dependent of gradients of fluid displacement.”
(53, p.173). Thus no fluid shift apparently
occurs if the impact duration is short enough.

But even though force varies linearly with
distance we do not know how force varies with
time in abrupt duration impacts, How force
varies with time, or how deformation varies
with time, is still empirically unknown, Maxi-
mum deformation of the impacted surface pro-
vides the maximum force, but not necessarily
time involved. In long duration accelerations
of low magnitudes, such as with the centrifuge,
forces can be controlled with respect to time,
and this is also true of some braking systems on
high speed deceleration tracks, In human free-
falls, on the other hand, it is impossible to in-
strument the experiment beforehand. At the
present time insufficient data are available on
controlled tests at very high impact velocities
to provide a valid basis for much needed re-
finements in calculations and assumptions as
to the exact nature of the time-force history of
the event, It is very difficult, for example, to
find materials that yield uniformly to constant
force.

Impact by definition is of extremely short
time duration, and yet a major problem is that
we are as yet unable to adequately identify
the impact dynamics as functions of time. For
the present, construction or employment of a
time index will allow some meaningful meas-
uring system to the impact events or study. In
recognition of this difficulty the classical but
imperfect description of impact time is derived
by assuming the velocity is a linear function
with respect to stopping distance, Time is
thus expressed as a simple expyession,

}

s 28
ea

Viiv Vv’ i
ee

or time equals distance divided by average
speed, ’

# lt is generally considered that there may be
a positive relatiogship between magnitude, time
duration, and degree of trauma. This has re-
sulted in various cushioning materials in ejec-
tion seats, for example; to distribute force

t=

through a greater time period. Many fall cases
bear out this expectation, i.e., that the greater
the time duration the less the injury received.
The following cases, for illustration, involve in-
dividuals each of whom fell a measured distance
of 50 feet (5 stories), impacting on their feet
(+G,). All impacts were at 56 ft/sec or 38
mph (corrected for sea level, standard air):

(1) An 18 year old Caucasoid male jumped
(or fell) from the roof of a 5-story apartment
building. The soil in which he impacted had
been so saturated by rain that he sank into the
ground 18 inches, distributing the force of im-
pact over .054 seconds, No apparent injury.

(2) A 15 year old Caucasoid male fell from a
ranch silo after being distracted by wasps. He
landed in a pile of hard-dry cow manure, which
cushioned his impact an estimated 3 inches.
He bounced, and fell on his right side, fractur-
ing his right wrist, an injury due to secondary
impact. Time duration: .0043 seconds.

(3) A 38 year old Caucasoid female fell from
a cliff, landing on her feet in loose gravel, and
injuring her back in secondary impact, Time
duration: .006 seconds.

The resilient qualities of these impacted
materials, which deformed in response to the
force applied over a relatively long time period,
were evidently quite effective in decelerating
the body with minimal, or no injury, in these
cases,

However, the most puzzling data resulting
from this investigation is that some individuals
survive free-falls terminating on non-yielding
rigid structures at exceedingly large magni-
tudes of force*with minor injury or, occasionally,
witk no apparent clinical trauma, In each of
these cases the time duration is ultra-short.

For examples,

(1) a 40 year pld Caucasoid male committed
infanticide and then attempted suicide, jump-
ing a distance of 44’ 5” from the roof of a tene-
ment, He landed, barefoot, on a granite block
at the sub-basement entrance-way. His only
injuries were a minimal fracture of the right
pubic ramus and of a cervical vertebrae, He
remained conscious after impacting and wan-
dered off, ‘despite impaction at 53.46 ft/sec

-17-—



e levels for in-
eats and in the
bcked were iden-
shoulder level),
000 g/sec for the
19,000 g/sec for
ence in transmis-
‘o the difference

P"magnitude experimentally studied with human
-¥olunteers, but the time durations may ap-
oach zero, As impacts at this extreme
are approached many puzzling questions arise.
Based upon voluntary impact tests lethality
fswould be expected to increase as magnitude
f :increases, but the fall cases to date do not show
Ea positive correlation with degree of trauma
based upon magnitude alone, It is possible
g*that human tissues may react differently to im-
pact energy if subjected to a high enough force
in an extremely short time period.

"Velocity in free-fall (V= V2gS) is mainly
, dependent upon distance fallen, requiring about
. 482 feet at sea level to reach a terminal veloc-
city of 120 mph, where S=distance and g=
82,1739 ft/sec’ (980 cm) at sea level. The
Fevalue for g varies with location, thus is 32.12
“ft/sec’ at Key West, Florida, and 32.23 ft/sec*
“at Fort Egbert, Alaska, Distance in all free-
falls was measured, utilizing either a standard
} steel tape measure (100’), or a specially de-
s.. signed 250’ weighted wire tape on a U-control
.. friction reel, and, in one case occurring on the
% Golden Gate Bridge, by an engineer’s transit
}. (46). The fall distances and velocities for 137
}: cases are plotted in Tables III and IV,

As previously noted, a case is not selected for
~ intensive study on the basis of distance of fall
- alone. Thus, individuals have survived falls of
. considerably greater distances than these, but
. if other pertinent information is found to be
unreliable, the case is not considered further.

In the past two years at least 90 pexsons have
survived falls of 100-900 feet, and 9 have sur-
vived falls of over: 1000 feet, However these
have generally precluded Accurate study be-
cause of complicating or doubtful data.

Velocity of frée-fall has been shown, first by
Galileo and subsequently,;by more exacting ex-
periments including those by Albert,Hinstein,
to be independent of mass, However there is
considerable evidence to indicate that air drag

but a very rapid
, in feet-first im-
ile impact forces
by bending the
(8), in studying
on of injuries in
jumping, noted
pical of the un-
Bulted in a frac-
of voluntary
pact appears to
of injury in feet-
ind an effort was
ee-fall subjects
or tense (stiff-
e individuals re-

” or “seared as
thers claimed to
bjective answers
, but those who
remembered im-
appear to suffer

relationships are
of the familiar g
this study, mag-
bf the velocity of
broviding a basis
making further
e of these falls
ration, consider-
an experiments,
act velocity, that
exceed 5000 in
set into the mil-
only are the g
imes the highesg

body, Schmitt, (43) in conducting wind tun-
nel experim: on subjects at several Yaw
angles and in five body positions obtained drag
} coefficiens for predicting drag forces on men
b of average stature under a variety of conditions.

does affect the velocity of the falling human,

-ll-

More recently Cotner (10) has employed a
closed-form solution for velocity at impact for
fall cases where body position and clothing
condition were observed to be constant, Other
work is in progress by Earley and the author
to determine the air resistance effects on veloc-
ity in free-fall. Velocity on the cases presented
in this paper has been corrected for air drag as
calculated in Figure 4 by Earley, A mean
body build of 4.7 C,S (drag coefficient x total
body surface area) was utilized, at which ter-
minal velocity is 120 mph.

In each case a careful description of clothing
worn at the time of the fall has been noted,
along with such body data as height, weight,
and body build. In most cases, clothing would
probably cause little drag, but in some cases an
overcoat, a light poplin jacket, or large skirts
could have a greater effect. This is an area
which will require further investigation.

Classic studies of falling bodies have been
performed on solid homogeneous materials, and
the calculation of G forces assumes a constant
force during acceleration. Impact acceleration
of a non-homogeneous body, however, does not
always act in this theoretical manner. If the
assumption is made that the reaction varies
linearly with the deformation of the yielding
reaction surface, the deceleration during im-
pact would also vary linearly and the peak ac-
celeration would be twice the value calculated
on the assumption of standard deceleration, At
impacts of very great magnitude and ultra-
short time durations this point, although gen-
erally overlooked, becomes critical in calcula-
tion of impact forces, This also brings up the
nasty question of just what is being measured.
In the cas¢ of a falling body it is presumed to
be a calculation of the energy imparted at the
initial point of contact to the outermost body
structure (being greatly dissipated as it is
transmitted uughout the body tissues), Use
of velocity at ‘impact, in ft/sec, may provide a
more meaningful basis for comparison of the
magnitude of force in free-fall impact.

IV. Material Impacted

The object impacted in free-falls is of great
importance as an injury or even survival de-
terminant. The relative elasticity or solidity of


ewan: STUDY POPULATION, BOTH SEXES (N=131)

mmm FEMALES (N=544)
ame MALES (N= 2740)

TOTAL POPULATION FOR
WHICH DATA AVAILABLE

}

(%) ST1VW4 WLOL
~21-

10-I9. 20-29 30-39 40-49 50-59 60-69 70-79 80-89 90-99

|-9

AGE (YEARS)

Ficure 5. Incidence of Survived Free-Falls by Age & Sex.


may provide clues or patterns which can open
entirely new approaches to the protection of
the body during high decelerative forces.

Not all deceleration research has utilized
human subjects, Studies have employed such
animals as mice (28, 29, 33, 42), rats (24, 26,
29), cats (21, 35, 42), dogs (19), rabbits (40,
41), goats (13), swine (52), bears (36),
chimpanzees (49,51), monkeys (66, 67), and
even giraffes( 22, 26). Other studies have in-
volved authropomorphic dummies (25), and
human cadaver materials (14, 18, 23, 30, 31),
as well as theoretical mathematical analog sim-
ulations (38, 62,65). While providing valuable
estimates, such techniques may not provide
data directly applicable to the human in the
upper non-reversible trauma region (that is,
that range between non-reversible injury and
death), Conclusions, and thus prediction, are
based upon variables which, although similar
in some respects, are not identical. Figure I
illustrates these different methods of studying
impact. Note that voluntary human exposure
may exceed the limits of reversible damage.

Materials and Method

Intensive case histories have been obtained
on individuals who have survived accidental,
suicidal, or homicidal free-falls, A free-fall is
defined as an unimpeded drop of a body from
a known point to a known impaction point.
Although reports of unusual fall experiences
are scattered throughout the medical literature,
De Haven (11) in 1942 first analyzed trauma
with respect to acceleration force in 8 cases of
falls in the transverse plane (a ninth cage was
reported in 1948(12)), i

To date over 12,000 cases of survived free-
falls occurring during the past/two years have
been collected and filed. Reports of individual
falls occurring throughout the United States
arrive at the rate of approxirhately 30 per, day,
and include about 96% of all reported freé-falls
in this country. In addition to that on survived

free-falls; information on approximately 5,000 ,

fatal falls has been collected, including docu-
m€ntation with autopsy reports in some cases.

Availability of stfch a mass of material allows,
as well as obviously requires, critical selection
of cases for further investigation. Currently

137 cases have been subjected to intensive
study. In each case selected investigation is
personally conducted at the site of the fall and
an effort is made to collect and obtain all in-
formation relative to the incident. To provide
a reliable basis for bio-physical calculation of
velocity and impact forces, the exact distance
of the fall, position of the body at impact, mate-
rial impacted and resulting deformation are
obtained, Complete medical histories includ-
ing roentgenograms, if taken, are obtained on
each subject, and the injuries correlated with
analysis of direction, magnitude, and distribu-
tion of force at impact. In addition, any other
variable which could have a direct or indirect
influence upon the particular case is noted.
For example: had the subject been drinking
prior to the fall? What sort of shoes was he
wearing? It must be emphasized that it is im-
perative in a study of this nature that each fac-
tor be determined by personal investigation,
because witnesses’ memories are often inac-
curate, the subject may know the least about
what happened, and news accounts may over-
estimate the distances involved. Conclusions
obviously can be no better than the basic data.

The cases generally selected for intensive in-
vestigation are those in which the distance of |
fall is great and the impacted object is one
relatively non-giving, such as concrete. Partic-
ular interest has been focused on cases of ver-
tical impacts of the buttocks or feet in (+G,)
headward accelerations, Abrupt deceleration
commonly refers to impact of less than .02 secs
duration, but, as is indicated by some of the
cases in this study, may approach infinity.

It should also be pointed out that there is a
mechanical difference between physical impac-
tion,sas in a fall, and a restrained impact in-
volving a deceleration, which may result in
somewhat different patterns of traumatic
responses.

It is difficult to present these data without
a brief comment upon the circumstances sur-
rounding their causation. Two of the most
common types of falls appear fo be that of
children falling from windows or porches, and
of workment falling from scaffolds, Others
run a wide gamut: a 91 year old r.ale fell
from a drawbridge while it was being raised, a

~2-—



(36 mph), at .0006 secs, time duration (as-
suming granite block deflected 016 inches).
Police at first refused to believe that he had
jumped.

(2) A 36 year old Caucasoid female, attempt-
ing suicide, jumped 71 feet from a 6 story build-
ing roof, plunged through a skylight (without
touching the framework) and impacted on a
concrete floor. No clinical injuries were found
except for cuts and abrasions. She impacted
at 65 ft/sec (44 mph) at .0004 seconds time
duration (assuming concrete deflected its maxi-
mum value of .016 inches),

According to past research indications, these
individuals should have received fatal injuries,
and yet each was only superficially injured.
Time durations of .0004 to .0006 seconds are
only 1/10th of the briefest time (.004 secs) re-
ported in human voluntary deceleration experi-
ments, and add to the possibility that, if an in-
dividual is very abruptly impacted, the tissue
résponse may preclude serious injury.

There is the possibility that, for time dura-
tions below a certain range, possibly .0006
seconds, where body tissues do not always ap-
parently respond as expected, survival may in-
crease under certain conditions, One example
is the use of Karate, originally developed dur-
ing the Tang dynasty in China as a form of
self-defense by peasants restricted from having
other weapons, Long years of training by the
expert, in which the individual strikes the in-
side of his thighs with the edge of his hand,
forms extensive scar tissue pads on both the
inside of the thigh and edge of hand. .Al-
though the abrupt, powerful Karate blow is
normally aimed at a portion of the body, a
Karate “black belt” expert can repgrtedly crack
solid wood with a single blow. ‘This impact
between human tissue and a hard surface may
have a direct bearing upon fall survivals in th 4
very short time duration range, and ancl)
Karate tests and measurements are planned’

VI. Physical Condition

Th general physical condition of the individ-
ual at time of impset is probably quite im-
portant to the degree of injury received as well
as recovery prognosis. In voluntary decelera-
fion tests, subjects have invariably been males

~18—

in good physical condition, Thus it may be
assumed that these tolerances established at
lower impact loads are close to the maximum
levels of voluntary tolerances for males.

Data from this study, dealing with a much
wider segment of the general population, ap-
pears to be in general support of this thesis.
Some of the most remarkable falls have been
survived by males who were athletes in excel-
lent physical condition, Similarly, the majority
of the female impacts of greatest velocities were
survived by healthy young females. As many
other studies have shown, the body is obviously
better able to cope with force fields if it is in
an optimum condition.

In a small number of instances previous fall
training may help to prevent more serious in-
jury. Thus certain athletes are well equipped
to survive a fall by knowledge of how to fall,
roll, and recover. This would particularly ap-
ply to wrestlers, tumblers, and judo (ju-jutsu)
experts. In addition, circus acrobats, by de-
veloping muscular co-ordination and training,
can fall long distances successfully without in-
jury. (Most of the fatal and serious falls oc-
curring in circuses are to high-wire performers
or other specialists not trained in falling.)
Parachutists, a class of highly-trained specialists
in fall techniques, are taught to land on their
toes, with feet together. They also keep their
knees and hips slightly flexed, relaxing the
muscles somewhat to absorb the shock at mo-
ment of impact. Such individuals are usually
in excellent physical condition, which certainly
contributes to survivability. Several ex-
paratroopers are included in this study, How-
ever too few cases have been obtained to date
for further comparison.

Experiments by Matthews and Whiteside on
the neurological state of human subjects who
are suddenly dropped in a chair, have resulted
in some pertinent dbservations. They suggest
that when. a muscle: becomes weightless “the
tensions are suddenly reduced in upper attach-
ments and increased in the lower; a group of
‘muscle fibers which had been exerting suffi-
cient contraction to maintain an isotonic state
suddenly act unopposed, and therefore shorten”
(34, p. 203). These movements within the mus-
cle due to the abrupt change in acceleration in
falling they interpret as being responsible for


rently being conducted. It will also be of
interest to examine the statistical characteris-
tics of fatal vs. survived free-falls in these age
groups.

From these data it appears that children,
particularly from age 1-4, are involved in, and
may survive, considerably more free-falls than
during any other age period. In addition,
there seems to be distinct evidence that chil-
dren in this age group receive less (clinically
diagnosed ) trauma than when older.

These findings may, however, be artifacts in
that children may receive injuries (particularly
brain or neurological trauma) not immediately
apparent, but which insidiously show up at a
later time. On the other hand anyone associ-
ated with children has often observed their
evident ability to attenuate impacts which
might disable those of us more physically ma-
ture. Undoubtedly among many physical rea-
sons for child survival of free-falls is the fact
that their cartilaginous skeletal structure at
this age is relatively flexible (and not rigid or
brittle), their proportion of subcutaneous fat
is greater than in the adult (and females have
thicker subcutaneous fat than males) (39),
thereby providing greater protection to internal
structures. Muscle tonys is also relatively
more relaxed in the younger ages.

However, as with adults, this appears to be
greatly dependent upon other factors, especi-
ally body orientation at impact. The follow-
ing table outlines 19 free-falls studied involv-
ing children from 16 months to 4 years,

Despite the many factors involved in each
case, a comparison of feet first (+G,) and head
first (—G.) impacts shows a great difference in
injury depending upon body orientftion at im-
pact. Although this may be as expected, it is
interesting to note that 6 of the 8 children in-
volved in +G, impactsireceived no discernible

injury and the other two receiyed only relay’

tively superficial injuries, despite impact v¢-
locities up to 55 ft/sec (37.5 mph), Only 1
individual out of 11 was uninjured in a —G,
impact.

IX. Other Factors

1, Race ¥

While racial or ethnic heritage per se may
not bé a factor in survival of impact trauma,

the possibility should not be eliminated on the
basis of present evidence. Members of some
groups are renowned for their climbing skill.
For example, the Mohawk Indians from upper
New York state have a legendary reputation
as fearless high steel construction workers,
more than 100 working in New York City
alone (7). Many Louisiana “Cajuns” work on
the off-shore oil rigs. But whether training is
involved rather than inherent characteristics is
unknown, as is the factor of incidence of ex-
posure, which may provide a statistical pitfall.
It has been shown that certain groups have ac-
climated to cold exposure, heat, and other en-
vironmental conditions. It is suspected that
certain physical types can withstand radiations
such as microwave radiation with greater tol-
erances. Thus certain groups may have su-
perior impact tolerances, but at this point no
racial factor, in the biological sense, can be
identified. The cases to date include 2 Mon-
goloids, 16 Negroids, and 119 Caucasoids.

2. Secondary Impacts

Many injuries occur upon impacts subse-
quent to the initial impact. This is particularly
true of +G, impacts in the feet-first body orien-
tation. In this case, one typical sequence seems
to be impact on feet > buttocks > back >
head, in which the ankles may be initially
fractured, compression lumbar vertebra frac-
ture might occur when the seat strikes the
ground, and head injuries, such as a subdural
hematoma, occur in a third or fourth phase of
the total impact. This probably occurs more
often than is realized, particularly on certain
types of impacted materials having high resil-
iency. For example, Case No. 2038, a 15 year
old youth, dropped feet-first 50 feet onto ma-
nure, bounced, landed on his side and frac-
tured a wrist in the secondary impact,

3. Meterological Conditions

In any fall occurring in outside environments
there are a number of factors associated with
the weather that. can greatly influence sur-
vivability, Rain or snow, for example, may
cause a slippery condition resulting in a fall,
but may also act to soften a ground impact
considerably and thereby result in less injury.

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A second factor found in this study, and be-
lieved to be of importance, is the incidence of
intoxication among free-fall survivors from
high jumps, Along with psychotic patients,
inebriated individuals also appear to have a
disproportionate survival rate among free-falls
of extreme distances, But, as is the case with
psychotics, this may simply be due to more
jumps made by these two classes, and until
more definite data is available concerning the
relationship between total falls and survived
falls this must remain unknown.

Presentation of further objective data is ob-
structed by the inconclusive nature of the med-
ical evidence in such cases, While the medical
history may contain a statement by the physi-
cian that the individual was intoxicated at the
time of the fall, and this may be subjectively
verified by police or other witnesses, no blood
tests were taken on any of the reported cases.
Similarly, other cases of survived free-falls
might have involved a degree of intoxication
not reported. In only one case, that of a young
male who jumped from the roof of a hotel, is
concrete evidence available. In his case two
witnesses kept track of the 60 ounces of scotch
and milk (he had an ulcgr) he consumed in
ithe two hours preceeding the fall.

Thus one factor which may be common to
both the intoxicated individual and the men-
tally disturbed, which has most often been re-
ported as paranoid schizophenia, concerns the
effect upon the neuro-muscular system, Since
previous studies have demonstrated the import-
ance to impact tolerance of muscle. tonus, thete
is substantial basis for considering this factor
in the high survival rate among jndividuals
abnormally relaxed in either or both of these
conditions. o

,

VUll. Age and Sex /

Chronological age in the study population
ranged from 1% to 91 years, and included
104 males and 33 females. As is shown in Fig-
ures 54nd 6; age must be considered a factor
in free-fall due to the déstribution of falls, Since
only 131 cases of the study population are
compared as to age, and there represent a se-
legted group, the first 3284 cases of survived

) age 8 to 12.

free-falls in our files were plotted for compari-
son and as a check on randomness of the se-
lected samples, These falls, representing 544
females and 2740 males, occurred during part
of the same time period as the selected falls,
Reference to Figure 5 shows an interesting
comparison between male and female falls.

In general the highest incidence of survived
free-falls occurs in childhood, sharply dropping
off by the teens. However an interesting dif-
ference is indicated between incidence of male
and female falls, with females having many
more falls to age 19, and males having more
falls in every age group from 20 to 65 years.
After age 65, females have proportionately
more survived free-falls than males. The study
population, even though a selected one, con-
tains less individuals in the 10-19 age group,
and more in the 20-35 age group, than the
larger population, However, it otherwise fol-
lows quite closely the expected proportions.

Figure 6 compares the incidence of sur-
vived free-falls in childhood for the study sam-
ple, and 268 females and 671 males from the
first 939 falls in our files,

Children, particularly from 1 year of age,
when they have started to experiment with bi-
pedal locomotion, to age 4, appear to be in-
volved in a disproportionate number of falls.
Females, particularly at age 2, have an inci-
dence of falls proportionately greater than
males at every age from 1-12, if considered in
relation to total life span, The lower chart
plots incidence of survived free-falls from age
1-12 as 100%, and while females in this group
have the highest peak (at 2 years), the rela-
tionships ghange somewhat as female falls drop
sharply and a rise in male falls occurs from
Reasons for these differences are
probably reflected ittmehanging interests and
social role, .As girls pass from childhood into
adolescence and adult status, exposure to en-
vironments conducive to falls also diminishes.
Probably the higher. incidence of male falls
from the teens to age 65 simply reflects the
difference in occupational hazards, A more
detailed study of age and sex relationships to
incidence of free-fall will soon be possible.
Analyses of over 10,000 survived cases are cur-

—~20~—



UM

ITY

160

j Beucture directly affects the deformation dis-
E fance and thus the time duration of impact. It
‘alto may affect survival by its contour char-
-apteristics, Thus soft, muddy ground is ob-
Slously preferable to jagged rocks upon impact.
aa i Survived free-falls have involved the follow-
Mig impact materials: concrete (45 cases),
j It roof or macadam pavement (9 cases),
ranging from rocky to sandy (45 cases),
ite (1 case), flagstone (1 case), steel (11
es), water (9 cases), snow (2 cases), wood
5 cases), and a pile of manure (1 case). Cases
ie impacting on concrete, steel, and rock (flat)
aces have been especially selected in this
vestigation because of the non-yielding char-
tistics of the impact material. Since accur-
p calculations of time duration at impact
= 2 S/V~V,) are dependent upon the
ible of distance of deformation (S) of
; teapacted object, utilizing non-yielding
‘ Hie s greatly increases the reliability of the
feulations.
'o determine the maximum deflection of
crete upon impact, the following calcula-
s were’ made by K. K, Kienow of Concrete
duit Corporation,
“In the first case a 4” thick slab of concrete,
wide and 10’ long and having a uniform soil
sure underneath (elasticity of the soil re-
ts in maximum deformation of the concrete),
loaded at the center to determine the maxi-
m deflection (A) which could be attained
Brior to concrete failure by cracking. y

_ bh ~ #8 .
In 776 int

re ;

Tov, ? 5
F S= > = 128 in’ , /

4 deflection diagram

moment diagram
f 6=6WL'=M
i" »
“ WL L WL’
Max moment = —_— x — =———-=M

a 2 "4" 8

By Moment Area:

pa IM 1,3 0 3ML' ML
2° 3° 4°2° 48” #16
ML?
= = 10’ = 120"
A= em L= 10 = 120

M max (w/o cracking) =
FS = 400 x 128 = 51,200 in#
(F = cracking = 400 psi)
s
51,200 x 120
“Tex 3 x 10" x 256

= 15.6 x 10-° = .0156 Maximum A

In this case the cracking moment, that is, the
maximum the concrete could deflect prior to
cracking, was calculated to be .0156 inches.
This forms a basis for the upper limit of con-
crete deflection, which is independent of force.

In a second case, a 4” thick slab of concrete,
also 4’ wide and 10’ long, was loaded at the
center (assuming an unyielding foundation),
although the concrete itself deflected, In this
case a 200: pound man was assumed to impact
feet first (1 square ft area) at a velocity of 65
ft/sec, with velocity after impact zero (no
bounce).

200 Ibs.
mass of body = 302 = 6.21 slugs
1FA =1mv
‘
PL
‘ =
A= AE
A® 1 sq ft.
: L=t=1/3ft.
E FT’ = Ein’ x 144
P=F
_FXxI/3__ F
ARS UME ~ 22Ein
‘or F = 432EA

-I15-—



TOTAL

78

2i

128

TION
. (AFTER GELL)

*

Falls in the buttocks-first position (+G,)

: occur less frequently than other types of re-
| ported position, but 10 cases are listed here be-

cause an effort was made to follow-up on im-
pacts in this position due to its’ particular
ence to crash forces in the vertical plane.

| This type of fall is also difficult to assess phys-

ically because, unlike the restrained laboratory
subject, the individual is free to fall at any
angle. Only under rare fortuitous circum-
stances can this angle be positively known, thus
most can only be estimated to be between 90-
135 degrees body position, To add to the com-
plexity of this problem, the direction of force is
occasionally changed by a “skidding” seated
impact. For example, in two recent falls
circus acrobats slipped while on the upswing
on the bar and landed initially in a seated posi-
tion, but with an additional forward momen-
tum, causing the resultant angle of force to
change about 90° in a very short time duration.
Incidentally, unlike acrobats, high wire per-
formers generally “fall dumb,” that is, they have
little or no experience in falling, even in prac-
tice, and simply do not even learn how to land
properly in a fall. This may have contributed
to two circus deaths in the last year.

Falls in the (+G,) transverse sideward di-
rection occurred in 8 cases selected, in the
prone (—G,) position in 3 cases, and in the
supine (+G,) orientation in 3 cases, Again this
is not representative of actual frequency but
rather selection.

“One body orientation which must be classi-
fied separately is that of impact in a crouched
position on the hands and knees. Usially this
is along the —G, axis, and ‘fiye such cases are
included, To the author's knpwledge decelera-
tion tests on humans in this’ position have not
been accomplished since it would appear to be
an impractical working position. However,
since trauma appears to follow a distinctive
pattern, the position is included here.

The extent and severity of impact trauma are
dependent upon many factors, but in general
#the patterns of injuries closely correlate with
the direction @f force and body orientation.
Thus, in the +G, feet-first impacts, most
severe structural trauma is related to the feet,
-ankles, and lower leg, while in the seated im-

pacts pelvic and vertebral trauma are prevalent,
and in the head impacts head, shoulder girdle,
and thoracic injuries are most noticed, as would
be expected, Table I shows the anatomical
distributions and frequencies of trauma in feet-
first (+G.) impacts. It is interesting to note
that more of the 152 fractures involved oc-
curred on the left side of the body in the 78
individuals in this group.

These injuries are fairly typical of the fall
trauma treated in general orthopedic practice,
that is, a high proportion of fractures of the
calcaneus, distal fibula and distal tibia, mid-
shaft of the femur and lumbar vertebrae, par-
ticularly L-4-T-12 area, Ciccone, (8) found
that in experienced parachutists, fractures of
the posterior tibial margin and multiple meta-
tarsal fractures were prevalent. (see also 37,
45) Most of the fractures of the upper ex-
tremities, such as distal radius, humerus, and
injuries to the skull, are not a result of initial
impact but probably occur during secondary
impacts. The most prevalent damage to in-
ternal structures is to the lungs and kidneys,
with hematoma of the renal pelvis most
frequent,

Table II provides an overall view of the re-
lationship between fracture patterns in free-fall
and the direction of force. The majority of
fractured skulls occurred in the head-first (—G,)
impacts as would be expected, but also occur-
red to a minor extent in feet-first and buttocks-
first (+G,), impacts, probably as a result of
secondary impact. Foot and ankle fractures
occurred in the buttocks, hands and feet, and
feet-first (+G,) impacts. No fractures were
reported in the supine or prone position (+G,)
but only six ‘individuals impacted in these posi-
tions. Buttocks first (seated) impacts (+G.)
are largely characterized by fractures of the
pelvis (31%) and vertebrae (23%), but fractures
of the legs (cB, fibula, femur) occurred only
in side (+G,) and feet-first (+G,) impacts.

Il. Distribution of Force

As with each of the factors listed, distribu-
tion of force at impact cannot be adequately
considered independent of other factors, Find-
ings indicate that the distribution of force
through the body is intimately connected with

-T-



6875. 17.

77-97. 19.

. Downing, T. O.

. Evans, F. G, and H. R, Lissner.

. Evans, F. G., and H. R. Lissner.

18.

21,

1961 “Fat Emboli in
Goats — I. Pulmonary fat embolism in
goats dying from the effects of massive
trauma.” Biophysics Division, U. S. Army
Chemical Research and Development Lab-
oratories, Army Chemica] Center, Mary-
land. CRDL R 3106, Proj. 4C99-02-002.

1955
“Studies in Pelvic Deformation and Frac-
tures.” Anat, Record 121:141-166,

1956
“Engineering Aspects of Fractures.” Clin-
ical Orthopaedics 8:310-322.

. Evans, F. G., H. R, Lissner and M. Lebow.

1958 “The Relation of Energy, Velocity,
and Acceleration to Skull Deformation and
Fracture.” Surg. Gynec. and Obst. 107:
593-601.

Evans, F, G., H. R. Lissner, and L, M.
Patrick. 1962 “Acceleration-Induced
Strains in the Intact Vertebral Column.”
J. Applied Physiol, 17(3) :405-409,

Evans, F. G., E. S$. Gurdjian, W. G, Hardy,
L. M. Patrick, and H. R, Lissner, 1961
“Intracranial Pressure and Acceleration
Accompanying Head Impacts in Human
Cadavers.” Surg. Gync, and Obst, 113:
185-190.

Fasola, A, F. 1955 “Anatomical and Phy-
siological Effects of Rapid Deceleration.”
Wright Air Development Center, Dayton,
Ohio. WADC TR 54-218.

y
Gell, C. F. 1961 “Table of Equivalents
for Acceleration Termjnology: Recom-
mended for General International Use by
the Acceleration Committee of the Aero-
space Medical Panel, AGARD.” Aerospace
Med. 32(12):1109-1111. 7

Greenfield, A. D, M. 1945 “Effects of
Acceleration on Cats, With or Without
Water Immersion.” J, Physiol. 104:5P-6P.

Goetz, R. H., J. V. Warren, O. H. Gauer,
J. L. Patterson, Jr., J. T. Doyle, E, N.
Keen, and”M. McGregor, 1960 “Circu-
lation of the Giraffe.” Circulation Res.
8:1049-1058,

24,

25.

27.

29,

30.

31.

33.

-27-—

Gurdjian, E. S., and J. E. Webster. 1955
“Mechanism of Scalp and Skull Injuries,
Concussion, Contusion, and Laceration.”
Proc. 2nd International Congress Neuro-
pathology, London.

Herrick, R. M. 1961 “Accuracy of Lever-
Displacement Behavior of Rats Following
Exposure to Positive Accelerations.” Avia-
tion Medical Acceleration Laboratories,
U. S. Naval Air Development Center,
Johnsville, Pa, NADC-MA-6111, April 19.

Hirsch, A. E, 1962 “A Comparison of the
Responses of Men and Dummies to Ship
Shock Motions, Part I.” Impact Accelera-
tion Stress, National Acad. Sci, - Nat. Res.
Council Publication 977, pp. 185-188.

Klenov, A. 1961 “Astronauts, Get Ready!”
Moscow Komsomolskoya Pravda, Dec. 2.

Kulowski, J. 1960 Crash Injuries: The
Integrated Medical Aspects of Automotive
Injuries and Deaths. Springfield, IIL:
Charles C. Thomas.

Kornhauser, M. and R. W. Lawton, 1961
“Impact Tolerance of Mammals.” Planet.
Space Science 7:386-394,

Libber, L. N. 1957 “Some Thresholds of
Injury from Application of High Linear
Accelerative Force to Rats.” J. Avia, Med.
28:166-170,

Lissner, H. R., M, Lebow, and F. G.
Evans, 1960 “Experimental Studies on
the Relation Between Acceleration and In-
tracranial Pressure Changes in Man.”
Surg. Gyn, and Obst. 111:329-338.

Lissner,* H. R. 1952 “Experimental and
Clinical Skull Fractures.” Instructional
Course Lectures, American Acad, Orth.
Surg. 9:277-281.

Lombard,"&%-F, 1949 “How Much Force
Can Body' Withstand?” Aviation Week,
Jan. 17.

Margaria, R. 1958 “Wide Range Investi-
gations of Acceleration in Man and Ani-
mals.” J. Aon. Med. 29:855-871.

Matthews, B, and T.C.D, Whiteside. 1960
“Tendon Reflexes in Free Fall.” Proc, Roy.
Soc, Ser. B, 153(951):195-204,



75 year old male fell into a bombshelter he was
constructing, a 69 year old female fell from a
tree while chasing her pet parakeet, a locomo-
tive engineer fell out of his cab, an eloper fell
off the ladder (and had to postpone the wed-
ding). Several individuals have dived into
empty swimming pools, or fallen off roller-
coasters, and others have been injured in at-
tempting to escape over a prison wall. Con-
struction on missile silos, off-shore drilling rigs,
skyscrapers, elevator shafts, smokestacks, and
water towers all produce survived (and fatal)
falls of considerable distances, but usually do
not provide usable data because the individual
rolls or impacts at several points. Similarly,
falls into wells or into mine shafts usually are
not true free-falls because of friction with the
sides due to slope or diameter, Another type
of fall which is frequently not strictly a free-fall
but often provides useful material is the sky-
diver parachute failure. These are appearing
with greater frequency as more individuals take
up this sport. In 18 such cases reported in the
last six months, three individuals have survived
partial free-falls, two impacting at 50-70 mph.
Accurate calculations on drag of partially
opened chutes are usually precluded in such
cases, but in one case photographs were ob-
tained during descent and at impact, showing
the exact profile, People have fallen from air-
craft in flight, and of 52 such cases in the past
year for which we have data, one individual
survived for 12 hours an impact resulting from
a fall of nearly 7 miles. Most falls appear to be
accidental (and preventable): however some
involve homicide or suicide attempts. Seyeral
investigations. involved apparent  infanticides,
and there is always the questionable case which
is classified officially as “accidental”—but could
have been either suicide or homicide. Some
87 persons, for example, have “accidentally”
fallen from the Golden Gate Bridge. /

A free-fall occurring “in nature” may predent
factors as neatly categorized and analyzed as
if accomplished in the laboratory. Usually,
however, there are so many factors which may
be involved in any one individual case that an
analysis of this type’ involving a large number
of cases becomes unwieldy in traditional treat-
ment, Due to these many environmental fac-
-

tors which have been found to have varying
influence upon the survivability of any partic-
ular fall, the biophysical and medical data are
presented in terms of these intra-dependent
variables found to date with related discussion
included in each section. The variables are
summarized in Figure 2.

I, Orientation of the Body ( Direction of
Force)

The position of the body in relation to force
directly influences the nature and extent of in-
juries, since structurally the human body can
resist greater forces prior to failure in some
directions. In this study the majority of the
impacts investigated were in the (+G,) feet-
to-head orientation, but five other positions
were also commonly encountered, In addition,
a small number were discarded either because
of insufficient information concerning impact
position or because they impacted in some other
variation, Figure 3 summarizes, by sex, body
position at impact in 128 cases studied.

The most common impact orientation in free-
fall appears to be in the feet-first position. The
sample is thus heavily skewed in this direction
with 78 out of 128 falls, in which the direction
of force was known, in this positive longitudi-
nal acceleration axis.

The second most common fall position
studied was head-first (—G,) impacts. In each
case care was taken to ascertain that the head
was in fact the initial contact point, and that
it took the brunt of the impact force prior to
secondary shoulder impact. Although it
might seem unlikely that an individual would
fall head-first very often, even in suicide dives,
it does‘occur, particularly in cases of electrical
shock. Several of the best documented cases
are those of workmen on steel girders being
shocked, and subsequently falling head-first.
In one such instance (Case #2017) the individ-

ual landed on the apex of his skull, only 8 :

. inches out from the center of the beam after a

fal of 13’ 4” onto concrete, Surprisingly, he
suffered only minor concussion and left the
hospital after 24 hours observation. In such
cases the fall may actually save the individual's
life by re-initiating respiration.

—4-



to intensive

obtain all in-

To provide
calculation of
exact distance
impact, mate-
formation are
stories includ-

, and distribu-
tion, any other
ect or indirect
case is noted.
been drinking
shoes was he
that it is im-
that each fac-
investigation,
re often inac-
e least about
nts may over-
. Conclusions
the basic data.
or intensive in-
he distance of
object is one
crete, Partic-
mn cases of ver-
feet in (+G.)
tt deceleration
s than .02 secs
y some of the
ich infinity.
that there is a

LETHAL TRAUMA
IRREVERSIBLE TRAUMA
VOLUNTARY LIMITS OF
HUMAN TOLERANCE
REVERSIBLE TRAUMA

Ficure 1, Methods of Determining Human Impact Tolerance.

may result in
of traumatic

ANIMAL TESTS

e data without
umstances sur-
0 of the most
to be that of

HUMAN FALL CASES
HUMAN IMPACT TESTS

ANALOG

‘HUMAN CADAVER STUDIES
SIMULATION

ANTHROPOMORPHIC DUMMIES

MATHEMATICAL

old r.ale fell
being raised, a



subs in 1

1
432Ein*® A* = zt mv*

432(3 x 10°) At= > (6.21) 65*

1300 x 10° A* = 13,000

13,000

= 18.0% _ = 0.1 x 10°F
1300 x 10" loft

A* = 3,22 x 10°* ft

3.22 x 107°
Ain= 75 = 268 * 10° in

= .000268

In this minimal case the deformation was
determined to be .000268”. Any bounce, of
course, would decrease this figure, and most
free-fall impacts do appear to involve bounces.
Obviously, in either case of concrete impaction,
practically all of the energy of the falling body
would be dissipated within the body tissues. In
both cases no bounce was assumed, but any

ounce would decrease these figures, On the
basis of these calculations it seems evident that
the cracking moment (maximum deflection)
of concrete will range from only 1/100th to
2/10,000ths of an inch. However, since no
cracks were found in any of the concrete im-
pacts these limits probably were not reached.

Water provides an entirely different problem,
since its relative deformation (depth individual
goes to, and elastic properties) may vary con-
siderably with the surface area of the body,
orientation of the body, and condition of the
surface of the water (e.g. trough, wave, or
smooth) as well as velocity of the current
High divers attempt to cleave the surface with
their hands and consistently make dives of
over 100 feet into small pools (of still water)
withouf apparent injury. All survived water
impacts to date in oWf series were feet-first,
possibly indicating that exposure of the least
surface area is important to survival, Further
tests on water impact are planned.

~16—

Steel provides an even stiffer surface, but
deformation may actually be measured by a
permanent “bow” in the structure, Soils vary
in hardness and to date no relative soil tests
have been made, although a relative index (r
value) will be made on a basis of soil samples
in future cases, Wood often deforms consider-
ably prior to breaking in impact, but presents
problems of different thickness, kinds of woods,
and support, among other factors.

To study the relationship between surface
impacted and trauma the cases were compared,
taking into account the bias of selection and
relatively greater proportion of soil and con-
rete impacts. A preliminary comparison {not
presented due to length), contrary to expecta-
tions, does not show a straight-line relationship
based upon relative hardness of material. In-
stead injuries (and fatalities) are distributed
in severity throughout the range of material
impacted, with survival with relatively minor
clinical evidence of trauma or, in some cases no
discernible injury, occurring about as frequently
on concrete impaction as upon soil impaction.
This is probably due to the complexity of fac-
tors, which must be considered in each case.

V. Time Duration

One of the most critical factors in decelera-
tion, as in acceleration, is that of the duration
of time that the force is applied. In impact
this generally refers to the time required to
reach the peak force at initial impact, While
linear and radial acceleration experiments may
last for a period of seconds or even minutes,
and voluntary human deceleration tests for
.004 to .42 seconds (53), the very abrupt im-
pacts associated with human free-falls often
range considerably lower and actually approach

/ zero when impacts agitiist non-yielding rock or

concrete surfaces are encountered.

The importance of the duration of time the
force is applied has been emphasized by pre-
vious’investigators, and findings by Stapp indi-
cate that when this: duration “is less than 0.2
seconds, the tissues react with damage to struc-
tural integrity, behaving like inert materials
under conditions of mechanical stress analysis,
where structural damage and failure are in-

str

fir
to
fir
fo

or
SE

du
su
tic


IMPACT
POINT

HX
RCS.

NO. OF_CASES
o'MALE 2 FEMALE

TOTAL

FEET

+G,

57

2

78

HEAD

6, |

z

2i

BUTTOCKS

+6,

(A-P)

SUPINE
(P-A)

BODY ORIENTATION

' HANDS & KNEES
Transverse (A-P)

Y
PRONE vont
oosel
opt;

SIDE
Rt. & left Lateral

f

8

Direction of Force ' 4

a

|: 99

29

128

' / is
% (9 ADDITIONAL CASES LANDED ,JN SOME OTHER COMBINATION.

11 CASES UNKNOWN.)

%€% PHYSIOLOGICAL COMPUTER STANOARD. VECTOR BASED ON DIRECTION
THAT A BODY ORGAN WOULD BE DISPLACED BY THE ACCELERATION. (AFTER GELL! depen¢

e

¥* Ficune 3. Body Position at Initial Impact.

—~6-

_

Falls
occur |
ported »
cause a
pacts i
pertine:
This ty.
ically b
subject,
angle.
stances
most cz
185 deg
plexity
occasio:
impact.
circus :
on the
tion, bi
tum, c
change
Inciden
former:
little o1
tice, an
proper]
to two:

Falls
rection
prone
supine
) ds not
| rather
|

“One
fied se
positior
is alon
include
tion te
been a
an im)
since t
pattern

The

the pa
the di
Thus,

severe
ankles,



emens STUDY POPULATION, BOTH SEXES (N=27)

(%)
tt

~~
=a

‘= = FEMALES (N=268)] TOTAL POPULATION FOR
~ tt / \ == MALES (N#671)J° WHICH DATA AVAILABLE wa
2
a
2 eb ~ 2
wu
pucee aN
a $57 / / ~ PLOTTED AS PROPORTION
z r . \ OF TOTAL LIFE SPAN
5 3
e
3
3
30 3
:
3
2st
4
. 3
4
\
= 27 : ‘
re} i ‘
= i iY y PLOTTED AS PROPORTION 4
e i/ ‘ i OF 12 YEAR SPAN
1
4 i \ ‘ ‘
a ‘
we

AGE (YEARS)

. Ficure 6. Incidence of Survived Free-Falls During Childhood by Age & Sex.

—22—



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BODY REGION
A. FRACTURES
1, Skull: Temporal
Frontal
Occipital
Maxilla

Mandible
Nasal

2. Upper Humerus
Extremities: Ulna
Radius
Carpals
Phalanges

3. Trunk: Scapula
Ribs - Sth
6th
7th
8th
1lth
Cervical vertebrae
Thoracic vertebrae
1-3
T-7
T-10
T-11
T-12
Lambar vertebrae
Lel
L-2
L-3
Led
L-5
(Pelvis) Sacral vertebrae
Pubic ramus
Ischium
Tlium
4. Lower Extremities:
(Leg) Tibia
Fibula
Patella
Fewur
(Ankle) Cuneiform H
Cuboid ‘
Navicular bone
Talus '
Calcaneous
(Foot) Metatarsals (4):
Phalanges (2,3)5)

B. SOFT TISSUE INJURIES

Cerebral contusion

Hematoma, right occipital area

Hematoma, right temporal are

Lyngs: Pneumothorax (1 bilateral)
hematoma

Kidney, hematomay

Bladder (displaced by hematoma)

Testes, contusion

m1

momen 4

eee eee 6

man 2

! momo 5
m1

mpm 3

wens 3

‘ meee 3

SS ee. 2

} ==55/
/ ;

, mam. 2
mm 2
cee ee aS

mmm 2

aul

Taste I Relation of Body Orientation (Direction of Force) to Trauma i> Feet-first (+G,)

Impacts, Anatomical Distribution and Frequency in 78 Ca

-~8-

i

lm
am



57.

58.

59.

Stapp, J. P. and W. C, Blount. 1956 “Ef-
fects of Mechanical Force on Living Tis-
sues: II. Supersonic Deceleration and
Windblast.” J. Avn, Med, 27(5):407-413.

Stapp, J. P. and W. C. Blount. 1957 “Ef-
fects of Mechanical Force on Living Tis-
sue: III. A Compressed Air Catapult for
High Impact Forces.” J. Aun. Med. 28(3):
281-290.

Stapp, J. P. and S, T. Lewis. 1957 “Ex-
periments Conducted on a Swing Device
for Determining Human Tolerance to Lap
Belt Decelerations.”. AFMDC TN 57-1.

Stapp, J. P., J. D. Mosely and C, F, Lom-
bard. 1962 “‘Megaboom’ Linear Wind-
blast Tests on Subjects and Protective
Equipment.” Northrup Space Laborator-
ies, Hawthorne, California.

Steward, W. K. 1955 “Lung Injury by
Impact with a Water Surface.” Nature
175:504-505,

Swearingen, J. J., E. B. McFadden, J. D.
Garner, J. G, Blethrow and W. Reed, 1960

“Protection of Shipboard Personnel

Against the Effects of Severe Short-Lived
Upward Forces Resulting from Under-
water Explosions.” NA ONR 104-51.

wm

61.

62.

66.

—29-

Swearingen, J. J., E. B. McFadden, J. D.
Garner and J. G. Blethrow. 1960 “Human
Voluntary Tolerance to Vertical Impact.”
Aerospace Med, 31(12):989-998.

Thompson, A. B, 1962 “A Proposed New
Concept for Estimating the Limit of
Human Tolerance to Impact Accelera-
tion.” Aerospace Med. 33(11):1349-1355,

Taylor, E, R. 1963 Biodynamics: Past,
Present and Future. ARL-TDR-63-10,
Proj. 7850. 6571st Aeromedical Research
Laboratory, Hollowman AFB, New
Mexico,

Tobin, W. J., R. Ciccone, J. T. Vandover,
and C, S. Wohl. 1943 “Parachute In-
juries.” Army Med, Bull, 66:202.

Von Gierke, H. 1961. “On the Relation
Between Steady State Response and Im-
pact Response of the Human Body.”
Symp, on Biomech. of Body Restraint and
Head Protect., June 14-15, U.S. Navy Air
Material Center, Philadelphia, Pa.

Young, J. W. and J. J. Swearingen. 1963
Unpublished data, C.A.R.I., Fed. Avia-
tion Agency, Oklahoma City.

Zuckerman, S, and A. N. Black, 1940
“The Effects of Impacts on the Head and
Back of Monkeys.” Rept, RC-124, Minis-
try of Home Security, England.

# U.S GOVERNMENT PRINTING OFFICE : 1963 © - 712-220



35.

36.

37.

38.

39.

Al,

43,

McDonald, R. K., V. C. Kelly, and R.
Kaye, 1947 “The Type and Degrees of
Injury Resulting from Abrupt Decelera-
tion: The Etiology of Pulmonary Hem-
orrhage in Cats Exposed to Abrupt De-

celeration.”, USAF School of Aviation
Medicine, Report No, 2, Res. Proj. 494,

Mosely, J. D. and James E. Cook. 1960
“Visceral Displacement in Black Bears
Subjected to Abrupt Deceleration.” Aero-
space Med, 31:1-8,

Neel, H. 1951 “Medical Aspects of Mili-
tary Parachuting.” Mil. Surgeon 108(2):
91-105.

Payne, P. R, 1961 “An Analog Computer
Which Determines Human Tolerance to
Acceleration.” Nat, Acad. of Sci. Sym-
posium on Impact Accel. Stress, Brooks
AFB, San Antonio, Texas, Nov. 27-29,

Reynolds, E. L. 1951 “The Distribution
of Subcutaneous Fat in Childhood and
Adolescence.” Monographs of the Society
for Research in Child Development, Inc.,
XV(50) No. 2.

Roman, J. A. and J, R. Prine. 1958 “The
Semi-Rigid Envelope as a Means of Pro-
tection from Impact-Preliminary Tests on
Rabbits.” USAF Aero Medica] Labora-
tories, TR 58-123.

Rushmer, R. F. 1944 “Comparison of
Experimental Injuries Resulting from De-
celerative Forces Applied to the Ventral
and Dorsal Aspects of Rabbits During
Simulated Aircraft Accidents.” AAF
School of Aviation Medicine; Report No, 1,
Research Proj. 30}. ,

,
Rushmer, R. F, 1944 ‘Internal Injuty
Produced by Abrupt Deceleration of Syfall
Animals.” AAF School of Aviation Medi-
cine, Randolph AFB, Texas, Report No. 1,
Research Proj. 241.

Rushmer, R, F,, E. L. Green, H. D, Kings-
ley. 1946 “Infernal Injuries Produced by
Abrupt Deceleration of Experimental Ani-
amals.” J, Aun. Med, 17:511-525.

44,

47.

48.

49.

51.

52.

53.

—28—

Schmitt, T, J. 1954 “Wind-Tunnel Inves-
tigation of Air Loads on Human Beings.”
Report 858. Aerodynamics Laboratory,
David W. Taylor Model Basin, Washing-
ton, D.C.

Siffre, M. 1951 “Traumatismes et Para-
chutages.” Rev. du Corps de Sante Mil.,
(Paris) 7:121-130.

Snyder, R. G. 1962 “A Case of Survival
of Extreme Vertical Impact in Seated Po-
sition.” C.A.R.I. Rept. 62-19, Fed. Av.
Agency, Oklahoma City.

Stapp, J. P. 1949 “Human Exposures to
Linear Acceleration: I. Preliminary Sur-
vey of Aft-Facing Seated Position.” AF
Tech Rept. 5915.

Stapp, J. P. 1951 “Human Tolerance to
Deceleration — Summary of 166 Runs.” J.
Aon. Med, 22(1):42-45.

Stapp, J. P. 1951 “Human Exposures to
Linear Deceleration: II. The Forward
Facing Position and the Development of
a Crash Harness.” WDAC TR 5915.

Stapp, J. P, 1952 “Human and Chimpan-
zee Tolerance to Linear Decelerative
Forces.” Conference on “Problems of
Emergency Escape in High-Speed Flight”,
Sept. 29-30, at Wright Air Development
Ctr., Wright-Patterson AFB, Ohio.

Stapp, J. P. 1954 “Methods of Research
in Aviation Medicine.” Activities Report,
Third Quarter, October. Holloman AFB,
New Mexico.

Stapp, J. P.” 1955 “Tolerance to Abrupt
Deceleration.” Collected Papers on Avia-
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122-139, London:

Stapp, J. P. “Yée1 “Human Tolerance to
Sevete, Abrupt Acceleration.” Gravita-
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Gauer, O. H. and G, D, Zuidema, eds.,
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Stapp, J. P. and W. C. Blount 1955 “Ef-
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blast.” J. Aun. Med, 26(4):268-288.



have varying
jof any partic-
ical data are
tra-dependent
ted discussion
variables are

jon of

lation to force
extent of in-

|. In addition,
either because
ming impact
in some other

tation in free-
t position. The
this direction
the direction
itive longitudi-
1

fall position
cts. In each
that the head
int, and that
force prior to
Although it
ividual would
suicide dives,

girders being
ling head-first.
7) the individ-
skull, only 8
je beam after a
urprisingly, he
and left the
In such

BIOLOGICAL
PHYSICAL CONDITION
MENTAL CONDITION
PROPERTIES

TISSUE

b ee
a ss. 8 w
a 8 “s 2 5)
~ 2.82, 53 w &
OS i'n eae s8e 8
~ \ ° Ly. Ory
WH 1 ‘ « WELLS o's
y\ a Z wot b&b a
6 62 gehus
an 1 Ela! 2g OF ro)
Q { e'aer g? ZS Fs
12> Ow ws Oz 2
1a fsa pepe a
, Vy 2g8\oz 08 x
, , W (U] qS5WG be,
. 12 42 GE Ee
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* A a

Fioun 2, Biophysical Factors Influencing Trauma in Free Falls.


the absence of reflex, Due to the critically
short impact durations often encountered in
free-falls, the physical properties of human
tissues may respond in acutely abnormal re-
actions. Time durations of .0006 seconds, or
less, may actually preclude a normal tissue re-
sponse. Impact may simply occur so suddenly
that the body tissues do not have time to re-
spond in sequence.

The non-homogeneity of body structures
with resulting complex reactions to force appli-
cations have always hindered predicability of
soft-tissue trauma, Very brief time durations
of force may well result in tissue behavior
similar to that of inert materials, Physical
properties of tissues subjected to mechanical
stresses involving compression, tensile and
shearing strengths, elasticity, viscosity and
frequency response must be considered, and
have been under study by a number of inves-
tigators. The human body is of heterogeneous
visco-elastic composition, and human variabil-
ity cannot be over emphasized.

Taking these 137 free-fall cases as a whole,
the clinical histories show a disproportionate
incidence of internal trauma to what would be
expected on a basis of extension of voluntary
tests, In a few cases, there was the unique
opportunity to compare the clinical diagnosis
with the autopsy report of the pathologist, It
is believed that follow-ups of fall cases in
which the patient subsequently dies of his in-
juries and is autopsied may provide particu-
larly useful comparative data now lacking, and
it is hoped to pursue this course in the future.
Internal trauma may provide, difficult dlagnos-
tic problems coupled with the fact that, unless
severe injury is involved, the /tissues may re-
cover without further assistande from the phy-
sician, It is suspected that supporting tissue
structures such as ‘the peritoneum, mesentery,
or ligaments are often damaged in impac}/ but
are not diagnosed due to more painful cémpli-
cations masking such injuries, This'is indicated
by the fact that interviewed fall patients often

complain of such things as “pain in the lower’

alidomen,” “testicles hurt,” etc, which often
match the subjegtive symptoms found at the
non-reversible injury threshold in voluntary
subjects exposed to velocities up to 19.6 ft/sec
by Swearingen (60). At 24 ft/sec (a 10 foot

fall) to 33 f/sec (18 feet) complaints were
very similar. One 69 year old male (Case
#2006) falling 25’3” (40 ft/sec) and landing
on his feet also noticed considerable testicular
pain subsequent to the fall. In an autopsy of
a 28 year old male who received fatal injuries
(Case #2022) in a feet-first impact, numerous
small areas of hemorrhage were found in the
left testis, Thus it is felt that internal injuries
may be more prevalent than the clinical his-
tories of these fall victims would indicate.

VU. Mental Condition

The majority of free-falls occur accidentally.
Falls officially listed as suicide or homicide
compose only a minor part of the total al-
though some cases are not so neatly classifiable.
Thus there is a distinct difference in motiva-
tion: the individual in the accidental fall, or
one who is thrown off a cliff by another person
in a homicide attempt, does not consciousl
want this action to occur, On the other hand,
the individual attempting suicide by jumping
is initiating purposeful action.

A large proportion of free-falls from the
greatest heights have involved suicide at-
tempts. For example, in the 11 falls of over
100 feet distance studied to date, 7 (and prob-
ably 9) were deliberate suicidal leaps. In
our society this is generally conceded to be ab-
normal behavior manifested by an abnormal
psychotic condition.

In comparing the medical histories of this
group of attempted suicides a striking common
factor in many of these cases was the diag-
nosis of “paranoid schizophrenia.” Since these
individuals had all survived free-falls of un-
usual distances and under calculated impact
forces exceeding 75 ft/sec, it would seem
proper to explore further the hypothesis that
psychotic patients may be able to withstand
impact forces more successfully than “normal”
individuals. It is' interesting, in this respect, to
note that the psychotic patient differs primar-
ily in one important respect in regard to falling
‘— he wants to jump. The act of jumping may
thus be a release for him, and unlike most of
us, this individual may enjoy the jump, As a
result he may be physically relaxed at the time
of impact, which appears to be, in itself an
important criterion for survival of free-fall.

~19~



Several construction workers have recently
been blown from high girders by winds, Winds
are also important in many leaps from bridges
— particularly from the Golden Gate Bridge
which often has a wind of 5-30 knots—since
this force may rotate the body and prevent
maintenance of a vertical attitude. The wind
may also whip up water, providing a trough
and crest wave configuration, along with strong
currents. Falls onto icy surfaces mean loss of
traction, and the center of gravity condition
can result in secondary impacts which might
have been prevented on other surfaces, The
weather also has a direct influence upon the
clothes and footwear being wom and thus may
affect fall survival in degree of protection,

DISCUSSION

It is evident from the foregoing that the
problem of investigation of free-fall cases is
vastly more complex than was initially thought
to be the case. Since this is primarily.a study
of extreme impacts, a high degree of selection
was necessary. However, such selection ne-
gates the more common statistical design of
experiments and requires new techniques for
reduction and presentation of data. One would
expect, for example, that there would be a high
positive correlation of impact velocity with
trauma. On the contrary, no such relationship
was found. In 78 cases of +G, feet to head
impacts, ranging from 7 ft/sec to 116 ft/sec,
the expected injury pattern of fractured ankles
is found throughout the series, but in no defi-
nite pattern of correlation with, velocity. j/Se-
vere injuries are found at low magnitudes of
force, while an apparent lack trauma is
found in cases scattered throughout the im-
pact range. o ; .

Other difficulties are presented by the’
subjective nature of certain information. Foro
ample, it is desirable to compare fallé occhr-
ring from great heights under similar condi-
tions between intoxicated and non-intoxicated
individuals. However, while the medical his-
tory fhay often contain a statement by the phy-
sician that the indivfdual was intoxicated, no
blood tests were taken to substantiate this or
indicate the degree of intoxication, Position of
-

impact is a most important factor, and yet
people do not always fall in neat x, y, z planes.
In fact, even in the feet-first position, they
often impact one foot first. In the seated po-
sition, the angle of impact may vary greatly,
and thus result in different trauma. It is also
very evident that a free-fall impact may often
consist of a series, or number of impacts, A
common feet-first impact sequence is: feet hit,
bounce, buttocks hit, bounce, back hits, and
finally head strikes, This pattern can be seen
in viewing the resulting injuries. For example,
the most common pattern consists of a talus
fracture or distal tibia, severe head abrasions
and lacerations; the latter occurring secondar-
ily, after the initial impact. It is also very dif-
ficult to find either a patient or witness who is
able to recall accurately and describe such gy-
rations, all of which occur in very short time
intervals, Careful analysis of injuries, particu-
larly superficial ones, along with examination
of tears and impact evidence on clothing can
often help overcome such problems.

Despite the problems associated with the
study of falls, definitive factual data are ac-
cumulating from the study of survived free-
falls that are not obtainable through voluntary
experimentation. It is believed that this ap-
proach is the most realistic means of obtaining
information concerning impact trauma in the
ranges above that to which human subjects
can be vohintarily exposed in the laboratory.
It should also be emphasized that the cases
presented in this paper represent extremes in
the impact continuum, and that man’s toler-
ances to deceleration forces are extremely
variable.

The work to date has resulted in case docu-
mentation of some individuals who have
survived impacts corresponding to several thou-
sand G’s. Why some individuals are not fa-
tally injured in certain cases of extreme impact
poses a most intriguing question, It is hoped
that analysis of a largex body of data will begin
to provide some answers

, SUMMARY

Physical and biological data have been pre-
sented on 137 of 168 cases of individuals who
have survived extremely abrupt impacts in free-
falls. Fall distances ranged up to 275’ and

~25—



HUMAN SURVIVABILITY OF EXTREME IMPACTS IN FREE-FALL

Richard G. Snyder, Ph. D.

ABSTRACT

Human deceleration tolerances beyond the limits imposed by voluntary experimental methods
were studied by means of intensive case histories of 137 individuals who have survived

extremely ab:
ranged up to

t impacts in accidental, suicidal, and homicidal free-falls. Fall distances
7 and calculated velocities up to 116 ft/sec (79 mph). Physical and bio-

logical data are presented on both sexes with an age range of 1% to 91 years, and with

impacts occurring in all body axis orientations.
affect

A detailed analysis of factors found to

survivability in free-fall impacts is made. These cases, out of some 12,000 free-falls
collected in the past two years, demonstrate that humans have survived impact forces

considerably greater than those previously believed tolerable.
injured in certain cases of extreme impact remains unanswered, but evidence

not fatall

Why some individuals are

suggests that human tissues do not respond as expected in extremely abrupt impacts having

time durations of less than .0006 seconds.

In the last decade considerable effort has
been expended in seeking knowledge of human
responses and limitations to deceleration,
or impact, forces, Whether one is concerned
with such problems as launch and re-entry
phases of interplanetary space vehicles, occu-
pant escape or crash survival in the supersonic
transport, or the more mundane research as-
sociated with increasing human suryival in
aircraft and automotive accidents, the ‘nagging
question of human design specifications for this
force field must be considered’ Scientists such
as Stapp (47-58), Swearingen (60-61), Beed-
ing (2-5), Tayldr (63), and others, have
contributed immensely to our knowledge gf de-
celeration effects upon the human organism.
Such experimental work with human subjects to
date has been limited to voluntary tests which

Presented at the 34th Annual Aerospace Medical Asso-
tiation meeting in Los Angeles, California, April 29 - May
2, 1963, -

See also, “Human Tolerances to Extreme Impacts in Free-
fall”, Aerospace Medicine, 34(8):695-709, 1963,

have only accidentally exceeded the injury
threshold limits. Forces beyond these levels are
usually thought @ priori to be so traumatic to
render the individual unable to perform a func-
tion and cause lethal or irreparable injury.
However, as data presented in this paper will
show, some individuals apparently are able to
tolerate impact forces many times above the
accepted limits, Why?

The purpose of this study, which has now
been in progifess for over two years at the Civil
Aeromedical Research Institute of the Federal
Aviation Agency, is to document factual data
concerning human survival of extreme impact
forces, and attempt to identify more concisely
the faetors which determine an injury or a sur-
vival, An ultimate objective would be to ap-
ply such knowledge for prevention or modifica-

‘ tion of lethal ‘or injurious levels in air crashes,
as well as other abrupt impact situations in-
volving very high impact forces. The investi-
gation of extreme limits of human tolerance(s)

-1-



VELOCITY
STANDARD} CALCULATED .
"t78e¢_ | trysec | mph | DISTAN
veS295 p CE
44.42 | 44 30.0 | 30' 8"
43.94 | 43 293 | 30°
43.69 | 43 29.3 | 29'8"
42.45 cy) 27.9 26'
41.68 | 41 27.9 | 27°
40.90 | 40 27.3} 26
40.31 | 40 27.3 | 25°3"
40.11 40 27.3 | 25°
39.71 40 27.3 24'6"
39.30 | 39 266 | 24'
38.69 | 39 266 | 23'6"
38.47 | 38 25.9 | 23°
36.98 | 36 245] 21'3"
36.76 | 36 2451} 21° 10
36.39 36 24.5 20'7" 568
35.87 | 35 23.9 | 20° pes
35.42 | 35 23.9! 19'6" 306
34.51 35 «23.9 | 18'6"
34.04 | 33 22.5 | 18! 3 i
33.56 | 33 225] 17'6"
33.07 | 32 21.8] 17° 7.59
32.66 | 32 21.8 16'7" 72
32.09 | 31 aut 16! 5.66
3i.ar | 31 2ul 15'4" 67
31.07 | 30 204 is! 63.16
30.28 | 29 19.7 14' 3" 62.14
29.74 | 29 19.7 13" 9" 50.92
29.47 | 29 19.7 I3' 6" ‘59.49
29.28 | 29 19.7 13'4" 86.72
28.55 | 28 19.1 12' 8° 85.56
28.08 28 19.1 2° 3" 3.46
27.79 | 27 18.4 12" 1.99
26.61 | 26 ad ut [50.73
25.78 | 25 17.0 lo" 4" 10
25.40 | 23 15.7 lo 9.50
24.72 | 23 15.7 g'6" 6.80
24.07 | 22 15.0 cy 8.63
22.68 | 2t 14.3 B 7.46
21.23 | 20 13.6 “7 6.43
19.24 | 18 12.3 5'10" 08
17.01 13 8.9 46K! 4.67
° 1 2 3 4 5 6 7
> NQ OF FREE-FALLS (N=73)

Type UI Distance Fallen and Velocity for Free-Falls Survived Up to 30 Feet.

-12-



r U
lr CALCULATED WITH H
r AIR DRAG, STANDARD 1
250 + AIR, SEA LEVEL n
r /
L /
!
- /
L !
1
200 + l
_ L
ty) —
ul
L 5 IN VACUUM
z L
H '507
w .
s) L
a
Fad L
2) L
a
‘ 100--
—
2 L
a .
a lor to ci
ASSUMPTION
50- BODY TERMINAL VELOCITY
“120 MPH 3
CpS = +4.7
. eflection
. ; oment d
e | q q 1 LJ q t q q 3
Or 20 40 60 80 100 120 140° 160 E (WL
_ VELOCITY @ IMPACT Max an
. FT / SEC

Ficure 4, Calculated Velocity in Free-Fall.
-4-



HUMAN SURVIVABILITY OF
EXTREME IMPACTS
IN FREE-FALL

RICHARD G. SNYDER, PH. D.
Chief, Physical Anthropology Section

63-15

a

iY Lo

FEDERAL AVIATION AGENCY
AVIATION‘MEDICAL SERVICE .
e AEROMEDICAL RESEARCH DIVISION
| CIVIL AEROMEDICAL RESEARCH INSTITUTE
OKLAHOMA CITY. OKLAHOMA

AUGUST 1963



«, (feet first)

Distance Body Material
Age Sex Fallen V(ft/sec)* Orientation Impactea Injuries
14 M 42" 51 +Gz (feet first) | soil NONE
14 Mu 25" 40 -G, (head first) | concrete cerebral concussion
ub M 17 32 -Gy (head first) | concrete fractured skull
. 2 M 62° 61 -G, (head first) | concrete chest contusion
. cerebral concussion
possible fractured skull
. M 15" 30 -G, (head first) | concrete contusion only
M 20° 35 ~Gz (head first) | concrete possible fractured skull
M 2s" 40 -G, (head first) | snow NONE
why ¥ 35° 47 “Gy, (head first) | concrete basilar skull fracture
a M 24'6" 40 +G, (feet first) | concrete NONE
a M 18'6" 3s -G, (head first) | concrete oblique fissure fracture,
right parietal;
cerebrs1 concussion
3 F 19°6! 35 +G, (feet first) | concrete & soil NONE
3 F 10'4" 25 +6, (feet first) | concrete & soil NONE
3 M 21'3" 36 +G, (feet first) | sandy soil NONE
3 Mu 14° 29 Gz (head first) | hard soil cerebral concussion
periorbital hematoma
contusion right eye
contusion upper lip
3 Fr 18*6" 35 -G, (head first) | concrete cerebral concussion
oe fractured skull
3 ¥ 50° 55 +G, (feet first) | hard soil hematoma, right occipital
area
ay bd 28' 41 -G, (head first) | hard soil cerebral concussion;
severe contusion, left
shoulder; fracture lamina
bilateral C-1; fracture
lamina bilateral C-2.
4 r 23° 38 +G, fhands & knees) macadam walk sprain, right ankle;
. ‘ laceration, chin
4 r 31 44 soil . NONE

* calculated V (See Chart 7)
** A year earlier fell 30' from second story of same buildifigewithout injury

)

Tanz V_ Impact Injuries Received by 19 Children from 1% to 4 Years of Age.

* 23 —


Civil Aeromedical Research Institute, Federal Aviation 1. Deceleration Civil Aeromedical Research Institute, Federal Aviation 1. Deceleration
Agency, Oklahoma City, Oklahoma. CARI Report 63-15. 2. Acceleration * Agency, Oklahoma City, Oklahoma. CARI Report 63-15. 2. Acceleration
HUMAN SURVIVABILITY OF EXTREME IMPACTS 3. Free-Fall HUMAN SURVIVABILITY OF EXTREME IMPACTS 3. Free-Fall
IN FREE-FALL by Richard G. Snyder. 4. Impact Trauma IN FREE-FALL by Richard G. Snyder. 4. Impact Trauma
5. Crash Injury 5. Crash Injury
Human deceleration tolerances beyond the limits imposed by Human deceleration tolerances beyond the limits imposed by .
voluntary experimental methods were studied by means of in- voluntary experimental methods were studied by means of in- &
tensive c: histories of 137 individuals who’ have survived tensive ‘case histories of 137 individuals who have survived
extremely abrupt impacts in accidental, suicidal, and homicidal extremely abrupt impacts in accidental, suicidal, and homicidal
free-falls. Fall distances ranged up to 275’ and calculated ve- free-falls. Fall distances ranged up to 275’ and calculated ve-
locities up to 116 ft/sec (79 mph). Physical and biological data locities up to 116 ft/sec (79 mph). Physical and biological data
are presented on both sexes with an age range of 1% to 91 years, are presented on both sexes with an age range of 1% to 91 years,
and with impacts occurring in all body axis orientations. A de- and with impacts occurring in all body axis orientations. A de-
d anal: of factors found to affect survivability in free-fall tailed analysis of factors found to affect survivability in free-fall 3
impacts is made. These cases, out of some 12,000 free-falls col- impacts is made. These cases, out of some 12,000 free-falls col-
lected in the past two years, demonstrate that humans have lected in the past two years, demonstrate that humans have
survived impact forces considerably greater than those previously survived impact forces considerably greateg’thah those previously
believed tolerable. believed tolerable. .
Civil Aeromedical Research Institute, Federal Aviation 1. Deceleration Civil Aeromedical Research Institute, Federal Aviation 1. Deceleration
Agency, Oklahoma City, Oklahoma. CARI Report 63-15. 2. Acceleration Agency, Oklahoma City, Oklahoma. CARI Report 63-15. 2. Acceleration
HUMAN SURVIVABILITY OF EXTREME IMPACTS 3. Free-Fall HUMAN SURVIVABILITY OF EXTREME IMPACTS 3. Free-Fall
IN FREE-FALL by Richard G, Snyder. 4, Impact Trauma IN FREE-FALL by Richard G. Snyder. ~ 4, Impact Trauma
5. Crash Injury . 5. Crash Injury

Human deceleration tolerances beyond the limits imposed by
voluntary experimental methods were studied by means of in-
tensive case histories of 137 individuals who have survived
extremely abrupt impacts in accidental, suicidal, and homicidal
free-falls. Fall distances ranged up to 275’ and ‘calculated ve-

ies up to 116 ft/sec (79 mph). Physical and biological data
are presented on both sexes with an age range of 1% to 91 years,
and with impacts occurring in all body axis orientations, A de-
iled analysis of factors found to affect survivability in free-fall
pacts is made. These cases, out of some 12,000 free-falls col-
lected in the past two years, demonstrate that humans have
ived impact forces considerably greater than those previously
believed tolerable.

Human deceleration tolerances beyond..the limits imposed by
voluntary experimental methods were studied by means of in-
tensive ‘case historiesmof 137 individuals have _ survived
extremely abrupt impacts in accidental, suicidal, and homicidal
free-falls. Fall distances ranged up to 275’ and calculated ve-
locities up to 116 ft/sec (79 mph). Physical and biological data
are presented on both sexes with pn age range of 1% to 91 years,
and with impacts occurring ii-ail body axis orientations. A de-
tailed analysis of factors f6und to affect ‘survivability in free-fall
impacts is made. These cases, out of some 12,000 free-falls col-
lected in the past two years, demonstrate that humans have
survived impact forces considerably greater than those previously
~ believed tolerable.

>



calculated velocities up to 116 ft/sec (79 mph).
This population included both sexes with an
age range of 1% to 91 years. A detailed anal-
ysis of factors found to affect survivability in
free-fall impacts was presented.

It has been shown that humans have sur-
vived impact forces considerably greater than
those previously believed tolerable. It is sug-
gested that muscular relaxation (as in intoxica-
tion or paranoid schizophrenia) may play an
important role in reducing trauma in some
cases, These data also indicate that, as the du-
ration of impact is decreased below .0006 sec-
onds and zero time is approached, body tissues
may not respond as expected and survival of
impact forces of normally fatal magnitude may
be increased.

ACKNOWLEDGMENTS

The author wishes to acknowledge with sin-
cere appreciation the assistance provided in
conducting this study by CARI staff scientists
Clyde Snow, M.S., who assisted in several in-
vestigations, J, J. Swearingen, M.S., and Jo?
seph W. Young, A.M., for use of unpublished
impact data, John C, Earley, M. Aero E., for
engineering assistance, Jim Scow, M.D., and
Robert Dille, M.D., for mfedical consultation,
Mary Lou Ramsey for sorting and filing data,
and Mary Lou Johnson for statistical assistance.
Additional assistance was provided by Kenneth
K. Kienow, B.S.C.E., of Concrete Conduit Co.,
who performed tests and calculations of ma-
terials impacted. In addition scores of physi-
cians, FAA Aviation Medical Examiners, Cor-
oners, Federal, State, and local police agencie’.
provided invaluable assistance withopt which
this investigation could not hgve been
conducted. ‘

a
REFERENCES ,

1. Amelar, R. D., and C, Soloman. 1945 “The/
Wages of Boxing is Trauma. Detection of
Renal Injury after Fights.” Journal Urol-
ogy 72:145.

2, Beeding, E, L., Jr. .1961 “Human Forward
Facing Impact Tolerances.” Presented at
32nd Annual Meeting Aerospace Medical
Association, Chicago, Illinois, April 24-27.

,

»

10.

11.

12,

~26~—

. Brossard, Chandler.

Beeding, E. L., Jr., and J, E. Cook, 1962
“Correlation Tests of Animals and Hu-
mans.” In Cragun, M. K. (Ed.) The Fifth
Stapp Automotive Crash and Field Dem-
onstration Conference, 125-129. Minne-
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Beeding, E. L., Jr. and J. D. Mosely. 1960
“Human Tolerance to Ultra High G Forc-
es.” Presented at 31st Annual Meeting of
Aerospace Medical Association, Bal Har-
bour, Florida, May 9-11,

Beeding, E. L., Jr., J. P. Stapp, R. R, Hess-
berg. 1959 Daisy Track Tests — Series of
reports, April 1957 through Dec, 1959, Air
Force Development Center, Holloman
AFB, New Mexico.

Brock, F, J. 1959 “Project Mercury Pilot
Support Systems Development, Live Spec-
imen Experiment” National Aeronautics
and Space Administration, Report 6875,
Serial No, 43, NASA 5-59, June 1, 1959,

1963 “Two Young

Steelworkers Make New York.” Look
27(6) :30-33.
Ciccone, R., and R. M. Richman, 1948

“The Mechanism of Injury and the Distri-
bution of Three Thousand Fractures and
Dislocations Caused by Parachute Jump-
ing.” J. Bone and Joint Surg. 30-A(1)77-97.

Coles, C. H. 1945 “Abrupt Deceleration
of Animals.” AAF, ATS Command Memo
Rep. TSEAL-6F-181, Wright Field, Day-
ton, Ohio.

Cotner, J.S. 1963 “Analysis of Air Resist-
ance Effects on the Velocity of Falling
Human Beings.” C.A.R.I. Report, Federal
Aviation Agency, Qklahoma City, Okla-
homa. In press.

De Haven, H. 1942 “Mechanical Analy-
sis of Survival in Falls from Heights of
Fifty to One Hundred and Fifty Feet.”
War Med. 2:586-596.

De Haven, H. 1948 “Informative Acci-
dent No, 7” N.R.C. Crash Injury Research,
N.Y. 7 May.

Sg tt



magnitude, orientation of the body (direction
of force), and time duration, among other fac-
tors, It is generally considered that the greater
the area over which the load is applied, the
smaller the load per unit area. This principle has
been applied to restraint systems which aim to
distribute the load over the skeletal framework
of the body rather than subjecting soft structure,
such as the abdomen, to extensive pressures.
While the results of this investigation are not
conclusive as to variations in the distribution
of force in free-falls, an interesting paradox is
observed. Thus in 12 cases of survived falls of
over 100 feet distance, 10 initial impacts were
in the feet-first position. Both feet provide an
approximate surface area generally not exceed-
ing 67 sq. inches in normal weight-bearing for
males, and 45 sq. inches for females. While
the assumption that concentration of force over
a small surface area, such as the feet, may be
theoretically not as desirable as distribution of
force over a large area (as in the prone or
supine position), the evidence from the 78 feet-
first impacts indicates that this may not be as
critical a consideration as other factors, While
one can object that selection of cases has re-
sulted in a skewed distribution of free-fall sur-
vivals in the feet-first, (+G,) position, these
cases do represent the extreme survival position
most readily occurring. Force is apparently
greatly attenuated in +G, impacts by bending
and flexion of the leg muscles, as well as tissue
and structural attenuation. On the other hand,
in cases of free-fall where the individual has
been impaled on a fence, or straddled a narrow
steel girder in a prone position,; the concehtra-
tion of force at structurally weaker points has
contributed to much more severe Anjuries.

Distribution of force is directly related to the
transmission and dissipation of energy through;
out body tissues, Most deceleration studi¢s
have been concerned with this distribution/in
body orientations of the seated forward-facing
or backward-facing position. Feet-first impacts
have previously been independently studied by
Sweatingen (60) and by Hirsch (25), regard-
ing injuries to lower ¢xtremities of naval person-
nel due to deckblast of underwater explosions,
and by Swearingen et al. (61) in voluntary
human drop tests. In this latter study it was

found that subjective tolerance levels for in-
dividuals impacted in rigid seats and in the
standing position with knees locked were iden-
tical (10 g at 600+ g/sec at shoulder level),
with input loads at 65 g at 10,000 g/sec for the
standing position and 95 g at 19,000 g/sec for
the sitting position. The difference in transmis-
sion rate was considered due to the difference
in the rigidity of the skeletal system in the
standing position as compared to the seated
compressibility of the gluteal musculature. In
addition, Swearingen found that there was an
attenuation of only 6-10 times, but a very rapid
transmission (400-1000 ft/sec), in feet-first im-
pacts with the knees locked, while impact forces
“were attenuated 36 times by bending the
knees.” Ciccone and Richman (8), in studying
the mechanism and distribution of injuries in
3,000 fractures in parachute jumping, noted
that landing stiff-legged, typical of the un-
trained individual, usually resulted in a frac-
tured heel. Thus the degree of voluntary
bending of the knee during impact appears to
be quite important in degree of injury in feet-
first impact. With this in mind an effort was
made to leam from the free-fall subjects
whether they were relaxed or tense (stiff-
legged) during the fall, Some individuals re-
ported that they were “petrified” or “scared as
hell” during the fall, while others claimed to
have been relaxed, Such subjective answers
are of questionable reliability, but those who
claimed to have relaxed and remembered im-
pacting with bent knees did appear to suffer
less severe injury.

Hl. Magnitude of Force

Force magnitude and time relationships are
generally expressed in terms of the familiar g
load and “rate of onset.” In this study, mag-
nitude is described in terms of the velocity of
free-fall at impact*thereby providing a basis
for comparing cases and for making further
calculations as desired. Some of these falls
involve such a short time duration, consider-

‘ably less than in previous human experiments,

and with such ultra-high impact velocity, that
the calculated g forces often exceed 5000 in
survived falls with rates of onset into the mil-
lions of g’s per second, Not only are the g
forces as much as 70 to 100 times the highest

-10-—

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. MELOCITY

CALCULATED
ft/sec | mph [DISTANCE
6 079.1 | 275°
Wl 78.7 | 246°
106 = 72.3 | 220°
1057.6 | 2B"
97 = 66.1 (78°
96 665.5 | 170°
zt | 86 58.6 | 135°
1.47 | 85 57.9 | 130°
43 | 82 55.9 | 121'6"
Ol 80 54.5 | 112'4"
98 | 78 53.2 | 107"
22 | 76 51.8 | 100°
9 | 73 498 92'
76.10 | 72 49.1 90°
6.68 | 71 48.4 69'
78.07 | 70 47.7 | 87'7"
7a% | 70 47.7 | @5'
73.82 | 69 47.0] 984
07 | 65 44.3 72!
7.59 | 65 443] 7I'
7.12 | 64 43.6 | 70°
8.66 | 62 42.2] 67°
64.67 | 61 41.6] 65°
6316 | 61 41.6]; 62°
62.14 | 60 40.9 60°
‘ 60.92 | 59 40.2 57's"
59.49 | 57 38.8] 55'
86.72 | 55 37.5 50°
55.58 | 54 36.8|] 46°
83.46 | 52 35.4] 44'S"
si.99 | $1 34.7] 42"
$0.73 | 50 34.1 40°
80.10 | 49 33.4 39g
49.50] 49 334] .38'I" |,
4080 / 48 327) 37° ff
4063 | 48 32.7 36'9"
47.46 | 47 32.0| 35°
46.43} 46 31.4] 336"
4608 | 46 31.4] 33' ¢
4a67 | 44 30.0 3
8 9 \ ° 1 2 3 4 5 6 7 8 9 to
rs + NO. OF FREE“FALLS = (N=68)

WTasze IV Distance Fallen and Velocity for Free-Falls Survived 31 to 275 Feet.

~13-—