foo monkey. It is niether legal nor safe. Unfortunately neither is going over the speed limit weaving in and out of traffic. But its rare you hear anyone complain about that or even make the realization that what they are doing is unsafe. At least people that do drafting and fas are aware of their surroundings and make an effort to be safe while doing it. Thats more than I can say for some of the high speed drivers I see on the road.

 

Hi Wayne,

An interesting approach. In 1972, I had a '66 VW MicroBus an in a trip to the west coast over the high plains, I had to draft to maintain safe speeds on the Interstates. I could cruise at 65-70 MPH if I stayed 'tucked in' and 'between the buffet walls'. If I got into buffet, I knew I was getting too far and could 'loose the bubble.'

What I remember was three distinct states:

1. Smooth - you are completely in the draft bubble but generally within a very short distance, 15-20 ft. of the truck. You have to back off of the throttle our risk running into the truck. You have to steer to stay in the bubble.
2. Buffet zone - about the length of my van where it would rock but auto-steer behind the truck. A rougher ride, there was more space but this is the limit. But you need to put on the accellerator and get back into the smooth zone.
3. Too far - when even maximum accellerator could no long keep up.

In your technique, are you pulling into the 'smooth' zone and coasting?

This weekend, I commuted 650 mi. from Huntsville AL to Kansas City KS and back. I had Murphy head winds the whole way with my Prius. Not wanting to suffer and traffic-stop delays, I would pull into the 'buffet zone' and use my fingers to monitor the auto-steer. The Prius cruise control allowed me to adjust in 1 MPH increments up and down. This really helped keep the MPG 'less bad' but I wasn't trying for maximum MPG.

I noticed the bus seems to do a better job of keeping speed going up hills. The tandom-trailer seemed to do OK too about keeping constant speeds. But I realized that having an accurate distance and relative speed instrument would have made this a lot easier.

Have you tried using any electronic instrumentation to monitor either distance or speed to the vehicles ahead?

Have you tried 'tuff' testing to see what the turbulence and laminar flow areas look like around your vehicle?

With my Prius, I'm loath to turn the ICE off due to reports that above 42 MPH, it is needed to avoid overspeeding MG1. But the ICE will 'idle' down very nicely so I don't feel the needed to perform the 'forbidden experiment.'

Working just in the buffet, auto-steer zone gave me about a 5+ MPG advantage and off-loaded some of the steering tasks. The ride was a less smooth but I didn't feel I was risk of being stopped for traveling too close. Basicly, I was trying to mitigate the 43 (F) temperature and direct headwind.

Bob Wilson