Increase range by 18% with Flated Cap

[Henry Ford]

There is no aerodynamic explanation for any gain of efficiency by adding a bed topper, much less an 18% gain. All the topper does is move a low pressure area from behind the cab to behind the topper.

Ford claims the wide tailgate top reduces the low pressure area behind the cab so you're probably reducing efficiency by adding any bed cover.

If someone really wanted to increase efficiency they'd add a topper that starts at the back of the cab and extends all the way to the tip of the open tailgate. Even then, it would take a lot of luck or access to a wind tunnel to get the shape right to maintain laminer flow over the entire surface.

Sponsored

 

[Yellow Buddy]

Good morning, I recently added a cap to my Pro from Flated that has increased the range by 18% to 2.7 mi/kWh. I posted a video of the range test and now with ~800 miles the range is still holding the 2.7. I met two other Lightning owners charging at A-Basin on our last ski day and we exchanged thoughts about the range increase. I've had a tonneau cover since day one while the other owners run an open bed and we've noticed roughly the same 2.3 range, as noted in previous posts. The same appears to be true with hard caps having no effect on range. Without doing the math, my guess is with the Flated cap weighing only 55 pounds the ratio of weight added versus the tunnel created is net positive.

See my range test on YouTube here, twodogsdennis




Rather than posting a lot of pics, I thought readers could check out the channel as they often do when others post about their YouTube, but here is a pic. As I said in the video, I've done a variety of terrain from 6,000 ft elevation to 11,991 ft, 70 degrees to 32 degrees.

Great, now I have to pick up one of these for testing...but call me skeptical.

Aerodynamically, you're creating a large turbulent suction area behind the truck rather than a smooth roll off, so it doesn't make much sense.

By experience, I've tested a number of things and have seen as much as a 30% increase in efficiency, only to find in extended testing that it levels out and likely attributed to another factor.

There's just so many darn variables. I see from another post you are from CO. The weather temp changes there may be the biggest factor as temp routinely changes efficiency, mainly due to 2 things imo.

1) Tire temps/pressure. Both air temp and radiant temp can affect running PSI, and I've seen between a 3-7 psi variation from cold pressures when running.

2) HVAC. Even in the exact same conditions with just different HVAC settings there can be a large variation. For example, with HVAC off in 75F/Sunny I can get 2.5-3.0 in my ER Lariat. Same temps, but flip the HVAC on and it'll drop down to 2.0-2.5. The AUTO HVAC complicates our conclusions because of this, and it would be best if you can do testing with it in the off setting.

 

[Danface]

Either you broke the laws of physics or your testing methodology was bad. Likely a combination of variables you can and cannot control led to this result. Weather, wind, feather foot, speed, etc.

 

[Bwanapete]

My range increases a lot when my wife is riding along in the truck.

 

[TheBigBezo]

I have had a bed cap for a year and it has not changed my efficiency at all. Like others said, a bed cap simply moves the “air pocket” behind the truck. If you really wanted to explore some aerodynamics, vortex generators along the upper and lower trailing edge of the truck could help reduce drag by mixing air behind the truck and reducing the profile drag. For my undergrad we did experiment with active flow control to reduce drag for blunt bodies. It will help prevent turbulent air from detaching which is ultimately what drives profile drag in our vehicles, that said, doing that for what is effectively a flat plate at 90 degrees is a tall if not impossible order.

 

[Firn]

Ford claims the wide tailgate top reduces the low pressure area behind the cab so you're probably reducing efficiency by adding any bed cover.

From what i have seen a bed cover can help efficiency, in the right conditions.

From my limited reading the tailgate top gives the air off the cab some place to "land" which slightly helps efficiency. I expect that this only works at the EPA testing speed (and maybe only on some cab/bed combos).

My guess is a bed cover might help at lower speeds (where it is less helpful) or on longer beds - some condition where the air off the cab can "touch down" .

 

[pullinggs]

I had about 5000 miles on mine before adding a cap. No meaningful change in efficiency over the next 5000 miles (and it was possibly a slight decrease).

 

[twodogsdennis]

Great, now I have to pick up one of these for testing...but call me skeptical.

Aerodynamically, you're creating a large turbulent suction area behind the truck rather than a smooth roll off, so it doesn't make much sense.

By experience, I've tested a number of things and have seen as much as a 30% increase in efficiency, only to find in extended testing that it levels out and likely attributed to another factor.

There's just so many darn variables. I see from another post you are from CO. The weather temp changes there may be the biggest factor as temp routinely changes efficiency, mainly due to 2 things imo.

1) Tire temps/pressure. Both air temp and radiant temp can affect running PSI, and I've seen between a 3-7 psi variation from cold pressures when running.

2) HVAC. Even in the exact same conditions with just different HVAC settings there can be a large variation. For example, with HVAC off in 75F/Sunny I can get 2.5-3.0 in my ER Lariat. Same temps, but flip the HVAC on and it'll drop down to 2.0-2.5. The AUTO HVAC complicates our conclusions because of this, and it would be best if you can do testing with it in the off setting.

So many darn variables is right. This type of reply is why I posted, an opportunity to discuss the same questions that Derek #1 and I had at A-Basin (long story). We surmised that the increase was due to a deflection in the turbulence behind the cab and the fact that the Cap from Flated dot com is only 55lbs, but that things would soon return to normal. Like I covered in an earlier video about a 400-mile day trip to SE CO, I've been amazed on occasion about the range increase or decrease. And like the experience in my ICE Silverado, crosswinds, headwinds, tailwinds, hot pavement, cold pavement, etc., all can change mileage and range.

Without getting out the slide rule, which would date me, I was intrigued that the range over 800 miles has been consistent at 2.7, whereas the instances when the Pro showed a drop to 1.8 or rise to 2.5 at 200 miles things soon went back to the ave of 2.3 as the miles accrued. The rise or fall from ave is typically easily to explain, from following heavy traffic at 75 mph or climbing through the Rockies at 15 degrees. Even on the recent 2600-mile trip, headwinds and calm winds effected hourly range but over-all the Pro finished at 2.3.

In these 800 miles, the Pro has twice done 5k of elevation gain at highway speed with 40-degree temp change and 50–100-mile trips at highway speed on flat terrain, each without HVAC and the default pro-power left on in the cab. If anything, this has given me ideas on how to improve my video reviews. I can't imagine this cap that I paid $600 for will have a long-term effect on range, but until that time, I'll enjoy the ride.

 

[twodogsdennis]

From what i have seen a bed cover can help efficiency, in the right conditions.

From my limited reading the tailgate top gives the air off the cab some place to "land" which slightly helps efficiency. I expect that this only works at the EPA testing speed (and maybe only on some cab/bed combos).

My guess is a bed cover might help at lower speeds (where it is less helpful) or on longer beds - some condition where the air off the cab can "touch down" .

I haven't noticed any long-term change with the tonneau cover in 12K miles, just that the stuff inside is dry and doesn't fly out.

 

[twodogsdennis]

I have had a bed cap for a year and it has not changed my efficiency at all. Like others said, a bed cap simply moves the “air pocket” behind the truck. If you really wanted to explore some aerodynamics, vortex generators along the upper and lower trailing edge of the truck could help reduce drag by mixing air behind the truck and reducing the profile drag. For my undergrad we did experiment with active flow control to reduce drag for blunt bodies. It will help prevent turbulent air from detaching which is ultimately what drives profile drag in our vehicles, that said, doing that for what is effectively a flat plate at 90 degrees is a tall if not impossible order.

We still talk about all of the calculations we did on flying blobs of Jello. As I said in another reply, I doubt this increase will have a long-term change on range but until that time I'll enjoy the savings.

 

[chl]

Great, now I have to pick up one of these for testing...but call me skeptical.

Aerodynamically, you're creating a large turbulent suction area behind the truck rather than a smooth roll off, so it doesn't make much sense.

By experience, I've tested a number of things and have seen as much as a 30% increase in efficiency, only to find in extended testing that it levels out and likely attributed to another factor.

There's just so many darn variables. I see from another post you are from CO. The weather temp changes there may be the biggest factor as temp routinely changes efficiency, mainly due to 2 things imo.

1) Tire temps/pressure. Both air temp and radiant temp can affect running PSI, and I've seen between a 3-7 psi variation from cold pressures when running.

2) HVAC. Even in the exact same conditions with just different HVAC settings there can be a large variation. For example, with HVAC off in 75F/Sunny I can get 2.5-3.0 in my ER Lariat. Same temps, but flip the HVAC on and it'll drop down to 2.0-2.5. The AUTO HVAC complicates our conclusions because of this, and it would be best if you can do testing with it in the off setting.

Yes, in general, turbulence will increase drag, with some exceptions.

For example, turbulence can be used to prevent flow separation from lifting surfaces, which can improve lift and reduce drag in certain situations. Turbulence generally increases drag due to increased friction and energy dissipation, but it can also delay flow separation, which can reduce pressure drag. This is particularly relevant for objects like golf balls and certain airfoil designs.

Anyway, an elliptical shaped front to rear would be effective to reduce drag I believe, it is the way airplane wings are designed to improve efficiency.

An example in a vehicle (soon to be brought to market I hope) is the Aptera design:

 

[chl]

Mutant Aptera-Lightning

 

[MaintGrl]

Just a curious question, with this Flated Cap, does it have a wired third Brake light?

 

[twodogsdennis]

Just a curious question, with this Flated Cap, does it have a wired third Brake light?

There is no wiring in Flated caps or toppers

 

[MaintGrl]

There is no wiring in Flated caps or toppers

So, w/o a third brake light I believe they would be illegal in California.

Sponsored