Cube topper vs aero topper vs topperless. (200 KWH battery)

John Forde

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Guesstimating CT Wh/mile @ 70 MPH

Cube topper 420 Wh/mi, range 475 miles
Aero topper 360 Wh/mi, range 555 miles (best value?)
Topperless 350 Wh/mi, range 570 miles

Thoughts? Quantified guesstimates?
Tesla Cybertruck Cube topper vs aero topper vs topperless. (200 KWH battery) CT Topper cube vs aero
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what is wh/mi to miles per kwh? my leaf uses that. it gets 3.8 avg...
and what kind of miles per kwh does a something like a model x get?
 
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John Forde

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I have a Model Y. It's rated at 248 Wh/mi. Get's that in perfect conditions at 63 mph. We average about 280 Wh/mi @ 65 mph & 330 Wh/mi @ 75 mph.
Your Leaf @ 3.8 mi/Kwh = 263. Wh/mi
 
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John Forde

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Because so much of the aerodynamic drags is in the area of separated airflow behind the vehicle a well designed foldout 'whale tail' could both lower the height of the separation from 57" to 41" and narrow it from 80" to 60" This would reduce the separated area from 4500" sq to about 2500" sq. Just a guess but this would seem to increase efficiency range by 10-20%. You'd just have to fold the whaletail to supercharge.

Tesla Cybertruck Cube topper vs aero topper vs topperless. (200 KWH battery) Screen Shot 2020-07-17 at 8.19.32 AM copy 2


Tesla Cybertruck Cube topper vs aero topper vs topperless. (200 KWH battery) CT WT
 


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Guesstimating CT Wh/mile @ 70 MPH

Cube topper 420 Wh/mi, range 475 miles
Aero topper 360 Wh/mi, range 555 miles (best value?)
Topperless 350 Wh/mi, range 570 miles

Thoughts? Quantified guesstimates?
CT Topper cube vs aero.png
No aeronautical engineer, sailor, results defy experience. Top example; aero-design entry bellow to a large chord depth in middle terminating down to a small concave separation. Flyboys call that a wing. A high lift shape that we use on sailboats to power through chop and medium wind<14kts.
Bottom example; smooth transition off the Cybertruck fwd slope, breakover angle>30° terminates at the vehicle limit in-line and 90° to vertical. Fluid dynamics coaching used shaping underwater hull and keels teaches that air attachment separates with that greater than 30° angle. That separation ==turbulence=drag until it cleanly breaks-off at the nice 90° point.
Both examples fail the efficiency envelope adding additional force vectors in lift and drag. Forced to choose? I‘d redesign the bottom example as a collapsible shell. $0.02
 
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John Forde

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Good idea! I am interested in this one. Maybe a dozen pics. Source is just some rendering house.

Tesla Cybertruck Cube topper vs aero topper vs topperless. (200 KWH battery) cybertruck-tesla-3d-model-low-poly-obj-fbx-ma-stl-unitypackage-uasset-3


Tesla Cybertruck Cube topper vs aero topper vs topperless. (200 KWH battery) cybertruck-tesla-3d-model-low-poly-obj-fbx-ma-stl-unitypackage-uasset-1


Tesla Cybertruck Cube topper vs aero topper vs topperless. (200 KWH battery) cybertruck-tesla-3d-model-low-poly-obj-fbx-ma-stl-unitypackage-uasset-5
 

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Vortex generators are used to maintain laminar flow over the surface. They do not create turbulent airflow. As the wing or surface gets bigger or smaller the airflow can separate from the surface and create turbulent airflow. The Vortex generator gives the airstream guidance to maintain smooth flow over those surface.

How do Vortex Generators Work? - YouTube
 
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John Forde

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I'll just leave this here..... :cool:

Curious as to what conclusion you would like us to draw. Cybertruck is quite different from the F 150. I saw another video that explained why no tailgate was less efficient than tailgate up (makes the entire back of the cab a high drag area) But I have not seen WHY netting improves efficiency or why tailgate down is least efficient.
 


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Curious as to what conclusion you would like us to draw. Cybertruck is quite different from the F 150. I saw another video that explained why no tailgate was less efficient than tailgate up (makes the entire back of the cab a high drag area) But I have not seen WHY netting improves efficiency or why tailgate down is least efficient.
I think the only conclusion is "It's complicated, counter-intuitive, and controversial". :)
 

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Guesstimating CT Wh/mile @ 70 MPH

Cube topper 420 Wh/mi, range 475 miles
Aero topper 360 Wh/mi, range 555 miles (best value?)
Topperless 350 Wh/mi, range 570 miles

Thoughts? Quantified guesstimates?
CT Topper cube vs aero.png
You are suggesting that the CT efficiency will be close to the Model X? The btteries will be two generations newer, the weight will be higher, the drag forces will be (much) higher, and the battery pack size will probably be different than you think. I am wondering why you think the range will be greater than what Tesla published and suggest that you revise your predictions downward to be more reasonable (or publish your algorithm).

https://insideevs.com/news/451212/epa-range-efficiency-2021-tesla-model-x/
 

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I was going by this one:
I like that video and it is a reasonable set of calculations. But how did you arrive at the range estimates being higher than Tesla published? Using CleanerWatt's numbers the DM CT would have a 107 KwH battery pack and the TM CT would then have to have a 177 KwH battery pack for the published ranges of 300/500 respectively. Your ranges are all higher. You have 570 miles for the topperless (stock) variant. 15% higher. Why? I recall someone at some point claiming that the CT range would be higher but it wasn't Elon that said it. Is that what you are going by? Just curious.
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