fairing for trailer questions

[skyking]

So Phil, can you see in your mind's eye what I am about? I know bob wants graphics. I have some wrenching to do or I'd teach myself some

I will be going up 14" overall height on the combo, I just think a fairing on top of cab to roll things on a bit nicer, with a longer transition to horizontal and some nice side radii will be worth the troubles. The subsequent transition from fairings to actual trailer will have no increase in frontal. The trailer will widen about 6" per side over the first 6' or so.

[aerohead]

Originally Posted by skyking

So Phil, can you see in your mind's eye what I am about? I know bob wants graphics. I have some wrenching to do or I'd teach myself some

I will be going up 14" overall height on the combo, I just think a fairing on top of cab to roll things on a bit nicer, with a longer transition to horizontal and some nice side radii will be worth the troubles. The subsequent transition from fairings to actual trailer will have no increase in frontal. The trailer will widen about 6" per side over the first 6' or so.

*I'm the anal retentive,so I'm always going to do the hardest to fabricate compound curvature.The empirical data indicates that these forms deliver the lowest drag.
*However,some will argue as to whether the 'ideal' is justified when something 'less' is statistically 'close' in performance.'I'm like the poor b---ard in Dirty Harry........"I just gots to know!"
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If we looked at your RAM in the wind tunnel we'd see that your cowl/windshield/A-pillars/and windshield header does a fine job of getting the air over and around the greenhouse of the truck.
*If you were to scale this area up to the larger dimensions of the trailer face,you could expect similar results in the wind tunnel.So this would be a 'guaranteed' minimum roof fairing.There's no way it wouldn't perform.(this is exactly what I'm doing for Gilkison's APEX,using a discarded rear hatch off John's former Highlander as the 'base.')
*If you wanted to go beyond this,according to Hucho's references,as well as R.G.S.White's investigations,you'd get to the drag minimum.
*You just need to play it out in your mind.Do I want to put in 300-hours and get 100%,or put in 40-hrs and get 90% (or somethin' like that).
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Personally,I would do as you and Sven7 have been talking about with the double 'Template'.But again,the Black Widow 'double-windshield' approach to fairings would be an okay 1st runner-up.And a lot easier to fabricate.
Your the boss of this,so it's your call.
For me,if I go 'all the way',then I never have to wonder what the 'extra' effort might have netted at the gas station.
And like Howard Hughes,I'll continue to go on and on,spending my (time) and money on.............. It's just what I do.

[skyking]

Been outside installing the new injectors, and looking at that roof hard. It is a nice shape now, and it would be a work of art ( 50 hours minimum ) to graft on something tasteful, removable, that won't damage the paint job. I'm thinking the same shape, just starting at the aft edge of the cab will be less costly.