Cessna 402C - Page 104

SECTION 5
PERFORMANCE
Interpolation Method
If the approximation method yields a value larger than can be tolerated,
a
more exact value should be determined using the interpolation method.
The example wei9ht (6200 pounds) is 6000 pounds plus 200/500 or .4 times
the difference
between 6000 pounds and 6500 pounds [i.e.: 6000-pound value
+ .4 (6500-pound value - 6000-pound value)]
The example pressure altitude (2400 feet) is 2000 feet plus 400/1000 or
.4 times the difference between 2000 feet and 3000 feet [i.e.: 2000-foot
value
+ .4 (3000-foot value - 2000-foot value)] .
The example temperature of 16
0
e (61°F)
is 10
0
e plus 6/10 or .6 times the
difference
between 10
0
e and 20
0
e [i.e.: 10
0
e value + .6 (20
0
e value - 10
0
e
value)].
Interpolating Values for Normal Takeoff Distance:
Ground Roll (7 interpolations required)
Altitude interpolation
at 10
0
e (500F) and 6500
pounds
Altitude interpolation
at 20
0
e (680F) and 6500
pounds
Altitude interpolation
at 10
0
e (500F) and 6000
pounds
Altitude interpolation
at 20
0
e (680F) and 6000
pounds
1 November 1979
2000-foot value + [.4 (3000-foot value -
2000-foot value)]
1680 feet + [.4 (1790 feet - 1680 feet)]
1680 feet + [44 feet]
1724 feet
2000-foot value + [.4 (3000-foot value -
2000-foot value)]
1840 feet + [.4 (2000 feet - 1840 feet)]
1840 feet + [64 feet]
1904 feet
2000-foot value + [.4 (3000-foot value -
2000-foot value)]
1400 feet + [.4 (1480 feet - 1400 feet)]
1400 feet + [32 feet]
1432 feet
2000-foot value + [.4 (3000-foot value -
2000-foot value)]
1530 feet + [.4 (1620 feet - 1530 feet)]
1530 feet + [36 feet]
1566 feet
5-3