Mã học phần TE3891, với thời gian thi 60 phút, đề trắc nghiệm áp dụng cho sinh viên chuyên ngành hàng không Trong máy bay có cánh cố định vật thể khí động học để tạo lực nâng là đôi cánh của máy bay được gắn cố định vào thân. Vận tốc ngang của máy bay (cũng đồng nghĩa với vận tốc dòng chảy bao máy bay nếu xét trong hệ quy chiếu gắn với máy bay) có được nhờ lực tác động ngang sinh ra nhờ động cơ (có thể thông qua cánh quạt hoặc dòng khí phản lực). Động cơ quay cánh quạt (hoặc phụt dòng khí phản lực) sẽ tạo phản lực đẩy máy bay chuyển động tương đối với không khí về phía trước, khi chuyển động tương đối như vậy cánh máy bay sẽ bị dòng khí chảy bao bọc xung quanh và tạo hiệu ứng lực nâng khí động lực học tác động từ dưới lên, khi vận tốc máy bay đạt đến giá trị nào đó lực nâng sẽ đủ lớn để thắng trọng lực và máy bay sẽ bay được. Còn đối với máy bay trực thăng cánh nâng là cánh quạt nâng nằm ngang ở trên phần thân (hoặc trên hai cánh), nó đồng thời còn để tạo lực đẩy ngang làm trực thăng chuyển động ngang.
Trang 1BỘ MÔN KỸ THUẬT HÀNG KHÔNG & VŨ TRỤ
ĐỀ THI QUÁ TRÌNH – HỌC KỲ 2 - NĂM HỌC 2020-2021
TRƯỞNG BỘ MÔN
PGS TS Vũ Đình Quý
GIẢNG VIÊN
TS Đinh Công Trường
CÂU HỎI:
1 High speed propellers are designed to
A operate at supersonic tip speeds
B operate at high forward speeds
C rotate at high RPM
2 A left-handed propeller is one that
A rotates clockwise when viewed from the rear
B is fitted to an engine on the left side of the aircraft
C rotates clockwise when viewed from the front
3 Forces acting on a propeller are
A torque, thrust and centrifugal
B centrifugal, twisting, and bending
C torsion, tension and thrust
4 The blade angle at the root is
A same from tip to root
B less than the tip
C greater than the tip
5 The purpose of propeller twist is
A to maintain Blade Angle along the blade
B coarsen the blade angle at the root
C to maintain Angle of Attack at the same value along the blade
6 The forces acting on a propeller blade are
A thrust, aerodynamic and tension
Trang 2B bending, twisting and centrifugal
C thrust and torque
7 Blade angle at the root is
A low
B master blade angle
C high
8 Blade angle is taken from the chord and
A propeller shaft
B plane of rotation
C relative airflow
9 What forces act on a propeller blade?
A Thrust and torque
B Bending, CTM and ATM Where CTM: Centrifugal Twisting Moment;
ATM: Aerodynamic Twisting Moment
C Bending, thrust, torque
10 CTM will
A try to bend the blade away from the engine
B cause the tips to rotate at supersonic speeds
C turn the blade about the lateral axis
11 When in reverse pitch, CTM will tend to move the propeller blades towards
A a positive pitch
B a negative pitch
C a position depending on rpm
12 As a propeller blade moves through the air, forces are produced, which are
known as
A lift and torque
B thrust and torque
C lift and drag
13 A rotating propeller imparts rearwards motion to a
A large mass of air at low velocity
B small mass of air at high velocity
C small mass of air at low velocity
14 Propeller efficiency is
A the ratio of output speed to input propeller speed
B the ratio of the useful work done by the propeller to work done by the
engine on the propeller
C the ratio of the work applied to the geometric pitch to useful work on
the C.S.U
15 Geometric Pitch is the distance moved
A in one revolution
Trang 3B in one revolution when slip is maximum
C in one revolution without slip
16 As propeller rotation speed increases the centrifugal turning moment on the blades will
A decrease
B increase
C remain constant through RPM range
17 Propeller torque is the resistance offered by the propeller to
A feathering
B rotation
C changing pitch
18 The angle between the resultant airflow direction and the propeller blade plane
of rotation is known as
A angle of attack
B helix angle or angle of advance
C blade angle
19 Aerodynamic Twisting Moment
A turns the blades to high pitch
B turns the blade to windmill
20 Propeller blade angle
A is constant along the blade length
B increases from root to tip
C decreases from root to tip
21 Coarse pitch is used for
A take off and climb
B landing and power checks
C maximum economical cruise in level flight
22 Effective pitch is
A geometric pitch plus slip
B distance moved in one revolution
C pitch measured at the master station
23 Torque acts
A in the same direction as the plane of rotation
B in opposition to the direction of rotation
C at right angles to the plane of rotation
24 The purpose of blade twist is to
A reduce angle of attack at the blade root
B to even out thrust distribution across the propeller
C to ensure that tip speed does not go faster than Mach 1
Trang 425 Thrust is greatest
A at 70 to 80% of propeller length
B the same all along the length
C in the first 50%
26 Changes the pitch of a blade
A bending forward
B about its twisting axis
C towards the feather plane
27 High speed aerofoils are employed at
A the master station
B the root
C the tips
28 A right hand propeller
A rotates clockwise when viewed from the front
B is always fitted to the starboard engine
C rotates clockwise when viewed from the rear
29 The chord line of a propeller is
A a line joining the tip to the root of the blade
B a line joining the leading and trailing edges
C a line joining the tips of the blades
30 The plane of rotation is defined as
A the plane in which the propeller rotates
B the plane in which thrust force acts
C the angle at which the blade strikes the airflow
31 A windmilling Propeller has
A a small positive blade angle
B pitch measured at the master station
C geometric pitch plus slip
32 A windmilling Propeller has
A a small positive angle of attack
B a small negative angle of attack
C a small positive blade angle
33 Windmilling causes
A maximum propeller drag
B Centrifugal Twisting Moment
C propeller underspeeding
34 The primary purpose of a feathering propeller is to
A prevent further engine damage when an engine fails in flight
Trang 5B eliminate the drag created by a windmilling propeller when an engine
fails in flight
C prevent propeller damage when an engine fails in flight
35 The primary purpose of propeller is to
A provide static and dynamic stability to aircraft
B change engine horsepower to thrust
C create lift on the fixed aerofoils of an aircraft