Does anybody know if any in the RV industry areusing wind tunnel test results in manufacturingbuild specifications ? I was watching MotorWeek and they showed / demonstrated the effect of rear end drag created by a what was a "boxed" rear end. (the "smoke" broke up immediately after passing the rear of the vehicle ). Apparently, the smoother the transition post vehicle the less drag...modifications included "smoothing" under the vehicle. I don't understand all the engineering/aerodynamics but does seem plausible to apply testing to the RV industry. My review of the European RV market seems to indicate they are paying attention.So, why is this important ? Average cost of gal. of gas between $3.20 - $3.60 (diesel more)... and,the experts "predicting" only going higher. Might be time to give a little more then lip service to RV aerodynamics. What say the congregation ? Interestingly, the wind tunnel effects have been appliedto just about any type watercraft, or aircraft...just haven'tseen the RV in the discussion.Charles

Mmmm...A flat rear wall affords things like windows, spare tires, ladders...etc.Maybe a contoured rear end just isn't thought to be that important.I do think air dumping off the sides, top and bottom of a large vehicle does actually help push the box at highway speeds due to the air void. Kind of like the pickup tailgate down myth.The soft round corner back end capped units do have a stylish pleasant look however.

It would be interesting to see some studies of RV aerodynamics but as every RV is some sort of compromise, after a certain point improved aerodynamics will likely be at the expense of something else.My present 5th wheel has very good aerodynamics for a 5er but the trade off is reduced bedroom closet space and basement size. I'm thinking that contouring the 8' X 8" rear end enough to make a real difference in aerodynamics could make an RV quite a bit longer with a decrease in functionality. When it comes to efficient use of space, nothing is more functional than a box.

If you want better MPG, just keep it light and slow down. Or, buy an Airstream.

Thats_Ok wrote:Mmmm...I do think air dumping off the sides, top and bottom of a large vehicle does actually help push the box at highway speeds due to the air void. Kind of like the pickup tailgate down myth.Actually the high pressure up front, the turbid air alongside and under the vehicle, and the low pressure at the back all combine to generate considerable aerodynamic drag.Leaving a pickup tailgate down actually hurts mpg due to the swirling affect and creation of a low pressure zoneStudies have been going on since the 1970's but more interest has been shown lately.......wind tunnel studies of semi trucks/trailers ie: Cab side/top extensions, side fairings and rear wings.The rear area has been toughest to improve upon due to the need for large flat doorsAerodynamics ResearchTractor Trailer AerodynamicsV-shaped trailers has been one attempt at reducing drag.Problem is like an octagon home....kinda neat looking but lots of wasted space

Wind Tunnel testing ???? | Good Sam Community

26 Replies

sch911
Explorer
Sep 28, 2013
One look at the back of most RV's answers that question don't you think?
Old-Biscuit
Explorer III
Sep 28, 2013
Thats_Ok wrote:
Mmmm...

I do think air dumping off the sides, top and bottom of a large vehicle does actually help push the box at highway speeds due to the air void.
Kind of like the pickup tailgate down myth.

Actually the high pressure up front, the turbid air alongside and under the vehicle, and the low pressure at the back all combine to generate considerable aerodynamic drag.

Leaving a pickup tailgate down actually hurts mpg due to the swirling affect and creation of a low pressure zone

Studies have been going on since the 1970's but more interest has been shown lately.......wind tunnel studies of semi trucks/trailers ie: Cab side/top extensions, side fairings and rear wings.
The rear area has been toughest to improve upon due to the need for large flat doors

Aerodynamics Research

Tractor Trailer Aerodynamics

V-shaped trailers has been one attempt at reducing drag.
Problem is like an octagon home....kinda neat looking but lots of wasted space
Highway_4x4
Explorer
Sep 28, 2013
If you want better MPG, just keep it light and slow down. Or, buy an Airstream.
Johno02
Explorer
Sep 28, 2013
Look at these

Airtabs
wilber1
Explorer
Sep 28, 2013
It would be interesting to see some studies of RV aerodynamics but as every RV is some sort of compromise, after a certain point improved aerodynamics will likely be at the expense of something else.

My present 5th wheel has very good aerodynamics for a 5er but the trade off is reduced bedroom closet space and basement size.

I'm thinking that contouring the 8' X 8" rear end enough to make a real difference in aerodynamics could make an RV quite a bit longer with a decrease in functionality. When it comes to efficient use of space, nothing is more functional than a box.
deleted-2
Explorer
Sep 28, 2013
Mmmm...
A flat rear wall affords things like windows, spare tires, ladders...etc.
Maybe a contoured rear end just isn't thought to be that important.

I do think air dumping off the sides, top and bottom of a large vehicle does actually help push the box at highway speeds due to the air void.
Kind of like the pickup tailgate down myth.

The soft round corner back end capped units do have a stylish pleasant look however.

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Wind Tunnel testing ????

26 Replies

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