Aircraft Design Mcqs - Set 20

1)   Find the approximate value of velocity of best climb. Consider Thrust loading as 1.08, wing loading as 377 unit, CD0 as 0.025, K as 0.0075 and sea level density as 1.225 unit.

a. 98.46
b. 37.45
c. 12.1
d. 189.982
Answer  Explanation 

ANSWER: 98.46

Explanation:
No explanation is available for this question!


2)   Which of the following is correct value for rate of climb if an aircraft has free stream velocity of 125 m/s? Consider steady climb at climb angle of 10°.

a. 21.70 m/s
b. 12 m
c. 35 m/min
d. 1.302 min/m
Answer  Explanation 

ANSWER: 21.70 m/s

Explanation:
Rate of climb = free stream velocity*sine (climb angle) = 125*sin (10) = 21.70 m/s.


3)   To operate at R/C of 7.08 m/s, determine the value of excess power. Consider weight of the aircraft as 13127.5 N.

a. 92.942 kW
b. 1000W
c. 13127 N
d. 1.312KN
Answer  Explanation 

ANSWER: 92.942 kW

Explanation:
Excess power = (R/C) * Weight = 7.08*13127.5 = 92.942 kW.


4)   Consider steady climb from an altitude of 10km to 15km. If rate of climb is 20 m/s then, determine the time to climb.

a. 250s
b. 25 min
c. 4.16 hr
d. 0.07 min
Answer  Explanation 

ANSWER: 250s

Explanation:
Time to climb = change in altitude/rate of climb = (15-10)*1000/20 = 250s.


5)   Corner speed is defined as __________

a. velocity for maximum instantaneous turn
b. maximum lift velocity
c. maximum aerodynamic efficiency
d. minimum instantaneous turn speed
Answer  Explanation 

ANSWER: velocity for maximum instantaneous turn

Explanation:
Velocity for maximum instantaneous turn is termed as corner speed. Corner speed is defined by intersection of the stall limit and the Structural limit. For a typical fighter, corner speed can vary between 300 to 350 knots.


6)   During level turning flight, lift of wing is canted.

a. True
b. False
Answer  Explanation 

ANSWER: True

Explanation:
In a typical level turning flight Maneuver, the lift of the wing is canted. As a result of this, horizontal component of the lift will exert the centripetal force required to turn. Typically, total lift is n times more than that of the weight of an aircraft. Hence, the above statement is true.


7)   If load factor of level turning flight is found to be 1.2 and flight speed is 120m/s then, determine turn rate.

a. 3.107 degree/s
b. 1.2 rad/s
c. 0.03 rad per second
d. 1.2
Answer  Explanation 

ANSWER: 3.107 degree/s

Explanation:
No explanation is available for this question!


8)   Let’s consider we are designing an aircraft which can have 0.075 rad/s as its turn rate during level turning operation. If load factor is set to be 1.1 then, at which velocity we should fly our aircraft to obtain mentioned requirement.

a. 59.8unit
b. 590unit
c. 5980unit
d. 0894unit
Answer  Explanation 

ANSWER: 59.8unit

Explanation:
No explanation is available for this question!


9)   During level turning operation my aircraft has load factor of 2. Find the required bank angle for this level turning operation.

a. 60°
b. 60rad
c. 120rad
d. 2.1rad
Answer  Explanation 

ANSWER: 60°

Explanation:
Bank angle = arccosine (1/load factor) = arccosine (1/2) = arccosine 0.5 = 60°.


10)   What will be the turn radius if flight speed is 50unit and load factor is 2? Consider Level turn.

a. 147.13unit
b. 180unit
c. 50unit
d. 20unit
Answer  Explanation 

ANSWER: 147.13unit

Explanation:
No explanation is available for this question!


11)   If an aircraft can slow down during turn then, it is termed as __________

a. instantaneous turn
b. non instantaneous turn
c. straight flight
d. cruise segment
Answer  Explanation 

ANSWER: instantaneous turn

Explanation:
If an aircraft can slow down during turn then, it is termed as Instantaneous turn. Here, load factor will be limited by maximum lift coefficient or structural strength of the aircraft. Cruise segment is part of mission profile of an aircraft. At cruise all forces and moments are balanced.


12)   The aircraft _____________ during a sustained turn.

a. cannot be slowed down
b. can be slowed down
c. can lower its velocity
d. can increase lofting process effort
Answer  Explanation 

ANSWER: cannot be slowed down

Explanation:
In sustained turn, aircraft is not allowed to slow down. During sustained turn aircraft cannot be slowed down or lose altitude during turn. In sustained turn thrust has to be equal to the drag. Lift is load factor times weight.


13)   An aircraft is in sustained turn with thrust loading of 0.8 and aerodynamic efficiency of 6. Determine the approximate value of maximum load factor.

a. 4.8
b. 3
c. 1
d. 12
Answer  Explanation 

ANSWER: 4.8

Explanation:
Maximum load factor = thrust loading*aerodynamic efficiency=0.8*6 = 4.8.


14)   An aircraft weighing 200kg is in level turning operation. Find the value of vertical component of lift.

a. 1.962 KN
b. 200N
c. 2KN
d. 0.2KN
Answer  Explanation 

ANSWER: 1.962 KN

Explanation:
Given, mass = 200kg
Weight = 200*9.81 = 1962 N. At Level turn, Vertical component of lift is equal to weight.
Hence, for given level turning flight Maneuver, vertical component of lift = weight = 1962N = 1.962KN.


15)   Turn rate is defined as _______

a. ratio of radial acceleration and the velocity
b. ratio of lift to drag
c. product of thrust and velocity
d. drag
Answer  Explanation 

ANSWER: ratio of radial acceleration and the velocity

Explanation:
Turn rate is defined as the ratio of radial acceleration Divided by the velocity. Typically, turn rate is denoted by degree per second. Lift to drag ratio is called aerodynamic efficiency of the aircraft. Thrust into velocity will result in power.


16)   For a typical gliding flight, thrust will be ________

a. zero
b. equal to the lift
c. always same as drag
d. always same as weight
Answer  Explanation 

ANSWER: zero

Explanation:
For a typical gliding flight, Thrust Will be zero. Gliding flight is often termed as unpowered flight. Lift and drag during gliding flight will be determined by using glide angle.


17)   The tangent of glide angle is ________

a. equal to drag to lift ratio
b. lift to drag ratio
c. inverse of thrust
d. equal to thrust
Answer  Explanation 

ANSWER: equal to drag to lift ratio

Explanation:
The tangent of glide angle is equal to the drag to lift ratio. Lift to drag ratio is called aerodynamic efficiency of the aircraft. Tangent of Glide angle is inverse of the Aerodynamic efficiency or inverse of the lift to drag ratio.


18)   If aerodynamic efficiency of the glider is 20 then, found the value of corresponding glide angle.

a. 2.86 unit
b. 3.8
c. 5.6
d. 12.12
Answer  Explanation 

ANSWER: 2.86 unit

Explanation:
Glide angle = arctan (1/Aerodynamic efficiency) = arctan (1/20) = 2.86 unit.


19)   A typical glider has weight of 150N and has glide angle of 2.5°. Find Lift produced by the glider.

a. 149.85N
b. 150kN
c. 322N
d. 120Kn
Answer  Explanation 

ANSWER: 149.85N

Explanation:
Lift = weight* cos (glide angle) = 150*cos (2.5°) = 149.85 N.


20)   Glider with glide angle of 4.2° is gliding with gliding ratio of _____

a. 13.6
b. 12.9
c. 15
d. 25.4
Answer  Explanation 

ANSWER: 13.6

Explanation:
Glide ratio = 1/tan (glide angle) = 1 / tan (4.2°) = 13.6.


21)   Typically, a high performance unpowered aircraft is called ________

a. sailplane
b. glider
c. jet
d. twin engine
Answer  Explanation 

ANSWER: sailplane

Explanation:
Typically, a high performance unpowered aircraft is termed as sailplane. A glider is crude, low performance unpowered aircraft. This is based on typical sailplane terminology.


22)   Find the velocity required for maximum range. Consider a sailplane has wing loading of 110N/m2 and K/CD0 of 0.35.

a. 10.3m/s
b. 10.3mph
c. 12.5mph
d. 9.2mph
Answer  Explanation 

ANSWER: 10.3m/s

Explanation:
No explanation is available for this question!


23)   If a glider needs to be flown at maximum range then, at which value of CL we should fly this glider? Consider CD0/K is 2.8.

a. 1.67
b. 3.2
c. 5.6
d. 2.5
Answer  Explanation 

ANSWER: 1.67

Explanation:
No explanation is available for this question!


24)   Which of the following is correct for a typical glider?

a. Drag D = W*cos (gamma)
b. Drag D = W*arcsine (gamma)
c. Drag D = W
d. Drag D = Thrust T
Answer  Explanation 

ANSWER: Drag D = W*cos (gamma)

Explanation:
Above equation is used to provide information about drag of atypical glider. Drag can be given by, Drag D = W*cos (gamma) where, D is drag, W is weight of the glider and gamma is the glide angle.


25)   If my glider has lift coefficient at maximum lift to drag as 1.5 and induced drag factor K is 0.007 then, find parasite drag coefficient.

a. 0.01575
b. 0.01 N
c. 0.02N
d. 0.0157N
Answer  Explanation 

ANSWER: 0.01575

Explanation:
Parasite drag coefficient = K*lift coefficient2 = 0.007*1.5*1.5 = 0.01575.


26)   All the gliders are unpowered.

a. True
b. False
Answer  Explanation 

ANSWER: True

Explanation:
Typically, gliders are built with zero thrust. However, in modern days there gliders which operates with some power plant. Hence, statement is not correct. Not all the gliders are unpowered, some are powered as well.


27)   If a sailplane has glide ratio of 45 then, find horizontal distance travelled by this sailplane. Consider altitude loss of 1000ft.

a. 45000ft
b. 1000ft
c. 3456ft
d. 987ft
Answer  Explanation 

ANSWER: 45000ft

Explanation:
Horizontal distance = glide ratio*altitude loss = 45*1000 = 45000ft.


28)   Sink rate can be used to ____________

a. determine the time a glider may remain in the air
b. determine and estimate takeoff gross weight
c. estimate only wing loading
d. calculate weight to thrust ratio
Answer  Explanation 

ANSWER: determine the time a glider may remain in the air

Explanation:
The time a glider may remain in the air can be determined by using the sink rate. Sink rate is the product of aircraft velocity and sine of the glide angle. It is the vertical velocity.


29)   A glider has aspect ratio of 20 and CD0 of 0.02. In order to attain maximum range, determine the value required aerodynamic efficiency. Take e as 1.

a. 28.02
b. 20
c. 30
d. 43
Answer  Explanation 

ANSWER: 28.02

Explanation:
Aerodynamic efficiency= 0.5*(π*e*aspect ratio/CD0)0.5
= 0.5*(π*1*20/0.02)0.5 = 28.02.


30)   Determine the value of sink rate of glider which is operating with 4.2° of glide angle and has speed of 120m/s.

a. 8.78m/s
b. 9.8ms
c. 56.5ms
d. 8.7ms
Answer  Explanation 

ANSWER: 8.78m/s

Explanation:
Sink rate = speed*sine (glide angle) = 120*sine (4.2°) = 8.78m/s.


31)   Graphical representation of sink rate of sailplane is called ____________

a. typical speed polar
b. drag polar wing
c. lift curve of wing
d. propulsion systems
Answer  Explanation 

ANSWER: typical speed polar

Explanation:
The graphical representation of sink rate for sailplane is called speed polar. Speed polar is also known as hodograph. Drag polar is graphical representation of drag characteristics. Lift curve is used to provide relationship between lift and angle of attack.


32)   Velocity for the best glide ratio is 100ft/s. Determine velocity for minimum sink rate.

a. 76ft/s
b. 124m/s
c. 23fts
d. 45 fts2
Answer  Explanation 

ANSWER: 76ft/s

Explanation:
Minimum sink rate velocity = 0.76*best glide ratio velocity = 0.76*100 = 76ft/s.


33)   Variometer is used for _____________

a. informing pilot when glider is in lift
b. increase lift
c. thrust reversal
d. increase thrust produced
Answer  Explanation 

ANSWER: informing pilot when glider is in lift

Explanation:
Variometer is used to provide information to the pilot about glider. It is used to provide data about when glide is in lift. Thrust reversal are used to increase drag during landing and to reduce landing distance.


34)   Consider turning glide operation with bank angle of 1.5 and Weight of 125 unit. Find lift.

a. 125.042
b. 56
c. 120
d. 345
Answer  Explanation 

ANSWER: 125.042

Explanation:
Lift= Weight/cosine (bank angle) = 125/cosine 1.5 = 125.042 unit.


35)   Determine the value of turn rate. Consider glider has centripetal acceleration of 10 and velocity of 9.5.

a. 1.052
b. 9.5
c. 10
d. 2.8
Answer  Explanation 

ANSWER: 1.052

Explanation:
Turn rate = centripetal acceleration/velocity = 10/9.5 = 1.052 unit.


36)   Determine the value of best glide ratio velocity. Consider velocity for minimum sink rate is 10 fps.

a. 13.15 fps
b. 20 fps
c. 11 fps
d. 34 fps
Answer  Explanation 

ANSWER: 13.15 fps

Explanation:
Given, velocity for minimum sink rate v = 10 fps
Velocity for best glide ratio = v/0.76 = 10/0.76 = 13.15 fps.


37)   Consider turning gliding flight. Turn rate is given as 0.2 unit and velocity of flight is 10 unit. Find the value of turn radius.

a. 50
b. 100
c. 2
d. 8
Answer  Explanation 

ANSWER: 50

Explanation:
Turn radius = velocity/turn rate = 10/0.2 = 50 unit.


38)   Find the range of glider which has L/D of 13.6 and is descending from 5km.

a. 68km
b. 12 m
c. 12 inch
d. 68 m
Answer  Explanation 

ANSWER: 68km

Explanation:
Range = altitude*L/D = 5*13.6 = 68km.


39)   If KCD0 is 0.014 then, find lift to drag ratio for minimum sink.

a. 3.66
b. 36.6
c. 1.4
d. 24
Answer  Explanation 

ANSWER: 3.66

Explanation:
Lift to drag ratio of minimum sink (0.1875/KCD0)0.5
= (0.1875/0.014)0.5
= 3.66.


40)   Consider a glider is descending from 2km altitude. If it covers range of 30km then, at which aerodynamic efficiency the glider was flying?

a. 15
b. 60
c. 12
d. 21
Answer  Explanation 

ANSWER: 15

Explanation:
Aerodynamic efficiency = range/altitude = 30/2 = 15.