An investigation of a thermal ice-prevention system for a C-46 cargo airplane 7: Effect of the thermal system on the wing-structure stresses as established in flight Page: 4 of 43
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NACA ARR No. 5G20
Forces. .The authors wish t-o.acknowledge with appreciation
the valuable assistance, during the. ncet--t-- -the flight
tests, of Mr. Robert Deland of the Curtiss-Wright Corporation.
Description of Equipment
The 0-46 airplane'(fig. 1) is a twin-engine, 16w-wing,
transport-cargo monoplane powered by Pratt & Whitney model
R-2800-51 engines having a sea-level rating of 2000 horse-
power each.' The wing' span is 108 feet, the wing area 1360
square feet, and: thenormal gross weight 45,000 pounds.
The details of construction of the left-wing outer panel
in which the stress measurements were obtained are shown in
figure 2. The wing is of all-metal stressed-skin construction
with spars.at.-30 and 70 percent 'of the chord. The skin is re-
inforced with spanwise hat sedtions.and extruded stringers.
At the wing root (station 0) the outer panel .is attached to
the inboard section through splice angles along the upper and
lower surfaces of the wing. The wing profile varies from an
NACA 23017 section at station 0 (chord = 198 in.) to an NACA
4410.5 section at statin 412 '(chord '= 66 in.).
A complete description of the revisions to the.0-46 air
plane for thermal ice prevention is given in reference 4;
however, a brief oit'line of the alterations as- they affect the
wing structure will also be given herein. The heated air for'
ice prevention is obtained from 'exhaust-gas-to-air heat ex-
changers installed on each side of 'the nacelles as may be seen
in figure 1. The air fro'm the outboard exchangers is directed
to the outer-panel leading-edge heating system shown in fig-
ures 2 and 3. The details shown in figure 3 comprise the
major revisions to the wing, the only other alterations being
small reinforced holes in the spar webs (fig. 2) for circula-
tion of the' heated air.
The changes in stress were measured ith 'standard Bald win-
Southwark wire resistance-type strain gages. In determining
the location of the gages, consideration was given 'to the
stress reports for the unheated wing and the measured tempera-
ture distribution in the wing as presented in references 5 and
7. .The stress reports showed that the margins of safety were
appreciably lower at the wing root than near the tip'; while
the temperature data indicated that, in general, the span ise
distribution of temperature rise for a given chord location
was approximately constant'. The assumption was made that, for
a given chord location, the stress -'change along the span would
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Jones, Alun R. An investigation of a thermal ice-prevention system for a C-46 cargo airplane 7: Effect of the thermal system on the wing-structure stresses as established in flight, report, September 1945; (https://digital.library.unt.edu/ark:/67531/metadc61827/m1/4/: accessed April 21, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.