Principles of Flight 05-09

Question 1

The increased rotor thrust due to forward speed during the transition from hover to forward flight is referred to as __________.

Answer 1

Effective Translational Lift (ELT)

Question 2

Effective Translational Lift (ETL) takes effect at about ______ knots forward indicated airspeed. (As per class PoF slides)

Answer 2

10 - 20

Question 3

ETL is the noticeable point where the disc experiences clean air causing the aircraft to _______.

Answer 3

Balloon

Question 4

As the helicopter transitions and accelerates, what aerodynamic structure helps compensate for the aircrafts tendency to pitch nose down?

Answer 4

Horizontal Stabiliser

Question 5

Induced Flow Roll is exhibited at low speeds due to:

Answer 5

Differences in the magnitude of the Induced Flow (IF) experienced by portions of the rotor disc.

Question 6

Induced Flow Roll is due to the fact that the IF experienced by the front half of the rotor disc is _____ than the IF experienced by the rear half of the rotor disc.

Answer 6

Less

Question 7

During flapback the advancing blade flaps ____ and the retreating blade flaps _____.

Answer 7

During flapback the advancing blade flaps UP and the retreating blade flaps DOWN.

Question 8

Place these labels in the correct order as they apply to the sequence of transition from hover to forward flight.
- Effective Translational Lift
- Initial Height Loss
- Torque Reduction
- Flapback, Inflow Roll

Answer 8

1. Initial Height Loss
2. Flapback Inflow Roll
3. ETL
4. Torque Reduction

Question 9

A Low Frequency - Lateral vibration would most likely be caused by?

Answer 9

Main rotor blades out-of-balance.

Question 10

A Low Frequency - Vertical vibration would most likely be caused by?

Answer 10

Main rotor blades out-of-track.

Question 11

A Medium Frequency vibration would most likely be caused by?

Answer 11

Downwash from the main rotor impinging on the structure.

Question 12

A High Frequency vibration would most likely be caused by?

Answer 12

Engines, Gearboxes and hydraulic pumps.

Question 13

In order to dampen vertical vibrations, the helicopter rotor system and the damping mass vibrate with the same frequency, with a phase shift of _______ degrees.

Answer 13

180

Question 14

What type of Power can be described as:
The power required to overcome the parasite drag created as the fuselage is propelled through the air.

Answer 14

Parasite Power

Question 15

Rotor profile power is the power required to turn the rotor blades at operating RPM, at minimum pitch, plus includes the power to:
(Select ALL that apply).

A. Overcome the friction (drag) inherent in the rotor system.
B. Drive the tail rotor system.
C. Drive ancillary equipment (Pumps, Generators, etc).
D. Overcome the drag created as the fuselage is propelled through the air.

Answer 15

A. Overcome the friction (drag) inherent in the rotor system.
B. Drive the tail rotor system.
C. Drive ancillary equipment (Pumps, Generators, etc).

Question 16

The power required to overcome the drag that results from the rotor blades having to generate total rotor thrust is referred to as?

A. Parasite Power
B. Rotor Induced Power
C. Rotor Profile Power
D. Port Adelaide Power

Answer 16

B. Rotor Induced Power

Question 17

How could a pilot increase the excess power available?

Answer 17

Reduce All-Up Weight

Question 18

All other factors being equal, an increase in All-Up-Weight will ________ the power required curve.

A. Increase
B. Decrease

Answer 18

A. Increase

Question 19

Regardless of why it occurred, overpitching will result in ________.

Answer 19

Rotor RPM decaying rapidly unless collective is lowered.

Question 20

What portion of the lift equation would have the most relevance to operating at a high Density Altitude (DA)?

Lift=CL 1/2p V2 S

Answer 20

p (Rho)

Question 21

In autorotative flight at a high density altitude, you would expect your rate of descent to be ________ than at Sea Level.

Answer 21

Greater

Question 22

A higher AUW (All Up Weight) will ______ your rate of descent during autorotative flight.

Answer 22

Increase

Question 23

Raising your collective lever during autorotative flight will normally cause your rotor RPM to _______.

Answer 23

Decrease

Question 24

Name one of the three beneficial factors mentioned in class that occur during the flare:

Answer 24

• Deceleration
• Increased TRT
• Increased Rotor RPM

Question 25

The avoid curve or 'Dead Mans Curve' depicts the flight regimes to avoid relative to ______ and ______.

Answer 25

Height (Altitude) and Airspeed.

Question 26

The reason not to operate in the 'Avoid areas' of the Dead Mans Curve diagram is because ______.

Answer 26

There may be insufficient time or altitude for a recovery to a safe engine-off landing.

Question 27

**Stability** is classified as either _______ or ________.

Answer 27

Static or Dynamic

Question 28

Within each category, stability is defined as being _______, ________ or _______.

Answer 28

Positive (Stable) Neutral Negative (Unstable)

Question 29

An aircraft that returns to its **original position** after being disturbed is said to be statically _________.

Answer 29

**Stable** (Or to have positive static stability).

Question 30

An aircraft that **remains in its new position** after being disturbed is said to be statically _________.

Answer 30

**Neutral** (Or to have neutral static stability).

Question 31

An aircraft that **continues to move away from its original position** after being disturbed is said to be statically ________.

Answer 31

**Unstable** (Or to have negative static stability).

Question 32

**Lateral Stability** is stability in _______.

Answer 32

Roll

Question 33

**Longitudinal stability** is stability in ______.

Answer 33

Pitch

Question 34

**Directional Stability** is stability in _______.

Answer 34

Yaw

Question 35

If an aircraft is known to have **Negative Dynamic Stability**, you would expect any induced oscillations to: **A.** Increase **B.** Decrease **C.** Stay the same

Answer 35

**A.** Increase

Question 36

**Retreating Blade Stall** (RBS) would be exhibited in the EC135 by the nose pitching _______ and the aircraft rolling _______.

Answer 36

Pitching **UP** and the aircraft rolling **LEFT**.

Question 37

Name three of the factors discussed in class that can lead to **Retreating Blade Stall** RBS.

Answer 37

1. High Forward Speed 2. High All Up Weight 3. High Density Altitude environment. 4. Excessive/abrupt control movements. 5. High G-load manoeuvres. 6. Turbulence.

Question 38

In order to recover from **Retreating Blade Stall** RBS the Pilot needs to....

Answer 38

Lessen the AoA on the retreating blade.

Question 39

In order to recover from **Retreating Blade Stall** RBS the Pilot needs to lessen the AoA of the retreating blade. What are some ways to lessen the AoA on the retreating blade?

Answer 39

1. Lower collective 2. Reduce severity of manoeuvre. 3. Reduce airspeed.

Question 40

**Ground resonance** occurs primarily with _____ ______ rotor heads.

Answer 40

Fully Articulated.

Question 41

Helicopters with a _______ **undercarriage** are more prone to ground resonance.

Answer 41

Wheeled.

Question 42

Three areas that contribute to **ground resonance** occurring are:

Answer 42

1. Rotor System Design, Wear of Faults. 2. Landing Gear Design. 3. Construction of landing platform.

Question 43

Name the two types of **roll over** discussed in class.

Answer 43

1. Static Roll-Over 2. Dynamic Roll-Over

Question 44

A typical **static roll over angle** for a helicopter would be _____ degrees.

Answer 44

45

Question 45

**Static roll-over** occurs when the aircraft's _____ of _____ moves outside the aircrafts base of support.

Answer 45

Centre of Gravity.

Question 46

Name one of the conditions mentioned in class that might precipitate a **static roll-over**.

Answer 46

1. Landing on a slope exceeding critical roll angle. 2. Landing platform collapse. 3. Undercarriage sinks into mud, snow, etc. 4. Undercarriage fails structurally. 5. Ship takes roll exceeding critical angle.

Question 47

For an aircraft to experience **dynamic roll-over** the rotors must be ______, generating ______ and have a wheel or skid ______ to the ground.

Answer 47

For an aircraft to experience dynamic roll-over the rotors must be **turning**, generating **lift** and have a wheel or skid **fixed** to the ground.

Question 48

To recover from a developing **dynamic roll-over** situation, the pilot should _____ the collective and attempt to ____ the rotor disk.

Answer 48

To recover from a developing dynamic roll-over situation, the pilot should **lower** the collective and attempt to **level** the rotor disk.

Question 49

Onset of **Vortex Ring State** (VRS) is indicated by: (Name as many as possible).

Answer 49

1. Significant vibration 2. Random pitching and rolling 3. Fluctuating power demands and torque indications. 4. Random yawing. 5. Slow control response. 6. Rapid increase in the rate of descent.

Question 50

A pilot should recover from **VRS** by:

Answer 50

**Increasing forward airspeed**. *and after suitable airspeed achieved* **Increase collective** to reduce rate of descent.

Question 51

**Loss of Tail Rotor Effectiveness** (LTE) is generally caused by one of three events. Name them.

Answer 51

1. Weathercock Effect 2. Tail Rotor Vortex Ring 3. Main Rotor Vortex Interference.

Question 52

**Main Rotor Vortex Interference** would most likely occur with winds located from the _____ to ____ o'clock position.

Answer 52

Main Rotor Vortex Interference would most likely occur with winds located from the **10** to **11** o'clock position.

Question 53

The best way to counter **Loss of Tail Rotor Effectiveness** (LTE) is:

Answer 53

Not let it happen in the first place. *- Make pedal turns always slow and controlled. - Be prepared that tail will 'flick' when passing through wind.*