Question 1
A 3D airfoil is called _____________
A. wing
B. airfoil
C. engine
D. lofting
View Answer
Answer: Option A
Explanation:
Wing is generated by elongating an airfoil. Airfoil is 2D shape. Engine is main source of power. Lofting is skin modelling.
Question 2
A jet fighter is operating at Mach number of 1.4. Wing chord is 1m then, find the location of aerodynamic centre.
A. 0.4m
B. 0.4
C. 0.8m
D. 0.8
View Answer
Answer: Option A
Explanation:
Given, jet fighter aircraft which is cruising at Mach 1.4.For such high speed aircraft, location of the aerodynamic center is given by,Location of aerodynamic center = 40% of chord = 40% of 1 = 0.4*1 = 0.4m.
Question 3
A twin turboprop engine is flying with 120m/s. Wing of the aircraft has span of 2m and lift co-efficient as 0.15 with aspect ratio as 9.2. Find the lift produced by the wing.
A. 574.18 N
B. 574.18
C. 120 N
D. 620 N
View Answer
Answer: Option A
Explanation:
Given, a twin turbopropVelocity V = 120m/s, CL = 0.15, Aspect ratio = 9.2, span b=2mAspect ratio = b*b/S9.2 = 2*2/sS = 0.434m2Now, lift is given by,L = (1/2)*ρ*V2*S*CL = 0.5* 1.225*120*120*0.434*0.15 = 574.18N.
Question 4
A typical wing has aspect ratio of 7 and span of 2m. If taper ratio T = 0.2 then, find the value of root chord.
A. 0.4761m
B. 0.61m
C. 0.81m
D. 0.71cm
View Answer
Answer: Option A
Explanation:
Given, span = 2m, aspect ratio = 7 and taper ratio T = 0.2The root chord is given by,Croot = 2*S / (b*(1+T))Here, S is not given but aspect ratio is given.Aspect ratio AR = Span square / S = 2*2 / S7 = 4/ SS = 0.5714 m2Hence, Croot = 2*S / (b*(1+T))= 2*0.5714 / (2*(1+0.2)) = 0.4761m.
Question 5
A wing has root chord of 2m and taper ratio of 0.5. Determine what will be the value of tip chord?
A. 1m
B. 1.5m
C. 1
D. 1.5
View Answer
Answer: Option A
Explanation:
Given, wing has root chord of 2mTaper ratio T = 0.5Now, taper ratio T = tip chord / root chordTip chord = T*root chord = 0.5*2 = 1m.
Question 6
An aircraft with elliptic wing planform has parasite drag coefficient as 0.6. Lift coefficient of wing is 0.25 and aspect ratio is 7.5. If induced drag co-efficient is 0.0235 then, find total drag coefficient for the wing.
A. 0.06235
B. 0.5235
C. 0.6
D. 0.0235
View Answer
Answer: Option A
Explanation:
Given, parasite drag co-efficient = 0.6, induced drag coefficient = 0.0235Total drag coefficient = Parasitic drag coefficient + induced drag coefficient = 0.6+0.0235 = 0.06235.
Question 7
An aircraft with elliptic wing planform has parasite drag coefficient as 0.9. Lift coefficient of wing is 1.8 and aspect ratio is 8.5. Find total drag coefficient for the wing.
A. 1.021
B. 0.9
C. 0.121
D. 0.25
View Answer
Answer: Option A
Explanation:
Given, elliptic wing, parasite drag coefficient CD0 = 0.9Lift coefficient CL = 1.8, Aspect ratio AR=8.5Now, Total drag coefficient = Parasitic drag coefficient (CD0) + induced drag coefficient (CDi)CDi = CL*CL / (ᴨ*e*AR) = 1.8*1.8 / (ᴨ*1*8.5) = 0.121Hence, Total drag coefficient = CD0 + CDi = 0.9 + 0.121 = 1.021.
Question 8
Canard pusher aircraft uses wing sweep to change location of aerodynamic centre.
A. True
B. False
View Answer
Answer: Option A
Explanation:
Canard pusher aircrafts are heavier at rearward part. At tail weight is more. By sweeping the wing we can alter the location of aerodynamic center for balance.
Question 9
Excessive dihedral can produce _____
A. dutch roll
B. thrust
C. pitch
D. deflection at nose
View Answer
Answer: Option A
Explanation:
Dihedral is upward deflection of wing. It is used to provide roll stability. If excessive dihedral is provided then, it will lead to dutch roll; continuous side to side motion involving yaw and roll.
Question 10
For high aspect ratio strength of the wing tip vortex is low.
A. True
B. False
View Answer
Answer: Option A
Explanation:
Wing tip of high aspect ratio wing is far from root as compared to low aspect ratio wing. The wing affected by higher ratio will be less and the strength of tip vortex will be less as well.
Question 11
If a sailplane is to be designed then, the aspect ratio of the sailplane will be ______
A. higher than military aircraft
B. same as military aircraft
C. lower than military aircraft
D. exactly half of the military aircraft
View Answer
Answer: Option A
Explanation:
Sailplanes are different from military aircrafts. Sailplanes are designed to glide through air. For such requirements, it will require higher lift capability which can be provided by using higher aspect ratio wings than military aircrafts.
Question 12
If aspect ratio of wing is 8 and S=0.1m2 then, what will be the span of wing?
A. 0.89m
B. 0.89cm
C. 0.89
D. 0.89inch
View Answer
Answer: Option A
Explanation:
Given, wing Aspect ratio AR=8, S=0.1m2Aspect ratio = span square/ reference area8 = span square / 0.1Span square = 8*0.1 = 0.8Hence, span = 0.89m.
Question 13
If root chord is 2m and tip chord is 0.9m then, find taper ratio.
A. 0.45
B. 0.55
C. 0.65
D. 0.25
View Answer
Answer: Option A
Explanation:
Taper ratio is defined as,Taper ratio = tip chord/root chord = 0.9/2 = 0.45.
Question 14
If taper ratio is T and span is b with surface area as S then the root chord is _____
A. Croot = 2*S / (b*(1+T))
B. Croot = 2*S / (b*(3+T))
C. Croot = 2*S / (2b*(1+T))
D. Croot = 2*S / (1+T)
View Answer
Answer: Option A
Explanation:
Taper ratio represents how much wing is tapered. For any given area S, span b and taper ratio T, root chord is given by,Croot = 2*S / (b*(1+T)). The value of root chord will be different for different aircrafts.
Question 15
The ratio of tip and root chord is called ____
A. taper ratio
B. sweep
C. aspect ratio
D. slope
View Answer
Answer: Option A
Explanation:
Taper ratio is the ratio of tip chord of wing to root chord of the wing. Aspect ratio is square of span divided by area. Sweep is angle between wing and fuselage reference line.
Question 16
What is the function of wing twist?
A. To improve stall characteristics at tip
B. To reduce lift by tail
C. To provide lofting
D. To increase engine thrust
View Answer
Answer: Option A
Explanation:
Wing twist is used to delay the stall at tip typically. Wing twist can be used to rearrange the lift distribution of the wing. Lofting is skin modelling.
Question 17
Which of the following is correct?
A. Weight will be more for higher aspect ratio wing
B. Military aircraft have much higher aspect ratio
C. Civil aircraft are flying at hypersonic speed
D. Lofting is a conceptual design of wing
View Answer
Answer: Option A
Explanation:
Aspect ratio affects span and reference area. For same area if aspect ratio is more then, the corresponding value of span will be more as well. This will increase material requirements and which increases weight of the wing.
Question 18
Wing and airfoil both are 3D phenomena.
A. True
B. False
View Answer
Answer: Option B
Explanation:
An airfoil is a 2D concept. Airfoil is cross sectional shape of the wing. When airfoil has finite span it is called a wing.
Question 19
Wing aspect ratio is defined as _____
A. span square divided by reference area
B. span square multiplied by reference area
C. span square plus reference area
D. span square
View Answer
Answer: Option A
Explanation:
Aspect ratio of wing gives relation between span of wing and wing reference area. It is defined as the ratio of span square to the reference or planform area. Higher aspect ratio wings will be long with less area.
Question 20
Wing planform is affected by _____
A. sweep only
B. aspect ratio, sweep angle, taper ratio
C. aspect ratio only
D. taper ratio only
View Answer
Answer: Option B
Explanation:
Wing planform is shape of the wing when viewed from top. Aspect ratio will affect span and area. Overall planform will be affected by aspect ratio, taper ratio, sweep etc.
Question 21
Wing sweep is used to ____
A. increase critical mach number
B. decrease critical mach number
C. increase lofting
D. increase drafting
View Answer
Answer: Option A
Explanation:
If wing is at some finite angle from fuselage reference line then it is called wing is sweep by that much degree. Main function of sweep is to increase critical mach number. Lofting is skin modelling and drafting is drawing phenomena.