Citation Encore 560 Spécifications télécharger pdf (Page 342)

SECTION VII

FLIGHT PLANNING AND PERFORMANCE

MODEL 560

FLIGHT PLANNING

Thorough flight planning suggests establishing a preflight goal such as maximum range, minimum time

enroute, or maximum fuel reserve within the parameters defined by the Airplane Flight Manual takeoff, climb

and landing requirements. Tables for Maximum Cruise Thrust, .65 Mach, and Long Range Cruise are

presented in this chapter to aid the crew in determining how best to achieve that goal. Maximum cruise

thrust results in minimum time, long range cruise at optimum fuel consumption and .65 Mach represents a

balance between the two.

Maximum range at a given altitude is dependent upon airframe efficiency and can be defined in still air

as that point on the total drag curve where the relationship of velocity to total airplane drag is most

favorable. The cruise angle-of-attack necessary to achieve that point is constant, but airspeed required is

affected by airplane weight. The higher the weight, the higher the airspeed necessary to achieve optimum

cruise angle-of-attack. This is in evidence when the long range cruise FLIGHT PLANNING tables are used

and result in longer block times for the lighter weights. Enroute, as fuel burnoff occurs, thrust and airspeed

required for best range will decrease as specific range increases due to improved performance at the lower

operating weights. This should be considered when planning short stage lengths to avoid carrying

excessive weight in stored fuel not operationally necessary.

Wind existing at cruise altitudes requires a more involved planning process to realize best range

because it requires a true airspeed faster or slower than that at which optimum range angle-of-attack is

achieved in still air. This minimizes the effects of a headwind, or takes maximum advantage of a tailwind.

The airplane's broad altitude capability also brings into consideration engine efficiency. Since the fuel flow

necessary for a given true airspeed decreases with an increase in altitude, a higher headwind component

may be tolerated at the upper flight level with best results in terms of ground distance covered to fuel

consumed. Conversely, large increases in headwind velocity with altitude may dictate a lower cruise level

to obtain the best fuel to distance relationship.

To assist altitude selection taking into account upper winds, Cruise Tables in the Flight Planning and

Performance Section present specific range as nautical miles per 100 pounds of fuel for different winds.

In comparative calculations, the highest number always represents best specific range. The Maximum

Range mode will generally result in optimum specific range, but high headwinds may suggest an increased

power setting to realize a shorter trip time without affecting total fuel burn appreciably. For example, at

37,000 feet and 15,000 pounds gross weight with a 100-knot headwind, Maximum Range and Maximum

Cruise Thrust give 28.7 and 24.3 nautical miles/100 pounds, respectively. In that case, Maximum Range

will produce only 4.4 nautical miles more distance per 100 pounds of fuel while the ground speed at

Maximum Cruise Thrust would be approximately 90 knots faster. For the absolute best range or maximum

fuel reserve goal however, cruising at the altitude/wind/thrust combination with the highest specific range

number will produce optimum results.

Climb and descent at maximum speed available to achieve desired vertical rate can be used in

conjunction with Maximum Cruise Thrust for the minimum time goal. Fuel economy, however, is better

served by using the climb and descent schedules presented in the PERFORMANCE chapter of this section.

Once the cruise mode and altitude has been determined, enroute time and fuel required can be

approximated from the appropriate FLIGHT PLANNING tables.

7-14 Configuration AA 56OMB-01

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Citation Encore 560 Spécifications Page 342

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