Drafting

[dmckinstry]

I dunno, I think you need to draft behind a bus, not a Roadster! You need that huge brick making a path through the air.

It should make some difference, but I don't know how much or if 30 ft is close enough. After all, bicycler racing teams draft each other and they're usually traveling much slower than 65 mph. Of course, they're also much much closer than 30 ft.

 

[Doug_G]

It should make some difference, but I don't know how much or if 30 ft is close enough. After all, bicycler racing teams draft each other and they're usually traveling much slower than 65 mph. Of course, they're also much much closer than 30 ft.

Yeah, the problem is I think you'd have to get uncomfortably close. On my last road trip I tried drafting behind a bus, to see if I could get a "free" 5 kph. I found I had to drive a little closer than was entirely comfortable. Mind you, my stopping distance is a lot better, so it probably wasn't as bad as it looked. But I got the distinct impression I was annoying the bus driver a little, once he realized I was back there.

 

[samcarney]

But I got the distinct impression I was annoying the bus driver a little, once he realized I was back there.

I feel the same way, so on a trip with my cousin, a semi-driver for the past 30 years, I asked if tailgaters annoyed him. His reply was, "I have 55 feet of trailer behind me, it doesn't bother me at all"

 

[smorgasbord]

From Mythbusters on Wikipedia:

Controlled road test: fuel consumption decrease from baseline at 55 mph (89 km/h):

100 ft (30 m) 11%
50 ft(15 m) 20%
20 ft (6 m) 27%
10 ft (3 m) 39%
2 ft (1 m) 28%

The Build Team discovered that the closer the car was to the big rig, the less drag is produced, thus the more fuel saved. At just 10 feet (3.0 m), the car managed to increase its fuel efficiency by 40%. Drafting at 2 feet (0.61 m) was slightly lower than the ten-foot distance, mainly because Grant had to keep working the car pedal to maintain distance from the truck. However, that did not dispute the fact that drafting actually can increase a car's fuel efficiency if a constant velocity is kept. However, the Build Team has warned that drafting is incredibly dangerous because the truck driver may not be able to see cars that are that close, and the driver of the car may not be able to react in time if the truck were to make a sudden stop (they noted that at two feet, a person has less time to act than it takes to blink).

So, even at the relatively safe 50ft and 100ft distances, there's noticeable benefit. For me, though, I'd rather sit a bit longer at the charger than drive a few hours right behind a truck. If you really need the range, slowing down is another option - both safer and more fun.

 

[bonnie]

From Mythbusters on Wikipedia:



So, even at the relatively safe 50ft and 100ft distances, there's noticeable benefit. For me, though, I'd rather sit a bit longer at the charger than drive a few hours right behind a truck. If you really need the range, slowing down is another option - both safer and more fun.

Agreed. On my last roadtrip, I inched up behind a truck, just to see if I could feel a difference. Oh yeah, I did. All of a sudden the kwh dropped, noticeably so. But I was extremely uncomfortable at that close distance, so experiment ended. It's good to know, but not something I see myself using on a regular basis. I like taking risks, but only the kind I have some control over - this one, I'm totally at the mercy of someone I don't know.

I'll take the charger and a good book.

 

[Doug_G]

I feel the same way, so on a trip with my cousin, a semi-driver for the past 30 years, I asked if tailgaters annoyed him. His reply was, "I have 55 feet of trailer behind me, it doesn't bother me at all"

I think the bus driver felt differently. He kept watching in his side mirror to see if I pulled back in behind him after he passed a truck. I wasn't right on his rear but of course he had no way of knowing that.

 

[vfx]

I dunno, I think you need to draft behind a bus, not a Roadster! You need that huge brick making a path through the air.

Not at all. Same sized vehicles like bicycles, NASCARs, and semis do it. Four Roadsters close enough together could actually benefit from a draft quite well..

After having been on many Roadster Rallys (drives) I find that everyone has a comfort factor how close they like to follow. For the best photography it's best if everyone scrunches together and getting cars to drive close together is impossible without professional drivers.

 

[zack]

Well, you can always shoot with a long lens nearly straight on and compress them all. 8^D

 

[vfx]

Well, you can always shoot with a long lens nearly straight on and compress them all. 8^D

Watch that Speed and motion video of the Tesla LA 2011 Rally Ian posted. Three cameras. All with cars spread out. To compress you need to stack the cars on top of each other. A lot harder and less effective when they are moving.

 

[TEG]

I dunno, I think you need to draft behind a bus, not a Roadster! You need that huge brick making a path through the air.

Bigger / wide is better. When I got behind this (mobile home/wide load) it felt like I started to roll down hill:

 

[TEG]

One problem with drafting close is that the truck in front may think you want to pass, and tries to get out of your way.
Hard to let them know that you want to stay behind them.

 

[zack]

Watch that Speed and motion video of the Tesla LA 2011 Rally Ian posted. Three cameras. All with cars spread out. To compress you need to stack the cars on top of each other. A lot harder and less effective when they are moving.

Well video's another thing. I was thinking still.

 

[vfx]

Well video's another thing. I was thinking still.

Curvy roads that Rallys prefer also make stacking difficult.

 

[Doug_G]

Not at all. Same sized vehicles like bicycles, NASCARs, and semis do it. Four Roadsters close enough together could actually benefit from a draft quite well..

Yes, but my point was if you get a big brick of a bus you don't have to get uncomfortably close to it. I think you'd have to be right on the tail of a Roadster.

 

[vfx]

I think you'd have to be right on the tail of a Roadster.

That would be fun!

 

[smorgasbord]

One problem with drafting close is that the truck in front may think you want to pass, and tries to get out of your way.
Hard to let them know that you want to stay behind them.

In some vehicles, seeing small cars directly behind you can be hard. My wife claims that in her X5 I'm so low that if I'm close enough, she's seeing directly over me. At one point she slowed down because she thought I was stuck on the side of the road a ways back - because she didn't see me in her mirrors.

 

[TEG]

I once lived on a cul-de-sac where people frequently turned around in private driveways when they realized the road didn't go through.
I had someone back into my driveway and smash the front of my X 1/9 many years ago.
They started to drive away but I heard the noise and ran out. The person in the SUV said "I can't be responsible because your car was too small to see."
(And it was in my driveway no less.)

 

[Doug_G]

They started to drive away but I heard the noise and ran out. The person in the SUV said "I can't be responsible because your car was too small to see."

"Tell it to the judge, buddy."

 

[Lloyd]

They had an episode on Mythbusters about drafting, and if i remember correctly you had to be less than 50 feet for drafting to have a meaningful effect, which is really a dangerous distance to be following!

 

[smorgasbord]

They had an episode on Mythbusters about drafting...

Look back about 15 posts in this thread.