Aerodynamic optimization for towing 2.53 m width and 4 m height obejcts

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The main task for my Cybertruck will be to tow house segments from the construction hall to the building ground.
The main problem for range is here air resistance. The typical speed will be 90 km/h.
When the drag = 1, this would mean:

25 m/sec * 10 m² area * 1.3 kg (1 m³ air) * 25²/2 * cw 1 = 101 kW.

Assuming 1% rolling resistance, Cybertruck loaded to 3500 kg, trailer 3500 kg

25 m/sec * 0.01 rolling resistance * 7000 kg * 9.81 m/sec² gravity = 17 kW.

So something mounted on the Cybertruck for aerodynamic optimization could drastic increase range.
118 kW, half of this is 59 kW. So bringing down cw to 0.4 would double the range. Any ideas and solutions welcomed.

 

Ogre

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How far are you towing them? How many are there total?

Unless you are towing hundreds of things hundreds of miles, it’s unlikely to be worth optimizing. If it is worth optimizing, it’s unlikely with the little information you’ve provided anyone here can help.

Likely the best/ only practical optimization will be **drive slower**.
 
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I assume the average distance to a customer will be 200 km.
Per house are 7 transports. One construction hall will be designed for 60 houses per year.
So 200 km * 60 houses * 7 transports per house are 84,000 km/a towing and 84.000 km/a on the way back. So will need 2 Cybertrucks per construction hall.
 

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I assume the average distance to a customer will be 200 km.
Per house are 7 transports. One construction hall will be designed for 60 houses per year.
So 200 km * 60 houses * 7 transports per house are 84,000 km/a towing and 84.000 km/a on the way back. So will need 2 Cybertrucks per construction hall.
So buy the Cybertruck with 500 miles (800km) range. You pay $20k (USD) more but likely never need to do anything to optimize range.


Just noticed this from the top post.

Assuming 1% rolling resistance, Cybertruck loaded to 3500 kg, trailer 3500 kg
If you load 3,500 kg into the Cybertruck (seems unlikely unless it’s steel plates or something) it will destroy the suspension of the truck. Also, if you load the truck to it’s max capacity, you can’t also tow a load.
 


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....
Also, if you load the truck to it’s max capacity, you can’t also tow a load.
It that really true?

My understanding is the tongue weight of the trailer needed to be accounted for in the truck's payload allowance (3,500 lbs for Cybertruck). Cybertruck payload allowance of 3,500lb must include weight of everything the truck is carrying in it (frunk contents, driver, all passengers, other cabin contents, bed contents, sail panels) and the trailer tongue weight. Tongue weight depends on the trailer's load weight distribution (balance) over its length and the wheel configuration under the trailer.

There is actually a specification that is critical but for which Tesla has not told us the value.
Each truck that is towing has a maximum total weight for Cybertruck itself, truck payload (max 3,500 lbs), trailer weight, trailer payload. This value s Gross combined vehicle weight rating (GCWR).
* edit. above example is using lbs measurement not kg.


If Founder's used a standard type flat bed trailer (no front wheels, 2 axle tot 8 rear wheels) with 3,500 lbs on top of trailer but balanced so tongue weight was 420lbs (12% of load), Founder might be able to carry 3,080 lbs in the Cybertruck itself (frunk contents, driver, all passengers, other cabin contents, bed contents, sail panels).

---------------------------------

GVWR vs. GCWR: What's the Difference, and Why Does It Matter? How to properly measure towing capacity, payload, and more.
Aug 18, 2021
Motortrend
https://www.motortrend.com/features/gvwr-vs-gcwr/

Gross combined vehicle weight rating (GCWR), however, is the maximum weight of a vehicle and its attached trailer. This figure is also inclusive of all passengers and cargo in both the tow vehicle and the trailer. This is also sometimes referred to as gross combined vehicle weight rating (GCVWR).

---------------------------------

What is the minimum tongue weight? What Is Proper Tongue Weight?
For conventional trailers with ball-mounted hitches, proper tongue weight is roughly 10 to 15 percent of the total loaded trailer weight.

GMC Life - Tongue Weight Is Key To Safe Towing
https://www.gmc.com/gmc-life/trucks/why-tongue-weight-is-important-for-safe-towing

---------------------------------

etrailer.com - Determining Trailer Tongue Weight
In order to make sure your trailer is properly loaded, you need to know your trailer tongue weight. Tongue weight is the weight that the fully loaded trailer exerts downward on the hitch ball of the tow vehicle. Typically, your tongue weight should be 10-15% of your total trailer weight. If you don't know the tongue weight of your trailer, there are several different ways you can measure it.
https://www.etrailer.com/faq-how-to-determine-trailer-tongue-weight.aspx

---------------------------------
 
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It that really true?
Well it is certainly true that 3,500 kg is too much weight for the truck.

Whether or not you can have a full load plus a trailer I am less certain of. I’d thought you combined tongue weight with payload to figure your load, but just going off of memory.
 

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Well it is certainly true that 3,500 kg is too much weight for the truck.

Whether or not you can have a full load plus a trailer I am less certain of. I’d thought you combined tongue weight with payload to figure your load, but just going off of memory.

Ooops, I did not notice the kilograms designation. 3,500 kg is 7,700 lbs. Yes, you are right that is way over Cybertruck's limit.

I am pretty sure the loaded trailer's tongue weight must be subtracted for the towing truck's payload allowance.
 

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Cybertruck Tri motor is supposed have payload limit of 3,500 lbs ( 1,587 kg) and towing of 14,000 lbs ( 6,350 kg)

Assuming the Cybertruck's GCWR allowed.

Here is my example redone in metric measurements with towing total 6,350 kg (trailer & trailer load). If Founder's used a standard type flat bed trailer (no front wheels, 2 axle tot 8 rear wheels), total weight 6,350 kg (trailer + trailer load) and with tongue weight of 762 kg (12% of load), Founder might be able to carry 825 kg ( 1,818 lbs) in the Cybertruck itself (frunk contents, driver, all passengers, other cabin contents, bed contents, sail panels).

* edit - need to subtract weight of flat bed trailer
 
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Cybertruck Tri motor is supposed have payload limit of 3,500 lbs ( 1,587 kg) and towing of 14,000 lbs ( 6,350 kg)

Assuming the Cybertruck's GCWR allowed.

Here is my example redone in metric measurements with towing total 6,350 kg (trailer & trailer load). If Founder's used a standard type flat bed trailer (no front wheels, 2 axle tot 8 rear wheels), total weight 6,350 kg (trailer + trailer load) and with tongue weight of 762 kg (12% of load), Founder might be able to carry 825 kg ( 1,818 lbs) in the Cybertruck itself (frunk contents, driver, all passengers, other cabin contents, bed contents, sail panels).
This is more or less what I was trying to say.
 


JBee

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Hi Roland!

And welcome to the forum!

First up lets have a look at your assumptions a bit. I think your drag coefficient of 1 is too high, because the Cybertruck (CT for short) will be driving in front of the load on the trailer and effectively be making a hole to make it slip through easier. The CT will displace about 1/3 of your frontal area before the load, but will also have extra drag from what ever gap you have between the CT and the load around the tow hitch area.

The best way to combat this would be as was also mentioned previously:
a) Limit your travelling speed - halving your speed will quadruple your available energy, so even incremental changes in velocity will have a big impact on EV range
b) You can use a trailer mounted wind deflector like this, but bigger to fit the load, that you install on the load temporarily for transport to bring down the drag coefficient:

NoseCone-Box-Trailer-2.jpg


c) You can also do the same to the rear if you have enough available length on the trailer:

Trailer-Tail-300x158.jpg


d) It's also important to consider the aerodynamics at the ground level around the trailer, between the load and the ground. These areas are common to improve aerodynamics:

Different combinations of fairing on the baseline semi-trailer truck... |  Download Scientific Diagram


e) A wind deflector roof mounted on the CT bed itself will probably work the best, similar to this shape, but not as much of angle: (Ignore the camper part ;) )

$24,000 Space Camper for Tesla Cybertruck Promises Clever, Stylish EV  Lodging


f) a extendable hitch - these are available in Europe on "Jumbo" transport trucks, where the trailer is pulled close to the pulling vehicle to reduce turbulence and drag around the tow hitch area.

g) Any combination of the above, but ideally a combination of a CT roof deflector, a top mounted load defector, load side skirts, and the extendable hitch would have the greatest effect. The rear deflectors are optional. All the parts could be constructed in such a way they are removable and can return on the empty trailer back to the factory for the next load. You should be able to achieve 0.5-0.6Cd like that.

The other thing is to have a look if you can optimise the load shape itself, to be lower profile. I'm assuming you are doing either house modules or tiny home style construction? If so then you are actually transporting more air volume around than "meaningful" goods. So if you can then maybe an option is to borrow the popup shoebox design from your country mans RV maker Action Mobile:

http://www.actionmobil.com/en/news-events/blog/technology-special-action-mobil-elevating-roofs-1

In regards to vehicle loads, are you planning to use a trailer that is pulled by the tow ball, or will it be a articulated/5th wheel trailer which is mounted in the bed? The fifth wheel type needs to be constructed in such a way that it doesn't hit the CT side sails as they are higher than a normal pickup bed. If you used a 5th wheel trailer, the aerodynamic wind deflectors could be mounted directly to that, meaning you wouldn't have to detach/reattach them with each load.

The other advantage of the 5th wheel design, is that you can add about 1 - 1.2 tons of weight to the CT bed, meaning on a TM CT you would have around 7,500kg available for trailer and load. With a normal tow hitch version that would only be around 6500kg including trailer mass.

Failing that, I can only suggest to build you factory on a Austrian mountain top and only deliver to customers that are downhill from you! ;) :ROFLMAO:

Feel free to ask for more details if you need them.
 

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Cybertruck Tri motor is supposed have payload limit of 3,500 lbs ( 1,587 kg) and towing of 14,000 lbs ( 6,350 kg)

Assuming the Cybertruck's GCWR allowed.

Here is my example redone in metric measurements with towing total 6,350 kg (trailer & trailer load). If Founder's used a standard type flat bed trailer (no front wheels, 2 axle tot 8 rear wheels), total weight 6,350 kg (trailer + trailer load) and with tongue weight of 762 kg (12% of load), Founder might be able to carry 825 kg ( 1,818 lbs) in the Cybertruck itself (frunk contents, driver, all passengers, other cabin contents, bed contents, sail panels).
I'd expect a maximum tongue weight of around 250-300kg, but not more as it will not be stable to drive the CT like that with so much weight behind the rear axle, which would lift the front wheels off the ground and overload the rear axle. Load placement is critical because of the lever effect it has.

P.S. This means the CT could have around 1.2 tons payload including passengers, whilst towing maximum trailer load. Definitely not one or the other.
 
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firsttruck

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Cybertruck Tri motor is supposed have payload limit of 3,500 lbs ( 1,587 kg) and towing of 14,000 lbs ( 6,350 kg)

Assuming the Cybertruck's GCWR allowed.

Here is my example redone in metric measurements with towing total 6,350 kg (trailer & trailer load). If Founder's used a standard type flat bed trailer (no front wheels, 2 axle tot 8 rear wheels), total weight 6,350 kg (trailer + trailer load) and with tongue weight of 762 kg (12% of load), Founder might be able to carry 825 kg ( 1,818 lbs) in the Cybertruck itself (frunk contents, driver, all passengers, other cabin contents, bed contents, sail panels).
This is more or less what I was trying to say.

Agree.

Basically if Founder has about 7,500 kg and 7,500 kg to transport he will have to make at least two trips with the Cybertruck Tri-motor and trailer (per trip, approx 825 kg + 6,350 kg - weight flat bed trailer).
 
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The main task for my Cybertruck will be to tow house segments from the construction hall to the building ground.
The main problem for range is here air resistance. The typical speed will be 90 km/h.
When the drag = 1, this would mean:

25 m/sec * 10 m² area * 1.3 kg (1 m³ air) * 25²/2 * cw 1 = 101 kW.

Assuming 1% rolling resistance, Cybertruck loaded to 3500 kg, trailer 3500 kg

25 m/sec * 0.01 rolling resistance * 7000 kg * 9.81 m/sec² gravity = 17 kW.

So something mounted on the Cybertruck for aerodynamic optimization could drastic increase range.
118 kW, half of this is 59 kW. So bringing down cw to 0.4 would double the range. Any ideas and solutions welcomed.
Get the rumored titanium edition quad motor 1000 mile range. At $119,000 a pop, it might be the right fit for you.
 

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I assume the average distance to a customer will be 200 km.
Per house are 7 transports. One construction hall will be designed for 60 houses per year.
So 200 km * 60 houses * 7 transports per house are 84,000 km/a towing and 84.000 km/a on the way back. So will need 2 Cybertrucks per construction hall.
I think you should have a semi-trailer designed for you by a trailer building company that will maximize ease of loading/unloading of your modular houses. This will allow the house to be delivered in one trip instead of 7. It will probably just be a flatbed. I know you are probably thinking it would be more ideal for the houses to arrive in stages but, even if you need to get a permit to park the trailer on/near site during construction, I think the ease of logistics will make this more than worthwhile. Letting the assembly crew proceed at their own pace without the logistics of deliveries is worth a lot. You can either hire a trucking company to deliver your trailer or buy your own tractor. This is not an ideal application for the Tesla semi because of the low utilization factor. Just get an older tractor that is in the last 25% of its useful life.

There is so much pent up demand for Cybertrucks and Tesla semi's that no one should be under the illusion that by buying one they are helping to speed the transition to sustainable transport. All EV trucks that can be produced will be gobbled up and put into service with or without your support so what really matters is the utilization factor of new EV trucks (regardless of whether it's your company that's using them or not).

 

 
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