Dry operating weight что это

Прежде всего нам нужно знать средний расход топлива на эшелоне для нашего типа ЛА, например (X) фунтов/час.
Зная расстояние по маршруту и среднюю путевую скорость на эшелоне (с учетом прогноза на ветер), можно высчитать время полёта (t), накинув лишних 15-20 минут, так как самолёт не на всех этапах полёта будет лететь с расчётной путевой скоростью. Тогда, накинув лишние 5500 фунтов топлива, что обеспечит нас возможностью кружить в зоне ожидания не менее 30 минут, либо добраться до ближайшего запасного аэропорта, получим следующую формулу:

Конечно же, точным он является всего лишь относительно, так как едва ли мы сможем учесть все погодные явления, хотя такие погодники, как ASE, AS2012 могут дать кое-какие представления о погодных условиях по маршруту, особенно о ветре.

Топливо на основной маршрут должно учитывать:
1. Топливо на маршрут (trip fuel)
2. Непредвиденные обстоятельства (contingency fuel)
3. Руление и ВСУ (taxi fuel)
4. Добавочное топливо (extra)

Топливо на запасной маршрут должно учитывать:
1. Топливо на маршрут (alt trip fuel)
2. Непредвиденные обстоятельства (contingency)
3. 30 минут зоны ожидания (holding fuel)

Топливо по маршруту можно рассчитать с помощью FMC (Progress Page), который учтёт все этапы полёта, либо умножив время (с добавкой в 20 минут) пути на средний расход топлива.

Топливо на непредвиденный случай (внезапно появившийся встречный ветер) составляет 0,05 от общего топлива по маршруту.

Включим в расчёт топлива на руление и на ВСУ (для разных типов это разные значения, можно узнать экспериментально, либо по РЛЭ), а так же на случай ухода на второй круг.

Аналогично рассчитывается топливо на запасной маршрут (FMC ALT DES PAGE).

Поправка на непредвиденный случай так же составляет 0,05 от общего количества топлива по запасному маршруту.

В итоге получим формулу:

FUEL = [1,05 TRIP FUEL + TAXI FUEL + EXTRA] + [1,05 ALT TRIP FUEL + HOLDING FUEL]

Для Boeing 737 имеем следующие значения:

100 фунт/мин или в боле точном варианте 84 фунт/мин.

Время работы ВСУ (ночь) 30 минут.
Время, необходимое на руление

10 минут (зависит от ситуации).
Минимальное время для зоны ожидания 30 минут.

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Weight and Balance

Weight and balance

Principles of Balance

This case occurs when forces affecting an aircraft and moments from these forces are in balance that
means: Thrust equals Drag and Lift equals Weight.

Thrust equals Drag when an aircraft flies at constant speed:

T = D

In this situation two vertical forces remains to be taken into consideration: Lift and Weight.
Lift L is hung in the Centre of Lift and depends on value of a constant speed of an aircraft.
Weight Q is placed in the Centre of Gravity COG and depends on the loading of an aircraft.
The centre of gravity of a body is defined as the point at which its total weight may be considered
to act as a concentrated force.
These two points: Centre of Lift and Ce ntre of Gravity do not usually cover.
In this case a pair of forces is created and aircraft can tend nose down and up because of a moment which
occurs.

Moment equals force multiplied by arm, on which this force affects.

Moment = Force x Arm

To balance an aircraft, that means to eliminate the influence from above moment, additional force
coming from horizontal stabilizer Fн is created.

L + Q + Fн = 0 M(L) + M(Q) + M(Fн ) = 0

A force coming from horizontal stabilizer Fн depends on an angle of swing of stabilizer.
This angle has limited range. That’s why moment coming from a pair of forces Lift L and Weight Q
must not exceed strictly defined value, limited by a moment obtained from a force coming from
horizontal stabilizer M(Fн ).

The Safe Range of COG for an aircraft type, for characteristic aircraft weights,
is specified by the manufacturer and is ex pressed in terms of percentage of MAC.

Index expresses an influence of the component weight forces on change of COG position depending on
location of the forces relatively to Ref. Station.
Index – it is an equivalent of moment coming from the component weight forces relatively to their
positions to Ref. Station.

The conversion from index value to per cent of MAC is obtained from a graph.
The graph represents MAC grids in function of ai rcraft characteristic weight and index values.

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Dry operating weight что это

Reduced V 1 (15 ft screen height) is possible to use. In connection with reduced braking action, as on a wet runway, a rejected takeoff close to V 1 becomes even more critical than described above. For such cases, a reduced V 1 can be used to transfer safety margin from the continued takeoff case to the rejected case to better balance the margins between the two options.

In accordance with CAA regulations, V 1 on wet and contaminated runway is based on obtaining 15 ft at the end of takeoff distance instead of the normal 35 ft. Takeoff weight calculations must be designed to consider V 1 reductions. Otherwise the contamination may degrade acceleration, after the engine failure, so the aircraft will not lift off before the end of the runway.

V R = Rotation speed is the speed at which, for the purpose of determining required takeoff runway length, rotation of the aircraft is initiated.

V 2 = Takeoff safety speed is the speed used to determining the performance during the initial climbout. In these calculations, V 2 should be reached prior to attaining a height of 35 ft above the runway surface.

V Fl up and V Sl in are minimum speeds for retraction of FLAPS and SLATS after takeoff.

V Clean is the speed to be used in the final segment of a takeoff with engine failure, i.e with «CLEAN» aircraft (after flap/slat retraction).

V P = Pattern speed is «maneuvering speeds» and gives better margin to stall. Used in low level holdings, procedure and circuits.

V P clean «PATTERN CLEAN», normally the lowest speed with all engines running.

V MO Max operating IAS, limited by structural requirements.

M MO Max operating Mach, limited by high speed aerodynamics.

Rough Air Speed is the speed which should be used in connection with severe turbulence.

V ref is reference speed used to derive other speeds for different phases of flight by adding of fixed increments. The amount to be added are stated in the respective aircraft operating manual. When V ref is used without additional flap suffix, it is based on the full landing configuration. Occasionally it is necessary to use V ref based on other flap setting. In such cases the configuration is always indicated as a suffix (V ref 20 ).

Landing runway length requirements are based on V ref at 50 ft over the runway threshold.

Weight and balance.

In connection with issuance of loadsheet and flighplan, some specific load control terms are used. This table shows the explanation in alphabetic order.

LW = Landing Weight. Takeoff weight minus trip fuel.

MLW = Maximum Landing Weight. Weight limitation for landing, governed by structural and/or operational requirements.

MTOW = Maximum TakeOff Weight. Weight limitation for takeoff (brake release), governed by structural and/or operational requirements.

MZFW = Maximum Zero Fuel Weight. Structural weight limitation.

RW = Ramp Weight. Takeoff weight plus taxi fuel, i. e. weight of loaded aircraft before starting the engines.

TOW = Takeoff Weight. Gross weight of aircraft at brake release for takeoff, i.e. actual zero fuel weight plus takeoff fuel.

ZFW = Zero Fuel Weight. Dry operating weight plus total traffic load.

Ballast fuel. Non-usable fuel used for balancing purpose (only possible on some aircraft). The ballast fuel is separated from takeoff fuel (usable fuel) and loaded ia a separate tank. the fuel must not be consumed or jettisoned during flight.

Block fuel. Weight of total amount of fuel on board before starting taxi.

Burn-off fuel. Taxi fuel plus trip fuel.

TOF = TakeOff Fuel. Weight of total usable fuel onboard at the moment of takeoff (brake release).

Trip fuel. Weight of the precalculated fuel consumption from takeoff to touchdown at the next point of landing.

Allowed traffic load. The weight remaining after the subtraction of the operating weight from the allowed takeoff weight.

Underload. difference between allowed traffic load and load actually carried.

BI = Basic Index. Center of gravity at basic weight (BW) expressed as an index value.

CG = Center of Gravity. Point about which an aircraft would be balanced if suspended.

DOI = Dry Operating Index. Center of gravity at dry operating weight expressed as an index value. Basic index (BI) corrected for the balance influence of the loads included in dry operating weight (DOW).

DLI = Dead Load Index. Dry operating index (DOI) corrected for the balance influence of the load in compartments.

LIZFW = Loaded Index at Zero fuel weight. Deadload index (DLI) corrected for the influence of passengers in cabin (fuel not included).

MAC = Mean Aerodynamic Chord. Imaginary reference line (chord) dividing the wing areas producing the same amount of lift. Location of CG of loaded aircraft is given as a percentage of the MAC.

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