This is a fluid dynamics issue, tight corners will affect the flow and reduce the efficiency of the piping. To keep the flow consistent you will need to account for that.
I should add that an inline fan is not difficult and might be the easiest way for you to do what you want and ensure enough flow. We did an inline fan.
Your duct or piping system will have to be sized based on the fan you buy, we used 4" because we use that in our wood shop and fans in the US are easy to find in this size so we printed an adapter to the enclosure. Our main reason for the mod was to ensure effective air clearing and it works great.