une dégénérescence des facettes articulaires… Les facettes, en
présence de disques sains, supportent environ 10% de la compression du
poids du corps, et le complexe corps vertébral-disque-corps vertébral supporte
90% du poids. Dans le cas d’une dégénérescence discale, les facettes doivent
supporter un poids de plus en plus important, pouvant aller jusqu’à 50-70% du
poids total. ”
__(k10) Ligne 23
“Apart from the immediate dangers of involuntary movements occurring
during a high speed manoeuvre the cumulative effects of G-force on the
pilot’s head &body cause pilot fatigue which also impairs pilot performance.
It would therefore be to a pilot’s advantage if the effect of high G-forces
could be compensated for or reduced in some way.”
__(L1) “Abstract… crewmembers are subjected to periodic high acceleration
loads that cause fatigue & a decrease in operating capacity. Restraining
the torso of a crew member &pulling the crew member back against the
ejection seat… would help prevent such fatigue.”
__(l6) lignes 33-45 “Tactical aircraft currently being developed has increasing
maneuvering capability with accompanying increasingly high acceleration loads
on the crewmembers. Resisting such high accelerations or “G” force loads can
cause excessive crew fatigue & a decrease in a crewmember’s peak operating
capability. Therefore, there is a need to assist crewmembers in resisting
the g loads experienced in high accelerations maneuvers in order to prevent
excessice fatigue & loss of operating capability. Known torso
restraint retraction systems do not fulfil this need because they are not
adapted to respond to in flight accelerations conditions.”
D’APRES LEUR ANGLE, LES SANGLES NE PASSENT PAS SOUS
ARMPITS , PAS DE TRACTION DU BUSTE NI DE SUPPORT FESSIER AMMOVIBLE
__(m5) lignes 9-17
“…improved aircraft manoeuverability is counterproductive if the
resulting forces imposed on the unprotected pilot are beyond human tolerances.
One can only speculate as to the number of fighter aircraft lost as a result of
pilot blackout…”
__(o) “Spinal impact associated with
ejection may result in vertebral compression fractures. The most common
fracture sites are T-12 and L-1, although other sites may be involved due
to poor body position (Rotondo, 1975).”
“One of the most vulnerable sites for injury of the spinal column
is the region around the eleventh and twelfth thoracic vertebrae (T11-T12).
From the eighth thoracic to the first lumbar vertebrae is the region of
greatest frequency due to the convergence of a multitude of factors. The
forward bending movement during ejection is accentuated because the center of
gravity of the head and torso is considerably anterior to the spinal plane
(Nuttal, 1971).”
“A tight coupling between the occupant and the seat helps to keep the
dynamic response and acceleration "over shoot" of the occupant within
tolerable limits.”
“The ballistic powered shoulder harness inertial reel is mounted to the
back of the seat with its straps connected to the parachute risers which in
turn are attached through the parachute release fittings to the occupant's
upper portion of the PCU torso harness… During ejection, a cartridge is fired
to retract the shoulder harness which helps to position and restrain the
occupant for ejection. Under some conditions, it simply tightens the harness,
straining against centrifugal or inertial forces acting on the occupant's
torso. The seat backrest, head rest, bucket, and sides provide passive
restraint in addition to the active restraint harness described above… injuries include improper position of the body at time of ejection,
varied tension of the restraint harness, inverted or negative G flight
conditions at the time of ejection, improper seat and seat back cushioning,
offset between body center of gravity and the upward and backward
(approximately 18o from vertical) thrust line of the catapult, and
through-the-canopy ejection. The 18o mentioned
varies considerably from one seat to another.”
__(p896) cap 22-20 “We can demonstrate a clear relationship between through-the-canopy
ejection with higher peak G catapults and the incidence of vertebral fracture.
We "know" that improper body position (including a loose harness)
increases the risk of injury.”
__(p897) cap 22-21 “Overshoot effects can be particularly severe on internal organs,
which have their own dynamic response to catapult forces. Krefft (1974) discusses the various forces and stresses imposed on the
internal organs during ejection. These organs may be subject to severe
deformation and tensile stresses. During ejection, the vertical acceleration
forces may combine with the transverse shock from the ram air pressure.
This transverse jolt against the thorax is immediately transmitted to the heart
at its location at the anterior internal chest wall. Here, the shock leads to a
compression where hemodynamic forces can exceed the elasticity modulus of the
tissue, and ruptures may be sustained because of local overstretching. It must
be pointed out, however, that these are extremely remote possibilities.”
__(q17-18) “LUNG CAPACITIES :
The Diaphragm descends under +Gz acceleration due to the increased
weight of the abdominal contents &the increased weight of the diaphragm
itself. As it descends, it acts like a piston in a cylinder to draw in air into
he chest.
Diaphragms descends by:
1cm at +2Gz ~ 300 ml
2cm at +4Gz ~ 500 ml
Diaphragmatic descent explains the increase in FRC seen in under
increased +Gz acceleration.
If, however, the subject wears an anti-G suit (which inflates above +2
Gz), the abdominal bladder of the garment splints the diaphragm, &prevents
diaphragmatic descent (the diaphragm may even be elevated). Therefore there is
no increase in FRC, and it may even become reduced.”
AVEC NOTRE SYST. LE DIAPHRAGME DESCEND DEPUIS PLUS HAUT => FRC AUGMENTE
__(q31-32) “Neck Pain
predisposing factors : /High +Gz
acceleration /High +Gz sustained for
long periods /High G onset rate /Helmet weight /Age /Flight
hours /Unprepared for manoeuvre.
Mechabnism of neck pain
a) Acute in-flight pain: /Ligamentous injury--muscle strain /cervical disk bulge , annular tear, C3-4
(Hämäläinen 1993) /compression
fracture (Andersen 1991)
/Fractured spinous process
/Facet joint dislocation
b) Degenerative disease: /Disk degeneration /Osteophytes…
Lifetime incidence of neck pain has beeb reported in the following
studies:
60% USN (Knudson 1988) 48% FAF
(Hämäläinen 1993) 63.6% 1 year
prevalence USAF (Vanderbeek 1988)
89.1% ‘checking 6’ in Japanese F15 (Kikukawa 1995)…
Some studies noted increased incidence with increased aircraft agility…
meta-analysis has now demonstrated a high level of probability that degenerative
spinal disease occurs more commonly in fighter pilots than age-matched
controls.
G related neck injury may become more prevalent over the next few years.
Unfortunately aircrew helmets are tending to become heavier rather than
lighter, with the addition of night vision equipment, FLIR cameras &helmet
mounted display systems. The centre of gravity of helmets & optics is a
major determinant of neck strain.”
__(q38) “… Gz
improvement, but gives more when used in combinaison with elevated legs.”
IV. What
loads (maximum) could support the chest & armpits (discharge & fatigue
counter measure)?
__(a15) f°8 “Arrested fall
simulating : …simulated fall, to
ensure that recorded shock loadings were below the levels that were known to
cause injury”
__(a18) f°11 “Figure 5 showing
some upper torso applied traction.”
__(a21) f°14 “Human volunteers
test” [Dr Amphoux Chest harness
: no linkage with pelvis]
“free falls with no unterward results, but two rib fractures after some
0,6m fall tests” [but without buttock supporting the lower body]
__(a26) f°19 [Same tests] “As reported in Hearon in Brinkley
(1984)… 30 drop tests… maximum arrest force of 4.8 KN, fall distance of 0.8m … 7G…
volunteers wore chest harness”
[Mais ici tout le poids
apparent du full body, sous 7G, est absorbé dans le upper torso --harnais décrit en (a21) f°14. Les épaules supporteraient la
même force sous 14G (soit le double =force éjection) si le pelvis est soutenu.]
__(a22-23) f°15-16 Reader.
“Waist belt suspension.”
__(a72) f°65 “Conclusions
: …Drop test conducted with
human have produced tolerable deceleration of 5-12G… force equivalent of 4.9
– 13,2 kN applied in the… Z axis via parachute shoulder riser straps”
__(a73-74) f°66-67 “Feet first trajectory, fall arrest human
drop tests :
Aircraft ejection seat criteria only apply with the spinal column
being kept erect…
Parachute opening criteria… feet first
trajectory only, based on shoulder structure strength
__(a79) f°72 [With dummy] “interactions between components, the
stretching of the safety harness & the flexing of the dummy all contribute
to energy dissipation”
__(a89) f°82 Stevens G.W.H. (1968) “Ply-Tear Webbing as an Energy Absorber”
__(a92) f°85 “APPENDIX …personnel wearing abdominal belts
should be subject to no more than 5g deceleration …(safe upper limit)”
[=> Epaules et surtout
abdomen supportent 500kg avec colonne en extension]
__(a94-97-101) f°87-90-94 [Studying prevention of ejection or
crash accident injuries]
“APPENDIX, FREE FALL ARREST
NEW BODY CONTAINMENT DEVICE”
[Fall arrest “life jacket harness” [chest upper torso harness without
legs straps] preferred to waist belt & even to ejection seat
harness with leg straps: “straps around the legs… would have increased the
arrest load.” Note that our collapsing
buttock support advantageously replaces these legs straps.]
“A garment enveloping the whole of the upper torso. The principle
configuration of the straps was as such to encircle the torso & arm holes
of the lifejacket, and to provide a self-tightening feature… When a
fall-generated impact force was applied via the strop which connected the
harness to the aircraft, the loops of webbing around each arm hole would
tighten. This would hold the lifejacket closely around the upper torso, and
would offer two main advantages: …distributing the arrest load over
the whole upper torso. During testing, it was noted that the tension
around the chest… did not prevent breathing.”
“Suspension : Comfort
when suspended was acceptable… high loads under the armpit and over the
lower ribs… acceptable in an emergency.”
“Drop test :
>> a free fall of 1.0m…
at this drop height with other harness assemblies, the velocity…imposes…
10G on the dummy…
>> however with the life
jacket harness, a free fall of 1.14 m produced a peak arrest load of
5,6 kN, equating to a deceleration of only 5.3G…
>> free falls of 2.0 m
and 3.0 m realised peak arrest loadings of 7.4 kN and 10 kN
and maximum deceleration of 7G and 9.5G respectively…
…the life jacket-harness rose up over the dummy’s chest until fully
arrested by the armpits straps and the self tensioning of the assembly around
the chest… relative movements reduced the expected loads because the
deceleration pulse time & distance were effectively increased… if the
fall arrest forces were needed to be cushioned further then ‘ply-tear’
webbing could be utilised in the lifejacket-harness.” [=tear-web material = energy absorber
within lanyards]
__(a109) f°102 “Conclusion. This findings in this appendix
generally support & reinforce the conclusions in the main report
(section 5) and the future research directions & recommendations for
further work (section6).”
“…close correlation between body harness design, energy absorbing
design and parachute opening testing practice… and that of corresponding
practices within the fall arrest industry.”
__(b19) f°8 “Harness
suspension: review & evaluation of existing information, by Paul
Seddon. Amphoux studied 5 subjects …ages of 18 & 59 during passive
suspension, using a torso harness, a parachute harness, a waist belt
with shoulder straps and a thoracic belt… The longest suspension time for
the torso harness was 43.25 minutes. The parachute harness was
tolerated for 28.17 minutes” [Full body harness => compression] “the
thoracic belt for one minute… 2 subjects… using the waist belt with shoulder
straps lasted one minute &3 minutes… (1982)”
__(b59) f°48 "[FALL
ARREST, Amphoux 1983 Toronto Fall Protection Seminar] …The pelvis was the
most favourable place for the part where the stress of the harness straps would
be applied.” [but with extreme compression] “However, the shoulders
& thorax could endure forces of the same level… (6KN =1350 pounds)”
__(b60) f°49 “… Amphoux
considered the point of attachment to the (full body) harness. He explained
that whatever the place of attachment, the cervical column (i.e. the spine at
the neck) would always be compressed. Tests carried out notably by the Japanese
& the Americans on dead bodies had indicated that the resistance of the
vertebrae to compression was less than to tension (idem P. 66, f°55)…
especially true in the most fragile part… the neck…”
See : www.dodsbir.net/sitis/view_pdf.asp?id=96-6.PDF Evaluation of an Energy
Absorbing Truck Seat for Increased Protection from Landmine Blasts, Alem & Strawn, Aircrew Protection Division, USAARL MINE CENTER BLAST EA (Energy
Absorber) SEATS :
_page 17 f°14 fig 1,
neck tension force : 750 to
250 LB
_page 28 f°25 fig 12, lumbar spine forces (100HZ
filter) : tension +700 LB to
-1329 compression
_page 20 f°17 fig 4,
Passenger EA seat acceleration : tension +22.76 LB to -42.76 compression.
(b60) f°49 continuation : “It
would be better for the compression to be localised on the body of the
vertebrae and not on the posterior joint, which were too fragile… Attachment
point would be better on the back than pre-sternal… 1800 pounds (8KN) is considered the appropriate maximum
arrest force… harnesses are to be used in arresting falls… (12 KN =
2,700 pounds threshold of significant injury incidence as for parachutists).”
__(b80) f°69 “Recommendations
for further work… As the majority of the body weight is usually taken by
the sub-pelvic &pelvic parts of the body, both during the arrest of a fall
& in suspension, research could be undertaken to examine the most
ergonomic designs for leg loops/thigh/waist support straps. In addition, similar
work could be undertaken for the chest &shoulder sections of
full body harnesses, as these also play a part in taking some of the load
in a fall & in providing support after the fall.”
__(c20) f°13 “center gravity of the trunk is in front
of the spinal column so that considerable muscular effort is required to
keep he spine in ‘optimum alignment’. The muscular effort thus
induces disc forces that are much higher than would be expected from the weight
of trunk above the disc… lumbar spine… intervertebral discs in this region
of the spine are 3 times stronger than the vertebrae… the apparent strengh
of the lumbar spine at these accelerations is the support given by the surrounding
muscular wall and other body tissue.”
[So as a fatigue counter-measure, tension may alleviate this posture
effort & in profit of the straining manoeuvers]
__(d94-102) f°85-93 “CAGGED LADDER TESTS 5 & 6”
[without sliding arrest device, ATDummy is free here]
[6 : freiné par le contact du
dos et arrêt par 1 armpit supporte l’ATD étiré aussi par une jambe
en l’air. è TENSION NO INJURY] [5 : arrêt par les armpits mais accéléromètre inopérant
2G estimés. è TENSION NO INJURY]
__(d164) f°155
[Suspension à 1 (ou 2) armpit dans l’accélération finale]
“tests 5, 6… no spinal injury… tests 5, 6 : Injury would probably been limited to the
armpits & arms…” [But would
certainly not, with adequate chest harness arrest fall and without the weight
of the lower body. Test
6 : vertebraes support +4,18 G
headwards in tension]
__(d197) f°188 [fig. 103 test 6 z axis amplitude : +4,18G to
-4,58G . Au moins 3 fois, in the time trace]
__(e54)
”Mine blast... human neck criteria with axial compression loading : 4912 N (at
0 ms)...
human neck criteria with axial tension loading : 4052 N (at 0
ms)”
__(e56) Table 6 : “Other than the specific z-axis
(vertical) requirement, the injury criteria can also provide guidance
in standard crash impact testing orientations…
Recommended
Injury Criteria for Landmine testing:
Dummy
lumbar spine axial compression force
6673 N (0 ms)
Dummy
lumbar spine axial tension force
12700 N (0 ms)”
To
confirm the ratio in Amphoux reports from studies on cadavers. See upper
(b60-f°49) & below (f28)
__(e76)
Restraint system: “pre-load of
100-lbs. Applied”
Comfort: “Occupant discomfort may induce fatigue that can contribute to and
cause crash”
__(e77) Figure 37
“Adverse Loading Effects of Shoulder Straps Loads”
“…shoulder
straps at an angle below the horizontal adds additional compressive
force to the occupant’s spine.” (So even in the [-5,0]° range)
__(e93) “hazards associated with the operational environment of military
wheeled-ground vehicle also place a vertical (z-axis) response requirement
on the vehicle’s occupant protection system. Occupant inertial response to mine
blast forces and rough terrain maneuvers [Fatigue] requires
that the energy associated with these hazards be managed to preclude
spinal injuries.” [Also mentioned in #II]
__(e95) “The most predominant impact direction
for a helicopter occupant is vertical (i.e., eyeballs downward). A
shoulder harness increases human tolerance without injury for the vertical
direction from 4-G’s to 25-G’s, an improvement factor of six. A shoulder
harness occupant survivability in the vertical impact scenario because it
retains the occupant’s pre-crash position (i.e., upper torso remains
essentially upright), keeping the spinal column aligned properly and allowing
it to carry much higher crash loads… Laterally, the shoulder harness increases
tolerance by a factor of two.” [more tolerance improvements can be expected
with our method by a new factor, because of reduced compression]. Already
mentioned in #I. See also (f34).
__(f28) “Neck injury tolerance values : Axial compression
(-Fe) -4000N
Axial
tension (+Fz) 3300N [See higher, (e56)]
__(f49) “restraining methods
that will not contribute to injuries during a crash. Restraints should be
applied to portions of the body best able to withstand high impact
forces &accelerations like the shoulders… &pelvis.”
(Already mentioned at # III)
__(f56) “…pelvic restraint in
the prone position would provide the advantage of tension rather than
compression loading of the lumbar spine… upper torso would displace forward
during a crash.”
__(f82)
“1st restraint concept”
of the Prone pilot as indicated in Figure 4.22 (f76).
“…massive
spinal compression force was induced by the mass of the upper body &pelvis
impacting into the shoulders straps. This led to the conclusion that
sufficient pelvic restraint was vital to avoid high compression loads to
the spine in a frontal impact scenario.”
ET
A CONCLUSION QUE CECI EST TRANSPOSABLE, A L’IMPACT VERTICAL, AU SOULAGEMENT DE
LA COMPRESSION LOMBAIRE SOUS LE POIDS DU BUSTE, EN MODE ASSIS NORMAL.
__(g34-35, f°23-24) [Charge on the facets] "Les disques dégénérés se caractérisent
par une réponse en déplacement plus grande que les disques sains : le
nucleus perd en incompressibilité et le réseau fibreux de l’annulus est
endommagé.
TRADUCTION PARTIELLE
__(g153-f°142) “Finally, disc degeneration effects on
creep properties have been demonstrated, notably stating higher creep rates for
more degenerated IVDs (Kazarian, 1975; Keller, et al., 1987; Li, et al., 1995).
Hirsh et Nachemson… ont été les premiers à
déterminer que la dissection des arcs postérieurs avait peu d’influence sur le
comportement en compression…
Keller et al… notent également, comme l’a fait
Kazarian… avant eux, que le taux de fluage augmente de façon très importante
(facteur 2) dans le cas de disques dégénérés : ceux-ci deviennent moins
visco-élastiques. Le fluage (charge constante) est responsable d’une
perte de hauteur globale des individus entre le matin et le soir… 18mm en
moyenne pour une personne jeune… 13mm pour une personne plus âgée."
__(g47-48, f°36-37) "Chapitre 3, Imagerie et Evaluation de la
Mobilité : …Avec les multiples sollicitations qu’il doit
quotidiennement subir, le DIV est progressivement soumis à des dégradations
liées en partie au vieillissement, plus qu’aucun autre tissu mou du système
musculo-squelettique… Ce phénomène, appelé dégénérescence discale…s’exprime au
travers de modifications biochimiques principalement localisées dans le nucléus
pulposus (baisse de la teneur en eau et en protéoglicanes) qui perd son aspect
gélatineux. Ces altérations imposent au réseau de collagène de résister à des
charges plus importantes, ce qui engendre des initiations de ruptures menant à
des fissures radiales ou circonférentielles macroscopiques dans l’annulus
fibrosus… à terme des modifications de volume et de forme, notamment une perte
de hauteur. A ces endommagements intra-discaux peuvent s’associer une arthrose
des facettes articulaires et la formation d’ostéophytes sur les corps
vertébraux."
TRADUCTION CI-DESSOUS
VERIFIER
__(g144) f°133 “…better
understand low back pain factor… Aging &large daily loadings progressively
damage the IVD… Disc Degeneration (DD)… biomechanical changes mainly localized
in the nucleus pulposus (decrease of water content &proteoglycans), which
loses its gelatinous aspect. These alterations enforce the collagen network to
sustain higher stress, hence initiating macroscopic radial or circumferential
tears in the annulus fibrosus. Over a long period, these sequential events lead
to volume &shape modifications, such as a loss of disc height. Extra discal
damage (osteoarthritis, ostheophytes) can also appear… influence the mechanical
properties of the functional spinal unit… (FSU…).”
__(g69-f°58)
"Finalement, l’effet de la dégénérescence de DIV sur ses propriétés
en fluage a été mis en évidence à plusieurs reprise, faisant état notamment
d’un taux de fluage plus élevé dans le cas des DD [Disk Degeneration]."
__(g157)
“…The presence of tears in the collagen network influenced instantaneous
deformation; Hirsch &Nachemson (1954) demonstrated that his phenomenon was
more evident with a higher load (1000N).
…more
dehydrated discs… had less damping capabilities than the other.”
__(g161) “Though able to sustain high load magnitudes
in various directions according to the individual posture… better
understanding of the mechanisms implied in degeneration &their consequences
on IDVs load-carrying performance is therefore of high clinical significance.”
__(k10) Ligne 23
“Apart from the immediate dangers of involuntary movements occurring
during a high speed manoeuvre the cumulative effects of G-force on the
pilot’s head &body cause pilot fatigue which also impairs pilot performance.
It would therefore be to a pilot’s advantage if the effect of high G-forces
could be compensated for or reduced in some way.”
__(L1) “Abstract… crewmembers are subjected to periodic high acceleration
loads that cause fatigue & a decrease in operating capacity. Restraining
the torso of a crew member &pulling the crew member back against the
ejection seat… would help prevent such fatigue.”
__(l6) lignes 33-45 “Tactical aircraft currently being developed has increasing
maneuvering capability with accompanying increasingly high acceleration loads
on the crewmembers. Resisting such high accelerations or “G” force loads can
cause excessive crew fatigue & a decrease in a crewmember’s peak operating
capability. Therefore, there is a need to assist crewmembers in resisting
the g loads experienced in high accelerations maneuvers in order to prevent
excessice fatigue & loss of operating capability. Known torso
restraint retraction systems do not fulfil this need because they are not
adapted to respond to in flight accelerations conditions.”
D’APRES LEUR ANGLE, LES SANGLES NE PASSENT PAS SOUS
ARMPITS, PAS DE TRACTION DU BUSTE NI DE SUPPORT FESSIER AMMOVIBLE
__(m5) lignes 9-17
“…improved aircraft manoeuverability is counterproductive if the
resulting forces imposed on the unprotected pilot are beyond human tolerances.
One can only speculate as to the number of fighter aircraft lost as a result of
pilot blackout…”
__(q31-32) [Anti fatigue]
“Unfortunately aircrew helmets are tending to become heavier rather than
lighter, with the addition of night vision equipment, FLIR cameras &helmet
mounted display systems. The centre of gravity of helmets & optics is a
major determinant of neck strain.”
__(q37-38) [Anti
fatigue] “High +Gz
associated forearm pain :
High venous pressure exists in the arms if they are in a dependant
position (ie below heart level) under high +Gz acceleration. This may be up to
270 – 300 mmHg at +9Gz. These high pressures are associated with deep, poorly
localised pain, which may be due to venous or arterial over-distension…
Possible solutions to armpain include raising the arms (high stick
&throttle) to minimise the height of the hydrostatic column, providing
arm counter pressure with or without hand counter pressure, and (possibly)
reducing PBG pressure.”
“… Gz improvement, but gives more when used in combination with
elevated legs.”
__(t26) [Anti fatigue]
“heat stress hot topic…”
V. May our system be active
partially at parachute opening shock?
__ Yes! only with the collar inflation device.
__(f95) “…dynamic overshoot of the head …in
the prone position was limited by the inclusion of a chin rest…” [justify our
airbag collar in conventional position]
“Connecting the helmet to the existing harness system of the prone
positioned pilot will go a long way to alleviate these problems without
restricting the head’ freedom of movement…
__(p905/906) cap 22, 29/30 “The higher the altitude for a given speed, the higher the opening shock
will generally be. The higher the speed, the higher the opening shock will
generally be. Asymmetrical inflation of the canopy produces high localized
stresses in the canopy, premature inflation results in a larger than normal
mass (i.e.,including trapped air) being accelerated at line stretch… Terminal
velocity increases at altitude, with the result that parachute opening shock is
generally increased to a point where damage to the parachute structure or
injury to the aircrewman may result… High-speed parachute opening tests
(200-300 KEAS) were conducted years ago to determine parachute system integrity
and the effects of acceleration and opening shock levels with regard to human
injury (Dahnke, Palmer, & Ewing, 1976). These results showed that
high-speed parachute opening can produce catastrophic damage to the canopy…”
__(p906/908) cap 22, 30/32 5/25G+ Parachute range opening shock.
“Smaller canopies impart a greater G-loading during opening than do
larger ones.”
__(r) “A 20G impact is not even particularly severe; parachute-opening
shocks reach that level. Catapult ejection forces & the abnormal
vertebral column NS Bahgwanani
volume 20 summer 1976 N°1 ”
VI. How
retention for loading above 1G can be expected/forwarded & be positively
comforted? (After Madsen p. 3,
After Pretoria thesis)
__(a80) f°73 “Thresholds could also be based on areas
of the body rather than blanket approaches”
__(a109) f°102 “Conclusion. This findings in this appendix
generally support & reinforce the conclusions in the main report
(section 5) and the future research directions & recommendations for
further work (section6).”
“…close correlation between body harness design, energy absorbing
design and parachute opening testing practice… and that of corresponding
practices within the fall arrest industry.”
__(b19) f°8 “Harness
suspension: review & evaluation of existing information, by Paul
Seddon. Amphoux studied 5 subjects …ages of 18 & 59 during passive
suspension, using a torso harness, a parachute harness, a waist belt
with shoulder straps and a thoracic belt… The longest suspension time for
the torso harness was 43.25 minutes. The parachute harness was
tolerated for 28.17 minutes (Full body harness => compression); the
thoracic belt for one minute… 2 subjects… using the waist belt with shoulder
straps lasted one minute &3 minutes… (1982)
__(b30-32) f°21-23 “TILT
TABLE & DOUBLE –STROP SUSPENSION TESTS,
[P Madsen et al. 1996/97, Aviation, Space &Environment Medecine,
1998]. Although low blood pressure
caused by being in a vertical plane ¬ moving is usually not a problem,
some patients faint (which can lead
to death)…
Test 2 :
…subject to be suspended in a double padded strop arrangement. One strop
was placed around the thorax & connected to a rope, and the other strop was
passed under the legs just behind the knees &connected to the rope in the
same place as the first strop. On lifting the subject into a suspended
position, a sitting position was assumed, so that the upper part of the legs
was roughly just above horizontal:
Figure 2 : Suspension with a double-strop device (after Madsen). Thorax is
upright & venous return is secured by elevation of the legs…
subjects remained suspended without moving for one hour or until
pre-syncopal symptoms or signs appeared… only the female subject
…was taken down after 50 minutes.
This subject also took part in the head-up tilt tests where she
experienced pre-syncopal symptoms after only 5 minutes. (See “Tilt
Table”)… Leg elevation prevented vasovagal reactions in 8 out of 9
subjects… a much lower risk of pre-syncope than during the head-up tilt test
(1).
__Sous 1G c’est le mode de suspension le plus
durable (1 heure+) sans blessures. See
syncope phenomenon in “Horizontal Tilt Table” (Capter title). Il se rapproche de notre system de
“fatigue counter measure” lors de son initialisation : notre support
s’affaissant les genoux sont plus haut que le pelvis + traction aux
épaules. Alors que tous les autres (full-body, chest harnesses, waist belts…)
sont dangereux beaucoup plus vite :
Le full body ne tire pas sous les bras et les jambes pendent.
Le waist belt + sit harness n’élève pas les genoux. Le chest harness
occasionne du venous pooling dans les jambes qui pendent. __Sous forts “G ” nos sangles dépaules
soulagent la sitting posture, mieux que sans traction. Les genoux
sont plus au dessus du bassin qui s’enfonce dans le support
ammovible : « venous return is
secured » => flux au cerveau maintenu + longtemps =>
G-LOC retardé
__(b43) f° 32 “If the legs
& arms aren’t moving, there is no pumping action, & blood tends
to stagnate in the arms &legs… there is less blood return to the heart… to
the head… what leads to the faintness.” (pre-syncope =pre-LOC)
__(b51) f°40 “interest of ‘muscle pumping’ …
legs in a substantially horizontal position or with the knees elevated (note
35).”
Our system adds more movement liberties to the pelvis-legs &
chest-arms regions.
__(b80) f°69 “Recommendations
for further work… As the majority of the body weight is usually taken by
the sub-pelvic &pelvic parts of the body, both during the arrest of a fall
& in suspension, research could be undertaken to examine the most
ergonomic designs for leg loops/thigh/waist support straps. In addition, similar
work could be undertaken for the chest &shoulder sections of
full body harnesses, as these also play a part in taking some of the load
in a fall & in providing support after the fall.”
__(f56) “…pelvic restraint in
the prone position would provide the advantage of tension rather than
compression loading of the lumbar spine… upper torso would displace forward
during a crash.”
__(f82)
“1st restraint concept”
of the Prone pilot as indicated in Figure 4.22 (f76).
“…massive
spinal compression force was induced by the mass of the upper body &pelvis
impacting into the shoulders straps. This led to the conclusion that
sufficient pelvic restraint was vital to avoid high compression loads to
the spine in a frontal impact scenario.”
ET A CONCLUSION QUE CECI EST
TRANSPOSABLE, A L’IMPACT VERTICAL, AU SOULAGEMENT DE LA COMPRESSION LOMBAIRE
SOUS LE POIDS DU BUSTE, EN MODE ASSIS NORMAL
__(f82) “From this exercise it was however
realised that there would exist a combination of belt slack &pretention
between the pelvic restraints &shoulder straps that would result in an
acceptable spinal loading scenario between the extreme tension
&compression cases : In the 3rd restraint concept in
Figure 4.24, (f77)… (Test 2, frontal impact) The lumbar spine load &head
acceleration results for the three prone concepts are contained in Figure E4
&E5…” (f 136).
[Figure
E4 :
Prone concept 3, +7000N extension
(green curve) –5000N compression]
__(f85) “Conclusion : Although compression of he spine in the conventional pilot
position can be limited by following
the recommended shoulder harness &safety belt installations, it will
always be present due to the resultant force caused by the angle of the
shoulder straps & the seat structure below the pilot”. [cf. JAR 23 562 spec. (f123-124)]
__(f94) “Conclusion : …In comparison with the normal seated
&supine seated positions a pilot in the prone position would be exposed
to much lower spinal compression forces due to the orientation of the body
with respect to a crash load with both vertical &horizontal components…
The results of the different prone concepts indicated that spinal compression
during frontal impact case could be limited if adequate pelvic restraint was
provided. On the contrary, if the pelvis was restrained adequately but not with
sufficient upper body restraint a huge tension force was induced in the spine.
When analysing the final prone support-restraint proposal, it was however
discovered that a good balance between the two restraint systems could result
in acceptable spinal loads.”
__(f96) “…best results were obtained with restraint concept 3…” (test 2 with frontal impact)
VII. If one can really want
it, can engineering be found/developed to permit additional space at the
buttock rotation
__ Solution could be Longer & deeper seat base, possibly fixed below
the floor. The McDonnell F4H Phantom 2 ejector seat had an movable buttock permitting
access to systems under the floor without removing the seat (v192-193) ;
space could be found or managed.
__(f50) “provide energy absorbing mechanisms &materials in the
structural design that would attenuate crash forces…”
VIII. In what particular phase
(how) can the system act during the push-pull effect?
__ See ABSRACT, 2.3) frame VIII.
IX. Is the head of tall pilot so
much higher that our retention can’t be placed for their shoulders?
__ See ABSTRACT, 2.3) frame IX : Our pilot isn’t higher, more, buttock collapses.
IX bis. Might dynamic overshoot be reduced at catapult
ignition?
__ See ABSTRACT, 2.1) frame IX bis. Of course it is agreed!
__ With our device, earlier participation during vertical impact,
& less dynamic overshoot
X. Could
our design/system be complementary and act together with the current one?
__ See ABSTRACT, 2.3) frame X
__ It could be explored a
vertically back rest movable, to annihilate the traction friction when the
current device would act horizontally.
XI. Is a blanket approach, from a white paper
constructive? (Also see question VI,
last terms)
__(q1) “Ut Secure Volent” [Tronc Ailé en
suspension du blason 2005 de : RAF Centre of Aviation Medecine]
__(q38) “Future G protection:
In order to extend much beyond +9 to +12 Gz for prolonged periods, alternative
strategies are required.”
__(u10) “…the occurrence of soft and hard tissue injury during every day
flight has become a greater and greater operational problem. There have been a
several reports by Australia, Belgium, China, Finland, Sweden, and USA over the
past ten years or so which have documented the increased incidence of injury,
typically associated with exposures of +4 Gz and above. So, the problem
exists - but the data to correct the problem does not. There are a variety
of unanswered questions of interest to our Workshop…”
“Chairman’s Note : This is an important topic for us as a research community to address. It goes to the very
heart of issues surrounding the protection and long-term health and safety of
pilots flying high performance aircraft. I would like to thank Barry for
submitting this topic, and urge all participants to carefully consider the
issues involved and the questions that Barry has raised. I hope that this
topic provokes a lively and constructive debate, and provides the impetus for
many ongoing collaborative research efforts.” Idem in ABSTRACT 2.4) frame
XI.