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What can be said of isolated rotors’ stability with respect to translations and rotations?

They are statically unstable but dynamically stable,

They are statically stable but dynamically unstable,

They are statically and dynamically stable,

They are statically and dynamically unstable,

They are statically unstable but dynamically stable,

They are statically stable but dynamically unstable,

They are statically and dynamically stable,

They are statically and dynamically unstable,

Why can helicopters have a higher dynamical stability than isolated rotors?

Because of the position of the centre of gravity,

Because of vertical (and, to a lesser extent, horizontal) tailplanes,

Because of the presence of the swashplates,

Helicopters have a lower dynamical stability than isolated rotors.

Because of the position of the centre of gravity,

Because of vertical (and, to a lesser extent, horizontal) tailplanes,

Because of the presence of the swashplates,

Helicopters have a lower dynamical stability than isolated rotors.

What can be an important consequence of the dynamic instability of helicopters?

Flight safety is endangered,

A low pilot’s workload,

A high pilot’s workload,

Performances are reduced,

Flight safety is endangered,

A low pilot’s workload,

A high pilot’s workload,

Performances are reduced,

How is dynamic stability improved on most modern helicopters?

By means of electronic control systems, which sense the motion and act on the rotor’s controls

By means of electronic control systems, which sense the motion and act on rotor thrust,

By means of the flapping hinges,

By means of lead-lag hinges,

By means of electronic control systems, which sense the motion and act on the rotor’s controls

By means of electronic control systems, which sense the motion and act on rotor thrust,

By means of the flapping hinges,

By means of lead-lag hinges,

How could dynamic rollover be defined?

Instability related to a roll maneuvre in the air,

Instability related to a roll maneuvre on the ground,

A landing technique,

Final phase of the emergency landing,

Instability related to a roll maneuvre in the air,

Instability related to a roll maneuvre on the ground,

A landing technique,

Final phase of the emergency landing,

What is “blade sailing”?

An excessive rigid and elastic motion of rotor blades occurring when the rotor speed is low and the helicopter on the ground,

An excessive rigid and elastic motion of rotor blades occurring when the rotor speed is zero and the helicopter is airborne,

An excessive rigid and elastic motion of rotor blades occurring when the blades are damaged,

An excessive rigid and elastic motion of rotor blades occurring when the pilot has forgotten to switch on the centrifugal force,

An excessive rigid and elastic motion of rotor blades occurring when the rotor speed is low and the helicopter on the ground,

An excessive rigid and elastic motion of rotor blades occurring when the rotor speed is zero and the helicopter is airborne,

An excessive rigid and elastic motion of rotor blades occurring when the blades are damaged,

An excessive rigid and elastic motion of rotor blades occurring when the pilot has forgotten to switch on the centrifugal force,

The forces acting on a rotating blade are:

Aerodynamic and centrifugal forces,

Aerodynamic forces,

Centrifugal forces,

Inertial and centrifugal forces,

Aerodynamic and centrifugal forces,

Aerodynamic forces,

Centrifugal forces,

Inertial and centrifugal forces,

Explain the reason why co-axial helicopters do not have a tail rotor.

Co-axial rotors are counter rotating; the lift force transmitted by the gearbox to the rotors are consequently opposite,

Co-axial rotors are counter rotating and consequently the aerodynamic interaction is enough to guarantee torque balance,

Co-axial rotors are counter rotating; the torques (moments) transmitted by the gearbox to the rotors are consequently opposite,

Co-axial rotors are counter rotating and consequently generate lift force in opposite directions,

Co-axial rotors are counter rotating; the lift force transmitted by the gearbox to the rotors are consequently opposite,

Co-axial rotors are counter rotating and consequently the aerodynamic interaction is enough to guarantee torque balance,

Co-axial rotors are counter rotating; the torques (moments) transmitted by the gearbox to the rotors are consequently opposite,

Co-axial rotors are counter rotating and consequently generate lift force in opposite directions,

Have rotorcraft drones (UAV) been popular in the recent years? (i.e. have many of them been sold?)

Yes, rotorcraft drones have been very successful for many different types of mission,

Yes, rotorcraft drones have been very successful but mainly as toys,

Yes, rotorcraft drones have been very successful but mainly for delivery service (e.g. Amazon),

Yes, rotorcraft drones have been very successful in spite of being very difficult to develop,

Yes, rotorcraft drones have been very successful for many different types of mission,

Yes, rotorcraft drones have been very successful but mainly as toys,

Yes, rotorcraft drones have been very successful but mainly for delivery service (e.g. Amazon),

Yes, rotorcraft drones have been very successful in spite of being very difficult to develop,

Name two materials currently used in the manufacturing of (the structural parts of) rotor blades:

Wood, aluminium alloy,

Carbon-fibres, glass-fibres,

Aluminium alloy, rubber,

Steel, aluminium alloy,

Wood, aluminium alloy,

Carbon-fibres, glass-fibres,

Aluminium alloy, rubber,

Steel, aluminium alloy,

When compared to fixed wing aircraft with similar payload, are helicopte rmore or less manoeuvrable (in terms of time necessary to achieve a given roll or pitch rate)?

Helicopters are normally much more manoeuvrable,

Both vehicles are equally manoeuvrable,

Helicopters are normally much less manoeuvrable,

Small helicopters are much less manoeuvrable, large helicopters are as manoeuvrable as fixed wing aircraft,

Helicopters are normally much more manoeuvrable,

Both vehicles are equally manoeuvrable,

Helicopters are normally much less manoeuvrable,

Small helicopters are much less manoeuvrable, large helicopters are as manoeuvrable as fixed wing aircraft,

Are helicopters more or less aerodynamically efficient than fixed wing aircraft with similar payload?

Helicopters are much less efficient, aerodynamically,

Helicopters are only slightly less efficient, aerodynamically,

Helicopters are just as efficient, aerodynamically,

Helicopters are slightly more efficient, aerodynamically,

Helicopters are much less efficient, aerodynamically,

Helicopters are only slightly less efficient, aerodynamically,

Helicopters are just as efficient, aerodynamically,

Helicopters are slightly more efficient, aerodynamically,

Which options are available if, on ground, power available is lower than power required to hover in-ground-effect (for instance following a sudden temperature increase)?

None,

Rolling take-off if permitted by the helicopter (e.g. wheeled landing gear or smooth ground),

Vertical take-off,

Rolling take-off if permitted by the helicopter (i.e. the helicopter has a small wing),

None,

Rolling take-off if permitted by the helicopter (e.g. wheeled landing gear or smooth ground),

Vertical take-off,

Rolling take-off if permitted by the helicopter (i.e. the helicopter has a small wing),

What could be an unpleasant consequence of a horizontal wind component (from behind) on the ground while taking off?

Higher fuel consumption,

Vortex ring,

Lower fuel consumption,

Autorotation,

Higher fuel consumption,

Vortex ring,

Lower fuel consumption,

Autorotation,

Gyroplanes (also known as autogyros) are aircraft with a rotor and a propeller; what is the function of the rotor?

Generate thrust force (forward),

Generate drag force,

Generate lift force,

Generate lift in emergency landings (autorotation),

Generate thrust force (forward),

Generate drag force,

Generate lift force,

Generate lift in emergency landings (autorotation),

What do helicopters and wind turbines have in common?

Both rotors work in “vortex ring” state,

The rotors have very similar rotation speed,

Both rotors can work in “windmilling” state, that is to say, they can dissipate energy into the flow,

Both rotors can work in “windmilling” state, that is to say, they can absorb energy from the flow,

Both rotors work in “vortex ring” state,

The rotors have very similar rotation speed,

Both rotors can work in “windmilling” state, that is to say, they can dissipate energy into the flow,

Both rotors can work in “windmilling” state, that is to say, they can absorb energy from the flow,

What is ground effect?

An increase in aerodynamic efficiency when hovering / flying close to ground due to a high-pressure cushion,

A reduction in aerodynamic efficiency when hovering / flying close to ground due to a high- pressure cushion,

A loss in stability when hovering / flying close to ground due to a high-pressure cushion,

A loss in manoeuvrability when hovering / flying close to ground due to a high-pressure cush- ion,

An increase in aerodynamic efficiency when hovering / flying close to ground due to a high-pressure cushion,

A reduction in aerodynamic efficiency when hovering / flying close to ground due to a high- pressure cushion,

A loss in stability when hovering / flying close to ground due to a high-pressure cushion,

A loss in manoeuvrability when hovering / flying close to ground due to a high-pressure cush- ion,

Below which height from the ground is ground effect significant?

Approximately 20 × R, with R = rotor radius,

Approximately 2 × R, with R = rotor radius,

Approximately 0.2 × R, with R = rotor radius,

Approximately 100 m,

Approximately 20 × R, with R = rotor radius,

Approximately 2 × R, with R = rotor radius,

Approximately 0.2 × R, with R = rotor radius,

Approximately 100 m,

Is ground effect beneficial or detrimental to helicopter flight?

Detrimental, controls are much less effective,

Detrimental, you need more power to fly,

Beneficial, you can fly with less power,

Detrimental, controls are much less effective,

Detrimental, you need more power to fly,

Beneficial, you can fly with less power,

What is a very important requirement for helicopters, which affects the design of rotor blades and blade tips in particular?

Take-off mass,

Price,

Noise,

Max speed,

Take-off mass,

Price,

Noise,

Max speed,

Helicopter gearboxes are complex mechanical devices. The complexity is a consequence of . . .

...the presence of numerous monitoring devices,

. . . the fact that gearboxes are air cooled,

. . the large transmission ratio between input and output shafts,

. . the small transmission ratio between input and output shafts,

Keyboard commands:

= turn,

= for-/backward,

= scroll

...the presence of numerous monitoring devices,

. . . the fact that gearboxes are air cooled,

. . the large transmission ratio between input and output shafts,

. . the small transmission ratio between input and output shafts,

A gearbox is a device which allows changing the direction and the rotation speed of a shaft. How many gearboxes are there on a conventional helicopter (i.e. with a main rotor and a tail rotor)?

Only one: main gearbox,

Two: main and tail gearboxes,

Two: main and intermediate gearboxes,

Three: main, intermediate and tail gearboxes,

Keyboard commands:

= turn,

= for-/backward,

= scroll

Only one: main gearbox,

Two: main and tail gearboxes,

Two: main and intermediate gearboxes,

Three: main, intermediate and tail gearboxes,

What is the function of the intermediate gearbox?

Change the direction of the shaft and also reduce the rotation speed,

Reduce the rotation speed,

Connect the engines to the main rotor,

Change the direction of the shaft,

Keyboard commands:

= turn,

= for-/backward,

= scroll

Change the direction of the shaft and also reduce the rotation speed,

Reduce the rotation speed,

Connect the engines to the main rotor,

Change the direction of the shaft,

Gearboxes are flight critical systems. In case of a gearbox failure, the pilot may need to:

reduce forward speed and land vertically in order to reduce power required

perform an emergency landing in the case the helicopter has only one gearbox,

perform an emergency landing only if the helicopter is Category B,

switch off the engines and perform an emergency landing,

Keyboard commands:

= turn,

= for-/backward,

= scroll

reduce forward speed and land vertically in order to reduce power required

perform an emergency landing in the case the helicopter has only one gearbox,

perform an emergency landing only if the helicopter is Category B,

switch off the engines and perform an emergency landing,

Which statement is true about helicopter engines?

Helicopter engines are air-cooled,

Helicopter engines are designed to be installed on helicopters only,

Helicopter engines are conventional engines that may be installed on helicopters and on fixed wing aircraft,

Helicopter engines are more powerful than those installed in fixed wing aircraft,

Keyboard commands:

= turn,

= for-/backward,

= scroll

Helicopter engines are air-cooled,

Helicopter engines are designed to be installed on helicopters only,

Helicopter engines are conventional engines that may be installed on helicopters and on fixed wing aircraft,

Helicopter engines are more powerful than those installed in fixed wing aircraft,

What are typical requirements for helicopter engines?

Oil cooled, able to sustain high power settings and/or large pitch and bank angles,

Oil cooled, able to sustain high power settings for longer times and/or large pitch and bank angles,

Air cooled, able to sustain high power settings for longer times and/or large pitch and bank angles,

Air cooled, able to sustain high power settings and/or large yaw angles,

Keyboard commands:

= turn,

= for-/backward,

= scroll

Oil cooled, able to sustain high power settings and/or large pitch and bank angles,

Oil cooled, able to sustain high power settings for longer times and/or large pitch and bank angles,

Air cooled, able to sustain high power settings for longer times and/or large pitch and bank angles,

Air cooled, able to sustain high power settings and/or large yaw angles,

Does the helicopter pilot need to control the power manually, on modern turbine helicopters?

Yes, the pilot controls the engines power setting, an automatic systems adjusts the attitude of the helicopter,

No, the pilot only controls the rotor, an automatic systems adjusts the power setting so that the pitch angle of the blades are maintained,

Yes,thepilotcontrolstheenginespowersetting,anautomaticsystemsadjuststhepitchangles of the blades,

No, the pilot only controls the rotor, an automatic systems adjusts the power setting so that the rotation speed of the rotor is maintained,

Keyboard commands:

= turn,

= for-/backward,

= scroll

Yes, the pilot controls the engines power setting, an automatic systems adjusts the attitude of the helicopter,

No, the pilot only controls the rotor, an automatic systems adjusts the power setting so that the pitch angle of the blades are maintained,

Yes,thepilotcontrolstheenginespowersetting,anautomaticsystemsadjuststhepitchangles of the blades,

No, the pilot only controls the rotor, an automatic systems adjusts the power setting so that the rotation speed of the rotor is maintained,

The function of a helicopter turboshaft engine is to provide mechanical power . . .

..to the rotors through the gearbox,

..to the FADEC system,

..to the rotors

. to the rotor in the air and to the landing gear on the ground,

Keyboard commands:

= turn,

= for-/backward,

= scroll

..to the rotors through the gearbox,

..to the FADEC system,

..to the rotors

. to the rotor in the air and to the landing gear on the ground,

Engines are installed on the roof of the helicopter; the engineers optimize the design of the installation in order to minimize mainly . . .

.the manufacturing costs

.the Coriolis forces

.the aerodynamic drag force

.the aerodynamic lift force

Keyboard commands:

= turn,

= for-/backward,

= scroll

.the manufacturing costs

.the Coriolis forces

.the aerodynamic drag force

.the aerodynamic lift force

A wheeled landing gear allows . .

...easier taxiing,

...a more comfortable taxiing,

. . easier hangaring, taxiing, rolling take-off and landing,

. . easier hangaring, safe landing on unprepared surfaces,

Keyboard commands:

= turn,

= for-/backward,

= scroll

...easier taxiing,

...a more comfortable taxiing,

. . easier hangaring, taxiing, rolling take-off and landing,

. . easier hangaring, safe landing on unprepared surfaces,

A skid landing gear allows the designers to .

. . increase the cost and the weight of the helicopter,

.make the helicopter fly more comfortably,

...save cost and weight,

..make the helicopter look cool,

. . increase the cost and the weight of the helicopter,

.make the helicopter fly more comfortably,

...save cost and weight,

..make the helicopter look cool,

Can landing gear design affect ground resonance?

No, ground resonance only depends on the stiffness of the fuselage,

Yes, landing gear design determines the dynamics of the helicopter on the ground,

No, ground resonance only depends on the stiffness of the rotor blades,

Yes, landing gear design influences the kinematics of the rotor blades,

No, ground resonance only depends on the stiffness of the fuselage,

Yes, landing gear design determines the dynamics of the helicopter on the ground,

No, ground resonance only depends on the stiffness of the rotor blades,

Yes, landing gear design influences the kinematics of the rotor blades,

A good reason to install a skid landing gear could be:

allowing the helicopter to land on rough terrain,

making hangaring easier

allowing taxiing,

providing a support for passengers climbing in and out of the fuselage,

allowing the helicopter to land on rough terrain,

making hangaring easier

allowing taxiing,

providing a support for passengers climbing in and out of the fuselage,

Most wheeled landing gear are equipped with dampers; this is necessary to prevent . .

...stability,

.uncomfortable taxiing,

.damages to the fuselage while taxiing

...ground resonance,

...stability,

.uncomfortable taxiing,

.damages to the fuselage while taxiing

...ground resonance,

In some cases, skid landing gear are not equipped with dampers; how can energy be dissipated and stability guaranteed?

by special devices installed in the main gearbox,

through friction between skid and ground,

through collective and cyclic pitch controls,

by allowing automatic systems to control the helicopter,

by special devices installed in the main gearbox,

through friction between skid and ground,

through collective and cyclic pitch controls,

by allowing automatic systems to control the helicopter,

What could be a good definition for ground resonance?

A stable mode involving the motion of the blades around the lead/lag hinge,

An unstable mode involving the oscillations of the helicopter on the ground and the motion of the blades around the lead/lag hinges,

An unstable mode involving the oscillations of the helicopter on the ground and the rotation of the rotor,

An unstable mode involving the oscillations of the helicopter on the ground,

A stable mode involving the motion of the blades around the lead/lag hinge,

An unstable mode involving the oscillations of the helicopter on the ground and the motion of the blades around the lead/lag hinges,

An unstable mode involving the oscillations of the helicopter on the ground and the rotation of the rotor,

An unstable mode involving the oscillations of the helicopter on the ground,

How is ground resonance prevented on most helicopters ?

By installing dampers on rotor blades,

By installing springs on landing gear and rotor blades,

By installing dampers on landing gear,

By installing dampers on the landing gear and rotor blades,

By installing dampers on rotor blades,

By installing springs on landing gear and rotor blades,

By installing dampers on landing gear,

By installing dampers on the landing gear and rotor blades,

The Fenestron is an anti-torque system consisting of a rigid rotor surrounded by a shroud; what are the advantages of this particular design?

Greater safety for ground personnel,

Smaller acoustic footprint (= less noisy), safety when operating on ships,

Smaller acoustic footprint (= less noisy), greater safety for ground personnel,

Smaller acoustic footprint (= less noisy),

Greater safety for ground personnel,

Smaller acoustic footprint (= less noisy), safety when operating on ships,

Smaller acoustic footprint (= less noisy), greater safety for ground personnel,

Smaller acoustic footprint (= less noisy),

What is the function of the shroud in a Fenestron system, beside protecting the tail rotor?

Generate an additional lateral aerodynamic force,

Provide a contact point for landing,

None,

Protect components of the drive system (shafts and tail gearbox),

Generate an additional lateral aerodynamic force,

Provide a contact point for landing,

None,

Protect components of the drive system (shafts and tail gearbox),

NOTAR is an acronym for NO TAil Rotor. The device with this name consists of low-pressure air flowing through the tailboom, which is expelled through lateral openings generating a lateral force by deviating the rotor downwash. What are the main advantages of this system with respect to a conventional tail rotor?

Smaller acoustic footprint (= less noisy), reduced safety for ground personnel,

Smaller acoustic footprint (= less noisy), greater safety for ground personnel,

Smaller acoustic footprint (= less noisy),

Greater safety for ground personnel,

Smaller acoustic footprint (= less noisy), reduced safety for ground personnel,

Smaller acoustic footprint (= less noisy), greater safety for ground personnel,

Smaller acoustic footprint (= less noisy),

Greater safety for ground personnel,