Course 6 - Section 16 - Aircraft Performance

Question 1

Taking off into the wind means:

Answer 1

• Less runway required
• The aircraft lifts off at a lower ground speed
• Good directional control is maintained

Question 2

Landing into the wind means:

Answer 2

-Ground speed is slower
-Less runway is used
-Good directional control is maintained

Question 3

Enroute flights in crosswinds

Answer 3

A crosswind occurs when the wind is not parallel to the path of the aircraft

For practical purposes, this would be when the wind is blowing at an angle between 20 degrees and 90 degrees to the track of the aircraft

Anytime an aircraft is operated with a crosswind component (out of wind), drift is encountered

Question 4

Crosswind Final Approach

Answer 4

An aircraft on final approach would need to “crab” into the wind or “drop a wing” to maintain runway centreline

This introduces the risk of a pilot not having sufficient control of the aircraft at low airspeeds to compensate for the drift

Many accidents that have occurred during landing and takeoff have been attributed to pilots operating in a crosswind and eventually losing control of the aircraft

Question 5

Heading (Define)

Answer 5

The heading is the degrees, measured clockwise, between magnetic north and the direction that the nose of the aircraft is pointing

Question 6

Track (Define)

Answer 6

The track is the path of an aircraft over the ground

If an aircraft flies directly upwind, downwind, or in conditions of no wind, the path over the ground is the same as the heading

Question 7

Drift (Define)

Answer 7

Drift is the measure (in degrees) between the heading of the aircraft and the track of the aircraft

Question 8

Wind drift correction angle

Answer 8

An aircraft must establish a wind correction angle that will counteract drift and maintain
the desired course

** ON THE EXAM BE CAREFUL, PAY ATTENTION TO IF THEY GIVE YOU AN AIRCRAFTS HEADING OR ITS TRACK. TRIPLE CHECK YOUR ANSWER!

Question 9

List the types of aircraft engines

Answer 9

Piston
Jet
Turboprop

Question 10

Piston Engines

Answer 10

A piston engine is similar to the internal combustion engine used in cars.

PISTON ENGINES OPERATE EFFICIENTLY UP TO APPORXIMATELY 12,000 FEET

Question 11

Piston Engine Disadvantages

Answer 11

• They have many complex parts
• They generally have a greater weight ratio (the engine’s weight as a ratio to the entire weight of the aircraft)

Question 12

Piston Engine Cooling

Answer 12

In most cases piston engines are cooled by air

air flows by the cylinders which have heat-dissipating vanes that increase the area exposed to the airflow

Question 13

Two Types of Piston Engines:

Answer 13

Horizontally Opposed
Radial

Question 14

Horizontally Opposed Piston Engines (Advantages and Disadvantages)

Answer 14

Horizontally opposed engines have an even number of cylinders set opposite each other. These are the most common forms of reciprocating engine found on light single and twin-engine aircraft (C402, C172)

Advantages
-Reduced drag
-better visibility
-ease of maintenance
-lightweight
-low vibration

Disadvantages (if more than 6 cylinders)
-Cooling problems
-increased drag from air scoops

Question 15

Radial Engines (Advantages and Disadvantages)

Answer 15

The physical construction of a radial engine is similar to that of a wheel. Radial engines have an odd number of cylinders (usually 5,7 or 9) arranged in a circle. They are usually found on older transport or specialty aircraft such as the DHC3 (Otter)

Advantages
-Compact
-Accessible for maintenance
-Lightweight
-Supplies good power for its size and weight

Disadvantages
-Interference to forward visibility
-Imposes considerable drag

Question 16

What are the two categories of Jet engines?

Answer 16

The jet engine is the best performing type of engine

Turbojet
Turbofan

Question 17

Turbojet

Answer 17

LOW ALTITUDE OPERATIONS ARE NOT ECONOMICAL FOR JETS

(The amount of thrust generated by a jet engine depends on the weight of the air it consumes. Since air at lower altitudes is denser than at upper altitudes, more fuel is required to produce the right air-fuel ratio. Thrust decreases with altitude because of the decrease in air density. However, high altitude loss of thrust is offset by reduced aircraft friction due to the surrounding air (drag))

Question 18

Turbofan

Answer 18

The turbofan is an improved version of the turbojet engine.

THE FAN GIVES THE TURBOFAN THE BENEFIT OF ADDITIONAL PAYLOAD CAPACITY AND A GREATER RANGE!

Advantages (compared to turbojets)
- greater fuel efficient
- quieter operation
- better low-altitude performance
- lower landing speeds

Disadvantages (compared to piston engines)
- high fuel consumption at low altitudes

Turbofan engines are found on most of today’s commercial and executive jets, as well as fighter aircraft

Question 19

Turbofan efficient altitudes

Answer 19

The turbofan engine is designed for high-speed, high-altitude operations. Efficiency improves as the altitude increases, reaching optimal performance between

33,000 and 37,000 feet

Question 20

Turboprop

Answer 20

The turboprop combines the properties of the propeller and the jet engine

The gas turbine engine can be used to drive a propeller instead of producing pure thrust.

In the turboprop engine, the energy of the heated gases is almost completely expended in the turbine, leaving only a small amount of velocity energy to produce thrust when ejected from the exhaust nozzle

Approximately 90-95% of the available power is derived from the propeller while only 5-10% is derived from thrust

Question 21

Turboprop Advantages and Disadvantages

Answer 21

Much like a jet engines, turboprop efficiency improves with altitude, however, the propeller efficiency drops off at higher altitudes due to the thin air

And much like piston engines, for low aircraft speeds at low altitudes where the air is denser, a propeller is more efficient than a jet engine

Advantage
- Greater horsepower for less weight

Disadvantage
- Propeller restricts it altitude

Question 22

Turboprop Efficient Altitude

Answer 22

Depending on the individual aircraft, turboprop aircraft generally operate most efficiently in the altitude range of

13,000 to 25,000 feet

Question 23

Aircraft speed by engine type

Answer 23

Piston: up to 250 knots*
(most general aviation aircraft like C172 will maintain speeds between 100 and 120 knots)

Turboprop: 200 to 300 knots
(Some turboprop aircraft, such as the deHavilland q400)–can reach speeds of over 350 knots, placing them very close to the performance of some of the slower jet aircraft)

Jet: 300 to 500 knots
(There are several types of military jets capable of exceeding 500 knots quite easily, but the vast majority will operate between 300 and 500 knots)

Question 24

Aircraft Altitude by Engine Type

Answer 24

Piston: Ground to 12,000 feet
(There are turbocharged aircraft capable of attaining altitudes as high as 25,000 feet which can cause issues having slow moving aircraft operating at the same altitudes as faster turboprops and jets)

Turboprop: 13,000 to 25,000 feet
(Many modern turboprop aircraft are capable of altitudes much higher than 25,000 feet. This can cause issues operating in the same altitudes as fast moving jets)

Jet: 25,000 feet and above

Question 25

Rate of Climb by Engine Type

Answer 25

Piston Engine: 500-1500 FPM
Turboprop: 1500-3000 FPM
Jet Engine: 1500-6000 FPM

There is a large discrepancy in climb performance by aircraft equipped with jet engines. Most commercial airliners will not or cannot climb at more than 2000-3000 FPM.

Eg, a fully loaded boeing 787 dreamliner on a long-range flight on a hot day is performing well if it is initially able to maintain a climb rate of 1000 FPM. On the other hand, many executive jets are easily capable of climbing 3000-6000 FPM

Question 26

Rate of Climb Changing with Altitude

Answer 26

An aircraft will not maintain the same rate of climb from the time it departs until it reaches its flight planned altitude.

THE MAX RATE OF CLIMB IS NORMALLY ATTAINED WITHIN THE FIRST 5000 FEET OF CLIMB, DECREASING AS IT GAINS ALTITUDE

Question 27

Rate of Descent by Engine Type

Answer 27

Piston: 500-1500 FPM

Turboprop: 1500-4000 FPM

Jet Engine: 2000-6000 FPM

Question 28

Rate of Descent Varying with Altitude

Answer 28

Question 29

Rate of Turn

Answer 29

The rate of turn refers to the number of degrees an aircraft will turn in a specific amount of time when it turns (banks).

The normal rate of turn, also known as the rate 1 turn or a standard rate turn is 3 degrees per second

Piston and Turboprop: Rate 1 - 3 degrees per second
Jets: Rate 1/2 - 1.5 degrees per second

Question 30

Turning Radius

Answer 30

Question 31

Run-Ups

Answer 31

Run-ups are a series of static checks that must be performed on certain types of aircraft prior to departing. The time required to do a run-up may vary considerably depending on the type of aircraft

Run-ups must be taken into consideration when planning ground traffic

Question 32

Run-Ups: Piston Engine

Answer 32

Question 33

Run-Ups: Turboprop

Answer 33

Question 34

Run-Ups: Jet Engine

Answer 34

None

All jet engine checks can be performed quickly while taxiing to a runway

Question 35

Acceleration Delay by Engine type

Answer 35

Acceleration delay is the amount of time that elapses between the point where the pilot applies power and the point where the aircraft responds to the command given

Piston: No Delay

Turboprop: Slight delay
(There are slight delays in acceleration for turboprop engines, the length of delay increasing with aircraft size. The reason for the delay is due to the time it takes the compressor to start turning quickly enough to develop the extra power required to respond. However, since turboprop aircraft are also equipped with a prop, they perform better at lower speeds than turbojet aircraft)

Jet: Long Delay
Jets have a considerable acceleration delay for the same reasons as turboprops. Since jets are generally larger aircraft fitted with bigger engines, they require more time to build up enough power to respond to commands. Consequently, you must give these types of aircraft sufficient time to be able to comply with instructions.

Question 36

Fuel Economy and Carbon Footprint by Engine Type

Answer 36

Piston: Very efficient within normal operating altitudes (generally below 12,000 feet)

Turboprop
Because the turbine engine was designed to operate at higher altitudes, anything below normal operating altitudes causes high fuel consumption and an increased carbon footprint. This is due to the higher air density at lower altitudes and the turboprop’s engine’s great capacity to compress air. The more air the engine ingests, the more fuel is required to maintain the proper air mixture to keep the engine running properly

Jet Engine
For the same reasons as turboprops, a turbojet consumes excessive amounts of fuel and creates a large carbon footprint at lower altitudes
The advent of the turbofan engine did much to alleviate the acceleration and fuel consumption problems of the turbojet engine. However, it is still important to be aware of these problems and to minimize the amount of time these aircraft operate at lower altitudes

Question 37

Foreign Object Debris (FOD) by Engine Type

Answer 37

Operational Hazards such as ingesting objects like birds, dirt and other material differ depending on the design of the engine

Piston: Does not ingest
(but prop can strike rocks, dirt, birds and other objects)

Turboprop: Does not ingest
(but prop can strike rocks, dirt, birds and other objects)

Jet: Ingests

There is one problem unique to jet engines– their tendancy to ingest objects, even large ones.

Question 38

Coarse Pitch

Answer 38

Coarse pitch is when the blade is set to a large angle of attack, which results in greater effective distance for a given RPM. This provides more efficient cruising speed at a comparatively lower RPM and power output

Question 39

Fine Pitch

Answer 39

Fine pitch is when the propeller is set to a lower angle of attack which creates less drag and rotates at a higher speed. This produces greater power for better take off and climb performance, however it is not efficient for cruising

Question 40

Fixed Pitch

Answer 40

Fixed pitch is a compromise between coarse pitch and fine pitch. The blade angle is set by the manufacturer to give the best performance possible in all phases of flight

This type of propeller is found on most training aircraft such as the Cessna 150 (C150)

Question 41

Variable pitch

Answer 41

Variable pitch is used to enable the pilot to select the most efficient pitch to maximize take off and cruise performance

There are two subtypes:
- Adjustable: Propeller blades that may only be adjusted while on the ground
-Controllable: Propeller blades that may be adjusted by the pilot while in flight

Question 42

Constant Speed Propeller

Answer 42

The constant speed propeller is a variable pitch propeller fitted with a governor. The governor alters the blade angle to maintain a constant RPM for all phases of flight

Question 43

Reversible Pitch

Answer 43

Reversible pitch is achieved by turning the propeller blades to the full reverse pitch position to produce a pushing action instead of a pulling action

The purpose
-decrease landing distance
-improve aircraft stopping performance in the event of a rejected take off
- enable an aircraft while on the ground to be reversed under its own power

As a safety feature, the nose wheel of the aircraft must be in contact with the ground before the pilot is able to select reverse pitch to prevent a crash

Question 44

Feathering

Answer 44

It is desirable to feather the propeller when it is necessary to stop an engine. This entails turning the blades to extreme coarse pitch to stop it rotating. This reduces drag, stops windmilling and reduces vibration

This setting is used to reduce drag in the event of an engine loss or to prevent wear caused by wind rotating the propeller when the aircraft is not in use

Question 45

Flaps

Answer 45

Primary purpose is to increase lift which improves take off performance and slower speeds during the approach phase of flight

Question 46

List the three types of flaps

Answer 46

Lift enhancing flaps - 0 degrees
Drag inducing flaps - 20 degrees
Lift or drag flaps - 40 degrees

Question 47

Lift enhancing flaps

Answer 47

zero degrees

Lift enhancing flaps permit a steeper climb-out angle. When deployed, these flaps will increase the wing camber and area producing more lift at a given airspeed. This results in the stall speed occuring later, as the stall speed is decreased

Question 48

Drag inducing flaps

Answer 48

20 degrees

drag inducing flaps permit slower approach and greatly increase stall speeds

Question 49

Lift or drag flaps

Answer 49

40 degrees

Lift or drag flaps permit steeper climb out and slower approach. Most smaller aircraft employ this type of flap, which slows the aircraft, but also generates sufficient extra lift to reduce the airspeed requirement. Depending on the selection of deployment angle, the stall speed is decreased

Question 50

TurboJet
Maximum efficiency and Advantages and disadvantages

Answer 50