Rotorcraft Flying Handbook, FAA-H-8083-21

affected by atmospheric wind is the angle of climb and
not the rate of climb.
SAMPLE PROBLEM 4
Determine the best rate of climb using figure 8-5. Use
the following conditions:
Pressure Altitude................................12,000 feet
Outside Air Temperature ...........................+10°C
Gross Weight..................................3,000 pounds
Power ...........................................Takeoff Power
Anti-ice ..........................................................ON
Indicated Airspeed .................................52 knots
With this chart, first locate the temperature of +10°C
(point A). Then proceed up the chart to the 12,000-foot
pressure altitude line (point B). From there, move horizontally
to the right until you intersect the 3,000-foot
line (point C). With this performance chart, you must
now determine the rate of climb with anti-ice off and
then subtract the rate of climb change with it on. From
point C, go to the bottom of the chart and find that the
maximum rate of climb with anti-ice off is approximately
890 feet per minute. Then, go back to point C
and up to the anti-ice-on line (point D). Proceed horizontally
to the right and read approximately 240 feet
per minute change (point E). Now subtract 240 from
890 to get a maximum rate of climb, with anti-ice on,
of 650 feet per minute.
Other rate-of-climb charts use density altitude as a
starting point. [Figure 8-6] While it cleans up the chart
somewhat, you must first determine density altitude.
Notice also that this chart requires a change in the indicated
airspeed with a change in altitude.
Density Altitude — Feet
12,000
10,000
8,000
6,000
4,000
2,000
0
RATE OF CLIMB/DENSITY ALTITUDE
2,350 LBS. GROSS WEIGHT
BEST RATE OF CLIMB SPEED VARIES WITH
ALTITUDE; 57 MPH AT S.L. DECREASING TO 49
MPH, IAS AT 12,000 FT.
400 600 800 1,000 1,200 1,400
Rate of Climb, Feet Per Minute
Figure 8-6. This chart uses density altitude in determining
maximum rate of climb.
RATE OF CLIMB — MAXIMUM
TAKEOFF POWER
This Chart is Based on:
Indicated Airspeed 60 MPH 52 KNOTS
N2 ENGINE RPM 100%
20,000
PRESSURE
ALTITUDE — FT.
18,000
HOT
DAY
ANTI-ICE ON
(Point D)
(Point E)
0
100
200
300
400
500
R/Correction — FT./MIN.
16,000
14,000
12,000
(Point B) (Point C)
3,200
3,000
2,800
2,600
2,400
2,200
2,000
GROSS WEIGHT
POUNDS
890 ft/min.
– 240 ft/min.
650 ft/min.
8,000
10,000
6,000
4,000
2,000
(Point A)
S.L.
–40 –20 0 20 40 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32
OAT — ° C ANTI-ICE OFF RATE OF CLIMB — FT./MIN. (X 100)
Figure 8-5. Maximum Rate-of-Climb Chart.
8-6