Learning the driving characteristics of our coaches in various conditions takes time and patience. In addition to learning to judge lane position and the distances required to turn and back up, there are day-to-day handling challenges. For example, occasionally, crosswinds and surges of air can be caused by passing big-rigs and busses. Although Monaco Coach Corporation produces some of the best handling and riding coaches in the industry and the time-tested and proven ability of the Roadmaster chassis has shown it to be second to none, a motorhome is not a sports car, especially when it comes to aerodynamics.

When you push masses of air with your coach, you tend to create equally large vacuums behind the coach (as evidenced by the collection of dirt on the rear cap of the coach). It is this vacuum that causes the less desirable handling characteristics of any vehicle and becomes very noticeable in large vehicles such as big-rigs and coaches. For this reason, some “seesaw” motion becomes evident when you are passed by a big-rig or when side wind gusts are present. This is because the air pushed by the big-rig or the gusts blowing from the attacking side winds create an uneven disturbance in the vacuum pocket directly behind the coach.

Vortex generators are not new technology. Used for decades in jet aircraft design, they are used to control airflow. You may have seen them on the wing of a jet airliner; they often look like small raised V’s. Airtabs are an adaptation of this concept, and they have been sized and shaped specifically for road vehicles. The design creates a number of small vortices and thereby stops the formation of one large one. This controls the airflow at the back of the vehicle reducing the effect of the large vertical eddy while improving airflow to the back of the vehicle. Placing these small vortex generators (Airtabs) along the top and sides of the coach negates the effect of air pushed by large passing vehicles (busses and semis) or cross winds, and provides a more stable air pocket for the coach to travel within. Other benefits cited by the manufacturer include a reduction of dirt accumulation on the rear cap of the coach (including the back-up camera) and the possibility of increased fuel economy.

Installation
Installation is simple; most any backyard mechanic can do the job in a couple of hours. The Airtabs come with a spacing template and comprehensive instructions. They are available in natural white and clear colors, and can adhere to most flat, nonporous material. The adhesive backing should not cause damage to painted surfaces. Airtabs are made of UV Stabilized Poly Styrene, which is a paintable surface. We elected to have ours painted to match the coach. Once we determined the layout of our installation, we delivered our Airtabs to our local paint shop who color matched our coach’s paint scheme and painted the Airtabs to match, including a clear coat.

Following the instructions, we prepared the surface and applied the Airtabs. No special tools were required. For trailers with corrugated siding, your Airtab distributor has optional methods to accommodate the installation.

On The Road
A before and after test of the Airtab is difficult to quantify. There are no testing standards available; however, that being said, we found that our coach no longer displayed the seesaw effect due to oncoming big rigs. And we have noticed a marked improvement in our confidence for driving into traffic laden with on-coming big-rigs. Also, while evidence of moderate to heavy crosswinds has been displayed (trees and bushes bending on the side of the road) we have not noticed their effect on our steering. Over the 600 to 700 miles we have tested Airtabs we have not noticed the usual buildup of dirt on the rear cap or backup camera lens, including the usual road grime buildup during travel in the rain.

As for fuel economy improvements, we have not been able to establish any measurable improvement. Was the installation worth the cost? You be the judge. If increased driving confidence and the absence of dirt build-up are desirable, then so are Airtabs.