Class a motorhomes aerodynamics

[j-c-c]

I would be very curious how much "flapping" would occur at speed with all the tractor induced turbulence. I'm sure there would be an improvement of sorts. I doubt State of Florida would approve or understand this "energy conservation device", its design leaves a lot on the table with incompleteness in its coverage, and I can't imagine the liability that exits if road debris or fatigue causes it to separate or be dragged behind like a moving banana peal for the following vehicle.
Other than that, I like the effort.

[freebeard]

It's stretched tight, but the air can get to both sides. Wingtip effects all the way down both sides.

I think it's the least interesting of their offerings.

BETTERFLOW - Next Step Aerodynamics

Their projection to 2032 has airflow much like Luigi Colani designs.

[sregord]

As before I failed to explain the reference
instead of hard plastic, wood or metal to “enclose” (create a flat bottom) the large underside of a 32 foot RV, could it be done similarly to a fabric covered kit airplane…framed and stretched ?

[j-c-c]

Originally Posted by freebeard

It's stretched tight, but the air can get to both sides. Wingtip effects all the way down both sides.

I think it's the least interesting of their offerings.

Their projection to 2032 has airflow much like Luigi Colani designs.

The free air on both sides is the issue, and why I mentioned the somewhat inept attempt to close off the many openings, I seriously doubt anyway a piece of fabric can be in that application tensioned tight enough to resist flapping in extreme fluctuations of temp for 100,000+ miles at speeds up to 70mph.

[freebeard]

As before I failed to explain the reference
instead of hard plastic, wood or metal to “enclose” (create a flat bottom) the large underside of a 32 foot RV, could it be done similarly to a fabric covered kit airplane…framed and stretched ?

Maybe I failed to explain the problem?

Aicraft fabric is doped. And covers a convex polygon. A flat frame would just be a drumhead.

[j-c-c]

Doped aircraft surfaces are I believe also are fully framed and airflow is only on one side of the fabric surface, not the case in the linked video. The fabric also is not stretched IMO, but more shrunk by the doping drying process.

That rear door contraption is right out of NASA spacecraft outer space unfolding mechanisms and likely equally expensive and fragile enough to never live past its first encounter with a loading dock.
The low hanging fruit ignored here is IMO, just completely cover the trailer roof with solar cells and incorporate regenerative braking for propulsion or auxiliary cooling for the trailer and be way far ahead of all the tweaks and gadgets in the slick (pun intended) produced video.

[Piotrsko]

Irish cotton would be shrunk by the "paint" which might be nitral buytarate cellulose, or just butaryte cellulose, but any more people are using synthetics like dacron that don't shrink much when dry and and are heat taughtened then have another synthetic coating applied to seal the surfaces and provide ultra violet resistance. They can be one sided, but that is generally reserved for aircraft that operate under 100mph. Aka "flying lawn chairs"

Fabric covered frames have about the same puncture resistance and shear strength as a piece of 1/4" marine plywood.

[aerohead]

Originally Posted by sregord

Ah... wheels on the ground.
So an extended (Mair 1.9 diameter) boattail should be a trailer...a la

If it only starts the flow in the right direction (<3-4')..a la Ahmed

* His ' cylinder-to- constant 22-degree down-slope angle' transition region constituted 98.7% of the torpedo's diameter. It's not the most efficient, although way better than PGA regulation golf balls.
* The Ahmed body has zero transition, and can't do any better than Cd 0.2298, with a 9-degree down-slope, compared to Cd 0.25 'naked.'
* If you throw in P. W. Bearman's 10-degree plan-view side angles, 10-degree diffuser, and upper edge chamfering, it implies perhaps a drag minimum on the order of Cd 0.166.
* the 1995, GM 'OPTIMUM' boat-tail, with 20-degree 'top', 10-degree 'sides', 10-degree diffuser, and 7% body height-radii ( all-around ), generated an 18-wheeler on the order of Cd 0.2261, down from from Cd 0.66 ( real wheels, not 'pylons' ).

[aerohead]

Commercial awnings on buildings around here are surviving 60-mph + thunderstorm gusts, fully exposed.
They're just tensioned Hypalon-coated fabric, laced to a very light, heli-arc- welded aluminum skeleton.
'Hiding' in the lee, behind an airdam, a taught fabric belly would be subjected to very little force.
NASA only gained a 5% drag reduction for a full belly pan on their semi-trailer, but hey, it's 5%.
If splash & spray is isolated, and cannot loft debris and water up on top of it, it seems like an okay 'solution.'
' Enclosed' within a perimeter of the airdam, 'rocker panels', and a diffuser, there'd just be dead air above it, and 'parallel' air licking the underside ( inverted bird bath on the belly ).

[j-c-c]

Originally Posted by aerohead

Commercial awnings on buildings around here are surviving 60-mph + thunderstorm gusts, fully exposed.
They're just tensioned Hypalon-coated fabric, laced to a very light, heli-arc- welded aluminum skeleton.
'Hiding' in the lee, behind an airdam, a taught fabric belly would be subjected to very little force.
NASA only gained a 5% drag reduction for a full belly pan on their semi-trailer, but hey, it's 5%.
If splash & spray is isolated, and cannot loft debris and water up on top of it, it seems like an okay 'solution.'
' Enclosed' within a perimeter of the airdam, 'rocker panels', and a diffuser, there'd just be dead air above it, and 'parallel' air licking the underside ( inverted bird bath on the belly ).

No Thunderstorm lasts up to 11? hours a day, 6 days a week at 60mph.
If it's subject to "very little force", how crucial/productive is it in the first place, but I don't necessarily agree with the initial premise anyway that it is hiding in any significantly calmer "lee" air flow.
I'm not questioning it's a "solution", I'm questioning its bang for buck, its longevity, its safety impact to others in a failure, the complexity needed to make it suitable in the first place.
I'll give it a pass for now on potential alternative similar better solutions fabric less, ie just box off the entire space.