4 ms·

> would increase fuel economy by 15-25% Makes you wonder if/why truck companies don't have aerodynamics experts on their payroll.

by amelius 9mo ago

n4r9 9mo ago
Those figures are from the 1970s, when presumably there was a lot more low-hanging fruit. Still, I wouldn't be surprised if they invest a decent chunk into computation aerodynamical work as part of their body design.
- roysting 9mo ago
  You’re also touching on a rather large ignored issue in this article, that this NASA truck aerodynamics project was directly connected to the 1973 oil crisis and a government wide effort to reduce oil consumption, not just some epiphany by some guy on a bike.
  - irishcoffee 9mo ago
    Both can be true. Sounds like the classic: necessity is the mother of invention I don't understand why you put such a negative spin on this. Who loses when trying to become more energy efficient?
cucumber3732842 9mo ago
They absolutely do design trucks for aerodynamics. Fuel economy is a huge avenue of competition for semi trucks. The reality is just that with the drive cycles and costs and tradeoffs of implementing all this it's not worth it to go this far. Second, this sort of "round the whole thing" approach has mostly been replaced with "the simulation says we can do a 90/10 if we just do X, someone print up a block and toss it in the wind tunnel and see how it does" type approach so the result tends to be more surgical modifications and use of dead air and less "smooth out the whole thing with fairings".
- embedding-shape 9mo ago
  > They absolutely do design trucks for aerodynamics I know next to nothing about trucks, and vehicles in general, but something I've noticed, and probably everyone else, is that trucks in the US looks very different from trucks in Europe, it's very easy to identify which one is a US-like truck vs a Europe-like one, because of the shape of the "cab" or whatever that part is called. So one design has to be clearly better than the alternative, given that aerodynamics works the same all around the world, but still the designs are uniquely... unique. But why is it like this? If trucks were designed for aerodynamics, shouldn't one of the designs have "won" by now, or are they truly equal in terms of aerodynamics?
  - pjc50 9mo ago
    Did a bit of research: https://news.ycombinator.com/item?id=47121031 https://news.ycombinator.com/item?id=47121031 - different countries have different legal requirements, despite air being the same everywhere.
    - embedding-shape 9mo ago
      Judging by the images only, those are all the ones I called "European" trucks though, the American ones are much longer. Is that also regulated so European trucks aren't allowed in the US and American ones aren't allowed in Europe? Because here in Europe it's really uncommon to see the US ones, and I'm guessing it's the opposite in the US? One of them must be better aerodynamically though, must'n it?
      - masklinn 9mo ago
        Europe has length limits on the entire thing, so US trucks would require shorter trailers, which nobody really wants. Euro trucks also have significantly smaller turning radii, which makes navigating european cities and country roads… feasible. Furthermore Europe has relatively strict speed limits on trucks, which makes aero something of a lesser factor since drag grows to the square of speed: european trucks at european speeds have a pretty significantly higher efficiency than US trucks at US speeds.
quickthrowman 9mo ago
They do, look for some semi-trucks on long haul routes, they have trailer skirts and/or trailer tails.
mapt 9mo ago
Part of the issue is the extreme constraints imposed on designers by road regulation, another is simply that the majority (75%?) of drag reduction is in a fishtail that needs to go on the container, the part of the truck that gets left behind at the loading dock, that is often not "owned" by the person who owns the truck.
trashb 9mo ago
Because the individual logistics companies are not developing the trucks. The aerodynamic properties of a truck are mostly determined by the model/brand, and this is a huge consideration at companies like Scania, Volvo or Mann. Not so much at the individual logistics companies.

> would increase fuel economy by 15-25% Makes you wonder if/why truck companies don't have aerodynamics experts on their payroll.

by amelius 9mo ago

> would increase fuel economy by 15-25% Makes you wonder if/why truck companies don't have aerodynamics experts on their payroll.

n4r9 9mo ago

Those figures are from the 1970s, when presumably there was a lot more low-hanging fruit. Still, I wouldn't be surprised if they invest a decent chunk into computation aerodynamical work as part of their body design.

roysting 9mo ago
You’re also touching on a rather large ignored issue in this article, that this NASA truck aerodynamics project was directly connected to the 1973 oil crisis and a government wide effort to reduce oil consumption, not just some epiphany by some guy on a bike.
- irishcoffee 9mo ago
  Both can be true. Sounds like the classic: necessity is the mother of invention I don't understand why you put such a negative spin on this. Who loses when trying to become more energy efficient?

cucumber3732842 9mo ago

They absolutely do design trucks for aerodynamics. Fuel economy is a huge avenue of competition for semi trucks. The reality is just that with the drive cycles and costs and tradeoffs of implementing all this it's not worth it to go this far. Second, this sort of "round the whole thing" approach has mostly been replaced with "the simulation says we can do a 90/10 if we just do X, someone print up a block and toss it in the wind tunnel and see how it does" type approach so the result tends to be more surgical modifications and use of dead air and less "smooth out the whole thing with fairings".

embedding-shape 9mo ago
> They absolutely do design trucks for aerodynamics I know next to nothing about trucks, and vehicles in general, but something I've noticed, and probably everyone else, is that trucks in the US looks very different from trucks in Europe, it's very easy to identify which one is a US-like truck vs a Europe-like one, because of the shape of the "cab" or whatever that part is called. So one design has to be clearly better than the alternative, given that aerodynamics works the same all around the world, but still the designs are uniquely... unique. But why is it like this? If trucks were designed for aerodynamics, shouldn't one of the designs have "won" by now, or are they truly equal in terms of aerodynamics?
- pjc50 9mo ago
  Did a bit of research: https://news.ycombinator.com/item?id=47121031 https://news.ycombinator.com/item?id=47121031 - different countries have different legal requirements, despite air being the same everywhere.
  - embedding-shape 9mo ago
    Judging by the images only, those are all the ones I called "European" trucks though, the American ones are much longer. Is that also regulated so European trucks aren't allowed in the US and American ones aren't allowed in Europe? Because here in Europe it's really uncommon to see the US ones, and I'm guessing it's the opposite in the US? One of them must be better aerodynamically though, must'n it?
    - masklinn 9mo ago
      Europe has length limits on the entire thing, so US trucks would require shorter trailers, which nobody really wants. Euro trucks also have significantly smaller turning radii, which makes navigating european cities and country roads… feasible. Furthermore Europe has relatively strict speed limits on trucks, which makes aero something of a lesser factor since drag grows to the square of speed: european trucks at european speeds have a pretty significantly higher efficiency than US trucks at US speeds.

quickthrowman 9mo ago

They do, look for some semi-trucks on long haul routes, they have trailer skirts and/or trailer tails.

mapt 9mo ago

Part of the issue is the extreme constraints imposed on designers by road regulation, another is simply that the majority (75%?) of drag reduction is in a fishtail that needs to go on the container, the part of the truck that gets left behind at the loading dock, that is often not "owned" by the person who owns the truck.

trashb 9mo ago

Because the individual logistics companies are not developing the trucks. The aerodynamic properties of a truck are mostly determined by the model/brand, and this is a huge consideration at companies like Scania, Volvo or Mann. Not so much at the individual logistics companies.