Vortex generators

[jerichorick]

Some place on one of the RV forums I read a post about vortex generators. These things are used on most airplanes to give them better lift, less drag and better slow speed control. You may be wondering why anyone would need them on a RV? Me too.
Without posting all of my searching I did find this video that has noting to do with the topic but is too good to pass up not posting: https://www.bing.com/videos/search?q...8&&FORM=VDRVRV
My next RV??

Back on topic. There are many great videos posted showing the positive effect of vortex generators on vehicles. With this understanding I started looking for a product for my coach. Because of price and design I chose there folks: https://airflowdeflector.com/home/vspoiler/
I bought the $199 set and applied the tabs to the rear of the coach as instructed. Didn't take much time or effort. Because of the 4 tab design it was very easy to place each set to line up in a neat look.

What did I notice when I drove the coach?
We just drove about 530 miles from Sonora, CA to Jamul, CA. We started our trip in the foot hills of the Sierra Mountains, went over the Grape Vine on I-5, around LA on I-405, back onto I-5, to 94 and into Jamul. We had a variety of terrain to travel and many different road conditions. One of the first things I noticed is that I was not steering as hard as usual. I had not realized that the coach had a slight tail waggle before I installed the v-spoilers. I also realized that the Blue Ox TruCenter seemed to be giving me better control and correction response. Next was to actively observe what happened when a truck passed or I passed a truck. The handling was much more stable and I didn't get that shoved feeling during the event. Also, only once during the total trip was I aware of wind. It seemed to be head-on and I could feel the coach pushing a bit harder.
Fuel economy is supposed to be another improvement with these things. I can't say. We got 8.2 mpg on the overall trip.

Another claim made was that of keeping the rear of the coach and tow cleaner. I do think this is true. We did not seem to pick up as much grime on the car or rear of the coach as usual.
Overall, I think these things were worth the money.

I have driven two trips since putting the v-spoilers on. Both gave me the same results. We are at this location for 6 months so I'll be doing a new study when we hit the road again. Next trip will be to the East Coast. That will be a real test.
I hope the pictures help to answer some of your installation questions, if any. You can click a picture to get a more detailed view. I didn't do the greatest job "enhancing" them, but they work.
Happy trails to all.

Rick Y.

[luvlabs]

Descriptions of how the coach rode better or didn't move when passed by a truck are anecdotal. Anecdotal results are often overly optimistic. In this case data rules and when you, or someone else, can produce hard data showing the benefit of these devices, I'll remain highly sceptical.

These devices have been on the market for years and yet no data exists on what they do for you. Aircraft use is backed by tons of wind tunnel testing data and the benefits are well known. No wind tunnel testing exists for motorhomes that I'm aware of.

[Meridian42e]

Not on my full body paint coach!

[creativepart]

I've been interested in these things for some time. I don't want to be a skeptic, but they seem too small to make much difference. If they were big like the folding foils on the back of semis I could see how they'd work. See photo below:

It would seem that RV manufacturers could do LOTS to improve air flow around our motorhomes. The expensive motorhomes with front, side and rear "rails" that incorporate awnings, smooth airflow over AC units and the roof and then defuse air at the back are really the only ones doing it and it's the right thing to do, I'd say.

Maybe if fuel prices skyrocket and sales plummet more manufacturers will try to reduce weight and improve aerodynamics to save their companies. But until consumers demand it, I don't see it happening.

[jerichorick]

I'll comment to both of you at once. I can only tell you what I HAVE experienced. I hope "anecdotal" is not referring to my experience as being delusional, self or otherwise. And, scientific study and test results?
https://spinoff.nasa.gov/Spinoff2008/t_3.html

https://www.youtube.com/watch?v=ZxKKpevwLqY

https://www.nasa.gov/offices/oct/hom..._aeroserve.htm
https://www.nasa.gov/offices/oct/hom...eroserve.htmll
There is one wind tunnel test of a 18 wheeler that I can't find now but it was the convincing video for me.
I was, and am, objective about these things. For years vortex spoilers have been used on aircraft and racing cars in different forms.

One thing that gets my goat a bit is any skeptic who speaks from their own misunderstanding from a lack of personal experience or education. You both are goat provokers in your approach on this topic. Research for yourselves.

Fancy paint protection? These can be custom painted.

One side effect that I didn't recognize immediately, only yesterday when talking about these with a friend, is that the coach engine ran cooler in the mountains. I first attributed this to the fact that I had cleaned the radiator (rear mounted) thoroughly with Simple just before we left on this trip. Never have I seen the temperature gauge read that low during heavy grade climbs. I didn't think to look at the actual engine temperature on the information screen. But, I did note it and I did attribute this as a results of the cleaning with Simple. I frequently wash the radiator.
We don't see the spoilers advertised. There is no interest in them because the industry has not generated on. We, as a people, buy because of advertising. This is a scientific fact. Much of it is useless junk but we think we need it or like it. (Anecdotal?)

For $200 I have experienced a change in the handling of my coach. I think that being a full-timer since 2005, and being on my third DP, having traveled coast to coast and border to border several times, qualifies me for making good and objective judgement calls about how my RV handles and responds to certain road conditions and what the rear of the coach and the car look like after a 500+ mile journey.
I do NOT wish for success. I recognize and acknowledge when levels of it are obtained in real time. In volunteering this is one of the requirements of the job. I don't have the luxury of anecdotally believing I have repaired a severe electrical issue. I observe and test the results and I must judge, not guess, that I have found and applied the correct solution. Same with my motor-home.
Happy trails and many of them.
Rick Y

[creativepart]

Rick, I only gave my personal opinion. It's not wrong nor right. It's an opinion based on no experience but a fair amount of research on the product I've done in the past. I don't doubt your account of the changes. I'm certainly not "goat provoking" you intentionally.

"Anecdotal" is not a negative term. It means that its not scientific results. Period. And as a full-time RVer since 2005 you know full well that every trip is different - the wind strength/direction, the coach loading, the road and traffic conditions are constantly changing and interacting. So, you know very well that it's difficult to make universal judgements after a couple of trips.

These may be great. I'm happy they work for you. Honestly I am. I'll be looking forward to your long term assessments of them. I'm 100% for the concept. I have my doubts about the application of the concept. I accept that my doubts may be unfounded and I hope your experience and others will prove me wrong.

[luvlabs]

Anecdotal data is not bad but it is simply an opinion, a feeling, or an observation but it can't be quantified.

Nice anecdotal article from NASA. Notice, there is not one piece of data in that article and the other links are bad. Fuel mileage before/after would be a good piece of data. Truck horsepower needed to maintain a set speed over a closed course before/after would be another good piece of data. But alas, nothing of value in that article from NASA.

Aerodynamic data on aircraft generate tons of data; race teams will spend tons of money on wind tunnel testing of race cars and generate tons of data; truck and RV manufacturers don't seem to care too much.

If you really want to prove these things, you need to measure data points that you can get without spending a fortune on equipment. You can measure fuel economy, get weather conditions on the route, drive the same route both ways. Then repeat the same route about 30 times and then do the statistics. Not fun but it will begin to answer questions.

[Pianotuna]

I use air tabs on my class C. They lowered the noise level. There was no noticeable change in fuel economy, except when there is a tail wind. With a strong tail wind economy went up 2mpg as measured by a scan gauge.


I noticed very little difference in sway when passing semi trucks going in the opposite direction, but that was good before the air tabs were installed.


I would buy them again.

[Ray,IN]

My SIL in fleet manager for a trucking company. His boss ordered them put on a test fleet of semi's. The results caused them to decide to not spend more money, any savings would not justify the costs involved.
If a large trucking company cannot justify the cost, I sure can't with my limited annual mileage.

[Sunstar 2012]

Originally Posted by luvlabs

Descriptions of how the coach rode better or didn't move when passed by a truck are anecdotal. Anecdotal results are often overly optimistic. In this case data rules and when you, or someone else, can produce hard data showing the benefit of these devices, I'll remain highly sceptical.

These devices have been on the market for years and yet no data exists on what they do for you. Aircraft use is backed by tons of wind tunnel testing data and the benefits are well known. No wind tunnel testing exists for motorhomes that I'm aware of.

Spinoff.nasa.gov will provide the data you need to evaluate vortex generating devices and the analysis done by NASA when trucks and RV vehicles looked like shoeboxs going down the road. Then skeptics can see the data.

Like many answers to questions are not know, we old folks have the advantage of google instead of coffee discussions that do not really provide knowledge. Take a look at the website and at least you will see that testing has been accomplished Ben though it has been done a while back. This research has been applied to the RV and trailer industry.

Enjoy the read and fix a cup of coffee while sitting and reading.

[jerichorick]

Originally Posted by Ray,IN

My SIL in fleet manager for a trucking company. His boss ordered them put on a test fleet of semi's. The results caused them to decide to not spend more money, any savings would not justify the costs involved.
If a large trucking company cannot justify the cost, I sure can't with my limited annual mileage.

I didn't put these things on for better fuel economy. I don't put enough miles on a year for this to make a big difference in my budget. I put them on to see if handling would improve any and to protect the towed.
I feel that the handling is improved for one simple reason. Experience. Years of experience and thousands of miles of driving RVs from coast to coast and boarder to boarder. I know the handling characteristics of my coach. The drive through the Serra foot hills and over the the coast of CA, down I-5 and over to Jamul was different in handling than before I put the V-generators on.

I have always had a right pull in the steering wheel. I installed the TruCenter to try to correct this pull. It helped some, but it was still noticeable, to the point that I would frequently try to correct it. On this last trip I was able to drive much longer distances without fiddling with the TruCenter, and the correction, once made, was more effective. That change in handling was so obvious. Being unaware of steering pull, having similar steering resistances left and right, is an observation worth noting in my book. I had less fatigue in my arms at the end of the days drive.
When we unhitched I didn't notice as much dirt accumulated on the towed or the back of the coach. It has always been a problem in the past. Not having the car coated in a significant layer of dust from the many construction zones we passed through was a nice greeting,

But, the one observation I noted I need to watch for more closely. The engine seemed to run cooler. The temp. gauge always reads at about 1/2 scale when climbing the Grapevine on I-5. It read a good bit cooler this time. At first I attributed it to the cleaning of the radiator with Simple Awesome just before we left Tuolumne, CA. I rinse the radiator nearly every time I wash the coach. So, cleaning it as I did may have resulted in it running cooler, or the V-generators are allowing better airflow through the engine room to the radiator.
So. In my case, fuel was never the greater motivator for buying and installing this product. What I was hoping for does seem to be what I got. All the above plus the possibility of the radiator breathing better.
Happy trails,
Rick

[Old Crows]

FWIW. You would "probably" have more benefit from fixing the turbulent flow in front and behind tires. Also, fixing the air flow around the wheel wells. The other place to look is to fix the airflow under the vehicle to use the high velocity, low pressure created to advantage AND create a diffuser under the rear valence to return this air stream to the negative pressure area created behind the bluff back.

DPs may do some drag reduction by scooping side flow and returning it to the area behind the RV. Probably minimal at best.

The intense low pressure area behind a bluff back is demonstrated by it's ability to "vacuum" up stones, dirt, debris off the road surface and loft it up behind the vehicle. Made worse by full width skirts and flaps.

[Ret.LEO]

Hey, I guess if nothing else the money spent by the OP in a attempt to help handling feels that it works for him. If it get scientifically proven/disproven for Coaches is still in the future apparently. In the meantime it's up to individuals to decide if they think they work or don't work for them and their particular application.
Does it actually work? Who know's except the user, for now.
Is it snake oil ? Only the user who doesn't think it works can answer that for now.
With scientific proof of working it will be a good investment.
With scientific proof saying they don't work, then it's just another bottle of snake oil.
It's up to the manufacturer to have some independent testing to answer the above questions.
In the meantime.........the O.P. feels good about them. Not hurting anybody, no harm, no foul

[jerichorick]

Originally Posted by Ret.LEO

Hey, I guess if nothing else the money spent by the OP in a attempt to help handling feels that it works for him. If it get scientifically proven/disproven for Coaches is still in the future apparently. In the meantime it's up to individuals to decide if they think they work or don't work for them and their particular application.
Does it actually work? Who know's except the user, for now.
Is it snake oil ? Only the user who doesn't think it works can answer that for now.
With scientific proof of working it will be a good investment.
With scientific proof saying they don't work, then it's just another bottle of snake oil.
It's up to the manufacturer to have some independent testing to answer the above questions.
In the meantime.........the O.P. feels good about them. Not hurting anybody, no harm, no foul

Thank you for your supportive words. I have never see a post get such negative replies as this one started receiving.

Because of the limited number of tabs, I only placed them, as suggested by the manufacture, in front of the front wheels. I have sent an email to the manufacturer for more supportive "scientific" evidence. Where I am located, my internet speed is slower than dial-up so I can't do research to the depth I did before I bought these V-generators.

The first negative comment seems to have generated a feeding frenzy. Thank you, once again, for your supportive comments posted in the appropriate light of the forum.
Rick

[dexcorm]

Hello Rick,


Proof of actual results will always vary according to driver habits, vehicle maintenance levels, road and weather conditions. Any attempt to save fuel, reduce road spray and increase stability is worth the effort. When the value exceeds investment, then the driver is always the winner.


With the many gadgets out that that "claim" to give value, give in-fact no value, that is the problem. People are skeptical to try new things. Let us know what your continued results/benefits are? Happy motoring....

[Ret.LEO]

Originally Posted by jerichorick

Thank you for your supportive words. I have never see a post get such negative replies as this one started receiving.

Because of the limited number of tabs, I only placed them, as suggested by the manufacture, in front of the front wheels. I have sent an email to the manufacturer for more supportive "scientific" evidence. Where I am located, my internet speed is slower than dial-up so I can't do research to the depth I did before I bought these V-generators.

The first negative comment seems to have generated a feeding frenzy. Thank you, once again, for your supportive comments posted in the appropriate light of the forum.
Rick

Hi Rick,
I have been on what felt like the receiving end before also. Not a fun place to be. If you think it got rough here.............don't post the same on IRV.....brutal!!!!

It is easy to feel like others have stepped on your toes with opposing views. Usually it's just the way things get worded.

I will still say without a doubt this is the friendliest site and forums on the net
Hang in there Remember that proverbial grain of salt with how others might word things. I'm sure no harm is ever intended

I'm a little bit away from adding a new Class C, been checking dealers vids and there have been a couple dealers mention the little generators and they say they have heard positive reports from those that have them.
I will add a set when I get our new Class C........can't hurt nothing, I've spent more than that on things that didn't work.
If nothing else...........they look cool and will start some interesting conversations.
Hang in there
Rick (also)

[jerichorick]

Originally Posted by dexcorm

Hello Rick,


Proof of actual results will always vary according to driver habits, vehicle maintenance levels, road and weather conditions. Any attempt to save fuel, reduce road spray and increase stability is worth the effort. When the value exceeds investment, then the driver is always the winner.


With the many gadgets out that that "claim" to give value, give in-fact no value, that is the problem. People are skeptical to try new things. Let us know what your continued results/benefits are? Happy motoring....

Thank you for these encouraging words. Experience is always a better teacher than any book learning. Been there. Done that a lifetime ago.


I did go into this with a tad bit of skepticism. I am not one that gets the results I expect. just the opposite. I need to prove your proof for my self.



The V-generators have lived up to most of their claims. There is enough evidence of how drag will effect any vehicle and has been published for as long as I can remember. My hobby was airplanes as a kid and I watched many movies about wind tunnel tests and the effect of drag on the fuselage and air foils of any aircraft. In later years I saw many studies on vehicle drag and the many things that were tried to combat it for better fuel economy. Many of the solutions found were not adopted in the real world because of cost or aesthetics. You must admit, the V-generators do nothing for the eye catching lines of my aerodynamic inept box on wheels.


What I was hoping for, and I believe I have achieved, is what I observed in my first posting. At the end of a long day of driving, if I feel less tired because of the effect of the V-spoilers on the handling of my coach, it is a good day.


Happy trails.
Rick