drafting semi's

[comptiger5000]

The person doing the drafting sees the most benefit, but the person being drafted definitely sees a small gain.

[cyborg054]

Okay - back in the day we used to draft all the time, and not just one vehicle behind a semi - up to three. Eventually the driver would get pissed off, what we saved in fuel and power he had to expend, and start getting nasty. What a drafter gains the draftee loses.

If you have seen Fast and Furious AND especially Tokyo Drift you will have an idea of the skill set needed to do it safely. Unless your reflexes are super good and your vehicle is in tiptop shape with super good brakes and suspension you could be dead, or worse a vegetable.

I have seen light vehicles hit the turbulence and get "thrown" off of the road. Think of water skiing and crossing the wake. The better the streamlining on a semi combo, the worse the turbulence wall is.

Good Luck and safe driving

[euromodder]

Originally Posted by sheepdog 44

Or is it best to draft behind a car?

In order to gain something from drafting a regular car, you need to be very close, almost on his rear bumper.
It can even be counter-productive at longer distances.
There's a thread about it somewhere on ecomodder, as it has been researched.

[drmiller100]

nascar baby.

both cars see a benefit. the front car is pushing the air in front, the back car is dragging the aero hole behind.

both cars are doing some work to benefit both.

[cyborg054]

Actually we worked with some Semi and Greyhound drivers and compared fuel logs for the Manning Park BC run. The gain in mileage for the person drafting was less than the extra cost of fuel for the person being drafted. Sorry I don't have the figures anymore but this was done in the late '60s.

In other words if you really are looking to be GREEN - don't draft!

One way we used to do it - in the 60s again - was to hitch a ride with a friendly car carrier who was dead heading. for a few cars didn't affect his mileage and we got to have a good nap.

[thx138]

I draft whenever I can. I drive a Ford Ranger (not very areo so it benefits more) and as you creep up behind a semi, I find that the my truck will start to get buffeted around even over 150 feet back. Once I creep up through that the scangauge will show improvements. 10-20% is easy and still remain a safe stopping distance behind. Yes I can outstop the semi, so I am not worried about that, but semi's have habits about kicking up road debris, which you do not have time to dodge (I have a nasty windshield to show for it - one incident in many years of drafting). Works best behind a fast moving truck with two 'box' trailers and without a crosswind. I can stay far enough back to see a side mirror on the truck ahead and still benefit. 150 feet or so.

[Vekke]

This happened today in Finland motorway. Guys knew there would be crash ahead from the radio and just kept that high speed in no visibility. See the results. Most drivers drive at two second safe distance on the motorway. Over 200 crashes in that weather all over Finland from the same reason.

The drivers visibility is about two second on the video. I mean visibility not the distance to next car. That is even worse situation because you cannot even see on the sides!

http://www.youtube.com/watch?v=gVTUH...1&feature=plcp

Luckily no one died!.

[mattbatson]

Originally Posted by Vekke

This happened today in Finland motorway. Guys new there would be crash ahead from the radio and just kept that high speed in no visibility. See the results. Most drivers drive at two second safe distance on the motorway. Over 200 crashes in that weather all over Finland from the same reason.

The drivers visibility is about two second on the video. I mean visibility not the distance to next car. That is even worse situation because you cannot even see on the sides!

Luckily no one died!.

I assume you posted that video to show that drafting is dangerous?

However, under certain conditions, it probably isnt safe to venture onto the highway at all.

[Vekke]

Just to prove you should match your speed to weather conditions. It does not really matter are you driving in a bad weather or too close to someone, if you cannot see enough the results are the same all over the world.

- Just to be clear I drive fast and usually if I draft on winter I still use the 3 second rule. When you try to stop from 100 km/h like these guys were driving it will take about 350-450 meters depending do you have studded or studdless winter tires, because road was on ice. 2 seconds is nowhere near a safe distance. They braked about 3-4 second and driver was able to steer to snow bank. If you sink about one car length to snow which is half a meter deep your speed has been about 50-60 km/h. That I know from my own experience.

[botsapper]

Car drafting a semi or was it the other way around?

http://www.youtube.com/watch?v=wiLj3MsLCrw