10 Range Flashcards

Question 1

Q

What is Specific Range, what are to two types and what type of speed are they associated with?

Answer

A

Specific Range is the best measure of fuel with distance

Two types are:

Specific Ground Range (SGR) which is related to Ground Speed
Specific Air Range (SAR) which is related to TAS

Question 2

Q

What are the equations for the two types of Specific Range (jet)?

Answer

A

SGR = GS / Fuel Flow = GS / (SFC x D)

- SAR = TAS / Fuel Flow = TAS / (SFC x D)

Question 3

Q

How is Fuel Flow related to Thrust and Power for a Jet AC and a Prop AC?

Answer

A

Jet: Fuel Flow is proportional to Thrust

- Prop: Fuel Flow is proportional to Power

Question 4

Q

What sort of consideration is Specific Fuel Consumption and what is the formula for a Jet AC and a Prop AC?

Answer

A

Specific Fuel Consumption (SFC) is an engine only consideration and is not affected by Drag (aerodynamic consideration)
Jet SFC = Fuel Flow / Thrust
Prop SFC = Fuel Flow / Power

Question 5

Q

In what conditions is the Specific Fuel Consumption for a Jet best?

Answer

A

Low Temperatures

- Engine is running at it’s design RPM (apox. 90 - 95% max)

Question 6

Q

What is the formula for the Specific Air Range of a Jet AC?

Answer

A

SAR = TAS / (SFC x Thrust Required)

In straight and level flight this can be written as:

SAR = TAS / (SFC x Drag)

Since Thrust = Drag in S and L

Question 7

Q

What is the speed for Maximum Range in a Jet AC?

Which curve can this be found on and where?

Answer

A

Speed for Maximum Range = 1.32 Vmd (Mmr: Mac Max Range)

- Found at the tangent to the Total Drag curve

Question 8

Q

What is the optimum altitude for Maximum Range on a Jet AC and why?

Answer

A

The optimum altitude for a Jet AC is high for two reasons:
1. Achieve a higher TAS for the same IAS and Drag
2. High altitude allows the engine to operate at the correct speed AND it’s optimum design RPM (90 to 95% Max)

Question 9

Q

What is the Specific Air Rang for a Prop AC?

Answer

A

Specific Air Range = TAS / (SFC x Pr)

Question 10

Q

What is the speed for Maximum Range in a Prop AC?

Which curve can this be found on and where?

Answer

A

Speed for Maximum Range is Vmd

- Found at the tangent to the Power Required curve

Question 11

Q

Why does altitude have a smaller effect on the Maximum Range of a Prop AC compared to a Jet AC?

Answer

A

Since Pr = TAS x Drag
And SAR = TAS / (SFC x Pr)
So the effects of increasing TAS are cancelled out

Question 12

Q

What is the Altitude for Maximum Range for a Prop called?

Answer

A

Full Throttle Altitude

Question 13

Q

What are the factors which affect the Range of an AC and how do they affect the speed for optimum range?

Answer

A

Increase in Mass: reduces Range, 1.32Vmd (Mmr) increases
Altitude: Maximum Range is only achieved at the optimum altitude, any deviation from this will result in a reduced Range

Question 14

Q

What happens to the following (and why) as a flight progresses and fuel is burned, reducing the AC mass:

Optimum Altitude
Specific Air Range
Optimum speed for max range

Answer

A

Optimum Altitude Increases:
- Less mass means less induced drag (and less Thrust is needed) so to keep at optimum design RPM, more altitude is needed

Specific Air Range Increases:

SAR = TAS / (SFC x Drag)
Less Drag means higher SAR

Optimum speed for max range decreases:
- Less Induced drag means lower Vmd so lower 1.32Vmd

Question 15

Q

What is the purpose of the Step Climb technique?

Answer

A

To increase Range by staying as close to the optimum altitude as possible as the flight progresses. Whilst complying with the ATC requirement of using flight levels