SAR/SGR/SFC Flashcards Preview

IFR > SAR/SGR/SFC > Flashcards

Flashcards in SAR/SGR/SFC Deck (39):
1

SAR

ANM/UNIT of FUEL

2

x ANM/1000kg

TAS/FF * 1000

3

Therefor SAR =

TAS/FF *1000

4

Add weather, get

SGR

5

SGR =

GS/FF * 1000

6

Example FF 4506 kg/hr TAS 463 kts

SAR = TAS/FF * 100 ===== 463/4506 * 1000 ===== 102.75 ANM/1000KG

7

If you want this figure in KG/NM -->

invert the formula - drop the 1000!

8

FF/TAS

= 4506/463 = 9.73kg/nm

9

High SGR is GOOD

the > the NM you get /1000kg of fuel, the better!

10

WAT- Wind affects SGR?

Weight Altitude, Temperature & Wind!

11

High weight = LOW SGR

Less Nm/1000kg - due increased Drag!

Higher gross weights at a fixed AOA result higher max range speeds (1.32 Vimd)!

12

Max range is based on fixed...

AOA Increasing weight moves the curve up and right meaning a higher speed is required to achieve the LIFT required by the increased weight!

13

ALTITUDE --> with fixed weight, increasing altitude increases SGR(good) UNTIL!

Optimum altitude for the weight and speed is achieved!

14

OPTIMUM ALTITUDE Is where the highest

SGR is achieved & where design RPM produces required thrust corresponding to wing AOA and Speed for the best performance (range)!

15

above/below OPT ALT SGR

SGR decrease! Due to increased thrust required which is only achievable by increasing engine RPM above design RPM!

16

TEMPERATURE Has little affect on SGR

Increase OAT = Increase FF BUT Increase OAT also = Increase TAS SO Much the same SGR results

17

Wind Maximum Range DEPENDS on

Wind

18

Max Range is determined by the (ratio)

GS/Drag ratio!

19

Drag being FF

GS/FF

20

In strong HWC's fly f.... than nil wind max range speed to

minimise the time the HWC is acting on it.

21

In strong TWC's fly s.... than nil wind max range speed to

give the HIGHEST GS/FF ratio!

22

Specific Fuel Consumption

a measure of engine efficiency!

23

SFC is the ratio of

kg of fuel/ kg or thrust

24

LOW SFC is b.....

BEST

25

Low SFC means that you are consuming less kg of fuel and producing a greater amount of

kg's of thrust!

26

SFC - RAT! Factors affecting SFC

RPM Altitude Temperature

27

RPM (design 92-98% of max)

Increase off RPM above Design RPM Increases SFC (More Kg of fuel/kg of thrust)

28

Low SFC is b...

BEST

29

Altitude

With increasing altitude, air density decreases as does both T & FF - yielding lower SFC UNTIL the tro.....

Thrust and Fuel Flow - below the tropopause.....

30

Decreasing temperatures in the tropopause results in

REDUCTION of SFC!

31

Above the tropopause SFC

increases back toward S.L. values!

32

Temperature condition - constant TAS & RPM If OAT increase thrust and FF will....

Decrease! Meaning SFC remains STABLE (very minor, insignificant changes possible!)

33

DRAG CURVE - moves DOWN and LEFT as f

Fuel is burnt!

34

DRAG CURVE - moves UP &; and LEFT with Fla...

Flap Selection!

35

DRAG CURVE - moves UP and DOWN with Al

Altitude!

36

Maximum endurence speeds are lower at lower gross... w....

at lower gross wieghts!

37

A low SFCratio means low fuel consumption compared to

Thrust produced

38

A high SFC is less....

Inefficient!

39

Regarding best AOC and excess thrust - as fuel is burnt the drag cure moves down and left resulting in a

Lower excess thrust speeds at lower gross weights!