How to fight climate change... for reals.

[Ashful]

When the colonial pipeline shut down I was able to change how I drive and went from 15 mpg to 18.5 around town. When most of the gas stations are closed and the lines are blocks long at the ones with gas you change how you drive.

After Katrina when gas went up. I didn’t use 2nd or 4th gear.

... but then you eventually went back to driving as you normally do? That was my point.

...non-linear losses associated with wind resistance, and impacts on energy consumption.

Not a mech.E, but I've taken more Newtonian physics than the average Joe. To my recollection, wind resistance is a friction loss, the force being linear with velocity. Since work = energy is simply force times displacement, I'd propose the losses due to wind resistance are likely linear, not non-linear. Maybe there's some secondary effect I'm missing, but whether it's wind resistance, rolling resistance, or any other factor that comes to mind, they're all linear WRT velocity.

What would be non-linear is acceleration. Acceleration alone is why my wife and I can get 31 mpg and 17 mpg gallon (respectively) in the same vehicle, despite having nearly the same final/highway velocity.

It's really frustrating to have a car that wants to go faster than I'm willing to as a driver.

Story of my life, I've always owned cars faster than I'm willing to drive them, I think the current sedan is rated near 200 mph. But I'd say the more frustrating thing is being stuck behind a minivan (or worse... a Prius) on a nice windy and desolate country road.

But this is all getting mighty far from woodgeek's point(s), with which I agree. If I can remember them correctly, or at least my own take-away:

1. Climate change solutions must be in alignment with a net (or apparent) cost savings for those voting/deciding on them.
2. Technology is our most likely path to these solutions.

 

[begreen]

Funny - Since I've started to drive an EV with at best an 80-mile range I've become painfully aware of the relationship between vehicle speed, the non-linear losses associated with wind resistance, and impacts on energy consumption.
It's really frustrating to have a car that wants to go faster than I'm willing to as a driver.
I guess the converse might even be more frustrating though.

I learned this when driving RVs and campers. The effect of wind resistance on a big front vehicle is immediately noticeable between 60mph and 70mph. Cruise control became my friend for maintaining a steady reasonable speed. If I am on vacation, why rush to get there 15-30 minutes earlier?

 

[SpaceBus]

As a human who has ridden a motorcycle with zero wind protection at high speeds, wind resistance is NOT linear. All naked bikes regardless of seating position have extreme buffeting and drag when you get up to 70 MPH, it's twice as bad at 80 and just keeps getting worse. Even a small wind deflector on the headlight changed the drag significantly, but the drastic difference in wind resistance as speed increases is still there, just not felt by the rider as you progressively add more and larger fairing. You can do this with a poorly designed convertible and get a similar effect.

 

[peakbagger]

See this https://www.engineeringtoolbox.com/wind-load-d_1775.html Air resistance varies with square of speed but the multiplier starts out real small so it does not matter much at low speeds but once the square get big it goes up quick.
I wish that calculator was in MPH

 

[stoveliker]

Not a mech.E, but I've taken more Newtonian physics than the average Joe. To my recollection, wind resistance is a friction loss, the force being linear with velocity. Since work = energy is simply force times displacement, I'd propose the losses due to wind resistance are likely linear, not non-linear. Maybe there's some secondary effect I'm missing, but whether it's wind resistance, rolling resistance, or any other factor that comes to mind, they're all linear WRT velocity.

Air drag is quadratic in speed.

Air friction with quadratic velocity dependence

I forgot why, but I suspect it's due to turbulence. (Or at least, flow dynamics, as I'm not sure if perfectly laminar flow would lead to a linear drag in the range of speed where laminarity (?) can be maintained.)

Edit: indeed, for a Reynolds number <<1 one can use a linear air drag. That's the laminar regime. That is not happening when you drive a car.
My gut was right.

Linear or Quadratic Air Resistance

I'm trying to model a rocket's position with air resistance as a factor. The rocket is fairly low-powered (Estes A8-3, 9.7N of thrust for 0.7 seconds), and I estimate it won't be going faster than...

physics.stackexchange.com

 

[EbS-P]

... but then you eventually went back to driving as you normally do? That was my point.


Not a mech.E, but I've taken more Newtonian physics than the average Joe. To my recollection, wind resistance is a friction loss, the force being linear with velocity. Since work = energy is simply force times displacement, I'd propose the losses due to wind resistance are likely linear, not non-linear. Maybe there's some secondary effect I'm missing, but whether it's wind resistance, rolling resistance, or any other factor that comes to mind, they're all linear WRT velocity.

What would be non-linear is acceleration. Acceleration alone is why my wife and I can get 31 mpg and 17 mpg gallon (respectively) in the same vehicle, despite having nearly the same final/highway velocity.

Story of my life, I've always owned cars faster than I'm willing to drive them, I think the current sedan is rated near 200 mph. But I'd say the more frustrating thing is being stuck behind a minivan (or worse... a Prius) on a nice windy and desolate country road.

But this is all getting mighty far from woodgeek's point(s), with which I agree. If I can remember them correctly, or at least my own take-away:

1. Climate change solutions must be in alignment with a net (or apparent) cost savings for those voting/deciding on them.
2. Technology is our most likely path to these solutions.

Drag force is V^2. Power is force times velocity. Maybe someone who teaches this for a living can put that together (winking at my self)

Oh Ok that means power requirements at constant speed go as V^3.

Now here’s the automotive part. One might assume fuel consumption is linear with power, but I don’t think that’s quite right as HP depends on torque and RPM. Making more torque takes more fuel and the rpm is directly related to speed.

 

[ABMax24]

Determining engine efficiency really requires a BSFC (brake specific fuel consumption map), that is developing in a lab with the engine on a dyno.

Better efficiency analysis though is part of the reason newer vehicles are coming with 10 speed or CVT transmissions. It makes it much easier for the ecm to find the perfect RPM for best fuel efficiency at any given load.

 

[stoveliker]

Yes, we recently bought a new-to-us (2018) vehicle after the newest vehicle we ever had was a 2010 car.
Unfortunately still ICE (it's the "big" vehicle we have; the smaller one that I drive will be at some point replaced by a plug-in vehicle).
However, I was surprised that it had an 8-speed (auto) transmission. 8 speeds. You can see that immediatly at the RPMs during driving. My 5+R stick shift runs much higher.

 

[peakbagger]

I wonder what the break point there is between CVTs and conventional transmissions? Effectively a CVT is a transmission with an infinite set of speeds. It may be that a CVT is a friction device while modern automatics mechanical lock up at upper speeds so on larger drivetrains the overall efficiency is higher with gears.

My Unimog is an 8 speed manual but I normally only use the upper 5 gears unless off roading or pulling stumps I need 4th gear for reverse as the reverse is locked out in 5th to 8th but I do have the lower 4 speeds for reverse.

 

[Ashful]

Air drag is quadratic in speed.

Air friction with quadratic velocity dependence

I forgot why, but I suspect it's due to turbulence

Thank you, I stand corrected. Although I have to admit, I can't remember why.

Maybe someone who teaches this for a living can put that together (winking at my self)

You're a physics teacher? No fair!

 

[Poindexter]

But this is all getting mighty far from woodgeek's point(s), with which I agree. If I can remember them correctly, or at least my own take-away:

1. Climate change solutions must be in alignment with a net (or apparent) cost savings for those voting/deciding on them.
2. Technology is our most likely path to these solutions.

I went through the thread just a couple days ago and pulled out the 12 things we had come up with so far that we as individuals could do to slow climate change. Post 65, it is on page three for me. Those 12 are the ideas we had come up with so far - with the side branches pruned out.

 

[SpaceBus]

I wonder what the break point there is between CVTs and conventional transmissions? Effectively a CVT is a transmission with an infinite set of speeds. It may be that a CVT is a friction device while modern automatics mechanical lock up at upper speeds so on larger drivetrains the overall efficiency is higher with gears.

My Unimog is an 8 speed manual but I normally only use the upper 5 gears unless off roading or pulling stumps I need 4th gear for reverse as the reverse is locked out in 5th to 8th but I do have the lower 4 speeds for reverse.

CVTs were banned in F1 since they could effectively keep the engine at peak power at any speed. I think the materials needed to make a CVT handle normal driving in anything larger than a midsize sedan keep them from being placed in trucks. Which is theoretically where they would be the most effective when combined with the proper final drive. Most people also hate driving them because it feels like a lawnmower. I've driven the Nissa Juke Nismo RS with the CVT and it was not that fun. When I wanted a "downshift" it felt like an eternity for the transmission/ECU to select the correct ratio.

 

[EbS-P]

... but then you eventually went back to driving as you normally do? That was my point.


Not a mech.E, but I've taken more Newtonian physics than the average Joe. To my recollection, wind resistance is a friction loss, the force being linear with velocity. Since work = energy is simply force times displacement, I'd propose the losses due to wind resistance are likely linear, not non-linear. Maybe there's some secondary effect I'm missing, but whether it's wind resistance, rolling resistance, or any other factor that comes to mind, they're all linear WRT velocity.

What would be non-linear is acceleration. Acceleration alone is why my wife and I can get 31 mpg and 17 mpg gallon (respectively) in the same vehicle, despite having nearly the same final/highway velocity.

Story of my life, I've always owned cars faster than I'm willing to drive them, I think the current sedan is rated near 200 mph. But I'd say the more frustrating thing is being stuck behind a minivan (or worse... a Prius) on a nice windy and desolate country road.

But this is all getting mighty far from woodgeek's point(s), with which I agree. If I can remember them correctly, or at least my own take-away:

1. Climate change solutions must be in alignment with a net (or apparent) cost savings for those voting/deciding on them.
2. Technology is our most likely path to these solutions.

I’m going to challenge point one. Someone must pay for for the R and D for the tech and initial products that won’t appeal to most based on their negative, subpar or extremely long ROI. The path to a widely adopted and finically acceptable product must start with money with little promise of return.
The Tesla model is going to be thrown around a lot I feel but I’m hesitant to suggest that as viable route for other products. Name another product where you can operate for more than a decade without ANY competition?

We have choose the outcome and at the same time decide what cost we are willing to bear to achieve that outcome.

I would gladly pay an extra 20% maybe even 30 % to buy 100% renewable electricity.

 

[EbS-P]

CVTs were banned in F1 since they could effectively keep the engine at peak power at any speed. I think the materials needed to make a CVT handle normal driving in anything larger than a midsize sedan keep them from being placed in trucks. Which is theoretically where they would be the most effective when combined with the proper final drive. Most people also hate driving them because it feels like a lawnmower. I've driven the Nissa Juke Nismo RS with the CVT and it was not that fun. When I wanted a "downshift" it felt like an eternity for the transmission/ECU to select the correct ratio.

They are not sporty, they are made to be efficient. Ford Maverick hybrid looks to have a CVT. My guess is the reliability of a 9 or 10 speed auto makes up for any efficiency gain of the CVT. These are made to get the mileage numbers on EPA tests. That’s what they are tuned for. CVT or automatic. They need something that they can keep the motor running in the Atkins cycle peak efficiency. This is not a peak power cycle.

I do find it interesting/odd Ford would use one in the hybrid maverick. Would make it feel more like an EV. And honestly the whole waiting for a downshift, aver driving an EV, just seems like weird now,

 

[begreen]

Name another product where you can operate for more than a decade without ANY competition?

Nissan Leaf & Ford Focus Electric were out a decade ago and on the market when Tesla only had a very pricey and rare sports car for sale.

 

[woodgeek]

Thank you, I stand corrected. Although I have to admit, I can't remember why.


You're a physics teacher? No fair!

There are two terms. One source of the resistance force is viscous friction (viscous drag) and it is linear in velocity. The other is due to the pressure difference between the front and the back (form drag). And that one is quadratic (approximately) bc the air in front has less time to get out of the way and picks up more energy at higher velocity.

In the car case, the second term dominates. The prefactor is the frontal area times a shape dependent constant, c_D.

Drag coefficient - Wikipedia

en.wikipedia.org

 

[ABMax24]

CVT's are also used in the performance world; snowmobiles, atv's, SxS, and UTVs use them extensively. They offer a high performing, light weight, and cost effective "transmission" for these machines. That being said they all operate at higher rpm to lower the effective torque on the belt and limit slippage. Both my SxS and Snowmobile operate in excess of 8,000 rpm and suffer a loss of efficiency as a result, along with decreased service life of the belts.

Torque handling capability is the limiting factor in all CVT's, and is the reason they are not found in anything larger than cars and small SUV's. IMO transmission technology has come a long way, and 10 speed transmissions with low viscosity fluid would still be my preferred option in a vehicle.

My first vehicle was a '98 F150, V6, RWD 5 speed manual, about the most efficient pickup you could get for that time. On a good day I was getting 13 L/100km. Now a 2022 GM 1/2 ton with a 3.0 L Diesel, 4wd, 10 speed auto, all the bells and whistles, gets 8 L/100km. A number that beats most mid-sized SUV's and even some small ones. Obviously more improvement is needed, but this is still nothing to scoff at, and a 1/3 reduction in fuel consumption for a similar truck is quite impressive in my books.

 

[JRHAWK9]

Back in '02 I removed the catalytic converters from my Firehawk. This resulted in much less CO2 coming out of my tailpipe and seeing CO2 is a greenhouse gas I feel I did something positive to limit the production of green houses gasses from that car.

7.1: Catalytic Converters

A catalytic converter is a device used to reduce the emissions from an internal combustion engine (used in most modern day automobiles and vehicles). Not enough oxygen is available to oxidize the …

chem.libretexts.org

 

[SpaceBus]

They are not sporty, they are made to be efficient. Ford Maverick hybrid looks to have a CVT. My guess is the reliability of a 9 or 10 speed auto makes up for any efficiency gain of the CVT. These are made to get the mileage numbers on EPA tests. That’s what they are tuned for. CVT or automatic. They need something that they can keep the motor running in the Atkins cycle peak efficiency. This is not a peak power cycle.

I do find it interesting/odd Ford would use one in the hybrid maverick. Would make it feel more like an EV. And honestly the whole waiting for a downshift, aver driving an EV, just seems like weird now,

You can tune a CVT for anything, but yes, in production cars they are normally tuned for fuel efficiency. CVT's are probably the "best" transmission option for most drivers. If they really did drive more like an electric car they would find more widespread adoption, but since peak power is rarely at peak efficiency RPM, they don't drive like EVs. If you wish to accelerate when the trans is in a peak efficiency ratio range, then it takes some time to "skip" down to the ratio range that gives best acceleration. I think a CVT that could handle the torque from an electric motor would probably be the best option for an EV rather than a planetary gear. An EV with a planetary gear makes peak torque at essential "one" RPM, but you can only do that at a stop. With a CVT you could get into the lower RPM range of the electric motor when you want, assuming the CVT has enough "range". The biggest downside is the CVT has a high level of parasitic losses due to the large surface area of the drive belts. Some of the efficiency gains negated by losses.

 

[SpaceBus]

CVT's are also used in the performance world; snowmobiles, atv's, SxS, and UTVs use them extensively. They offer a high performing, light weight, and cost effective "transmission" for these machines. That being said they all operate at higher rpm to lower the effective torque on the belt and limit slippage. Both my SxS and Snowmobile operate in excess of 8,000 rpm and suffer a loss of efficiency as a result, along with decreased service life of the belts.

Torque handling capability is the limiting factor in all CVT's, and is the reason they are not found in anything larger than cars and small SUV's. IMO transmission technology has come a long way, and 10 speed transmissions with low viscosity fluid would still be my preferred option in a vehicle.

My first vehicle was a '98 F150, V6, RWD 5 speed manual, about the most efficient pickup you could get for that time. On a good day I was getting 13 L/100km. Now a 2022 GM 1/2 ton with a 3.0 L Diesel, 4wd, 10 speed auto, all the bells and whistles, gets 8 L/100km. A number that beats most mid-sized SUV's and even some small ones. Obviously more improvement is needed, but this is still nothing to scoff at, and a 1/3 reduction in fuel consumption for a similar truck is quite impressive in my books.

I haven't driven any of the new 10 speed trucks yet, but I did love the 8 speed auto in a BMW 335i m-sport I drove. It wasn't a dual clutch, like found in the M3 proper, but it was lightning fast. Always in the right gear and we averaged 35 MPG highway on a road trip in a car that could run 13 sec quarter mile off the lot. Normally I'm a die hard manual transmission guy, but these new ZF designed torque converter autos and DCT's are great. They give you the right gear pretty much all the time, even in auto mode.
If I did my conversions right your truck is getting about 30 MPG, which is madness! My '06 six speed cummins dually is averaging 26 on rural roads. It's our farm truck, so I only use when picking up animal feed, gravel, etc., but I wouldn't mind another 20% better fuel economy. I would probably drive it a lot more. I'm hoping some PHEV diesel trucks come on the market which best leverage the strengths of both drive systems. The diesel is going to make more torque at freeway speeds than the electric motors and could probably keep a fairly heavy truck at speed *and* charge the batteries for low speed usage. Could also do away with loud J brakes and just have less noise in general at lower speeds.

 

[ABMax24]

I haven't driven any of the new 10 speed trucks yet, but I did love the 8 speed auto in a BMW 335i m-sport I drove. It wasn't a dual clutch, like found in the M3 proper, but it was lightning fast. Always in the right gear and we averaged 35 MPG highway on a road trip in a car that could run 13 sec quarter mile off the lot. Normally I'm a die hard manual transmission guy, but these new ZF designed torque converter autos and DCT's are great. They give you the right gear pretty much all the time, even in auto mode.
If I did my conversions right your truck is getting about 30 MPG, which is madness! My '06 six speed cummins dually is averaging 26 on rural roads. It's our farm truck, so I only use when picking up animal feed, gravel, etc., but I wouldn't mind another 20% better fuel economy. I would probably drive it a lot more. I'm hoping some PHEV diesel trucks come on the market which best leverage the strengths of both drive systems. The diesel is going to make more torque at freeway speeds than the electric motors and could probably keep a fairly heavy truck at speed *and* charge the batteries for low speed usage. Could also do away with loud J brakes and just have less noise in general at lower speeds.

I don't own an inline 6 3.0 diesel. But 2 family members and a former coworker do.

We have an '18 Colorado with the 2.8 inline 4 diesel. Which even being a smaller truck gets almost the same fuel mileage as the 3.0. I think our Colorado wins at higher speed though due to lower aerodynamic drag. On a calm day, on a a flat road, I've done as good as 7.5l/100km at 125km/h (78mph). This truck will do 6l/100km if we keep the speed below 85km/h.

 

[Riverbanks]

I saw a post about Mediterranean Sea salt, anyone try sea love sea salt? It's from n.c., I saw it on PBS "startup"

 

[peakbagger]

My Rav 4 Prime has a CVT and is the second fastest Toyota they sell in the US. I think total HP Gas and electric is 325 total.

 

[Ashful]

My Rav 4 Prime... is the second fastest Toyota they sell in the US.

lol... not far from citing the second hairiest bald guy, or second darkest albino.

Toyota has made some nice cars over the years (GR Supra, GT86, 2000GT), but the fact that a RAV4 is their current second fastest is perfect evidence of how far they've strayed from that goal.

 

[peakbagger]

5.5 seconds 0 to 60 is not that shabby for a normally aspirated car.

My GMC Syclone was 5.1 seconds and was turbo intercooled and ran premium.