Question 1
___________ can be considered as one of the most powerful aerodynamic consideration.
A. Wetted area
B. Number of spars
C. Number of ribs
D. Only wingspan
View Answer
Answer: Option A
Explanation:
Wetted area is considered as one of the most powerful aerodynamic tool. Wetted area is nothing but the actual area that will be in contact if fluid is flown over the body. Spar and ribs are structural members.
Question 2
Area rule can be used for high speed aircraft only.
A. True
B. False
View Answer
Answer: Option A
Explanation:
Area rule is primarily developed to reduce the supersonic wave drag effects. However, it is not limited to high speed aircrafts only. We can also apply same rule to design the civil and commercial aircrafts as well.
Question 3
Drag divergence Mach number will increase by using _______________
A. area rule
B. increment in total volume
C. increase in drag
D. drag increment at maximum area
View Answer
Answer: Option A
Explanation:
Drag divergence Mach number is that Mach number after which drag increases drastically. Area rule can be used to lower the drag up to 50%. By using area rule properly we can improve the drag divergence Mach number.
Question 4
If an aircraft is not designed properly then __________
A. it can experience excessive flow separation
B. it will have more lift
C. it will have less drag
D. it will have higher aerodynamic efficiency
View Answer
Answer: Option A
Explanation:
Overall aircraft design will decide whether the aircraft is streamlined or not. An inadequate and poorly designed aircraft can suffer from drag increment, excessive flow separation etc.
Question 5
Interaction of components will not affect aerodynamic design of fuselage.
A. True
B. False
View Answer
Answer: Option A
Explanation:
Interaction of various components will affect the aerodynamic design. Wing-fuselage interaction gives drag which is known as interference drag. If a design has not considered interaction of the various components with each other then it will result in unexpected performance. Wing wake can stall the horizontal tail, wing downwash will increase AOA seen by tail etc. are examples of interactions between various components.
Question 6
Poor wing fuselage will reduce lift loss.
A. True
B. False
View Answer
Answer: Option B
Explanation:
A poorly designed fuselage can lead to drag rise, flow separation etc. As a result of these adverse effects lift loss will increase. Fuselage is considered as one of the primary drags producing member in an aircraft. Hence, an adequate design should be provided to reduce the lift loss.
Question 7
Short and fat fuselage will have ___________
A. lower tail arm
B. higher tail arm
C. higher fineness ratio
D. higher wetted area
View Answer
Answer: Option A
Explanation:
Tail arm is nothing but the distance between cg of tail to cg of an aircraft, typically. Short and fat fuselage will have shorter tail arm or tail moment arm. Size of the fuselage will be reduced for such case and as a result of which the tail arm will be reduced.
Question 8
Supersonic wave drag can be reduced by using ____________
A. area rule
B. drag ruling
C. lift augmentation
D. drag augmentation
View Answer
Answer: Option A
Explanation:
R. whitcomb had developed a method to reduce the supersonic drag. The method is known as area ruling or area rule. In this method overall volume distribution of components are altered in such way that the resultant body should provide less drag.
Question 9
To reduce fuselage wetted area we can ___________
A. lower the fineness ratio
B. increase fineness ratio
C. always double the fineness ratio
D. always use long fuselage
View Answer
Answer: Option A
Explanation:
Wetted area can be used to determine the drag properties of an aircraft. Fineness ratio is nothing but the length of the fuselage divided by max diameter of the fuselage. Hence, if we lower the fineness ratio then the ratio of length to diameter will reduce which in turn reduces the wetted area.
Question 10
Vortex generator is used to ____________
A. reattach separated flow
B. increase volume
C. increase surface area
D. separate flow
View Answer
Answer: Option A
Explanation:
Vortex generator is small body placed on surface to reattach the separated flow. A flow flows around the vortex generator, it curls the flow. And as a result of which flow is being forced to swirl and to flow reattaches to the surface if it has separated.
Question 11
What is the base area of the fuselage?
A. Any unfair rearward facing blunt surface
B. Forward facing surface
C. Wing area
D. Fuselage cabin area only
View Answer
Answer: Option A
Explanation:
Base area is nothing but the rearward area of the fuselage. It is any unfair rearward facing blunt surface. Wing area is the product of span and chord for rectangular planform. Fuselage cabin will be located at front side of the fuselage.
Question 12
What is the disadvantage of short and fat fuselage?
A. Higher supersonic wave drag
B. Higher incompressible wave drag
C. Lower supersonic wave drag
D. Lower wetted area
View Answer
Answer: Option A
Explanation:
Wave drag is the supersonic phenomena. Wave drag does not exist for incompressible flow. Short and fat fuselage will offer minimization of the wetted area. This gives advantage in terms of friction properties. However, it suffers from higher wave drag at supersonic speeds.
Question 13
Which of the following is correct?
A. Fuselage can affect aerodynamic efficiency
B. Fuselage cannot affect aerodynamic efficiency
C. Aerodynamic efficiency is not dependent on the fuselage at all
D. Aerodynamic efficiency will always be half if fuselage is long
View Answer
Answer: Option A
Explanation:
Fuselage is primary drag producing component. The overall smoothness and how fuselage is designed will affect the drag properties of the aircraft. As a result of which fuselage will affect the aerodynamic efficiency of the aircraft as well.
Question 14
Which of the following is correct?
A. Base drag is affected by boat tailing
B. Base drag is not affected by boat tailing
C. Wing area is always same for every mission
D. Fuselage should be circular in shape always
View Answer
Answer: Option A
Explanation:
Tapering of the base area or aft fuselage section is called boat tailing. Boat tailing will affect base area. As a result of which pressure distribution is affected as well. Hence, as a pressure distribution varies drag due to base area will also change.
Question 15
Which of the following is incorrect?
A. Tightly packed fuselage will not affect maintainability
B. Waiting area can be minimized by lowering fineness ratio
C. Fineness ratio is division of length of fuselage to maximum diameter
D. Wetted area can affect the drag properties
View Answer
Answer: Option A
Explanation:
Tightly packed fuselage makes it difficult to access some vital components for maintenance. This will affect the maintainability of the aircraft. Wetted area can be reduced by tight packaging or by lowering the fineness ratio or by both.
Question 16
Why do we provide upsweep to the lower surface at aft fuselage?
A. To reduce drag
B. To increase drag
C. To increase lift
D. To maximize drag
View Answer
Answer: Option A
Explanation:
Fuselage is primary drag generating component of aircraft. A lower surface upsweep is provided to reduce drag penalty for typical aircraft. This upsweep will induce vortex flow pattern at the lower surface which can reduce the drag. However, for high speed aircraft it should be as low as possible.