crotch, feet, shoulders) of the different age groups
that one measurement remains more or less con-
stant with growth; ie, height of cg. above the
crotch. This measurement of 6+0.7 inches for a
zero to 6-month-old infant and 6.40.6 inches
for a 30 to 36-month-old child is surprisingly
close to that measured on the adult male of
5.90.9 inches.”

In addition, it may be noted that the height
of the cg. from the feet in terms of percent of
body stature remains fairly close and varies less
than 2 percent (55.55 to 57.30) in the first 3 years
of life. This agrees with Weinbach’s study* in
which he found a mean height of c.g. for chil-
dren 14 to 3.5 years of age in percent of body
stature to be 54.7.

uo

+b

a

C.G. ABOVE CROTCH (INCHES)

i

i

o1234 56 7 8 9

ADULT
MALE

10 11 12 13 14 15 16 17 18

AGE (YEARS)

Figure 2, Means of

Figure 2 combines the data in this report with
those from the author’s previous studies of body
c.g. positions in children (5 to 18 years) and the
adult male to present a nearly complete guide
for determining the location of the body cg. (as
measured from the crotch) in the standing posi-
tion. For the first 2 years the cg. of the body
is in excess of 6 inches above the crotch. From
ages 5 to 18 this measurement has decreased and
remains at about 5 inches. By the time a person
reaches 17 or 18 it has returned to remain at its
original measurement of about 6 inches.

cg. of children standing.

III. CONCLUSIONS

While the location of the body c.g. as refer-
enced from the crotch in the standing position
remains fairly constant. at 6 inches throughout
life, it does not follow that all age groups can be
equally well restrained against crash impact
forces with the same restraint equipment. Six
inches in an infant with a 9-inch trunk places the
cg. high in the chest, just below the armpits.
At 1 year of age, the trunk has increased in
length to 12 or 13 inches and the c.g. is located





ment shown in Figure 1. This equipment. con-
sists of a horizontal board with one end resting
on a spring scale and the other pivoted on a
hinge. While the spring scales are marked “not
legal for trade,” they were calibrated by weights
and found sufficiently accurate for this study.
The subject’s head was placed against the padded
board (5 inches from the fulcrum) and the loca-
tion of the body c.g. from the top of the head
determined from the formula:

36 (Scale Reading)

Body Weight —5=eg. from top of head

Where 386 inches=distance from fulcrum to the
center of the scale.

5 inches=distance subtracted for distance
from fulcrum to top of head.

The horizontal platform was marked at 1-inch
increments from the headboard to facilitate
reading body measurements with reference to the
top of the head. Distances were projected to the
scaled platform by pressing a drafting right-
angle triangle against body reference points and

taking readings at the point of contact of the
right angle.

Sex, race, age in months, weight, stature, scale
reading, distance from top of head to the upper-
most point of the crotch determined by firm pres-
sure applied with the triangle, and the distance
from top of head to the mid-point of the top of
the shoulder were recorded for each child at the
nursery. Later the investigators calculated trunk
length and distances of the c.g. from the top of
the head, from the crotch, from the feet, and
from the shoulders. In addition, the distance of
the c.g. from the feet was calculated in terms of
percent of stature. Attempts were made to study
150 erying, wiggling infants, but 15 had to be
eliminated as it was impossible to calm them
down enough to obtain accurate readings.

Il. RESULTS

A summary of the data accumulated in this
study is presented in Table I. It may be noted
from studying the c.g. measurements from various
reference points on the bodies (top of head,

Taste I. Summary of infant c.g. data.
N 4846%=10 17%179=34 1704 129-29 219412933 5%489=13 8+-89=16
Age in Months 0-6 6-12 12-18 18-24 24-30 30 - 36
Weight (pounds)
fean 15.1 19.4 23.5 25.4 27.9 29.9
Standard deviati 2 4.0 2.3 217 3.3 22 1.8
Stature (inches)
Mea - 24.9 28.2 31.2 33.1 35.6 36.9
Standard deviation 24 15 1.8 2.8 1.2 1.0
Top of head to erotch (inches)
17.1 18.9 20.2 20.8 21.7 22.1
13 18 Ll 10 a)
57 6.2 6.7 6.9 1.2 7.5
Standard deviation : 3B 5 5 4 13 v4
©... from top of head (inches)
AL. 12.5 13.8 14.7 15.5 15.8
- 1,3 9 1.3 1,2 11 5
- 6.0 6.3 6.3 6.0 6.2 6.4
Mandard deviation 2 7 8 7 ‘9 7 16
©... from Feet (inches)
- 13.8 15.7 17.4 18.4 20.1 21.1
etard deviation. - 1.4 1.4 La 1.7 .6 9
©..G. from shoulder (inches)
5.3 6.3 7.2 7.8 8. 8.3
La 9 11 11 1.2 5
55.5 55.6 55.8 55.5 56.6 57.3
Meedard deviation. - 2.3 2.9 2.6 2.9 17 15



at about the tip of the sternum. Between the
ages of 1 and 3 years, the trunk increases in
length to between 14 and 16 inches and the ag.
is located in the soft abdominal viscera. Not

until the child reaches his fifth or sixth year has
the c.g. dropped sufficiently and the pelvis devel-
oped enough in size to allow the seat belt to be
used as a safe and effective restraint device.

REFERENCES

1. Sweanincen, J. J. and J. W. Youne: Determination
of Centers of Gravity of Children, Sitting and Stand-
ing. Federal Aviation Administration, Civil Aero-
medical Research Institute, Oklahoma City, Okla-
homa, Report AM 65-23, August 1965.

2, Sweanrneen, J. J.: Determination of Centers of Grav-
ity of Man. CAMRL, CAA Project 53-203; USN

Contr. NAonr 104-51. ASTIA AD-10 410, Reprinted
as CARI Report 62-14, FAA, Oklahoma City, Okla.,
August 1962.

3. WeinsacH, A, P.: Contour Maps, Center of Gravity,
Moment of Inertia and Surface Area of the Human
Body. Human Biology, 10(3): 356-371, September
1938.


AM 69-22

DETERMINATION OF CENTERS OF GRAVITY
OF INFANTS

J. J. Swearingen, D. Av.T.
J. M. Badgley
G. E. Braden
and
T. F. Wallace

Approved by Released by
illite PU Siigel wo
J. Roperr Druze, M.D. P. V. Smart, M.D.
Cuter, Crviz ABROMEDICAL Fepverat Ar Sureron

INSTITUTE

November 1969

Department of Transportation

FEDERAL AVIATION ADMINISTRATION
Office of Aviation Medicine





Qualified requesters may obtain Aviation Medical Reports from Defense Documentation
Center. The general public may purchase from Clearinghouse for Federal Scientific and
‘Technical Information, U.S. Dept. of Commerce, Springfield, Va. 22151.


DETERMINATION OF CENTERS OF GRAVITY OF INFANTS

At the present time infants and small children
are not adequately protected against crash de-
celerations, both in aircraft and automotive trans-
portation. In addition, in the event of an aircraft
ditching, this young group of the population is
provided no personal flotation equipment.

Perhaps the main reason for the long delay in
developing protective equipment for children in
the age group of 1 month to 8 years by the design
engineers was the lack of basic anthropometric
data concerning body measurements and locations

of body cg. (center of gravity) for this group.
A previous report? published by the author has
been. used as a basis for numerous restraint de-
vices for children 5 to 18 years of age, and it is
hoped that the data presented here may serve the
same purpose for infants up to 3 years of age.

I. PROCEDURE

Arrangements were made with several nurseries
for making body measurements and determining
the location of body c.g. on the portable equip-

Figure 1.

1

Intant cg, vamucing equipment.