Wikipedia's definition:-
Drafting or slipstreaming is a technique where two vehicles or objects align in a close group reducing the overall effect of drag due to exploiting the lead object's slipstream. Especially when high speeds are involved, drafting can significantly reduce the echelon's average energy expenditure required to maintain a certain speed and can also slightly reduce the energy expenditure of the lead vehicle or object.
What was interesting was I found Mythbuster had an episode trying to confirm or debunk whether drafting could actually save fuel. Well pardon me for not having Astro at home. Not everyone is working hard trying to make Ananda Krishnan rich =P.
WARNING
The following knowledge is dangerous use wisely !!
They had a small-scale test in a wind tunnel that yielded the following results.
- 7 car lengths: 21% drag reduction
- 10ft: 60%
- 6ft: 80%
- 2ft: 93%
A full-scale test with a Cascadia truck
- 55mph control: 32mpg
- 100ft: 35.5mpg, 11% improvement
- 50ft: 38.5mpg, 20%
- 20ft: 40.5mpg, 27%
- 10ft: 44.5mpg, 39%
- 2ft: 41mpg, 29%
Truth is there is no way we can validate these data ourselves unless we know some truckers or bus owners that are willing to spare some idle time trying to prove this. Looking at the data if we were to do this on our roads, I would probably follow a bus or a truck at least 3 cars away and if it can maintain a constant speed. Driving behind these things scare me when I can't see what is in front. Then there are also dangers of cross wind.
Looking at the way people drive on our roads we will have a problem drafting behind a big vehicle due to the following vehicle.
- Existence of people that drive too slowly on the highways.
- Truck or bus drivers maintain erratic speed
- With so much power on the X why hold back your foot =P
Leave a comment if you have a personal experience on drafting.