Class a motorhomes aerodynamics

[freebeard]

Careful, that's aerohead's friend.

[sregord]

Hey there, I've been away...
First distracted with work(I'm retired as of January 1, 2023).
and then this Atmospheric River hit us in Reno/Virginia City pretty hard. New Year's storm snow was so heavy we had 2 big pine trees pull the roots out of the ground, then no power for 4+ days. I'm in Palm Springs for a while now...Moby is back home, partly under snow.

But I have been thinking about all this....adding a 62" boattail will be quite the storage box following us. Moving HVAC to the basement, wheel skirts, and clean up the underbody is all doable.

The weight(road load) of vehicle has been mentioned. Has anyone tried adding an adjustable(angle of attack) "wing" to both sides of a flat sided thing like Moby? the mirrors would be the limit (10") as far as how extended they could be. but a curved top- flat bottomed NACA 4 digit airfoil, 2' long?, and end platted...preferable near over the rear wheel axle. or is this too weird/dangerous an experiment to try?

[freebeard]

(I'm retired as of January 1, 2023)

Good luck! It took me two years to find out how burnt out I was. But I eased into it, some hit it like a wall and keel over.

I'd need a diagram. Is this like the trailer tail? You have fineness ratio going for you with opportunity for reattaching the air flow. Any protuberance at the rear will interupt that.

The extension would have negligible weight, but any cargo might affect oversteer/understeer. What do you think of aerohead's concept at #128 and #129? My proposal adds a hinged, solid difusser and a tube-and-skin upper shell.



Where the van had a stinger stored over the roof, a motorhome could have a second hinge and rectangular superelliptical plate.

[sregord]

Maybe that was too much in one post.
Aerohead's #128 post was the referenced length of 63" sorry I said 62" boattail...adding approx 5 feet to a 32 foot Moby would make for a big storage box.

[sregord]

Originally Posted by sregord

Has anyone tried adding an adjustable(angle of attack) "wing" to both sides of a flat sided thing like Moby? the mirrors would be the limit (10") as far as how extended they could be. but a curved top- flat bottomed NACA 4 digit airfoil, 2' long?, and end platted...preferable near over the rear wheel axle. or is this too weird/dangerous an experiment to try?

My curious thought was this... basically attaching a short winglet, similar to a Formula 1 front wing(up-side-down) to the side of the flat sided motorhome, to create a little lift.

[freebeard]

An electric blower energized Coanda nozzle* would only have to run intermittently, and could be modulated left to right to counter crossswind conditions.

Here's what bottomless money can get you:


cdn-1.motorsport.com/images/mgl/6DlJRxV6/s8/f1-malaysian-gp-2017-mercedes-f1-w08-barge-boards.jpg

The vanes on the left are to contain air spilling off a square front edge, but turn it around and the first vane could eat the boundary layer with each successive one reducing the final section.

I don't understand the longitudinal flutes [blue] at all, but they're very popular in these circles. The upright paddles [red] as well.

*You could fabricate a Coanda nozzle by intermittently slotting a larg diameter pipe and bending the intervening tabs 90 degrees on each end. Maybe put it on the tailpipe[s]?

[sregord]

Originally Posted by freebeard

[IMG]
Here's what bottomless money can get you:

I know ...kinda like Google

[aerohead]

Originally Posted by sregord

Hey there, I've been away...
First distracted with work(I'm retired as of January 1, 2023).
and then this Atmospheric River hit us in Reno/Virginia City pretty hard. New Year's storm snow was so heavy we had 2 big pine trees pull the roots out of the ground, then no power for 4+ days. I'm in Palm Springs for a while now...Moby is back home, partly under snow.

But I have been thinking about all this....adding a 62" boattail will be quite the storage box following us. Moving HVAC to the basement, wheel skirts, and clean up the underbody is all doable.

The weight(road load) of vehicle has been mentioned. Has anyone tried adding an adjustable(angle of attack) "wing" to both sides of a flat sided thing like Moby? the mirrors would be the limit (10") as far as how extended they could be. but a curved top- flat bottomed NACA 4 digit airfoil, 2' long?, and end platted...preferable near over the rear wheel axle. or is this too weird/dangerous an experiment to try?

Can you clarify what you mean by 'both sides'?
If the premise is to use 'lift' to reduce rolling -resistance, by reducing the load on the rear axle, I suspect that the aerodynamic interference drag created by the wing's induced drag, added frontal area, and aero drag, would undo any dubious R-R reduction, for a net drag increase.

[freebeard]

I think he means the two sides.

The 10" dimension suggests 'rudders' to make a converging duct. Why they would be at the axle line I have no idea.

[sregord]

Originally Posted by aerohead

Can you clarify what you mean by 'both sides'?

I guess the simplest example would be the canards on the front of a Rutan Long-EZ ....although they are too long (extended perpendicular from the side surface) & the cord of the airfoil could be twice or 3 times longer.
https://www.researchgate.net/publica...nt-airfoil.png
... one on each side of the MH.
..and yes the "the premise is to use 'lift' to reduce rolling -resistance, by reducing the load on the rear axle."

So I think you have answered the question