Figure 62. Tracks of proof cart on area patched 48 hours earlier.
ness, a bump analysis should be performed. This
area should be "dressed" with the chisel-
analysis will require that survey data be taken
tooth grader blade to blend its edges into
along several lines on selected segments of the
the surrounding ice surface and to provide a
runway. The most critical portions of the runway
uniform surface texture.
from a bump standpoint are in the touch-down
9. If there is any question about the integrity of
area and leading up to the lift-off area (areas where
the patched area, this location should be re-
the aircraft will be traveling at maximum speeds).
certified. This may entail simply taking one
If only one line of data are to be analyzed, obvi-
or a couple cores at the site to confirm that
ously the centerline of the runway should be sur-
no voids exist and that a randomly oriented
veyed. For the majority of heavy aircraft, bumps
polycrystalline ice has formed in the cavity.
with a frequency of less than 1 m on a graded
If there is any doubt as to the strength of the
runway are inconsequential. Thus, depending on
patched area, it should be proof rolled using
the ice-leveling method used, survey data may be
one of the methods outlined in the section
spaced anywhere from 2 m for a crudely leveled
on full-scale testing (Fig. 62).
ice surface to 10 m for a surface that was laser
graded.
We used a "cosine bump" analysis program
ROUGHNESS SURVEY
(Wills 1989) to produce an amplitude vs. wave-
length plot (Fig. 63). This provided us with maxi-
If a laser-controlled device was used to pro-
mum bump heights to compare with the military
duce the glacial ice runway surface the degree of
specification for allowable roughness levels for
smoothness will be far in excess of published stan-
the C-141 and C-130 aircraft. Figure 64 shows the
dards for aircraft, both in terms of critical short-
acceptable levels of smoothness for the C-141 and
wave (<3 m) and long-wave (>10 m) bumps.
the bump analysis results for the Pegasus runway
However, if there is any question of the suitabil-
following construction.
ity of the runway from the standpoint of rough-
60
Previous Page
