Trailer towing Range

Molotov

Well-known member
First Name
Richard
Joined
May 3, 2021
Threads
5
Messages
98
Reaction score
141
Location
Kansas
Vehicles
Model Y Performance
Occupation
Retired
Country flag
I wonder how efficient my Cybertruck will be when towing my little Casita. It's fairly aerodynamic, but my Ram 1500 Hemi averages 13 mpg towing it at 65 mph. I have never towed it with my MYP.
Tesla Cybertruck Trailer towing Range casita at burning man
Sponsored

 

CyberGus

Well-known member
First Name
Gus
Joined
May 22, 2021
Threads
53
Messages
4,093
Reaction score
13,188
Location
Austin, TX
Website
www.timeanddate.com
Vehicles
1981 DeLorean, 2023 Cybertruck
Occupation
IT Specialist
Country flag
I wonder how efficient my Cybertruck will be when towing my little Casita. It's fairly aerodynamic, but my Ram 1500 Hemi averages 13 mpg towing it at 65 mph. I have never towed it with my MYP.
casita at burning man.jpg
Fill it with helium balloons
 

ldjessee

Well-known member
First Name
Lloyd
Joined
Apr 22, 2020
Threads
14
Messages
1,080
Reaction score
1,292
Location
Indiana, USA
Vehicles
Nissan Leaf, Subaru Outback, Kaw 1700 Vaquero
Occupation
data manager & analyst
Country flag
Take a trailer with a flat front, but a tapered rear, then compare it to the v front, flat rear.
(Assuming the same height, width, and weight of the trailer)
The tapered rear will be much more ‘aerodynamic’ because the drag is significantly reduced. The v front does not reduce drag, it does not reduce the frontal area, and those two factors have significant influences on the ‘aerodynamics’ of a vehicle.

The little trailer is neat, but all the things sticking off of it or the disruptions to its lines… the roof top AC unit could be streamlined or put else where, the awning should be integrated into the interior, as well as make the door flush with the skin of the trailer.

Think of how some whales, dolphins, sharks, and such are shapedMoving thru water can be harder…
 

PilotPete

Well-known member
First Name
Pete
Joined
May 8, 2023
Threads
5
Messages
606
Reaction score
1,499
Vehicles
Porsche, BMW
Occupation
Pilot
Country flag
Take a trailer with a flat front, but a tapered rear, then compare it to the v front, flat rear.
(Assuming the same height, width, and weight of the trailer)
The tapered rear will be much more ‘aerodynamic’ because the drag is significantly reduced. The v front does not reduce drag, it does not reduce the frontal area, and those two factors have significant influences on the ‘aerodynamics’ of a vehicle.
I was agreeing with you, right up until you said “The v front does not reduce drag.” Yes, it does. In a trailer, its impact on drag reduction is not as great as the back (as you point out), but it DOES reduce some of the drag. The only possible exception to that would be if it were being towed by a van, the same size or larger, so that the trailer could sit in the “shadow” of the van.
 


Luke42

Well-known member
First Name
Luke
Joined
Aug 10, 2020
Threads
0
Messages
1,166
Reaction score
2,169
Location
Illinois, USA
Vehicles
Tesla Model Y, GMC Sierra Hybrid 3HB (2-Mode)
Country flag
Take a trailer with a flat front, but a tapered rear, then compare it to the v front, flat rear.
(Assuming the same height, width, and weight of the trailer)
The tapered rear will be much more ‘aerodynamic’ because the drag is significantly reduced. The v front does not reduce drag, it does not reduce the frontal area, and those two factors have significant influences on the ‘aerodynamics’ of a vehicle.

The little trailer is neat, but all the things sticking off of it or the disruptions to its lines… the roof top AC unit could be streamlined or put else where, the awning should be integrated into the interior, as well as make the door flush with the skin of the trailer.

Think of how some whales, dolphins, sharks, and such are shapedMoving thru water can be harder…
It is possible to increase drag via the taper at the back.

For instance, the R-Pod campers got this just-wrong and they have a stall-strip installed as a hacky way fix their aerodynamics.

I agree that tapering the back is a good idea, I just need to point out that the implementation details matter for getting the effect you're looking for.
 

fhteagle

Well-known member
Joined
Sep 28, 2022
Threads
1
Messages
162
Reaction score
349
Location
Telluride, CO
Vehicles
2013 Volt, CT Res x2
Country flag
Tesla Cybertruck Trailer towing Range 1694870251635


en.m.wikipedia.org/wiki/Drag_coefficient

Notice the "angled cube" vs "cube". Despite the angled cube presenting a wider total cross section to the wind at its mid point, because it gets to that maximum cross section and back more slowly and evenly, it actually has a lower coefficient of drag.

This is due to the "area rule" concept I talked of a few posts back.

https://en.m.wikipedia.org/wiki/Area_rule

There's actually one more shape missing from that chart, which is the "streamlined body" with the curves after it's maximum width point inverted. I remember papers on that shape claiming it was actually lower drag per unit volume. Apparently, detaching a toroidal wake at just the right size actually causes some air to push forward again on the rear end. This effect has been documented in fish, as an explanation for how they can stay mostly motionless in a flowing stream. Good luck utilizing that effect in the automotive world though, with all the complications like varying speed, cross wind, and the incompressible ground below you.
 
First Name
Bob
Joined
Oct 13, 2022
Threads
0
Messages
12
Reaction score
21
Location
New Hampshire
Vehicles
F150, SQ5, Cybertruck if Elon will build it!
Occupation
Project Manager
Country flag
1694870251635.png


en.m.wikipedia.org/wiki/Drag_coefficient

Notice the "angled cube" vs "cube". Despite the angled cube presenting a wider total cross section to the wind at its mid point, because it gets to that maximum cross section and back more slowly and evenly, it actually has a lower coefficient of drag.

This is due to the "area rule" concept I talked of a few posts back.

https://en.m.wikipedia.org/wiki/Area_rule

There's actually one more shape missing from that chart, which is the "streamlined body" with the curves after it's maximum width point inverted. I remember papers on that shape claiming it was actually lower drag per unit volume. Apparently, detaching a toroidal wake at just the right size actually causes some air to push forward again on the rear end. This effect has been documented in fish, as an explanation for how they can stay mostly motionless in a flowing stream. Good luck utilizing that effect in the automotive world though, with all the complications like varying speed, cross wind, and the incompressible ground below you.
Love that diagram and I feel like I intuitively understand the impacts of the different shapes with one exception - why is the half-sphere LOWER drag than the full sphere? The way I’ve always thought of aero, conceptually at least, is in terms of a “vacuum shadow” behind the shape moving through the air. In other words, if you had a wind tunnel and string/ribbons so you could see the air flow, at the point where the laminar flow detaches from the shape, the area between the boundary layer and the object represents a complex shape filled with different layers of vacuum pulling back on the object (drag). And filling in that shape with more “object” would effectively reduce the area of the vacuum shadow, reducing the drag. So basically the reason a airfoil has such lower drag than a sphere is that the vacuum shadow behind the widest point of the foil is “filled in” by the trailing structure of the air foil, so there is no vacuum shadow, at least at certain speeds. Given this, I’d almost expect the half-sphere going backwards (flat side first) to be close to the sphere‘s Cd, but higher, and the half-sphere with the curved edge going first and the flat side trailing would be much higher. Why is the half-sphere’s CD Lower than the full sphere? That makes no sense to me…
 

ldjessee

Well-known member
First Name
Lloyd
Joined
Apr 22, 2020
Threads
14
Messages
1,080
Reaction score
1,292
Location
Indiana, USA
Vehicles
Nissan Leaf, Subaru Outback, Kaw 1700 Vaquero
Occupation
data manager & analyst
Country flag
The way it was explained to me is that a sharp edge causes clean separation and so the air behind the flat surface tends to stay there in a turbulent air pocket, while the sphere causes irregular separation that can cause oscillations, but no static pocket of air remains, so drag is increased.
I could be misremembering or been informed badly… so please do not take my word for it.
 


PilotPete

Well-known member
First Name
Pete
Joined
May 8, 2023
Threads
5
Messages
606
Reaction score
1,499
Vehicles
Porsche, BMW
Occupation
Pilot
Country flag
No, that's a fine layman's explanation ^-^

Another thing that trips up is that it's different at different speeds.

-Crissa
Yep, and quick look at the actual chart on Wikipedia indicates that the shapes all have the same Reynolds number. But that number is calculated from four values, 3 of which are based on the fluid through which the object is passing. As pointed out, velocity is one of those values. And the two publications from which the numbers appear to be derived, are Dynamic response of pipe rack steel structures to explosion loads and Explosion Hazards and Evaluation. The former is a masters thesis, the latter is a published book. If you’re looking at lift and drag during an explosion, you’re looking at supersonic flow, where the behaviors are much different. I didn’t buy the book, but I did go over the paper. This chart appears to bd derived from a chart in the paper which is evaluating the backside load on small pipe and other construction materials when compared to the shock load on the frontside.

Shock wave formation and interaction are not an issue with any street legal vehicle.
 

ldjessee

Well-known member
First Name
Lloyd
Joined
Apr 22, 2020
Threads
14
Messages
1,080
Reaction score
1,292
Location
Indiana, USA
Vehicles
Nissan Leaf, Subaru Outback, Kaw 1700 Vaquero
Occupation
data manager & analyst
Country flag
I was taught some basic aerodynamics and theory of flight when going thru training to be a helicopter mechanic.
I guess some of it stuck.
The rest I learned from others on ecomodders.
 

PilotPete

Well-known member
First Name
Pete
Joined
May 8, 2023
Threads
5
Messages
606
Reaction score
1,499
Vehicles
Porsche, BMW
Occupation
Pilot
Country flag
I was taught some basic aerodynamics and theory of flight when going thru training to be a helicopter mechanic.
I guess some of it stuck.
The rest I learned from others on ecomodders.
Helicopters are proof that with enough power applied, anything can fly. :ROFLMAO:
 

ldjessee

Well-known member
First Name
Lloyd
Joined
Apr 22, 2020
Threads
14
Messages
1,080
Reaction score
1,292
Location
Indiana, USA
Vehicles
Nissan Leaf, Subaru Outback, Kaw 1700 Vaquero
Occupation
data manager & analyst
Country flag
Helicopters are proof that with enough power applied, anything can fly. :ROFLMAO:
Helicopter definitely beat the air into submission… but one show of weakness, and down you go…
Sponsored

 


 


Top