TM 1-1520-240-10
7-8-1
SECTION VIII. DRAG
7-8-1. Description.
The drag chart (fig. 7-8-1) shows the torque change re-
quired for flight due to drag area change as a result of
external configuration changes.
7-8-2. Use of Charts.
The primary use of the chart is illustrated by the example.
To determine the change in torque, it is necessary to
know the drag area change, TAS, PA, and FAT. From the
table below find the drag area change associated with
the configuration, or estimate if necessary. Enter chart
at known drag area change, move right to TAS, move
down to PA, move left to FAT, then move down and read
change in engine torque.
7-8-3. Conditions.
The drag chart is based on operating at 100% RRPM.
Table 7-8-1. Change in Drag Area of Typical Exter-
nal Loads
LOAD
DRAG
AREA
CHANGE
SQ FT
CONTAINERS: (1)
8 FT x 8FT x 20 FT CONEX
150/100(2)
ISU-60
62
ISU-90
81
(2) ISU-90
115(2)
(2) 500 GAL FUEL CELLS
40
(3) 500 GAL FUEL CELLS
60
(4) 500 GAL FUEL CELLS
80
TRUCKS: (1)
HMMWV (ENCLOSED VEHICLE)
49/28(2)
HMMWV (TOW LAUNCHER)
54/31(2)
M34 1/2 TON DUMP
100
M35 2 1/2 TON CARGO
80
HOWITZERS:
M2A1-105MM
50
M102-105MM
50
M198-105MM
149/50(2)
HELICOPTERS:
OH-58 HELICOPTER
93(3)
UH-60 HELICOPTER
175(3)
AH-64 HELICOPTER
170(3)
CH-47 HELICOPTER
230(2)(4)
1)
RIGGED IN ACCORDANCE
WITH FM 10-450
(2)
WITH DUAL POINT SUSPEN
SION
(3)
RIGGED IN ACCORDANCE
WITH TM-1-1670-260-12&P
(UNMARK)
(4)
RIGGED IN ACCORDANCE
WITH TM 1-1520-240-BD
DATA
BASIS:
ESTIMATED/
FLIGHT
TEST
