Factors Affecting Range Performance

APPENDIX H

INTERMEDIATE FLIGHT PREPARATION WORKBOOK

Engine Loss

The loss of an engine will significantly degrade climb performance and lower the performance

ceilings of the aircraft. Time to climb, fuel to climb, and distance in climb will all increase and

performance ceiling will be lowered.

Cruise Definitions

VMO

Maximum Operating Speed

Maximum Operating Mach number

MMO

MCRT

Maximum Cruise Thrust Limit

Best Endurance

The speed for minimum fuel flow in level flight (approximately 0.5 AOA

units)

Maximum Range The level flight speed at which the maximum value of nautical air miles per

pound of fuel is obtained (approximately 0.18 AOA units)

Long Range

The level flight speed above the speed for maximum range speed at which

99% of maximum range is obtained

H104. FACTORS AFFECTING RANGE PERFORMANCE

Outside Air Temperature Specific

OAT variations from the ICAO standard day have no effect on range when less-than-rated power

is required. However, cruise time and fuel flow will be modified slightly because TAS and

engine fuel consumption vary with temperature at a given M. These relationships are true

whether cruising at maximum range (climbing flightpath) or constant altitude. For maximum

range cruise where rated power is required (such as 1-engine operation), an increase in

temperature means a reduction in range, altitude, M, time, and an increase in fuel flow. For

constant altitude cruise at rated power, an increase in temperature reduces the maximum

allowable weight and M that can be flown at that altitude. The effects of temperature on cruise

range, altitude, miles per pound of fuel and mission time are shown as curves of specified

temperature departure from the ICAO standard day.

Wind

When winds are calm, GS equals TAS. When flying into a headwind, GS equals TAS less the

headwind component. When flying with a tailwind the reverse is true. Additionally, wind

affects maximum range values as a result of changes in maximum range TAS. When striving for

maximum range, it is advantageous to reduce the time of exposure to a headwind component and

increase the time of exposure to a tailwind component. This is accomplished by varying the

H-6 T-1A PERFORMANCE MANUAL EXTRACTS