Drafting a semi
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Joined: Mar 2011
Posts: 11,950
Likes: 5,076
Hi David,
I recall a study from years ago (can't find it online) that measured braking reaction time -- determined by the time that the event occurs until the brake pedal is depressed. It was .44 seconds. That's a best case scenario where the driver knows that an event is coming and is prepared for it.
Other studies suggest that true reaction time is 1 to 3 seconds to see an event, recognize it as a danger, and react to it when the driver is in a normal, relaxed posture.
I recall a study from years ago (can't find it online) that measured braking reaction time -- determined by the time that the event occurs until the brake pedal is depressed. It was .44 seconds. That's a best case scenario where the driver knows that an event is coming and is prepared for it.
Other studies suggest that true reaction time is 1 to 3 seconds to see an event, recognize it as a danger, and react to it when the driver is in a normal, relaxed posture.
Lead Driver
Joined: Nov 2007
Posts: 5,139
Likes: 209
Hi David,
I recall a study from years ago (can't find it online) that measured braking reaction time -- determined by the time that the event occurs until the brake pedal is depressed. It was .44 seconds. That's a best case scenario where the driver knows that an event is coming and is prepared for it.
Other studies suggest that true reaction time is 1 to 3 seconds to see an event, recognize it as a danger, and react to it when the driver is in a normal, relaxed posture.
I recall a study from years ago (can't find it online) that measured braking reaction time -- determined by the time that the event occurs until the brake pedal is depressed. It was .44 seconds. That's a best case scenario where the driver knows that an event is coming and is prepared for it.
Other studies suggest that true reaction time is 1 to 3 seconds to see an event, recognize it as a danger, and react to it when the driver is in a normal, relaxed posture.
Tuned
Joined: Jan 2009
Posts: 269
Likes: 3
From: Newnan, GA
Exactly....so driving is risky, always......
60 MPH is 88 feet per second.
1 car length is what? Let's say 10 feet.
Your time to react to anything that happens on or with that truck is .11 seconds.
Average human reaction time is .15 to .30 seconds.
So, anything that comes off of that truck, or it hits and throws up, or whatever, is going to hit you before you can see it and react.
1 car length is what? Let's say 10 feet.
Your time to react to anything that happens on or with that truck is .11 seconds.
Average human reaction time is .15 to .30 seconds.
So, anything that comes off of that truck, or it hits and throws up, or whatever, is going to hit you before you can see it and react.
Did you see the video clip up above of the 2x4 in the windshield? They were not following close and got nailed. Driving is chancy at best in any situation. Yes the more room and more visibility one has, the more time to react.
Did you know that 2 airliners on a head-on collision course at cruise speeds CAN NOT AVOID THE COLLISION when relying on sight alone? The closure rate is too high and the pilots reaction time and the aircraft reaction time is too slow to change the course in time to avoid the collision. WE STILL FLY.......
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From: Central Coast of CA
Stewart
Posting Guru
Joined: Oct 2003
Posts: 1,198
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From: Tulsa, OK
Can we get back to the topic?
I think, like Excursionator1, that the important message here is that there is plenty to be gained if we can reduce aero drag on these 'bricks' call Excursions. At 66 mph, a 2005 6.0 will get about 18 mpg in clear air. So..a serious reduction in drag will net at least a 20% - 25% increase in fuel economy.
Drafting may not be the wisest way to do this, but we can at least take heart that we could gain MPG if we reduce drag. One way to do this is to reduce frontal area (e.g. lower the truck or use smaller tires). Another way to reduce drag is to use a bigger air dam on the front bumper. This would reduce the amount of air tumbling around all the under body hardware. Has anyone tried this yet? If you look at a 2008 - 2010 or a 2011 SuperDuty, you can see that Ford is doing this on the newer trucks.
I think, like Excursionator1, that the important message here is that there is plenty to be gained if we can reduce aero drag on these 'bricks' call Excursions. At 66 mph, a 2005 6.0 will get about 18 mpg in clear air. So..a serious reduction in drag will net at least a 20% - 25% increase in fuel economy.
Drafting may not be the wisest way to do this, but we can at least take heart that we could gain MPG if we reduce drag. One way to do this is to reduce frontal area (e.g. lower the truck or use smaller tires). Another way to reduce drag is to use a bigger air dam on the front bumper. This would reduce the amount of air tumbling around all the under body hardware. Has anyone tried this yet? If you look at a 2008 - 2010 or a 2011 SuperDuty, you can see that Ford is doing this on the newer trucks.
Post Fiend
Joined: Oct 2002
Posts: 11,314
Likes: 4
At what 'style' cost though ?
Have seen "custom" jobs that had 3 foot tall air dams in front and they were butt-ugly!
I am actually looking for a front bumper/valance, etc... right now since I totaled a Chevy pickup and slightly damaged the left front bumper...
while looking at things like this:
Xenon Ford Excursion Xenon Front Bumper Cover - 12251
not sure I want to go TOO custom though...
Have seen "custom" jobs that had 3 foot tall air dams in front and they were butt-ugly!
I am actually looking for a front bumper/valance, etc... right now since I totaled a Chevy pickup and slightly damaged the left front bumper...
while looking at things like this:
Xenon Ford Excursion Xenon Front Bumper Cover - 12251
not sure I want to go TOO custom though...
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Lead Driver
Joined: Nov 2007
Posts: 5,139
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while looking at things like this:
Xenon Ford Excursion Xenon Front Bumper Cover - 12251
not sure I want to go TOO custom though...
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