Calix Aero Loader reversed skibox test
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- Опубликовано: 9 сен 2024
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How many people will tell you “your roof box is on the wrong way round” 🤣😂
LOL, exactly my thought. I will start a business selling large stickers for the box with the words "THE BOX BELONGS THIS WAY, SUCKERS".
I find it amazing that we have had roofboxes for some half a century, before anyone actually started experimenting with a proper aerodynamic shape. Think of all the noise and fuel consumption people have had til deal with in those decades.
I mean aerodynamics is not a new discipline. I never understood why those roof-boxes were shaped like a reverse wing. Doesn't make sense. 🤷🏼♂️
@@RufftaMan looks I guess, also, companies are lazy- they only want money, someone was first, others copied and nobody bothered to test if there is a better way, since people bought.
I personally can't quite understand why you'd need a roof box anyway?
Of course manufacturers know and test. But who would buy a box looking wrong with everyone telling you to fix it? The looks matter à lot to consumers. They would never risk it, business wise.
@@gregft1979 People got used to crazier things before. And to me it always looked wrong the other way around.
Just slap some fuel-savings numbers on that thing and people will buy it.
Looks "odd", but also, on ICE, higher load on the engine increases efficiency. This is why ICE cars does not see such a huge change as EVs when adding a trailer, as the engines will have a more open throttle, causing less pumping loss, and higher pressure when igniting which increase the efficiency etc. An engine is at the highest efficiency when it is about 80% from max power at the given revs, and about 2k rpm tends to be the sweet spot. Engineering explained had a great video on this recently.
530 litres?! What does that mean? I only know banana boxes
You know after drinking 1060 0.5l bottles .
Lol
Banana box... New International stardard unit!!😆😆
@@Konve We don't allow partial banana boxes on this channel. If one whole banana box doesn't fit inside that fairing it has a volume of 0 banana boxes.
@@Konve There's no way this holds 10 banana boxes without crushing them.
You missed the 3rd test - driving the same trip without any box.
Yes I was hoping for that too, now we can only speculate: 160 Wh/km w/o box?
Then the traditional box adds a whopping 90 kWh/km and the reversed box still adds 68 kWh/km
@@Acamperfull ; with my Model 3 LR DM '19 my Hapro Traxer 8.6 box added around 30% to the consumption. When I set 220 Wh/km as reference in Abetterrouteplanner it worked perfectly (instead of 170 Wh/km as standard) on my trips. Spot on.
Find his "Tesla Model 3 roof box test" video. Seems to be same temperature and conditions. 186wh/km without box and 211 wh/km with box.
205Wh/km @110kmh +2C....found from Björns table
Like a fish - blunt end first. I guess it's easier to push fluid out of the way than to drag along a column of vacuum.
(Aerospace engineer here) I just always love how aerodynamics defy 'common sense'. When travelling at slow speeds (anything significantly lower than Mach 1), the rear is much more important than the front...
Is that how you explained it to your woman? :)))
The box in reverse looks a lot more like an aeroplane wing, where it would be designed to maintain laminar flow of air as far back as possible. The 'correct' direction would create more turbulent air at the trailing edge.
Very impressive result.
The main problem I foresee is possible reduced longitudinal stability due to moving the center of pressure forward. And increased lift, of course.
BTW, Kamm tails (aka Kammbacks), such as you see on SUVs, intentionally induce turbulence behind the vehicle to induce a sort of "virtual" tail.
@@Markle2k how about backward and upside down so it creates downforce?
From my flight training the most efficient shape is a traditional “teardrop” shape, rounded front, tapered point at the back. Aerodynamics is of course more complex than that, but that is the most aerodynamic shape, and almost anything on a subsonic plane will generally follow that shape.
Turbulent air is only usually used when laminar air is expected to detach from the objects surface, as turbulent air can cling better to the surface. Vortex generators are used on the upper wing surfaces to induce turbulent airflow to allow greater angles of attack before the wing stalls, at low angles of attack they do not usually improve aerodynamics. As Markle2k says, most vehicles with a flat back are designed to create a virtual tail behind them, kind of like how the bubble of air in a pickup bed improves efficiency vs putting the tail down.
@@MrPaukann exhaust gases change the equation as a tapered point at the base of a rocket is pointless because the exhaust has to go somewhere.
@@danielvanced5526, my point was that Cd isn't the only variable in the equation. Cross-section's area is there too.
Bjorn, thanks for sharing this, it's interesting, but you really needed 1)A control with no box or rack, 2)With rack, but no box, 3)With the SAME box with the "normal" mounting, and 3)SAME box with "backward" mounting. That said, it is interesting.
Thanks for confirming physics.👍
I tested my calix 600l last fall on my Ioniq(empty ofc), ~12% lower at 110km/h and ~20% lower consumption at 120km/h with it flipped compared to traditional. Great that calix had gotten around to get one designed properly!
Thanks for the test and video Björn!
Thanks for the video Bjorn.
As an engineer, I've been putting my large Thule ski box backwards for years. I do get a lot of people telling me it's on backwards. :) But then I explain to them that having the bigger end at the front is similar to a raindrop, which is the most aerodynamically efficient shape for speeds lower than the speed of sound. It's also similar to an airplane wing.
"lower than the speed of sound" - Since I occasionally go transonic, I still put my roof box on skinny end forward. Efficiency really takes a hit in that range.
A raindrop isnt shaped like that though, also when its backwards, isnt it hard putting stuff in from the front?
Raindrops are spherical...
I got probably one of the first Aero Loaders in Norway and have been very happy with it so far :) consumption in 2021 M3 LR with Aero Loader at 80-90km/h is about 170-180wh/km in approx 0C weather. Only complaints is that it wobbles a bit in the front and the construction is a bit flimsy overall
Awesome content Bjorn! You made me take the jump to Tesla with your tests!
I watched so many aerodynamic videos from Formula 1 this makes perfect sense.
The main reason it's more effective is it creates less of a hole or low pressure zone behind the box as it slopes more together and redusing the low pressure zone.
imo it doesnt look weir at all, now its actually in shape of planes wing
How does a whale look? Like this box. This is closer to the shape with lowest drag coefficient. Just looks weird.
I was going to say a raindrop, but whale works too.
For people familiared with aircafts, this is the standard profile of the wings, caulings, fuselage... It's the logic step but I never thought about it! 😁
Looks weird because we are used to "the wrong" way
Wow, thanks for testing and confirming. Aerodynamics aren’t intuitive at all! I remember you placed a ski box on a hitch mounted cargo carrier with minimal increase in consumption, I wonder if you can even increase efficiency with a well designed hitch mounted box. Calix should definitely explore that option.
Most likely, the most aerodynamic addition to the car would be an add-on tail/slope you could mount to the hitch to complete the droplet look to your EV.
Me wants it!!1
It’s probably giving some lift tot he car based on the design. Electric cars are heavy so reducing the weight by adding lift would increase efficiency
@@Swimmerchild Not really, the mass is only increasing and the losses that relate to weight are not that big. Also, making aerodynamic lift always causes drag.
@@banaana1234 Also you would actively work to reduce grip and friction, doesnt sound entirely safe to me ... :P
Bjorn! thank you for the constant uploads and content! you're my favorite youtuber, for sure. :) cheers
Bjørn, please do an additional test run with a reversed Tesla 😎
The classic "ultimate aero" shape is a hemisphere facing into the wind with a 15 degree cone in the lee. So, this checks out with elementary aerodynamic principles. BTW, this shape is also inherently aerodynamically unstable (center of pressure is forward of center of mass) and wants to swap ends over and over and why you would see experimental "aero" cars with tailfins to keep them pointed forward at higher speeds. When the car would yaw, the fin moving into the airstream would move the center of pressure rearward while also correcting for the yaw.
BTW, that thing looks an awful lot like a wing in profile, so I would limit your speed because it probably generates lift, decreasing braking and cornering performance.
I always wondered why those boxes were always constructed against aerodynamics...finally someone got it! hint: there is a reason why an airplane wing has a certain profile :-)
Ever saw a raindrop fall with the pointy end down? No, me neither.
I found from your previous tests similar 110kmh +2C test with M3LR...205Wh/km...with that box 228Wh/km is only 11% / 23Wh more....impressive for that big box. Compared to regular one 250Wh/km is 22%/45Wh more so this model dops the power consumption to half!
These are great results.
The only observation is from the side profile:
The larger and hence (could be) heavier end of the box overhangs the steepest and most fragile part of the car where the wind screen and the panoramic roof meet.
The nine percent gain would mean it worthy of trying though not on a regular basis.
Everybody with the tiniest understanding of aerodynamics knows that closing the flow is much more important than opening it. I can't believe that it took decades for the industry to even begin thinking about minimizing the drag of roof boxes
Reminds me of ripleys Aliens.🤣🤣🤣
Test would be more correct if the 2 boxes was the same size (in liters)
A diff of a few internal litres shouldn't make such a big difference, compared to reduction of unwanted turbulence.
or both tested in normal and reversed configuration.
@@kompost1 Its 86% the size. 86% of the total consumption would be 215wh/k so its looking a lot like the result lines up pretty much perfectly with the difference in volume.
If you think its creating less turbulence have a look at a model 3 in a wind tunnel then think about how that would affect the air around either box. This is sitting too far forward on the car to make much difference since it will still be fighting the flow around the roof of the car toward the tail.
Thanks for sharing! The two dudes seem nice and know what they are talking about 👍🏽
Now if you look at the design, the Model 3 in reverse might also be a lot more efficient.
Time to redesign the electric cars. :D
in aerodynamic efficiency, the tail is more important than the front in order to reduce the coefficient of drag, because in the tail are generated undesirable turbolences.
the section is equal in the two cases but different cx.
It makes sense, its aerofoil (wing) shaped that way round so should have smoother airflow.
It might be causing lift due to the shape, so balance the load in the box with the lift created and get free carrying capacity through aerodynamics?
Nice work Bjørn. Huh - never knew there where an illegal way to mount the box.
Let me count the ways
* Not securing the load INSIDE the box, like slalom skis, which fly out in a crash...
* Non-centrally positioned box, exceeding 50-75kg weight limit, in a non-EV SUV which already has a high centre of gravity. Elk-test...
* ...
The shape makes perfect sense - Tear-drop shape! Kinda like a wing (or Whale as someone else mentioned!)
Did find this a bit promotional though for a particularly branded product. Time now for other maker to catch up!
They tested this in the German TV show VOX Automobil. If I remember correctly turning the box backward saved about 0.5-0.8 l/100km fuel.
I suppose most hatchbacks slope down at the rear (to aid Air flow). So this makes sense - nice one 🇧🇻
Paint some teeth on it and it's going to look like a Xenomorph from Alien
I saw the exact same thing ! 👍
Wing shape is the right shape :)
Just a tiny explainer here - 1dB rise in sound equates to 7% rise of loudness
Fluid dynamic secrets
It looks great imo
The box does look weird in that direction, but makes sense since that is how the Thule Aero bars are shaped (like an airplane wing).
2:47 Indian Stallone younger brother 😂
That will be the perfect complement for my future R5ev 🤔🤔🤔🤔
Lower drag shape is BLUNT end at the front, and long taper and slimmer at the back. Look at any airplane wing section.
I wish someone would also test cars backwards in the wind tunnel. I think that would yield some surprising results.
thx for the videos :)
When you think about it it really is the right way because it looks like the profile of an airplane wing and they are designed for the least air turbulence
Reminds of the movie Alien, with the box in reverse
Funny that box looks like a coffin with that black M3 feels like a hearse 🙂
I did it this way last year when we went on holiday because I had tried it before and had come to the same results. I just installed my skibox (XL) backwards. You won't believe how many people talked to me while charging. Some were just curious, others wanted to tell me I had made a mistake when mounting the box. You're right - this is the new standard.
Here's an article on this topic in German: teslamag.de/news/komisch-effizient-tesla-model-3-dachbox-falsch-herum-montiert-27673
It's an ALIEN head 👍( Xenomorph from the movie Aliens ! )
The new box makes perfect sense. Just look at aeroplane wing design.
aeroplane wings arent just designed for lowest resistance? they are also meant to give lift and to get air under their wings. so i dont understand that really.
EDIT: apparently they are only designed to get lowest drag coefficient for some reason.
@@jegbryrmegikke1 yep exactly. lift aside, the displacement of air as it leaves the wing is important. its interesting that the noise was also reduced, although this wasn't exactly a scientifc test. but still very interesting. :)
New test. Nice 👍. You can also do whith a bike. Good job
why don't cargo boxes have a golf ball like texture? my understanding is that would make the aerodynamics even better?
Nice... interesting... I don't understand how it can be more efficient when turned backwards, since that end is a bigger surface area striking the air. But amazing results!
I guess it makes it more of a ‘wing’ shape. Aircraft wings and helicopter rotor blades are thickest at the leading edge before thinning out at the trailing edge. This shape produces the most lift to keep aircraft in the sky. It could be a similar principle with the roof box
Way less turbulance at the back. = less drag. The air is being released cleaner.
Look at all solar racecars most of them have a similar shape.
Same for the Prius2 and old Saab 96, Citroen DS and CX: wide up front narrow faatback shape in the rear.
It resembles a raindrop falling through the air.
Teardrop shape is most efficient aerodynamically
People underestimate the amount of effect rear turbulence has on aerodynamic drag. The larger the rear area creates a sort of suction/low pressure behind the vehicle and works against the forward direction you’re travelling in. That’s why so many efficient vehicles have a tapered rear and. Prius, Ioniq, Teslas...
The frontal surface area is the same, it's not the shape that matters, it's the height and width at the highest point, shape matters for efficiency. I believe a double wedge (like a car shaped) would be even more efficient in this case, and wouldn't try to fly away ;) you'd lose some capacity tho. I don't understand why people need roof boxes anyway.
Well done!
Isn't the teardrop shape the most aero shape. My aero bike has these shapes. So it makes sense to me that placing the box backwards would result in less drag because there is less turbulance of the wind when exiting the back (i.e., the wind is smoothed out)
Like an airplane wing
Some company should create an extension to the normal box in a shape of a water drop. This way you could get perfect aerodynamics.
From now on I am putting my surfboard on tail first. Also roof racks create drag so they need to be snap on snap off.
Bad move. Putting the surfboard tail first does the opposite of this and puts the board's stabilizers ahead of the center of mass, reducing longitudinal stability. You should always mount naked skis on racks tail first to keep the center of pressure behind the center of mass (think of an arrow).
Good test. Had mine for 2 weeks now, satisfied so far, but it looks weird. Can you please test consumption with aeroloader bvs just roof rack? Would be interesting to see how much range you lose even with an aerodynamic roofbox. Edit: Nevermind, found you test ftom 1 year ago which showed 13% higher consumption. The H22 has 10% higher consumption compared with aeroloader so that means aeroloader increases consumption by 3%. Very impressive :)
Hey Björn, I see Model 3 SR+ (and maybe others) has just gained another 9 miles range since January this year - so that’s two increases in 3 months. Any idea what’s driven the second increase?
Looks weird but i guess makes sense; a time-trial cyclist's aero helmet has a high rounded front and tapered tail and a plane's wing is more rounded at the front and thinner at the rear...
Cool ideas make a big difference. A bit like… erm… Tesla!
I think the best result will come from minimizing the overhang in the front.
Now, maybe Bjørn understand why a lot of people in the comments wanted him to test a teardrop trailer a while back.
its a completely different box. subtle changes between generations can make big differences. should have tested the new box front and rear orientated.
Calix reverse box ftw!
LOL... oh, that doesn't work...
9% better consumption but 16% less space.
Old: 0.5W/l
New: 0.54W/l
So the regular box has still better efficiency.
Should compare this to a towhitch box. Consumption and noise
One or two DB of difference are ineffective to human ears. The real result is that you now have a kind of Bernoulli surface that let you reduce the drag so you can keep your consumption down, so you gained car efficiency at the same conditions, well done!
I would expect the roof box companies to have optimized the design for efficiency ages ago. Consumption and efficiency has always been a talking point when discussing roof boxes.
At last a manufacturer who understands a bit about aerodynamics.
Its great Calix is the first to use the airfoil shape whose drag coefficient is almost 0.04 en.wikipedia.org/wiki/Drag_coefficient
Great test. Have you tested a roof Box against a Tow Box noise and consumption wise?
That would be a Great test.
Hey bjorn, I've been watching your content for some time already, big fan!
I've got a quesiton for you, going on a road trip with my SR+ around Tunisia!
Tesla Club Tunisia organising overnight charging at the hotels and everything but, any special tips for doing a road trip on a country with very few charging stations?
9% reduction in consumption but 14% less cargo capacity. I mean a smaller box should have less drag. At what point does the box reach the maximum efficiency per liter? With only one size option we'll probably never know.
As someone who has had to deal with aerodynamics nearly all my life: well, duh! Of course it has to be that way round, the only "downside" would be a small amount of lift generated. Which could actually be an upside for rather heavy EVs. Probably could be even better if you model the interference between car and box and adjust the shape accordingly.
The angle of attack could be calibrated for highway speeds to cancel much of the lift. I'm sure the compressed air coming off the windshield and sweeping under the box might help cancel some lift (due to the low pressure it generates).
An urban myth tells of added rear spacers to increase Autobahn down force
Lift is no friend for a ground vehicle. It reduces braking and cornering performance. Aerodynamics is also very, very sensitive to minute differences. A bit of hard snow in the mounting rails could reverse any ideal configuration optimizations.
@@Markle2k Indeed, however, the question has to be asked, how much is the effect to begin with? How much lift could be generated, how much is offset due to the bernoulli-effect between box and car mentioned by @Mike, and how much does the car weigh? And of course, there is the market in which it is sold. Norway is not exactly known for its high speed roads, or drivers for that matter.
And of course, all aerodynamics is effected by "schmutz", that is true for cars by themselves, planes and so on, there is a reason why high performance gliders clean their wings leading edge during flight.
Only high performance cars routinely driven at high speeds need to really care about downforce.
@@Soordhin There have been invented aerodynamic profiles that were very optimized for efficiency that were extremely affected by surface contamination. Those were discarded for practical aircraft.
Aerodynamics is very non-linear.
Great video Bjørn. Would love to see more like this. For comparison, what would you expect the consumption to be without the box in these conditions? About 200 Wh/km ?
Good question. That would be very interesting to know. Because any box will create drag... It could also be different from car to car.
Find his "Tesla Model 3 roof box test" video. Seems to be same temperature and conditions. 186wh/km without box and 211 wh/km with box.
@@cmk55norway it was the same box which got 250Wh/km in test so conditions was not the same.
Man that thing look like a aero coffin or what lol 😂 💀
Test the Aero loader in both orientations instead
Looks like airplane wing and may create a bit of lift and totally opposite of the GT wing.
If it creates any lift depends on the angle of attack of the wing (box).
Makes you wonder what Autobahn speed you need to drive before the lift will offset the weight of the box and its contents.
I don’t know anything about aerodynamics, but wouldn’t this create lift as it is wing-shaped? That means lower consumption, but also less grip. I’d be interested to see a test where Bjorn measures the stopping distance with and without the roofbox.
Its 86% the volume of the other box. 86% of total consumption would be 215wh/k. If we know what the car without a box is we can work out how much difference there is between the boxes alone but it looks like its only the difference in volume.
That's not how it works. You have to look at frontal area of the box.
@@bjornnyland Frontal area of the box and coefficient of drag. That gives overall drag or CDa.
You also have to look at how the air interacts with the flow of the cars' own.
Have you never seen the profile of an airoplaen wing?
Not a surprise. Natural teardrop shape is very efficient. Science bitches.
The new owner of MC Hammer needs to buy one of these and rename the car Elvis.
I always thought this should be the correct way, nothing more aerodynamic than the teardrop shape. That's how rain drops, not in a wedge shape.
It seems "logical" : the shape of a drop of water, subject to deformation due to wind, is spherical on the front wind side, and becoming razor thin on the wind evacuation side.... the reverse box is respecting this physical principle more than the "straight" box. A gain of 10% is incredible
Well look at that. The wrong way is the right way! 👍
I obtain same consumption (223-228 Wh/km) @110km/h with Skiguard 830T. Model 3 LR 2019. Skiguard looks SO MUCH nicer than these two 😀
Around the same here with LR DM '19 with Hapro traxer 8.6 on top. 220 Wh/km is what I use on ABRP.
I am wondering if the weight of everything that is in the box affects the numbers when it comes to consumption. The more weight in the box, the more deformed it becomes.
Can you please tell in your car tests whether there is a trailer coupling for the vehicle. Cars are everyday objects with which someone wants to carry bicycles or a trailer.
i reverst, once for 500km, my thule-box - made almost no difference in consumption
But how does this make sense? The reverse box should create more drag, no?
Can you compare the aero loader with a rear loaded cargo box?
Based on those results, isn’t the Model 3 is being driven the wrong way around also?
Finally someone that gets it.
If you ignore the airflow around the car then yes. Where that and the box air interact this is no better than the standard box. Probably why the 86% volume lines up pretty much perfectly with an (assumed from other tests on model 3's) 86% or so in added drag.