I have been reading a lot of the threads in the Aerodynamics forum here in regards to my hopes/plans to self build a travel trailer. I found these images below from “Ahmed et al.” posted by Aerohead, the most helpful in terms of simplifying the thousand design questions and possibilities that have come up for me.
Here is the page link for that thread:
HTML Code:
https://ecomodder.com/forum/showthread.php/trailer-shape-better-20662-10.html
I do realize the images are geared toward buses but I am assuming that design wise they would be somewhat transferable to travel trailer design, with an understanding that the tow vehicle and relationship to the tow vehicle factors in greatly also.
From a construction and utility viewpoint it seems every vehicle in image 1, except for the bottom one with Cd of .131 seems reasonably doable.
In the second image they all seem doable but what I would do with the boattail space, utility wise is a big question for me. One possibility would be to have a rear exterior accessed storage shed or external kitchen.
Anyway, here are my main questions - again with some understanding that there are other factors involved:
- I don’t really understand how to translate percentage gains in Cd to possible percentage gains in fuel efficiency if that is even possible. If it is, then how would you translate the differences between the .314 vehicle and the .218 Cd for example?
- Does anyone know what the radius would need to be of the leading edges, side top edges and boattail edges to accomplish these kind of Cd numbers?
- Am I right to assume that the minimum degree taper of the boattail to achieve the .218 Cd is 10 to 12%?
- Lastly, is there any kind of formula for where the boattail can be cutoff off, where you get the majority of the benefit?
Image #1
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Image #2
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Thanks to everybody here for these resources. i appreciate it all very much!
Bill