Mythbusters Drafting episode - Page 4

ixtlann · 11-18-2007, 09:40 AM

This is one way to look at it, or another way to look at is that a car like an mar2 or del sol can achieve similar results or maximum results by following a lesser truck, ie were smaller etc so we can get the result by jut hangin behind a jeep cherokee or minivan etc. i tried this on my honda del sol (mr2 ish shaped) a few years ago it was ridiculous 48+ mpg i dont have a non draftin trip to compare it to though but thats obviously better then stock fuel economy.

Quote:

Originally Posted by slo-two

Didn't those Mythbusters use a minivan to test the drafting theory? With the aerodynamic grace of a somewhat smoothed brick? One would expect that drafting would do less good for a 2 because of our somewhat lower coefficient of drag and much smaller frontal area. On the other hand, drafting should be very effective for an xB or an Element or some other vehicle modeled after a cinderblock.

Is 38 MPG really much savings? My 91T gets about 34 on highways when not drafting, as long as I don't have the wide wheels on it. And having to buy a new windshield every 10K miles (due to rock chips, sandblasting, etc.) would be such a pain...

mr2-bob · 11-25-2007, 01:06 AM

I like the drafting with a buddy idea...at least you know he won't be pissed if you are on his bumper.

Back when I had a 1972 Honda CB450, I would only get 150 miles on a tank of gas...unless I drafted. I would ask permission from the trucker to draft, and most would say yes. It was very difficult to stay stable back there because of the eddies (turbulence) comming off from the back, but I would get over 200 miles on that same tank of gas if I stayed in the draft.

The eddies that come off from a truck moving above 65 mph are so strong that they literally will suck the car along when in the eddy if you get close enough. Moving Van semi's do this the best because their trailers are closer to the ground. (and you can test this in a swimming pool with two people. I've "towed" my daughter across the pool just by using the "draft" of my body once I got us both moving. I would take my hands away and she would stay right with me as long as I moved quickly through the water.)

Now, if you really pay attention to drafting in NASCAR, you will realize that several cars drafting in a line together use less fuel and go faster than a "train" of fewer cars drafting. Again, it has to do with air flow around a "body". Longer "bodies" create less drag than shorter bodies, even if both have the same cross section.

Engineering is fun.

ARZ · 12-11-2007, 11:32 PM

You can all call BS but, I personally have drafted many a Semi and delivery vans when I raced my bike (Bicycle) in high school and College, more than a dozen times I have seen over 60 mph on my bicycle computer. My personal best was 67mph. My personal best not drafting is 55mph (just a huge hill and a tailwind).

When we were going on certain rides I would change my big ring to a 55 tooth and adjust my front dérailleur and pay attention not to get to a bigger cog on the rear, when going slow. Hardest thing was this was back before lever shifters, my shifters were on the down tube. In the 40-50 mph range was easy as pie, it was just hard to find a Semi going that speed and to catch them at that magic acceleration speed. If they were heavily loaded or we caught them on a roll we might be able to stick with them thru that magical 30-45 mph range.

For some reason if you didnt have something like a strong tailwind or a hill that helped get you up to 35 MPH then we would almost always be too spent to maintain and gain speed and inevitably loose the draft. If the terrain stayed level and the road was smooth and the driver was steady it was surprisingly easy to go 55 mph for quite a while. When we were done we would always pull out so the driver could see us and we would yahoo and if the drivers saw us they would always give us the thumbs up.

GOOD TIMES!!!!

trdny · 12-14-2007, 12:14 AM

ARZ: many good riders can get up to those speeds without the hill or tailwinds. pure leg power.

fosley · 12-17-2007, 10:30 AM

Last time I did the math, at 50 mph the difference between 0 power and that Armstrong guy at peak power was about a 2 mph difference. That's assuming you're using a hill to get to 50 mph, so if you aren't, adding that difference (around 500 watts, as I recall) would get you the 2 mph--though that would mean you're putting out way more power than Armstrong, which isn't something I would require to be considered a "good rider".

Of course, the design of the bike makes a difference--they've gotten pedal-powered vehicles to over 200 mph--but I don't think 65 mph is normally acheivable without either a draft or a hill. According to my calculations, the fast road bikes where your body is horizontal (minimizing wind resistance) can get to just under 70 mph on an 18% grade, or just over 70 mph if you add in the 500 watts, but 18% is *steep*.

Mr2civic817 · 12-17-2007, 12:34 PM

I rather Spend 40$ a tank, then risk my life or my 2 then, Drafting behind an 18 wheeler, to save gas.

Mr2civic817 · 12-17-2007, 12:35 PM

I rather Spend 40$ a tank, then risk my life or my 2 then, Drafting behind an 18 wheeler, to save gas.

Recklesss · 02-06-2008, 06:05 PM

I was driving around in a 1986 Toyota 4x4 for a while. Great truck, but she was a 4 banger, and she maxed out around 55-65 mph (depending on which way the wind was blowing)

however, if i drafted up behind a big rig (it worked from a good 4 or 5 carlengths too) i could zip up to around 85 before i had to pass the truck...

then id hit another wall of air, but it still worked

LokiRx7 · 02-09-2008, 09:35 AM

I love how everyone condemns drafting. And yet unless you live in boon country you drive in traffic. I live in Ohio, and people regularly ride my ass anywhere from 15 feet to three feet away. This is when I am doing the speed limit, and they want to do 80 or 90. I can safely say that I regularly drive close to 50 feet or even less to the car in front of me. Do I have a choice? Not really, rush hour doesnt give you many options, people are all around you.

Truck drivers 9/10 times are superior drivers to 90% of the idiots I encounter on the road in a day. I feel much safer behind a Semi than I do the average person in traffic that taps the brakes every .025 seconds... On rare occasion a semi may change lanes to seemingly get away from me, if he does, I move on to another trucker. I work at UPS and alot of the truck drivers I talk to, dont really mind as long as they can see you (I.E you can see their mirrors)

If you really feel the need to talk about how dangerous drafting is, thats nice. Most of the people raising your premiums most likely dont even visit car forums, much less know what drafting is. Why dont you go to a street racing forum and preach there, I am not endangering anyone but myself, I seriously doubt the truck driver is getting injured in any way. And if anyone behind me gets involved they were following too closely. And on the subject of deer, do you know what happens when a semi hits a deer? It isnt often that the deer goes under the truck, usually there isnt much deer left over.

Anyway, figured I would put this to bed. I mean really, there are more people that tailgate other motorists than semis. If you feel the need to bash drafting go look up the soccer mom forums and give them a piece of your mind.

And FYI I dont draft regularly. I do it on long trips, but I dont take those that often. For the most part I get stuck, with little to no choice, in bumper to bumper 80 mph traffic.

scooterman · 02-09-2008, 10:03 AM

doing 70+ mph on a 18% grade on a bicycle is crazy. Your tires aren't wide enough to stop you, it would probably take several hundred meters to stop.
also 18% is very very very steep, there are a few hills around here that peak at 18-22%, it sucks ball riding up them, and there is one i will not ride a road bike down (24%) (mossy and wet, with a 180* corner at the end).

The fastest ive hit on my bike downhill is the mid 50's due to fear and not enough hill left. Fastest on a flat just under 40 w/o drafting. I've never had the opportunity to draft a truck on the road when on my road bike.

Now drafting i hit 44 on my mountain bike!!! behind a dump trunk, on this one road i road to work on. I didn't even notice how fast i was going i was just looking at the truck, i was at the end of the road in no time and looked down at the computer.

I wouldn't mind so much if someone was drafting me not like its worth drafting an mr2 anyway. But i wish we had some type of light on the car that signaled, hey i dont want to pass you im just gonna hang out back here and draft you.

I dont draft around here people will heavily apply the brakes for no reason other than they look down at the speedo and see omg im doing 80 slam on the brakes.

12-17-2007, 12:35 PM	#67 (permalink)
Mr2civic817 Cage Fighter Join Date: Oct 2006 Location: Arlington Tx Posts: 152 Thanks: 7 Thanked 3 Times in 3 Posts iTrader Rating: (1/100% )	drafting I rather Spend 40$ a tank, then risk my life or my 2 then, Drafting behind an 18 wheeler, to save gas.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

LinkBacks (?) LinkBack to this Thread: http://www.mr2.com/forums/aerodynamics/Toyota-MR2-17831-mythbusters-drafting-episode.html
Posted By	For	Type	Date
Toyota MR2 Message Board	This thread	Refback	09-04-2007 07:04 PM

11-25-2007, 01:06 AM	#62 (permalink)
mr2-bob Gotta Fly Join Date: Apr 2007 Location: Arizona Posts: 45 Thanks: 4 Thanked 4 Times in 4 Posts iTrader Rating: (0/0% )	I like the drafting with a buddy idea...at least you know he won't be pissed if you are on his bumper. Back when I had a 1972 Honda CB450, I would only get 150 miles on a tank of gas...unless I drafted. I would ask permission from the trucker to draft, and most would say yes. It was very difficult to stay stable back there because of the eddies (turbulence) comming off from the back, but I would get over 200 miles on that same tank of gas if I stayed in the draft. The eddies that come off from a truck moving above 65 mph are so strong that they literally will suck the car along when in the eddy if you get close enough. Moving Van semi's do this the best because their trailers are closer to the ground. (and you can test this in a swimming pool with two people. I've "towed" my daughter across the pool just by using the "draft" of my body once I got us both moving. I would take my hands away and she would stay right with me as long as I moved quickly through the water.) Now, if you really pay attention to drafting in NASCAR, you will realize that several cars drafting in a line together use less fuel and go faster than a "train" of fewer cars drafting. Again, it has to do with air flow around a "body". Longer "bodies" create less drag than shorter bodies, even if both have the same cross section. Engineering is fun.

12-11-2007, 11:32 PM	#63 (permalink)
ARZ No Skills Join Date: Nov 2007 Posts: 7 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	You can all call BS but, I personally have drafted many a Semi and delivery vans when I raced my bike (Bicycle) in high school and College, more than a dozen times I have seen over 60 mph on my bicycle computer. My personal best was 67mph. My personal best not drafting is 55mph (just a huge hill and a tailwind). When we were going on certain rides I would change my big ring to a 55 tooth and adjust my front dérailleur and pay attention not to get to a bigger cog on the rear, when going slow. Hardest thing was this was back before lever shifters, my shifters were on the down tube. In the 40-50 mph range was easy as pie, it was just hard to find a Semi going that speed and to catch them at that magic acceleration speed. If they were heavily loaded or we caught them on a roll we might be able to stick with them thru that magical 30-45 mph range. For some reason if you didnt have something like a strong tailwind or a hill that helped get you up to 35 MPH then we would almost always be too spent to maintain and gain speed and inevitably loose the draft. If the terrain stayed level and the road was smooth and the driver was steady it was surprisingly easy to go 55 mph for quite a while. When we were done we would always pull out so the driver could see us and we would yahoo and if the drivers saw us they would always give us the thumbs up. GOOD TIMES!!!!

12-14-2007, 12:14 AM	#64 (permalink)
trdny No Skills Join Date: Dec 2005 Posts: 115 Thanks: 2 Thanked 3 Times in 2 Posts iTrader Rating: (2/100% )	ARZ: many good riders can get up to those speeds without the hill or tailwinds. pure leg power.

12-17-2007, 10:30 AM	#65 (permalink)
fosley Some Skills Join Date: Aug 2007 Location: Tucson, AZ Posts: 91 Thanks: 0 Thanked 7 Times in 7 Posts iTrader Rating: (1/100% )	Last time I did the math, at 50 mph the difference between 0 power and that Armstrong guy at peak power was about a 2 mph difference. That's assuming you're using a hill to get to 50 mph, so if you aren't, adding that difference (around 500 watts, as I recall) would get you the 2 mph--though that would mean you're putting out way more power than Armstrong, which isn't something I would require to be considered a "good rider". Of course, the design of the bike makes a difference--they've gotten pedal-powered vehicles to over 200 mph--but I don't think 65 mph is normally acheivable without either a draft or a hill. According to my calculations, the fast road bikes where your body is horizontal (minimizing wind resistance) can get to just under 70 mph on an 18% grade, or just over 70 mph if you add in the 500 watts, but 18% is steep.

12-17-2007, 12:34 PM	#66 (permalink)
Mr2civic817 Cage Fighter Join Date: Oct 2006 Location: Arlington Tx Posts: 152 Thanks: 7 Thanked 3 Times in 3 Posts iTrader Rating: (1/100% )	I rather Spend 40$ a tank, then risk my life or my 2 then, Drafting behind an 18 wheeler, to save gas.

02-06-2008, 06:05 PM	#68 (permalink)
Recklesss Ruler of Signatures Join Date: Jan 2008 Location: Oregon Posts: 359 Thanks: 6 Thanked 7 Times in 6 Posts iTrader Rating: (0/0% )	I was driving around in a 1986 Toyota 4x4 for a while. Great truck, but she was a 4 banger, and she maxed out around 55-65 mph (depending on which way the wind was blowing) however, if i drafted up behind a big rig (it worked from a good 4 or 5 carlengths too) i could zip up to around 85 before i had to pass the truck... then id hit another wall of air, but it still worked

02-09-2008, 09:35 AM	#69 (permalink)
LokiRx7 MR2 + Flat Black = FAIL Join Date: Jan 2007 Location: N.C. Ohio Posts: 315 Thanks: 0 Thanked 15 Times in 14 Posts iTrader Rating: (1/100% )	I love how everyone condemns drafting. And yet unless you live in boon country you drive in traffic. I live in Ohio, and people regularly ride my ass anywhere from 15 feet to three feet away. This is when I am doing the speed limit, and they want to do 80 or 90. I can safely say that I regularly drive close to 50 feet or even less to the car in front of me. Do I have a choice? Not really, rush hour doesnt give you many options, people are all around you. Truck drivers 9/10 times are superior drivers to 90% of the idiots I encounter on the road in a day. I feel much safer behind a Semi than I do the average person in traffic that taps the brakes every .025 seconds... On rare occasion a semi may change lanes to seemingly get away from me, if he does, I move on to another trucker. I work at UPS and alot of the truck drivers I talk to, dont really mind as long as they can see you (I.E you can see their mirrors) If you really feel the need to talk about how dangerous drafting is, thats nice. Most of the people raising your premiums most likely dont even visit car forums, much less know what drafting is. Why dont you go to a street racing forum and preach there, I am not endangering anyone but myself, I seriously doubt the truck driver is getting injured in any way. And if anyone behind me gets involved they were following too closely. And on the subject of deer, do you know what happens when a semi hits a deer? It isnt often that the deer goes under the truck, usually there isnt much deer left over. Anyway, figured I would put this to bed. I mean really, there are more people that tailgate other motorists than semis. If you feel the need to bash drafting go look up the soccer mom forums and give them a piece of your mind. And FYI I dont draft regularly. I do it on long trips, but I dont take those that often. For the most part I get stuck, with little to no choice, in bumper to bumper 80 mph traffic.

02-09-2008, 10:03 AM	#70 (permalink)
scooterman megasquirted 5sfte Join Date: Dec 2007 Location: Northampton, MA Posts: 125 Thanks: 1 Thanked 14 Times in 8 Posts iTrader Rating: (2/100% )	doing 70+ mph on a 18% grade on a bicycle is crazy. Your tires aren't wide enough to stop you, it would probably take several hundred meters to stop. also 18% is very very very steep, there are a few hills around here that peak at 18-22%, it sucks ball riding up them, and there is one i will not ride a road bike down (24%) (mossy and wet, with a 180* corner at the end). The fastest ive hit on my bike downhill is the mid 50's due to fear and not enough hill left. Fastest on a flat just under 40 w/o drafting. I've never had the opportunity to draft a truck on the road when on my road bike. Now drafting i hit 44 on my mountain bike!!! behind a dump trunk, on this one road i road to work on. I didn't even notice how fast i was going i was just looking at the truck, i was at the end of the road in no time and looked down at the computer. I wouldn't mind so much if someone was drafting me not like its worth drafting an mr2 anyway. But i wish we had some type of light on the car that signaled, hey i dont want to pass you im just gonna hang out back here and draft you. I dont draft around here people will heavily apply the brakes for no reason other than they look down at the speedo and see omg im doing 80 slam on the brakes.