Refer to Figure 10-22. This chart is an example of a combined
takeoff distance graph. It takes into consideration pressure
altitude, temperature, weight, wind, and obstacles all on one
chart. First, find the correct temperature on the bottom left-
hand side of the graph. Follow the line from 22° C straight
up until it intersects the 2,000 foot altitude line. From that
point, draw a line straight across to the first dark reference
line. Continue to draw the line from the reference point in
a diagonal direction following the surrounding lines until it
intersects the corresponding weight line. From the intersection
of 2,600 pounds, draw a line straight across until it reaches the
second reference line. Once again, follow the lines in a diagonal
manner until it reaches the six knot headwind mark. Follow
straight across to the third reference line and from here, draw
a line in two directions. First, draw a line straight across to
figure the ground roll distance. Next, follow the diagonal lines
again until it reaches the corresponding obstacle height. In this
case, it is a 50 foot obstacle. Therefore, draw the diagonal line
to the far edge of the chart. This results in a 700 foot ground
roll distance and a total distance of 1,400 feet over a 50 foot
obstacle. To find the corresponding takeoff speeds at lift-off
and over the 50 foot obstacle, refer to the table on the top of
the chart. In this case, the lift-off speed at 2,600 pounds would
be 63 knots and over the 50 foot obstacle would be 68 knots.
Sample Problem 3
Pressure Altitude...............................................3,000 feet
OAT.........................................................................30 °C
Takeoff Weight............................................2,400 pounds
Headwind............................................................18 knots |
Refer to Figure 10-23. This chart is an example of a takeoff
distance table for short-fleld takeoffs. For this table, first find
the takeoff weight. Once at 2,400 pounds, begin reading from
left to right across the table. The takeoff speed is in the second
column and, in the third column under pressure altitude, find
the pressure altitude of 3,000 feet. Carefully follow that line
to the right until it is under the correct temperature column
of 30 °C. The ground roll total reads 1,325 feet and the total
required to clear a 50 foot obstacle is 2,480 feet. At this point,
there is an 18 knot headwind. According to the notes section
under point number two, decrease the distances by ten percent
for each 9 knots of headwind. With an 18 knot headwind, it
is necessary to decrease the distance by 20 percent. Multiply
1,325 feet by 20 percent (1,325 x .20 = 265), subtract the
product from the total distance (1,325 – 265 = 1,060). Repeat
this process for the total distance over a 50 foot obstacle. The
ground roll distance is 1,060 feet and the total distance over
a 50 foot obstacle is 1,984 feet.
Climb and Cruise Charts
Climb and cruise chart information is based on actual
flight tests conducted in an aircraft of the same type. This
information is extremely useful when planning a cross-country
to predict the performance and fuel consumption of
the aircraft. Manufacturers produce several different charts
for climb and cruise performance. These charts include
everything from fuel, time, and distance to climb, to best
power setting during cruise, to cruise range performance.
The first chart to check for climb performance is a fuel,
time, and distance-to-climb chart. This chart will give the
fuel amount used during the climb, the time it will take to
accomplish the climb, and the ground distance that will
be covered during the climb. To use this chart, obtain the
information for the departing airport and for the cruise
altitude. Using Figure 10-24, calculate the fuel, time, and
distance to climb based on the information provided. |