Aircraft Design Questions and Answers Part-18

1. If a wing has span of 12m. Find the approximated length of the aileron of starboard wing.
a) 2.4m
b) 20m
c) 15m
d) 25m

Answer: a
Explanation: For a typical wing, ailerons are extended from 50% of span to 90% of span.
Given, Span of wing b=12m. Since we need to find aileron length at one wing we will divide total wing span by 2.
Hence span of starboard wing = 12/2 = 6m.
Length of aileron at starboard wing (right wing) = |difference between 50% and 90% of span|
= |50% of 6m – 90% of 6m| = |0.5*6-0.9*6| = 2.4m.

2. High speed aircraft is affected by ____________
a) aileron reversal
b) flap inversion
c) drafting
d) independent from any disturbances

Answer: a
Explanation: Typical high speed aircrafts are affected by ‘aileron reversal’. Aileron reversal is generated as a result of much complex air loads. Air loads are strong enough that they twits wing itself. This results in wrong way rolling at certain speeds.

3.We can reduce aileron reversal by adopting ____________
a) inboard aileron
b) inboard fuel
c) thrust reversal
d) thrust decrement

Answer: a
Explanation: To reduce the degree of aileron reversal we often use an inboard aileron. Inboard aileron will reduce the excessive twisting of wing. Thrust reversal are used to decelerate aircraft.

4. Rolling tails can be used by high speed A/C.
a) True
b) False

Answer: a
Explanation: Rolling tail is nothing but the horizontal tail. This horizontal tail can be deflected nonsymmetrically. Rolling tails are used for decrease the effect of aileron reversal.

5.Determine the corrections or otherwise of the following assertion [A] and reason [R]:
Assertion [A]: Typically control surface are tapered with same taper ratio as primary component such as wing or tail
Reason[R]: Control surface is used to provide trim control to the A/C
a) Both [A] and [R] are true and [R] is the correct reason for [A]
b) Both [A] and [R] are true but [R] is not the correct reason for [A]
c) Both [A] and [R] are false
d) [A] is false but [R] is true

Answer: b
Explanation: Control surface is used to provide control to the aircraft. In general, we provide same taper ratio to the control surface as wing or tail. By using same taper ratio we can ensure that constant percent chord is being maintained by the surface.

6. Rapid oscillations of control surface due to application of the air loads is termed as __________
a) control surface flutter
b) control surface span
c) control surface trim
d) control surface effectiveness

Answer: a
Explanation: Rapid oscillation of control surface is called control surface flutter. This rapid oscillation can tear off the surface or wing/tail itself. This will induces excessive vibration as well. Effectiveness of control surface is measure of how effectively we can control the aircraft

7. Determine elevator chord if tail chord is 1m.
a) 0.25m-0.5m
b) 2.5m
c) 1.8m
d) 1.5-2m

Answer: a
Explanation: Given, tail chord T.C. = 1m.
In typical aircraft, elevator chord is 25% to 50% of tail chord.
Elevator chord = 25% of T.C. to 50% of T.C. = 25% of 1 to 50% of 1
= 0.25*1 to 0.5*1 = 0.25m-0.50m.

8. If vertical tail has length of the 2m then, find the value of rudder length.
a) 1.8m
b) 2.8m
c) 2m
d) 2.5m

Answer: a
Explanation: Given vertical length L = 2m.
For, typical aircraft rudder is extended up to 90% of the length of the vertical tail.
Hence, Rudder length = 90% of tail length = 90% of 2m = 0.9*2m = 1.8m.

9. A good sketch should include _______________
a) overall aerodynamic concepts, location of components etc
b) only lifting area
c) only drag area
d) only volume

Answer: a
Explanation: A good sketch is the one that highlights as much as detail as it can. It should include overall aerodynamic concepts, internal placements of components, landing gear location etc

10. What do you mean by the inboard profile’?
a) Most detailed drawing drawn to show greater details of internal components
b) First design of sketch
c) Inboard parts
d) Outboard parts

Answer: a
Explanation: before a design can be finalized it needs to go through number of iterations. After this iterative process we make a design which has most detailed information. This detailed layout is called inboard profile. Typically, it is far more detailed than the initial layout.