The purpose of the longitudinal control lines is ________

A)
to change lifting line slope
B)
only to produce control of lifting lines of same curve
C)
to connect tangent points at half distance only of same conic curve
D)
to connect end points, shoulder points and tangent point of different conic curves

Correct Answer :   to connect end points, shoulder points and tangent point of different conic curves


Explanation : Longitudinal control lines are used to develop smoothly – lofted fuselage. Longitudinal control lines will connect end points of different conic curves. It is also used to connect different shoulder points and tangent points to respective shoulder points and tangent points of different conic curves.