The size of an aircraft on a collision course will,
A. appear stationary on the horizon
B. appear stationary and increase linearly
C. increase linearly
D. increase exponentially.
[i](a) appear stationary on the horizon[/i]
Collision trajectory implies nil relative motion. However, appearing on the horizon is a sufficient but not a necessary prerequisite for collision. So, no.
[i](b) appear stationary and increase linearly[/i]
Collision trajectory implies nil relative motion. However, as the range decreases, the visual angle of the target must increase with the increase becoming very non-linear at relative close ranges. So, no.
[i](c) increase linearly[/i]
As the range decreases, the visual angle of the target must increase with the increase becoming very non-linear at relative close ranges. So, no.
[i](d) increase exponentially.[/i]
Very much so as the aircraft range gets within the final few seconds prior to impact.
For instance, see fig 5.10 p 142. The graphic plots various speeds against visual angle change but, in effect, is talking about distance against visual angle.
Engineering specialist in aircraft performance and weight control.
