f. Nomograph. A graph that enables one by
craft having various wheel loads and tire
the aid of a straightedge to read off the value
of a dependent variable when the value of the
3. Terminology. Certain terms peculiar to
independent variable is given.
this subject are defined as follows:
g. Penetrometer. Pen-e-trom-e-ter, an in-
a. Airfield Index. A measure of soil strength
strument for measuring the consistency of
obtained with the airfield cone penetrometer.
b. Aircraft Pa-w. One takeoff or one landing.
h. Single-Wheel Load. The gross load sup-
c. Coverage. One pass of a load wheel over
ported by a single-wheel of a main landing
each point within a traffic lane. In the case of
large, multiple-wheel aircraft, as few as two
passes may be required to apply one coverage;
4. References. a. TB ENG 37, Soils Traffic-
for smaller, single-wheel aircraft, as many as
10 to 20 passes may be required.
b. TM 5530, Materials Testing.
d. Equivalent Single-Wheel Load. The load
c. TM 5541, Control of Soils in Military
on a single-wheel main gear which will produce
effects equivalent to those produced by the total
load on a multiple-wheel assembly.
d. U.S. Army Corps of Engineers Drawings
MS3031, January 1965.
e. KIP. A unit of weight equal to 1,000
pounds used to express deadweight load.
USE A N D
d. The penetrometer's carrying case is con-
5. Description. a. The airfield penetrometer
structed from heavy duck.
is a probe-type instrument designed
measure soil strength. The overall length of
e. The extension rods (5) are graduated in
the assembled penetrometer is approximately
two-inch increments and are provided with
361/8 inches, and weighs approximately 2.6
wrench flats to facilitate removal and installa-
pounds (including the wrenches).
tion. The cone (6) also has a wrench flat to
permit removal and installation.
b. For ease in carrying, the penetrometer
can be disassembled into three main pieces:
f. The handle (2) is a metal cylinder which
two extension rods (5), each 125/8 inches
fits into the head (1) at the top of the pene-
long, and one piece 14-3/4 inches long, which
includes removing the cone (6) from extension
g. The spring, consisting of two separate
rod (5) and installing the cone (6) on the cone
sets of interwound coils which act as a single
rod (4), removing cone cover and handle (2)
unit, is stretched (tension) directly in propor-
from head (1) and securing cone cover (2)
tion to the load applied to the handle.
to bottom of housing (3).
h. The load-indicating device (7) is located
c. The two wrenches (midget open end, dou-
in the housing (3) and moves up and down as
ble head, 15 and 75 heads, overall length
the load on the handle (2) is varied. The pene-
33/4 in., nominal openings 11/32 in. Military
trometer scale (8) has been factory calibrated
description: CCG-W-636A-1, Type VI, Style
at ten times the indicated load; hence, 100 lbs.
B), and an extra cone which accompany the
reads 10 on the scale. The scale is marked 0-15
penetrometer can be carried in the cone cover
and reflects the load at any particular moment.