Hi AllGood, true, there's a lot to be gained there! We made the split between "power generation" and "power consumption" in the movie to state that aero works on the consumption side and indeed, in parallel the electric drive train works wonders for the power generation side!
@@RemoteSpeed007 We didn't dive into the details of fuel versus electric drive train efficiency yet! I guess you'd have to consider the entire ecosystem around those technologies to truly assess this :):)
What happens in crosswinds? Crosswind of moderate velocity would confer an adequate angle of attack on the truck side to generate considerable horizontal lift and drag, using what is effectively a very inefficient low aspect ratio "wing". A head-on relative wind is a 1/360 possibility - so not sure why there seems to be a fixation with the head-on aerodynamics for road vehicles generally. Wind angle should be varied in the design and the shape re-optimized? Perhaps movable flaps, vortex generators, or some other aerodynamic furniture could be considered to cancel the lift. (Of course, aircraft don't have this head-on issue).
Dear Clive, you are right: cross winds can strongly influence (and usually increase) the aerodynamic resistance. In practice, we often work with a 1-5° angle of attack for trucks & cars to take this effect into account. Lift forces are usually quite low for trucks, but the lateral forces can play an important role in truck-trailer stability. And yes, vortex generators have been applied - check the AirTabs for example. It's difficult to find solid data on their performance though.
Hi Meiron, in deed we didn't mention this as Tesla is (as far as we know) not developing trailers yet. But it's correct - there is a lot to be gained by tapering the rear. Some examples are Betterflow, Transtex, ... and this one from Wabco (now ZF): www.zf.com/products/en/cv/products_64600.html It does provide you with some numbers, lik a 1.1l/100km savings (as a max)
@airshaper Could you do a video like this also for the Tesla Cybertruck? Compared to the 'standard' US trucks like the Ford F-series. How much impact does the truckbed roll cover have?
Hi Rudi, we actually already published an article on this! www.linkedin.com/feed/update/urn:li:activity:6605065059917930496 Once we have obtained a more detailed 3D model, it may indeed make sense to pour it into a video, thx!
Hi, I wonder if possible to build a truck and trailer attached in an air-dynamic way that can generate lift (since a truck is much slower than a plane, it won't take off). Such lift can reduce the friction on road and further good for fuel economy.
Theoretically, that would be possible. In reality, however, generating lift usually comes at the expense of extra aerodynamic drag (and reduced safety because of the reduced grip). The drag penalty could be higher than the reduction in friction drag. Also, the shapes you would need to have to create even 'just' 1 tonne of aerodynamic lift at 90 km/h would be very dramatic, and that lift would still be very small compared to the total weight of the truck...so it's likely not going to result in a net positive result (but I could be wrong!).
Hi Georgi, indeed they can be very different! It allows for more aerodynamic shqpes, but then again, you loose cargo space if total length is limited (which again differs per country). Thx for the comment.
Cabovers stopped being popular in the US when the law were changed so that, while there was a limit on trailer length, there is no longer a limit on total length. The long nose "conventional" cab trucks ride better, are generally safer, and allow easier access to the sleeper, and most truckers were willing to sacrifice some maneuverability for these features. The Freightliner Argosy was the last of the long-haul cabovers in the US, but they stopped selling those here over a decade ago.
Why does 20% aerodynamic reduction convert to 10% efficiency increase? That might be true for passenger vehicles (PVs), but for Semis aerodynamic matter much less and rolling resistance much more than for PVs. If we compare Tesla Semi with Model S, it has about 20x more weight but the drag does not seem to be 20x more. Maybe it is around 3-5x more.
Dear Ferenc, that's correct in the sense that heavier trucks have a relatively higher contribution of rolling resistance. The graph at the bottom of this page is quite helpful: aerodyneuk.com/fuel-saving/truck-aerodynamics/ My 50% estimation was already quite a lot lower than the perhaps 75% contribution of aero for normal cars at highway speeds. But perhaps it should be even lower!
PS: perhaps check out this document, on page 5 it shows aerodynamic drag already overtaking rolling resistance & auxiliaries at 50 mph. Of course this depends heavily on the truck, but still, it shows the relative importance of aero.
@@AirShaper Thank you for your answers. I will check out the article you have linked here. Yes, speed of course matter. What I meant for PVs it seems 50% coming from the aerodynamic drag and 50% from rolling resistance on EPA cycle. I do not have data about this, but that is what I have compiled in my brain looking at different car versions, etc. (Like comparing standard range and long range Model 3s) However if aerodynamic matter as much as you say I am very surprised truck manufacturers did not improve that much more. It is easier to make an electric Semi more aerodynamic than an ICE one, but still. I can see that there are some aerodynamic devices which improve aerodynamics (as can be seen in the article you have sent), but this is just an option. So I see a lot of trucks without these. Maybe these are used with low speed. Maybe Tesla's Semi has one more advantage: it can be used on higher average speed. That can improve capacity.
@@toth1982 Yes, you would think more manufacturers focus on this. But it's a slow process, as regulations need to follow (to allow boat tails on trailers, ...). It's coming, just check sites like this one: wabco-solutioncentre.com/optiflow-sidewings/ (of course they will be optimistic, but still, quite interesting).
Hi Joseph, thank you for your comment. We chose this model because it's the standard in Europe right now and they represent the majority of trucks on our roads. The trucks with the engine in front of the cabine are very rarely used here. :) Kind regards, The AirShaper Team
Truck is somehow a combination of a boat and airplane therefore the original concept for building it like a car is wrong from the start. It must be done differently from the start and it is a way to lower the drag around 40% by not compromising the payload. Problem is that the whole bussines of vehicle manufacturing is stuck in one way road and nobody is tall enough to look above the wall on the end of that one way cull the sack. It is something amazing there for cars,truck,F1 but it need a bit more trials at my end and also some patent or industrial design to protect myself but I think that in 6 months I will be out teaching you guys. I just got lucky that this happened to me and Im not biassed working in automotive or aerodynamics. It is simple outside box idea.
I bet you do. But Im not sure if it will get public because some people would like to work on that concept. Will see how it will progressing. Take care.
Hi Eva, in terms of absolute drag values, a truck features a lot of resistance. But relative to its volume/frontal area/cargo capacity, it becomes a more positive story. The Tesla Semi has a claimed drag coefficient of 0.35, which is indeed higher than that of a modern car (0.20-0.30), but still better than that of a pickup truck (often 0.45 and above). Also, Tesla hasn't really touched the trailer. If you tackle that one too, you can go even further - see this concept for example: airshaper.com/blog/beyond-tesla-semi-with-the-future-truck-2032
That is only part of the efficiency achieved, the electric motors will bring an additional efficiency, guessing at least 50%
Hi AllGood, true, there's a lot to be gained there! We made the split between "power generation" and "power consumption" in the movie to state that aero works on the consumption side and indeed, in parallel the electric drive train works wonders for the power generation side!
@@AirShaper Yes, Would love to know what the total efficiency of an electric Tesla truck, vs a conventional diesel/gasoline truck is.
@@RemoteSpeed007 We didn't dive into the details of fuel versus electric drive train efficiency yet! I guess you'd have to consider the entire ecosystem around those technologies to truly assess this :):)
@@AirShaper This info would be very valuable to a potential truck buyer, Tesla vs the regular trucks.
@@RemoteSpeed007 I agree AllGood, it's what I would look for as a truck buyer as well :)
Great aerodynamics, only thing missing are diffusers on the lower back.
Wow great video with cool pictures off the simulations and the features off the truck
Bedankt Sten!!
Hi! Excellent explainer. Also, Transport Evolved sent me!
Ah great!! Say hi to Nikki if you will!
Have a good one!!Thank you!
You too!
What happens in crosswinds? Crosswind of moderate velocity would confer an adequate angle of attack on the truck side to generate considerable horizontal lift and drag, using what is effectively a very inefficient low aspect ratio "wing". A head-on relative wind is a 1/360 possibility - so not sure why there seems to be a fixation with the head-on aerodynamics for road vehicles generally. Wind angle should be varied in the design and the shape re-optimized? Perhaps movable flaps, vortex generators, or some other aerodynamic furniture could be considered to cancel the lift. (Of course, aircraft don't have this head-on issue).
Dear Clive,
you are right: cross winds can strongly influence (and usually increase) the aerodynamic resistance.
In practice, we often work with a 1-5° angle of attack for trucks & cars to take this effect into account.
Lift forces are usually quite low for trucks, but the lateral forces can play an important role in truck-trailer stability. And yes, vortex generators have been applied - check the AirTabs for example. It's difficult to find solid data on their performance though.
The truck in the end should be a special anti-drag. Cheers!
Any chance of getting the 3D model files to play around and potentially come up with innovative design alternatives?
Hi Pascal, just drop me a line at wouter@airshaper.com to discuss this
You haven't mentioned the rear part of the truck. Will a kind of round ending reduce air drag comparing to the traditional square cut ending?
Hi Meiron, in deed we didn't mention this as Tesla is (as far as we know) not developing trailers yet.
But it's correct - there is a lot to be gained by tapering the rear. Some examples are Betterflow, Transtex, ... and this one from Wabco (now ZF):
www.zf.com/products/en/cv/products_64600.html
It does provide you with some numbers, lik a 1.1l/100km savings (as a max)
@airshaper Could you do a video like this also for the Tesla Cybertruck?
Compared to the 'standard' US trucks like the Ford F-series.
How much impact does the truckbed roll cover have?
Hi Rudi, we actually already published an article on this! www.linkedin.com/feed/update/urn:li:activity:6605065059917930496 Once we have obtained a more detailed 3D model, it may indeed make sense to pour it into a video, thx!
Hi, I wonder if possible to build a truck and trailer attached in an air-dynamic way that can generate lift (since a truck is much slower than a plane, it won't take off). Such lift can reduce the friction on road and further good for fuel economy.
Theoretically, that would be possible. In reality, however, generating lift usually comes at the expense of extra aerodynamic drag (and reduced safety because of the reduced grip). The drag penalty could be higher than the reduction in friction drag. Also, the shapes you would need to have to create even 'just' 1 tonne of aerodynamic lift at 90 km/h would be very dramatic, and that lift would still be very small compared to the total weight of the truck...so it's likely not going to result in a net positive result (but I could be wrong!).
so the reason why busses and trucks (in europe) have a flat front is because of the limited space?
Limiter total length of the vehicle, indeed.
Some US trucks are twice as long as European. Mostly for cabin space
Hi Georgi, indeed they can be very different! It allows for more aerodynamic shqpes, but then again, you loose cargo space if total length is limited (which again differs per country). Thx for the comment.
Yes. I dont see why they are keeping the total lenght so short in their laws.
Cabovers stopped being popular in the US when the law were changed so that, while there was a limit on trailer length, there is no longer a limit on total length. The long nose "conventional" cab trucks ride better, are generally safer, and allow easier access to the sleeper, and most truckers were willing to sacrifice some maneuverability for these features. The Freightliner Argosy was the last of the long-haul cabovers in the US, but they stopped selling those here over a decade ago.
Why does 20% aerodynamic reduction convert to 10% efficiency increase? That might be true for passenger vehicles (PVs), but for Semis aerodynamic matter much less and rolling resistance much more than for PVs. If we compare Tesla Semi with Model S, it has about 20x more weight but the drag does not seem to be 20x more. Maybe it is around 3-5x more.
Dear Ferenc,
that's correct in the sense that heavier trucks have a relatively higher contribution of rolling resistance. The graph at the bottom of this page is quite helpful:
aerodyneuk.com/fuel-saving/truck-aerodynamics/
My 50% estimation was already quite a lot lower than the perhaps 75% contribution of aero for normal cars at highway speeds. But perhaps it should be even lower!
PS: perhaps check out this document, on page 5 it shows aerodynamic drag already overtaking rolling resistance & auxiliaries at 50 mph. Of course this depends heavily on the truck, but still, it shows the relative importance of aero.
@@AirShaper Thank you for your answers. I will check out the article you have linked here.
Yes, speed of course matter. What I meant for PVs it seems 50% coming from the aerodynamic drag and 50% from rolling resistance on EPA cycle. I do not have data about this, but that is what I have compiled in my brain looking at different car versions, etc. (Like comparing standard range and long range Model 3s)
However if aerodynamic matter as much as you say I am very surprised truck manufacturers did not improve that much more. It is easier to make an electric Semi more aerodynamic than an ICE one, but still. I can see that there are some aerodynamic devices which improve aerodynamics (as can be seen in the article you have sent), but this is just an option. So I see a lot of trucks without these.
Maybe these are used with low speed. Maybe Tesla's Semi has one more advantage: it can be used on higher average speed. That can improve capacity.
@@toth1982 Yes, you would think more manufacturers focus on this. But it's a slow process, as regulations need to follow (to allow boat tails on trailers, ...). It's coming, just check sites like this one: wabco-solutioncentre.com/optiflow-sidewings/ (of course they will be optimistic, but still, quite interesting).
you can,t use cab overs
Hi Joseph, thank you for your comment. We chose this model because it's the standard in Europe right now and they represent the majority of trucks on our roads. The trucks with the engine in front of the cabine are very rarely used here. :)
Kind regards,
The AirShaper Team
How does the Tesla truck turn? There is no gap to allow the turn?
In top view you can see a circular cut-out in the truck to allow for turning I think!
Truck is somehow a combination of a boat and airplane therefore the original concept for building it like a car is wrong from the start. It must be done differently from the start and it is a way to lower the drag around 40% by not compromising the payload. Problem is that the whole bussines of vehicle manufacturing is stuck in one way road and nobody is tall enough to look above the wall on the end of that one way cull the sack. It is something amazing there for cars,truck,F1 but it need a bit more trials at my end and also some patent or industrial design to protect myself but I think that in 6 months I will be out teaching you guys. I just got lucky that this happened to me and Im not biassed working in automotive or aerodynamics. It is simple outside box idea.
We're looking forward to see the first images of your concept!
I bet you do. But Im not sure if it will get public because some people would like to work on that concept. Will see how it will progressing. Take care.
1:45 (☞ﾟヮﾟ)☞ aaaaaaaay!
:D :D
Hello an engineer told me a truck is unable to be dynamic? I disagree
Hi Eva,
in terms of absolute drag values, a truck features a lot of resistance.
But relative to its volume/frontal area/cargo capacity, it becomes a more positive story.
The Tesla Semi has a claimed drag coefficient of 0.35, which is indeed higher than that of a modern car (0.20-0.30), but still better than that of a pickup truck (often 0.45 and above).
Also, Tesla hasn't really touched the trailer. If you tackle that one too, you can go even further - see this concept for example:
airshaper.com/blog/beyond-tesla-semi-with-the-future-truck-2032
Que podre
Hi Vitor,
are you planning to optimize a truck yourself?