The problem teb1272 is that when you say that the science of vortex generators is well established, you infer a correlation between known science of vortex generators and the dubious unproven claims of the Airtabs. This is a ploy often used by the marketing people to 'infer' a claim because of loose similarities between two objects. The scientific testing of the products rarely stands up to the claims.
There is another issue regarding the objectiveness of purchasers of a product. Because admitting that something they purchased was inferior, or did not work, the human nature is to consciously or sub-conscioulsy disguise the fact to avoid looking stupid for having purchased something that did not work. Thus the onjective opinions of owners needs to be factored.
So, it's little surprise that those who have some understanding of the real science and the claims for the product, do not agree with those who have purchased them and who now claim that they are so wonderful.
RV Park Finder
Fulltimers
2002 Beaver Santiam 38DST + Banks + 99 Jeep GC
DH,DW,Jake and Indie
While I understand the debate over AirTabs, let me offer four facts and four claims.
Fact One: AirTabs are a one inch vortex generator. My vertical tabs are 23" of stabilization.
Fact Two: AirTabs are a one inch vortex generator. My left side tabs are 26" of stabilization.
Fact Three: AirTabs are a one inch vortex generator. My right side tabs are 26" of stabilization.
Fact Four: The AirTabs cost $200. The son of my body repair friend painted them with three different colors of factory paint and clear coat for $65. My total cost installed for AirTabs is $265.
Claim One: I have tested them in a 50 knot quartering crosswind. The airflow over the tabs was 75 to 80 mph, based upon vector analysis. Since I have substantial flying time at 65 mph in a Cessna 150, I know that aerodynamic forces are effective even at lower speeds. At 75 mph total airflow, 75" of AirTabs IMHO are a significant stabilizing force. To the pilots on the list, I might note that crosswind limitations for a Cessna 150 or an F-106 were determined far more by actual flight experience than by wind tunnel data. Actual experience using AirTabs by motorhomers is also a valid source of data.
Claim Two: At least eight to ten RV.net members claim a fuel mileage improvement of 1% to 5%. The AirTab.com web site does include some wind tunnel tests to show the effectiveness of the vortex concept. While the data is wide ranging, there clearly is evidence that a number of members have a measurable improvement in fuel mileage. This is consistent with the claim that there is reduced drag. Those who note that the rear of the coach also has less dirt are affirming the same principle that the vortex generators reduce the flat plate turbulence, and therefore reduce aerodynamic drag.
Claim Three: Most trucks do not yet have AirTabs. But the fuel crisis first occured in 1974! It took the trucking industry three decades to implement widespread use of aerodynamic cabs on semi trucks! The fact that truck companies move slowly proves nothing.
Claim Four: The primary benefit of AirTabs is increased stability, and the small increase in fuel mileage is a bonus. Are 75" of AirTab vortices that increase stability worth $265 on a coach for which I wrote a check for $175,000? Is this cost effective? Friends, for me the AirTabs are a no-brainer.
Crespro
* This post was
edited 07/03/08 11:55pm by Crespro *
Crespro wrote: While I understand the debate over AirTabs, let me offer four facts and four claims.
There are only claims and no facts in your dissertation.
Empirical evidence in the form of unbiased testing is the only thing that can be considered a fact. Everything else is conjecture.
As a side note, your costs to paint these things are way under market. It costs $75 for a single quart of paint for my coach and I would need a minimum of 5 colors, plus clear coat, so that's 6 X $75 = 450 just for paint. Now I would have to find someone who can do the job, how many paint guys are going to do that for free? None I know. Ok, I sucker somebody into doing it for $150. Add the $200 for the plastic parts and the total will still take 7 years to recover plus they are unattractive to boot and will reduce the resale value.
I'll pass, thank you.
Again, I repeat myself once more. If you really want to save fuel, just slow down a bit. That will easily save your 5-10% and also make your coach more stable to boot. No installation necessary!
2007 Mountain Aire 4528
2006 CRV SE
Based in Memphis area
Crespro wrote: .........
Claim Two: At least eight to ten RV.net members claim a fuel mileage improvement of 1% to 5%. The AirTab.com web site does include some wind tunnel tests to show the effectiveness of the vortex concept. While the data is wide ranging, there clearly is evidence that a number of members have a measurable improvement in fuel mileage. This is consistent with the claim that there is reduced drag. Those who note that the rear of the coach also has less dirt are affirming the same principle that the vortex generators reduce the flat plate turbulence, and therefore reduce aerodynamic drag.
Claim Three: Most trucks do not yet have AirTabs. But the fuel crisis first occured in 1974! It took the trucking industry three decades to implement widespread use of aerodynamic cabs on semi trucks! The fact that truck companies move slowly proves nothing.
Claim Four: The primary benefit of AirTabs is increased stability, and the small increase in fuel mileage is a bonus. Are 75" of AirTab vortices that increase stability worth $265 on a coach for which I wrote a check for $175,000? Is this cost effective? Friends, for me the AirTabs are a no-brainer.
Crespro
Claim #2.. An ACTUAL savings of 1% to 5% for ME equates to saving almost 5 cents to 25 cents per gallon. Guess what? At the cost of purchase; painting; installation ( lets NOT hope removing) I'm not worried about the fuel savings at that rate!
Claim #3.. Then if most / many trucking companys are so slow in utilizing any sort of fuel savings devices...where does the comment by some that they are "wide spred" in the industry come from ( BOGUS..thats where)
Claim #4.. If the primary reason for Air Tabs is stability..then for me they strike out again because there aint a single thing wrong with the stability of my rig! I see that some that claim "great improvement" in that area are running short coaches ( either gasser or DP) and there is a multitude of items that can improve stability ina short coach..I know because I once owned a 28 foot P30 and ya canet get much worse than a box stock short P30 for handeling!!
Its a NO brainer for me also...a definate NO!
2000 Country Coach Allure; Cummins ISC 330 HP; 71/2 - 8 MPG regardless
2002 Jeep Liberty
Crespro wrote: To the pilots on the list, I might note that crosswind limitations for a Cessna 150 or an F-106 were determined far more by actual flight experience than by wind tunnel data. Actual experience using AirTabs by motorhomers is also a valid source of data.
I have to comment on this line. Being a pilot, I find it difficult to compare professional test pilots in well measured conditions to the average joe RV driver in absolutely unknown conditions. How is joe RV driver going to have any idea what the crosswind component is? Do you have a meteorological truck following you around during your test conditions? I guess back of the napkin math vs. multi-million dollar test equipment is about equal, or it is when using conjecture as your yardstick.
I don't want to be difficult here, but unless you have proven, verifiable test data, it's not anything but your guess.
If a hundred sheep jump over an invisible fence, does it mean there is in fact a fence or does it mean the sheep just think it's there?
Gsmitty77 wrote: Just finished our 2008 trip. I've (added) to my first impressions.
-Trucks passing us - Are not noticeably felt until the truck cabs bow wave passes the front of the our RV. I can feel the difference and comfort levels are higher as trucks go by. Thumbs up! (Still feel the improvement, quite happy)
-Cross winds - We hit two times of cross winds of 25 knot plus for stretches up to 45 minutes. The first time the winds were steady coming at us from the side at say 2:00 o'clock (front being 12:00). The second time the winds would change direction and seem to never settle down for more then two minutes at a time. VERY PLEASED with the improvement in handling. The steady side winds were no problem at all. The changing direction winds would only require the resetting of the RV away from the new side that the wind was coming. Very minor adjustments were required to the steering. Much more relaxing. Two Thumbs up!! (Much stronger winds coming down from Flagstaff to Prescott. Very sporadic, with 35-40 gusts reported on the local area news (Fire reports kept close eye on the winds and directions). This is the single biggest improvement that the Airtabs have contributed. Need to adjust some as wind gust direction change, but much less of impact with the Airtabs installed.)
-Fuel MPG - Don't know yet. Don't care. And not sure if I could give a fair assessment as we have added a bike rack with two bikes to our toad. This may have been enough to offset the difference in reduced drag from the Airtabs, plus say 100lbs for bikes, hitch and rack that are all new this trip. (I still don't care about MPG. Will report my numbers from 2007 to 2008. Different parts of the country so sure not intended to be a solid comparison. 2007 trip was 3327 miles, and 7.35 MPG. 2008 trip was 2498 miles and 7.95 MPG. Both adjusted for generator usage. Both run at the same speeds. But, 2008 included the Rockies with many, many miles in second gear at 4300 rpm. I'd say the 2008 was 25% more difficult on the rig then 2007. Also due to the heat in Monument Valley and Arizona in general, many hours required to run both roof and engine AC to keep inside temperatures below 90. 2007 trip was in Oct/Nov to Yellowstone and Teton's, very little AC usage on the 2007 trip. )
The Airtabs are doing what I wanted them to do, make driving more relaxing and stable with trucks and cross winds. They provide a margin of improvement well worth the cost. (I'm going to give my opinion that the MPG did improve by over .5 MPG, probably closer to .75 MPG)
Best to all,
Smitty
There have been three threads on AirTabs the past two months. They usually start with a user who is pleased with the AirTabs and then a few opponents of AirTabs who have no interest in using the product explain why the happy user should change his or her mind about AirTabs.
Bottom line -- AirTabs produce 1% to 5% better mileage and an increase in stability at modest cost.
Folks, this is America where we all have freedom to choose to buy Airtabs or not. Whether you use AirTabs or not -- may all of you on this July 4 continue to seek life, liberty and the pursuit of happiness.
There have been three threads on AirTabs the past two months. They usually start with a user who is pleased with the AirTabs and then a few opponents of AirTabs who have no interest in using the product explain why the happy user should change his or her mind about AirTabs.
Bottom line -- AirTabs produce 1% to 5% better mileage and an increase in stability at modest cost.
Folks, this is America where we all have freedom to choose to buy Airtabs or not. Whether you use AirTabs or not -- may all of you on this July 4 continue to seek life, liberty and the pursuit of happiness.
SAYING "it" dont make it FACT! 1% or even 5% ( thats percent now..not actual MPG increase) doesnt mean jack doodlie to many of us because we can DO BETTER if we slowed down!....THATS A FACT!!!
As far as "stability" goes...many of us ( with decent handeling coaches to begin with) dont need MORE stability and the only data that states "increase in stability" is that YOU SAY IT DOES!!!
"Because a person paints their home with Shermin Williams paint...then that proves it would be good to paint their motorHOME with also"!!...
Crespro wrote: Bottom line -- AirTabs produce 1% to 5% better mileage and an increase in stability at modest cost.
I'm sorry to have to correct you again, but the bottom line is that there is no proof one way or the other that this product is effective.
There is no difference between the "proof" provided and that famous commercial on the Weather Channel (...apply directly to the...) which doesn't even claim to do anything but people buy it and swear by the product.
I'm glad you are a satisfied customer of this product. It's great that it makes you feel good about your purchase. I'm very happy for you. Please though, just keep your opinions about the efficacy of it to simple claims unless you have actual empirical proof.
Thank you and be glad we live in such a great country where people can have open debate about any topic.
Edit:
I want to add that I have never said once that these devices don't work or that the people who claim they do are liars, cheats, thieves, etc. I have only stated that the claims people have made about these things are nothing but conjecture and opinion. It is not good science to base a decision to buy on hearsay, conjecture or personal claims, period. I believe in the scientific method of proof and any other way of demonstrating efficacy is not valid and irrelevant.
* This post was
edited 07/04/08 07:30pm by fourfurz *
Crespro wrote: Bottom line -- AirTabs produce 1% to 5% better mileage and an increase in stability at modest cost.
I'm sorry to have to correct you again, but the bottom line is that there is no proof one way or the other that this product is effective.
There is no difference between the "proof" provided and that famous commercial on the Weather Channel (...apply directly to the...) which doesn't even claim to do anything but people buy it and swear by the product.
I'm glad you are a satisfied customer of this product. It's great that it makes you feel good about your purchase. I'm very happy for you. Please though, just keep your opinions about the efficacy of it to simple claims unless you have actual empirical proof.
Thank you and be glad we live in such a great country where people can have open debate about any topic.
Edit:
I want to add that I have never said once that these devices don't work or that the people who claim they do are liars, cheats, thieves, etc. I have only stated that the claims people have made about these things are nothing but conjecture and opinion. It is not good science to base a decision to buy on hearsay, conjecture or personal claims, period. I believe in the scientific method of proof and any other way of demonstrating efficacy is not valid and irrelevant.
I agree, you never said that, but IMHO you sure inferred it more than once, including this post and edit..
Bob & Betsy - USN Ret'd '78 & FL LEO Ret'd '03 FMCA #F203528 '05 HR Endeavor, 40PRQ w/400 Cummins - With -'05 GMC Sierra LT, CC Z-71, the pusher '07 Arctic Cat 500A & Wilderness Kayak, riding in the pusher - Our Current Location
I achieved a substantial savings by slowing down from about 70 mph, to 55 mph last week on our trip down to Florida.
My MH handles fine on the road.
I've yet to see ONE semi with these things on them.
If you like them, more power to you. It's your rig. Only you should care how it looks.
2004 Coachmen Aurora on a FORD V-10 Chassis
2004 Jeep Liberty Don't take your organs to Heaven. Heaven knows we need them here! Dave has a dog named Muffy and Mike owns a Cockapoo!
