Pilot and student pilot community. Share your pilot lessons or aviation stories.



Performance Charts – Climb and Cruise Charts (Part Two)

by Flight Learnings

in Aircraft Performance

The next example is a cruise and range performance chart. This type of table is designed to give TAS, fuel consumption, endurance in hours, and range in miles at specific cruise configurations. Use Figure 10-26 to determine the cruise and range performance under the given conditions.

Figure 10-26. Cruise and range performance.

Figure 10-26. Cruise and range performance.

Sample Problem 6

Pressure Altitude………………………………………..5,000 feet

RPM…………………………………………………………2,400 rpm

Fuel Carrying Capacity………………38 gallons, no reserve

Find 5,000 feet pressure altitude in the first column on the left-hand side of the table. Next, find the correct rpm of 2,400 in the second column. Follow that line straight across and read the TAS of 116 mph, and a fuel burn rate of 6.9 gallons per hour. As per the example, the aircraft is equipped with a fuel carrying capacity of 38 gallons. Under this column, read that the endurance in hours is 5.5 hours and the range in miles is 635 miles.

Cruise power setting tables are useful when planning cross-country flights. The table gives the correct cruise power settings, as well as the fuel flow and airspeed performance numbers at that altitude and airspeed.

Sample Problem 7

Pressure Altitude at Cruise…………………………..6,000 feet

OAT…………………………………………..36 °F above standard

Refer to Figure 10-27 for this sample problem. First, locate the pressure altitude of 6,000 feet on the far left side of the table. Follow that line across to the far right side of the table under the 20 °C (or 36 °F) column. At 6,000 feet, the rpm setting of 2,450 will maintain 65 percent continuous power at 21.0 “Hg with a fuel flow rate of 11.5 gallons per hour and airspeed of 161 knots.

Figure 10-27. Cruise power setting.

-Click to Enlarge- Figure 10-27. Cruise power setting.

Another type of cruise chart is a best power mixture range graph. This graph gives the best range based on power setting and altitude. Using Figure 10-28, find the range at 65 percent power with and without a reserve based on the provided conditions.

Figure 10-28. Best power mixture range.

Figure 10-28. Best power mixture range.

Sample Problem 8

OAT…………………………………………………………..Standard

Pressure Altitude………………………………………..5,000 feet

First, move up the left side of the graph to 5,000 feet and standard temperature. Follow the line straight across the graph until it intersects the 65 percent line under both the reserve and no reserve categories. Draw a line straight down from both intersections to the bottom of the graph. At 65 percent power with a reserve, the range is approximately 522 miles. At 65 percent power with no reserve, the range should be 581 miles.

The last cruise chart referenced is a cruise performance graph. This graph is designed to tell the TAS performance of the airplane depending on the altitude, temperature, and power setting. Using Figure 10-29, find the TAS performance based on the given information.

Figure 10-29. Cruise performance graph.

-Click to Enlarge- Figure 10-29. Cruise performance graph.

Sample Problem 9

OAT……………………………………………………………….16 °C

Pressure Altitude………………………………………..6,000 feet

Power Setting…………………………..65 percent, best power

Wheel Fairings……………………………………….Not installed

Begin by finding the correct OAT on the bottom, left side of the graph. Move up that line until it intersects the pressure altitude of 6,000 feet. Draw a line straight across to the 65 percent, best power line. This is the solid line, which represents best economy. Draw a line straight down from this intersection to the bottom of the graph. The TAS at 65 percent best power is 140 knots. However, it is necessary to subtract 8 knots from the speed since there are no wheel fairings. This note is listed under the title and conditions. The TAS will be 132 knots.

Comments on this entry are closed.

Previous post:

Next post: