In aeroailas' answer I understand that the cones in front of the props/fans are called spinners.
In Farhan's answer I understand that the ehite marks painted onto the spinners act less as scarecrows and more plausibly as scare-crews.
In Daniel K's answer I understand that the marks may have yellow color for high contrast.
Then I found a picture from Wikimedia showing different patterns for the white marks:
Courtesy of Gese 151, shared under CC BY-SA 4.0 license.
There are also engines lacking such patterns, as shown for this Jetblue Embracer 190
Courtesy of John murphy, shared under CC BY-SA 2.0 licence
Here are my questions:
- Why to the airliners have such variety of patterns? What are the pros and cons of such patterns? Why are some patterns less common?
- Why don't they opt for other colors in practise for more contracst, like how British use to paint their trains yellow?
- Why do some models omit them? Is the change reducing costs? Is such reduction surpassing potential risks?