Quote:
Originally Posted by Gschuld
Yes, the corners mean a lot, even with the cross section of the trailer within the cross section of the Grand Cherokee. My design described originally in this thread has a full round 32 radius front section (top view) like the Aerovault trailers.
https://www.bre2.net/aerovault.info/
There is no need for such a heavily rounded upper section (in profile) as the Aerovault since the top of the designed trailer is 5 below the top trailing edge of the Grand Cherokee roofline.
The full rounded top view shape was intended to minimize the destabilizing effect of cross winds. Its debatable whether that is worth it. The front of the rounded shape would be within 20 of the bumper of the Jeep. I have a minor aesthetic interest in that shape as well.
George |
If the trailer was going down the road, solo, the large radii would be approaching the optimum nose for subsonic flow.
As a trailer though, in train behind the tow vehicle, the JEEP would be doing the initial flow penetration and only 4.5% of body- width-radius would be required for trailer's exposed leading edges, @ zero-yaw.
If the trailer face had this 4.5%, it would take care of the exposed sides, and actually reduce the volume of gap between the JEEP and trailer, covering the 'aero' requirement, although 'jack-knife' clearance would need to be maintained. With 20'' of tow-bar, you'd need to check that.
On NASA's semi-trailer project, the trailer gap = 19.7% drag increase @ zero-yaw, and 17% drag increase in wind-averaged flow. An inflated gap-filler could easily yield this 17-19% savings. If frontal areas were matched, you'd have a Cd 0.16 trailer. Lower with the boat-tail.