[drrbc]

Hello all,

I've got a small question that may not matter, but that I'm finding conflicting answers to. I'm hoping for someone to point me at what I've missed.

I'd been waiting for Bondo to get his company up and running so I could buy an aerolid for my 2013 SCrew. Well, it's been a long wait so I kinda decided to take matters into my own hands. I've got my materials, jigs, parts, screws, glue, etc. all together and I'm just a couple of days away (free time days) from bolting my lid(?) together and mounting it on my truck.

Which is when, of course, you remember things you should have previously thought about. But in an effort to make myself quit researching and move things forward I put on the back burner the question "does an aerolid affect the downforce on the rear of the truck to sufficiently change the rake angle when at highway speed".

The reason for asking is this: my build is a telescoping, stepped rig of four individual pieces of diminishing height and width following the 12º template curve in height and a 10º curve in width. I'm using Sintra foamboard formed to cover supporting ribs of flattened 3/4" schedule 40 PVC pipe. Front to back the sections are 10", 14", 14", and 14". Each section will telescope in 1" into the section in front of it, and is completely open front to back.

Think of taking a playing card and along its length folding down sides of equal height so that when you put it on the table you have two walls and a roof. Now with three more cards cut them so that you can make the same shape, but of diminishing size so that each smaller card (stepped) can be "telescoped" into the next larger.

Mine will be a 3/4 length "lid" (over a BakFlip G2 tonneau), which solves the problem of not being able to see out the rear, use of the cab top brake light, and bed access.

The individual pieces are easily removable (and broken down) which allows for easy use of the full bed length (if needed) and storage.

Its semi-rigid plastic construction should allow some side to side flexion in crosswinds- flattening on the windward side and bowing on the leeward (hopefully recapturing the airflow).

Where I get stuck is the 1º rake of the bed. Doing each individual piece with a added 1º front to back angle makes the thermoforming quite difficult and wasteful.

Early in this process I'd thought of using flaps (that I called "retrices" after the bird feather) attached halfway down the ventral surface of each "card" and extended past its length. In the case of airflow detachment over it, an individual "retrix" would lift into the low pressure area above it and effectively increase the length of the curve and hopefully flow re-attachment. IOW, an aerolid that dynamically changes its shape to capture the airflow.

But creating workable retrices is just too difficult and too unknown, and I really want this project over NOW!

Oh hell. After writing this I just don't think I've got another design change in me. Y'all give me a few weeks to slap this thing on and I'll try to get y'all some ABA 80 to 50 rolling times and some pics. Stick around- I'm sure it'll be worth a few laughs.