Cybertruck roof rack for work..... To carry long lumber on top or plumbing pipe

[Crissa]

What's range when there's a Supercharger on your path?

If it charges just as fast, a smaller pack doesn't mean more time charging.

-Crissa

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[Sirfun]

What's range when there's a Supercharger on your path?

If it charges just as fast, a smaller pack doesn't mean more time charging.

-Crissa

Unfortunately I think there are times when it will me longer charge times. With the current supercharger network there can be spaces where you would have to push the range on a Single motor. And charging slows down when charge past 80-85%. So in those instances when you're only charging in the optimum range with a larger pack, it might mean less time.

 

[Crissa]

With the current supercharger network there can be spaces ...

...Current network irrelevant. The single-motor will exist with a future network.

And charging slows down when charge past 80-85%.

...So don't charge past that point.

It just means stopping more often. But what it doesn't mean is stopping longer: Bigger battery just means you spend longer charging it.


-Crissa

 

[Luke42]

so unlike all other trucks it won't be light in the rear end.

The problem with is that, when it has 3500lbs in the bed, it will be heavy on the back.

Tail-heavy cars are prone to "oversteer", which really means that the back wants to become the front in low-traction (or partial traction) conditions.

Most regular street vehicles are set up to slide straight in low traction conditions (rather than oversteer), which means that:
a) the front wheels have bigger brakes and lock up before the rear wheels.
b) A front-heavy weight bias in all load conditions.

I've owned four pickup trucks over the years, and driven them in a variety of (over)loading conditions.

It looks to me like existing pickup trucks are nose-heavy, not because it's impossible to build a pickup with a 51/49 weight distribution, but because a 70/30 (or 60/40) weight distribution means the truck can be 51/49 when fully loaded.

If the CT has a 51/49 weight distribution when empty, I'd be reluctant to put 3500lbs in the bed without knowing how they plan to solve the oversteer problem.

 

[ldjessee]

If the CT has a 51/49 weight distribution when empty, I'd be reluctant to put 3500lbs in the bed without knowing how they plan to solve the oversteer problem.

If it did not have an air suspension and not be able to load level, I would agree, but with that ability, it should not be that big of an issue... Atleast, that is my understanding. I have never had the advantage of having an adjustable air suspension before.

I have had to move things around (like not put the majority of the weight on or past the rear axle, instead putting as much weight as possible forward in the bed).

 

[Luke42]

If it did not have an air suspension and not be able to load level, I would agree, but with that ability, it should not be that big of an issue... Atleast, that is my understanding. I have never had the advantage of having an adjustable air suspension before.

Leveling the truck won't make the oversteer tendency go away.

The center-of-gravity would still aft of the center-of-friction, even if the back isn't sagging.

It's like putting the fins on the front of the rocket in Kerbal Space Program, except that the friction of the wheels keep it straight when all four wheels are connected solidly to the ground.

But, as someone who faces Real Winter (and who has an aviation habit) my mental model of driving does not assume the wheels are connected solidly to the ground. This is a corner-case, but one I encounter on a regular basis.

 

[ldjessee]

Leveling the truck won't make the oversteer tendency go away.

The center-of-gravity would still aft of the center-of-friction, even if the back isn't sagging.

It's like putting the fins on the front of the rocket in Kerbal Space Program, except that the friction of the wheels keep it straight when all four wheels are connected solidly to the ground.

But, as someone who faces Real Winter (and who has an aviation habit) my mental model of driving does not assume the wheels are connected solidly to the ground. This is a corner-case, but one I encounter on a regular basis.

If the back of the CyberTruck is jacked up the back and the front is lowered then leverage would put more weight on the front wheels, thus correcting mostly the oversteer tendency (obviously not all cases).

That is why trucks would have stiffer springs on the back so that most of the weight is transferred to the front when empty, making them 'light' in the back. When loaded, then the back stiffer springs would be compressed, thus the weight is more evenly distributed.

 

[Luke42]

If the back of the CyberTruck is jacked up the back and the front is lowered then leverage would put more weight on the front wheels, thus correcting mostly the oversteer tendency (obviously not all cases).

How many feet are you planning to jack up the back of the truck in order to move the CG forward?

Let's diagram this using F-150 dimensions (250" long, 75" high). Let's put the CG about 10" aft of midpoint of the truck, about 135" from the front bumper, and at about 37" above the ground. These are fairly favorable assumptions for a vehicle with 3500lbs of cargo on the back axle.

You're going to have to lift the back of the truck much more than 10" in order to is move the CG forward 10", because the CG will track the outside of a circle with a radius of 90ish inches, centered on the front wheel.

You can only move the CG forward by jacking up the back if the CG is already very close to where it needs to be. It's a hack which works on an already-mostly-balanced vehicle, not the primary means of balancing the vehicle.

That is why trucks would have stiffer springs on the back so that most of the weight is transferred to the front when empty, making them 'light' in the back. When loaded, then the back stiffer springs would be compressed, thus the weight is more evenly distributed.

Trucks have stiff springs in the back to prevent the back end from sagging and wallowing under the weight, not to move the CG around.

Conventional pickups solve the CG problem by putting most of the empty-weight of the vehicle on the front wheels so that the CG is an appropriate location when it's fully loaded.

The tradeoff for this is poor traction on the rear wheels when the vehicle is lightly loaded. Also, stiff springs can provide a bumpy ride when lightly loaded.

 

[Dids]

How many feet are you planning to jack up the back of the truck in order to move the CG forward?

Let's diagram this using F-150 dimensions (250" long, 75" high). Let's put the CG about 10" aft of midpoint of the truck, about 135" from the front bumper, and at about 37" above the ground. These are fairly favorable assumptions for a vehicle with 3500lbs of cargo on the back axle.

You're going to have to lift the back of the truck much more than 10" in order to is move the CG forward 10", because the CG will track the outside of a circle with a radius of 90ish inches, centered on the front wheel.

You can only move the CG forward by jacking up the back if the CG is already very close to where it needs to be. It's a hack which works on an already-mostly-balanced vehicle, not the primary means of balancing the vehicle.



Trucks have stiff springs in the back to prevent the back end from sagging and wallowing under the weight, not to move the CG around.

Conventional pickups solve the CG problem by putting most of the empty-weight of the vehicle on the front wheels so that the CG is an appropriate location when it's fully loaded.

The tradeoff for this is poor traction on the rear wheels when the vehicle is lightly loaded. Also, stiff springs can provide a bumpy ride when lightly loaded.

You would think I was nodding agreement but it actually my head just bouncing from the stiff springs on horrible new england roads. It is going to be sweet relief to be able to soften when unloaded and stiffen when loaded. I think part of the oversteer can be corrected by the fly by wire...
But really I don't mind oversteer when fully loaded... I'm driving slow and careful anyway... its the horrible ride I have to put up with most of the time that I'm excited to lose.

 

[Luke42]

But really I don't mind oversteer when fully loaded...

It's possible that they may be able to compensate for this through traction control software.

However, replacing natural stability with drive-by-wire comes with tradeoffs when you start considering failure modes:
If the computer crashes, so does the plane.

I don't think that having an oversteer tendency while fully loaded is anywhere as tricky as the X-29, but it is an extreme example which shows the issues one might encounter when replacing inherent stability with software.

 

[Dids]

It's possible that they may be able to compensate for this through traction control software.

However, replacing natural stability with drive-by-wire comes with tradeoffs when you start considering failure modes:
If the computer crashes, so does the plane.

I don't think that having an oversteer tendency while fully loaded is anywhere as tricky as the X-29, but it is an extreme example which shows the issues one might encounter when replacing inherent stability with software.

I hope my cybertruck sounds exactly like that plane. What a cool plane!

 

[madquadbiker]

How many feet are you planning to jack up the back of the truck in order to move the CG forward?

Let's diagram this using F-150 dimensions (250" long, 75" high). Let's put the CG about 10" aft of midpoint of the truck, about 135" from the front bumper, and at about 37" above the ground. These are fairly favorable assumptions for a vehicle with 3500lbs of cargo on the back axle.

You're going to have to lift the back of the truck much more than 10" in order to is move the CG forward 10", because the CG will track the outside of a circle with a radius of 90ish inches, centered on the front wheel.

You can only move the CG forward by jacking up the back if the CG is already very close to where it needs to be. It's a hack which works on an already-mostly-balanced vehicle, not the primary means of balancing the vehicle.



Trucks have stiff springs in the back to prevent the back end from sagging and wallowing under the weight, not to move the CG around.

Conventional pickups solve the CG problem by putting most of the empty-weight of the vehicle on the front wheels so that the CG is an appropriate location when it's fully loaded.

The tradeoff for this is poor traction on the rear wheels when the vehicle is lightly loaded. Also, stiff springs can provide a bumpy ride when lightly loaded.

Being able to increase the air pressure in the rear bags will not only level the vehicle but you will feel safer and more comfortable with a heavy load, when I changed from the Toyota Hilux to the Nissan Navara which has rear coil springs instead of leaf springs, I was shocked the first time I had a 1 ton bulk bag of sand in the bed, it felt like the front wheels were about to come off the ground, very unnerving but when I swapped out the coils for air bags I have the best of both worlds, soft and compliant or stiffened up for carrying heavy loads, I’m only talking of going from 45psi where the ride is super smooth to around 100psi fully loaded.

 

[Sirfun]

The problem with is that, when it has 3500lbs in the bed, it will be heavy on the back.

Tail-heavy cars are prone to "oversteer", which really means that the back wants to become the front in low-traction (or partial traction) conditions.

Most regular street vehicles are set up to slide straight in low traction conditions (rather than oversteer), which means that:
a) the front wheels have bigger brakes and lock up before the rear wheels.
b) A front-heavy weight bias in all load conditions.

I've owned four pickup trucks over the years, and driven them in a variety of (over)loading conditions.

It looks to me like existing pickup trucks are nose-heavy, not because it's impossible to build a pickup with a 51/49 weight distribution, but because a 70/30 (or 60/40) weight distribution means the truck can be 51/49 when fully loaded.

If the CT has a 51/49 weight distribution when empty, I'd be reluctant to put 3500lbs in the bed without knowing how they plan to solve the oversteer problem.

Easy to solve the oversteer problem, just drive like a sane person knowing they have a fully loaded pick-up. Same thing happens in a Regular pickup.