Range and ground clearance

[drm]

I have read many times that high ground clearance impacts range, particularly at highway speeds. And this is why decent ground clearance is so far mostly found in larger EVs, and also why the Solterra range is so poor. Either smaller vehicles are affected more, or larger vehicles just have the space for a larger battery to compensate.

But it makes me wonder how Rivian will manage this in the R2, and especially the R3. Maybe they will just prioritize space for the battery. I mean, it's not like Rivian designs for aerodynamics.

Also, if the impact is mostly at faster speeds, maybe those of us who live close to our adventure will not suffer the range loss from having to drive a long way at speed to get there.

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[CobraJerky]

Rivian doesn’t design for aerodynamics?

Have you compared the R1T to the other electric trucks or is this a /s?

https://www.topspeed.com/aerodynamic-electric-trucks-currently-on-sale/

 

[White Shadow]

That's why the air suspension lowers the ride height slightly at highway speeds....it helps with efficiency. The R2 obviously doesn't have air suspension, but it is supposed to have pretty good ground clearance. The R3 vehicles aren't going to have the same ground clearance as the R2, right?

 

[drm]

Rivian doesn’t design for aerodynamics?

Have you compared the R1T to the other electric trucks or is this a /s?

https://www.topspeed.com/aerodynamic-electric-trucks-currently-on-sale/

I guess I was thinking of the R1S, since it is a bit more of a model for the R2. But Rivian's seem like rectangular boxes to me (as do those other trucks). Compared to say some of the mid-sized EV SUVs out there, which have more curved lines.

White Shadow - R2 listed 9.8" of clearance, which is probably a segment leader for mid-sized SUVs. I haven't seen anything for R3, but assumed it would be less. But we were told the R2 would be 300 miles plus. 300 is not segment leading range for a 2WD, but it's not bad.

 

[VSG]

and also why the Solterra range is so poor

The reason the Solterra range is so poor is because it's a bad design overall, not because of the ground clearance.

Ground clearance isn't one of the main factors that affect range.

 

[drm]

The reason the Solterra range is so poor is because it's a bad design overall, not because of the ground clearance.

Ground clearance isn't one of the main factors that affect range.

In what way? Battery too small? Or just an inefficient power train?

 

[Dave Cundiff]

I was pleased to see that topspeed.com rated R1T the most aerodynamic of the five they tested.

R1T was a little more aerodynamic than CyberTruck. Beauty can be functional!

 

[mkg3]

In what way? Battery too small? Or just an inefficient power train?

Soltera/BZ4 weighs about 4,500 lbs and useable battery of around 62 kWh. Has range of about 220 miles. It's rated as 102 MPGe whereas R1S is 64 MPGe so from efficiency point, Soltera/BZ4 is more efficient EV from power consumption perspective.

To your original point, the reason lower grand clearance is desirable for lower drag has to do with amount of air flowing under the vehicle. Less air going under and more over the vehicle result in lower drag even if it has the same drag coefficient.

How the drag due to separated flow from the tire rotation, and the air that gets pushed to the inside and outside of where the tire patch meets the road that interacts with clean flow under vehicle, has a huge effect on overall drag on the vehicle. This is the reason why when testing a road vehicle in the wind tunnel, one needs a rolling ground to simulate the moving vehicle. If not, the results are completely erroneous.

When a vehicle has a large ground clearance, the mixture of separated flow that affect clean airflow is greater due to more volume of air is flowing under the vehicle; hence, increasing drag.

In terms of R2, if R1 and R2 have the same drag coefficient, by definition R2 will be more efficient than R1S in the same condition because it has a smaller frontal area, and will be lighter weight, resulting in less force required to move the vehicle on the road.

 

[JasonK]

I was curious about his as well. I researched this some. I found out the ground clearance has minimal effect on aerodynamics as long as the bottom of the car is smooth an flat without exposed parts that create drag. The only effect that causes more drag with higher ground clearance is a larger aria of the front tires is exposed to air creating a small amount of extra drag but this is minimal.

 

[HaveBlue]

I think Engineering Explained did a video on this and the benefit was a .01 improvement in drag coefficient by lowering the vehicle. This video I think

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