SAR/SGR/SFC

Question 1

SAR

Answer 1

ANM/UNIT of FUEL

Question 2

x ANM/1000kg

Answer 2

TAS/FF * 1000

Question 3

Therefor SAR =

Answer 3

TAS/FF *1000

Question 4

Add weather, get

Answer 4

SGR

Question 5

SGR =

Answer 5

GS/FF * 1000

Question 6

Example FF 4506 kg/hr TAS 463 kts

Answer 6

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

Question 7

If you want this figure in KG/NM –>

Answer 7

invert the formula - drop the 1000!

Question 8

FF/TAS

Answer 8

= 4506/463 = 9.73kg/nm

Question 9

High SGR is GOOD

Answer 9

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

Question 10

WAT- Wind affects SGR?

Answer 10

Weight Altitude, Temperature & Wind!

Question 11

High weight = LOW SGR

Answer 11

Less Nm/1000kg - due increased Drag!

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

Question 12

Max range is based on fixed…

Answer 12

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

Question 13

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

Answer 13

Optimum altitude for the weight and speed is achieved!

Question 14

OPTIMUM ALTITUDE Is where the highest

Answer 14

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

Question 15

above/below OPT ALT SGR

Answer 15

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

Question 16

TEMPERATURE Has little affect on SGR

Answer 16

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

Question 17

Wind Maximum Range DEPENDS on

Answer 17

Wind

Question 18

Max Range is determined by the (ratio)

Answer 18

GS/Drag ratio!

Question 19

Drag being FF

Answer 19

GS/FF

Question 20

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

Answer 20

minimise the time the HWC is acting on it.

Question 21

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

Answer 21

give the HIGHEST GS/FF ratio!

Question 22

Specific Fuel Consumption

Answer 22

a measure of engine efficiency!

Question 23

SFC is the ratio of

Answer 23

kg of fuel/ kg or thrust

Question 24

LOW SFC is b…..

Answer 24

BEST

Question 25

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

Answer 25

kg’s of thrust!

Question 26

SFC - RAT! Factors affecting SFC

Answer 26

RPM Altitude Temperature

Question 27

RPM (design 92-98% of max)

Answer 27

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

Question 28

Low SFC is b…

Answer 28

BEST

Question 29

Altitude

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

Answer 29

Thrust and Fuel Flow - below the tropopause…..

Question 30

Decreasing temperatures in the tropopause results in

Answer 30

REDUCTION of SFC!

Question 31

Above the tropopause SFC

Answer 31

increases back toward S.L. values!

Question 32

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

Answer 32

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

Question 33

DRAG CURVE - moves DOWN and LEFT as f

Answer 33

Fuel is burnt!

Question 34

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

Answer 34

Flap Selection!

Question 35

DRAG CURVE - moves UP and DOWN with Al

Answer 35

Altitude!

Question 36

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

Answer 36

at lower gross wieghts!

Question 37

A low SFCratio means low fuel consumption compared to

Answer 37

Thrust produced

Question 38

A high SFC is less….

Answer 38

Inefficient!

Question 39

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

Answer 39

Lower excess thrust speeds at lower gross weights!