azbill

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This test means nothing without knowing the speed they were going.
In the video, they stated that the speed up the steep grade was 50mph.
 

Ssaygmo

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In the video, they stated that the speed up the steep grade was 50mph.
But do you honestly want to be sitting there at 50mph when you've got 750hp (or 1000hp) or so under your foot and you REALLY want to get into it and go the same speed as all the other traffic going up the hill? I get it, this video is for public consumption and they don't want to break speed limits, but they surely must have tested pushing it harder than that?!
When I take my truck over the grapevine in ca, I don't want to sit there at 50mph with the big rigs, I want to be pulling 70mph with all the other cars in the left lanes.
 

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But do you honestly want to be sitting there at 50mph when you've got 750hp (or 1000hp) or so under your foot and you REALLY want to get into it and go the same speed as all the other traffic going up the hill? I get it, this video is for public consumption and they don't want to break speed limits, but they surely must have tested pushing it harder than that?!
When I take my truck over the grapevine in ca, I don't want to sit there at 50mph with the big rigs, I want to be pulling 70mph with all the other cars in the left lanes.
You really want to be going 70mph with 11klbs in your back?
Also, the minimum speed for conducting that towing test is 40mph, for any vehicle and they went beyond that.
 

jjwolf120

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pulling 70mph with all the other cars in the left lanes.
Which is 15 miles over the speed limit for any vehicle that is towing, just to be clear on rules of the road. Also, there are far to many cars not going seventy in the left lane as you go up the grapevine, much to my irritation.
 

trickflow

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When I take my truck over the grapevine in ca, I don't want to sit there at 50mph with the big rigs, I want to be pulling 70mph with all the other cars in the left lanes.

Which is 15 miles over the speed limit for any vehicle that is towing, just to be clear on rules of the road. Also, there are far to many cars not going seventy in the left lane as you go up the grapevine, much to my irritation.
@Ssaygmo be careful if you actually do that. In CA over 10,000 lbs puts you in a different category and you will be held to the law under CVC 22406 and 22407. Basically this means that the speed limit for you is 35 MPH, not even 55 as jjwolf120 says. If you can actually get your truck up to 70 MPH while towing at max capacity you will be in for a 35 MPH OVER the speed limit ticket, which can also be reckless endangerment. Basically you could lose your license for doing that as well as endanger everyone else. I am by all means not telling you how to drive, but what you described if you do tow over 10k lbs is careless at best and criminal at worst.
 

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Seems like that is a large trailer and weight for what might be considered a mid sized truck. I have to be impressed seeing it pull that thing around with another vehicle inside. And its not true that the weight is not as important as wind resistance if you are driving up hills. Everyone knows how much your vehicle is stressed when pulling something up a hill especially for us in the Colorado mountains. I am hoping my 10' utility trailer with 1500lbs won't cut my range in half while getting to my mountain property.
 

azbill

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Seems like that is a large trailer and weight for what might be considered a mid sized truck. I have to be impressed seeing it pull that thing around with another vehicle inside. And its not true that the weight is not as important as wind resistance if you are driving up hills. Everyone knows how much your vehicle is stressed when pulling something up a hill especially for us in the Colorado mountains. I am hoping my 10' utility trailer with 1500lbs won't cut my range in half while getting to my mountain property.
I agree that pulling a trailer this large on that size vehicle is questionable. Many years ago, while driving to Sedona Arizona from Phoenix, I saw for my own eyes why this should not be done. That route has many steep up and down grades and can also get windy. As I came over a hill and started down one of the steep grades, at the bottom of the hill was a Ford Expedition (no, not an Excursion) along the side of the road with a triple axle enclosed trailer on its roof, but the Expedition was upright with the rear wheels way off the ground and three guys with brown underwear scratching their heads beside the road. The trailer hitch and sway bars appeared to still be connected and I have no idea how the truck itself did not flip. Based on an internet search, those trucks appear to be rated to pull 9000+ lbs, but I would not do it. I plan on pulling a boat and also a horse trailer, but the boat is 5000lbs and the horse trailer is rated at 7000lbs, but I never load it that much.
 

trickflow

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I agree that pulling a trailer this large on that size vehicle is questionable. Many years ago, while driving to Sedona Arizona from Phoenix, I saw for my own eyes why this should not be done. That route has many steep up and down grades and can also get windy. As I came over a hill and started down one of the steep grades, at the bottom of the hill was a Ford Expedition (no, not an Excursion) along the side of the road with a triple axle enclosed trailer on its roof, but the Expedition was upright with the rear wheels way off the ground and three guys with brown underwear scratching their heads beside the road. The trailer hitch and sway bars appeared to still be connected and I have no idea how the truck itself did not flip. Based on an internet search, those trucks appear to be rated to pull 9000+ lbs, but I would not do it. I plan on pulling a boat and also a horse trailer, but the boat is 5000lbs and the horse trailer is rated at 7000lbs, but I never load it that much.
Kind of reminds me of this. I am sure they crapped their pants when this happened....
 

nfrank

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Rivian ran the risk of flipping that trailer. I didn’t any sway control on their hitch. I wouldn’t have run it the way they did. A bit dangerous if some wind picked up or a big rig passes close going the opposite direction.
 

azbill

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Rivian ran the risk of flipping that trailer. I didn’t any sway control on their hitch. I wouldn’t have run it the way they did. A bit dangerous if some wind picked up or a big rig passes close going the opposite direction.
From what I saw in the video, they were loading it with sandbags onto the floor, so the center of gravity would have been low to help avoid flipping.
 

trickflow

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Rivian ran the risk of flipping that trailer. I didn’t any sway control on their hitch. I wouldn’t have run it the way they did. A bit dangerous if some wind picked up or a big rig passes close going the opposite direction.
Sway control does not necessarily need to be a mechanical device on a hitch like Anderson does. It can be electronic for example by putting brakes on the rear wheels on the truck on opposite sides to combat sway. We don't know what system they are using for this. And keeping in mind that the Rivian will have a low center of gravity and by much heavier than a mid-size truck, 11k pounds may actually not be that awful to tow with.
 

jarross

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I would have expected them to really push it. Like 15,000 pounds, and/or 70mph. A good testing program will find the limits of a vehicle.
They didn't really specify how fast they went, just that they exceeded the targets. It would have been great if they had been more specific with speeds attained.
 

ajdelange

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And its not true that the weight is not as important as wind resistance if you are driving up hills.
That depends. Taking 11,000 lbs up a 1 % grade is going to cost you 215 Wh/mi. Doing it at 55 mph assuming Cd = 0.4 and Af = 4 m^2 is going to cost you 250 Wh/mi. Those are pretty puny estimates for Cd and Af so drag will doubtless be bigger than that and its already bigger than the gravitational load. But move to a 3% grade and the gravitational load is now 645 Wh/mi which is more than twice the drag. Slow down 10% and the drag goes down 20%. That's why I say it depends.

Everyone knows how much your vehicle is stressed when pulling something up a hill especially for us in the Colorado mountains. I am hoping my 10' utility trailer with 1500lbs won't cut my range in half while getting to my mountain property.
Shoudn't. The formula for the energy used is .3048*∆h*(w/2.2)*9.8/3600000 so if your cabin is 5280 feet higher than your home base and the trailer weighs 1500 lbs you have
0.3048*5280*(1500/2.2)*9.8/3600000 = 2.98 kWh. That's less than 2% of the battery capacity in the 180 kWh configuration. I'd be more worried about drag in this case. Assuming the trailer to have about as much drag as the truck at 55 mph its going to require about 250 Wh/mi to overcome. As the total for the truck is going to be about 500 Wh/mi adding 250 would get you to 750 with the trailer or 3/2 the unloaded consumption. Range will clearly go down to 2/3 in this case but these numbers are pretty rough. Beat drag by slowing down.
 
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ajdelange

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Sway control does not necessarily need to be a mechanical device on a hitch like Anderson does. It can be electronic for example by putting brakes on the rear wheels on the truck on opposite sides to combat sway. We don't know what system they are using for this. And keeping in mind that the Rivian will have a low center of gravity and by much heavier than a mid-size truck, 11k pounds may actually not be that awful to tow with.
My understanding of it is that a gust of wind from a passing truck or whatever tries to push the trailer off the road to the passenger side. This puts huge counter clockwise torque on the tow vehicle which causes its front end to move in that direction. The driver sees this and put in a large steering input towards the right which puts a large clockwise torque on the tow hitch which tries to whip the trailer to the left. Picture just the right phasing here and its clear that you have a building oscillation with predictable results. Mechanical solutions try to get the pivot point up under the wheels (5th wheel, pivot point projection...) so the trailers input torque is reduced. In a vehicle with torque vectoring the motors can put the thrust necessary on each wheel in order to neutralize the trailer's torque input and the problem is this solved. No brakes would be used but acceleration could be automatically applied along with steering input. The issue I see is in the necessary sophistication in the anti sway control algorithms. It has to be pretty bullet proof. I think that there is tremendous potential to solve the sway problem with a vehicle that has computer controllable torque vectoring and steering but the algorithms must be super robust.
 

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