Lesson test: The frame, structures and 3D design

1.[2p]
Frame stiffness matters more than raw strength largely because

a floppy frame rings at low frequencies and feeds false vibration into the gyroscope

Correct

a stiff frame weighs less than a strong one

The answer is: a floppy frame rings at low frequencies and feeds false vibration into the gyroscope

strength has no effect on crashes

The answer is: a floppy frame rings at low frequencies and feeds false vibration into the gyroscope

stiffness sets the battery voltage

The answer is: a floppy frame rings at low frequencies and feeds false vibration into the gyroscope

2.[2p]
Carbon fibre plate is used as flat panels loaded in their plane because

the fibres are stiff along their length, so the sheet is far stiffer in-plane than through its thickness

Correct

it is cheaper that way

The answer is: the fibres are stiff along their length, so the sheet is far stiffer in-plane than through its thickness

it cannot be cut into other shapes

The answer is: the fibres are stiff along their length, so the sheet is far stiffer in-plane than through its thickness

it conducts electricity better flat

The answer is: the fibres are stiff along their length, so the sheet is far stiffer in-plane than through its thickness

3.[3p]
A cantilever arm's tip deflection under a fixed force grows as the cube of its length. If an arm is lengthened from 60 mm to 75 mm with the same section, by what factor does it flex more? Give two decimal places.

CorrectNot quite: 1.95

4.[2p]
The centre of gravity should sit at the centre of the four motors because

the control loop assumes thrust is balanced about the middle, and an offset wastes authority holding a lean

Correct

it makes the craft lighter

The answer is: the control loop assumes thrust is balanced about the middle, and an offset wastes authority holding a lean

it centres the battery's charge

The answer is: the control loop assumes thrust is balanced about the middle, and an offset wastes authority holding a lean

the motors spin faster there

The answer is: the control loop assumes thrust is balanced about the middle, and an offset wastes authority holding a lean

5.[2p]
A 3D printed part is weakest along the bond between its layers, so it should be oriented so the loads it carries run within the layers, not across them.

True

Correct

False

The answer is: True

6.[1p]
The X arm layout is preferred over the plus layout mainly because

it keeps all four propellers out of a forward camera's view and shares roll and pitch evenly

Correct

it uses shorter arms

The answer is: it keeps all four propellers out of a forward camera's view and shares roll and pitch evenly

it needs only two motors to be balanced

The answer is: it keeps all four propellers out of a forward camera's view and shares roll and pitch evenly

it places the battery at the front

The answer is: it keeps all four propellers out of a forward camera's view and shares roll and pitch evenly

7.[2p]
A flexible TPU part is chosen over a rigid plastic one for a flight controller soft mount because

it absorbs vibration and keeps propeller shake out of the gyroscope

Correct

it is stiffer than carbon fibre

The answer is: it absorbs vibration and keeps propeller shake out of the gyroscope

it conducts heat away from the board

The answer is: it absorbs vibration and keeps propeller shake out of the gyroscope

it prints faster

The answer is: it absorbs vibration and keeps propeller shake out of the gyroscope

1.[2p] Frame stiffness matters more than raw strength largely because

2.[2p] Carbon fibre plate is used as flat panels loaded in their plane because

3.[3p] A cantilever arm's tip deflection under a fixed force grows as the cube of its length. If an arm is lengthened from 60 mm to 75 mm with the same section, by what factor does it flex more? Give two decimal places.

4.[2p] The centre of gravity should sit at the centre of the four motors because

5.[2p] A 3D printed part is weakest along the bond between its layers, so it should be oriented so the loads it carries run within the layers, not across them.

6.[1p] The X arm layout is preferred over the plus layout mainly because

7.[2p] A flexible TPU part is chosen over a rigid plastic one for a flight controller soft mount because

1.[2p]
Frame stiffness matters more than raw strength largely because

2.[2p]
Carbon fibre plate is used as flat panels loaded in their plane because

3.[3p]
A cantilever arm's tip deflection under a fixed force grows as the cube of its length. If an arm is lengthened from 60 mm to 75 mm with the same section, by what factor does it flex more? Give two decimal places.

4.[2p]
The centre of gravity should sit at the centre of the four motors because

5.[2p]
A 3D printed part is weakest along the bond between its layers, so it should be oriented so the loads it carries run within the layers, not across them.

6.[1p]
The X arm layout is preferred over the plus layout mainly because

7.[2p]
A flexible TPU part is chosen over a rigid plastic one for a flight controller soft mount because