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Hi , thanks for your reactions. I think making it myself with PPF would be the best option indeed. Any suggestions on which PPF I should get to make the protective pads?
CharleyBC
Active Member
This is one of the best science-driven posts I’ve read!
Has anyone done similar work with hauling a couple bikes?
Has anyone done similar work with hauling a couple bikes?
StealthP3D
Well-Known Member
I'm not an expert in PPF but this application (paint protection under the rack pads) has somewhat different requirements than for general, whole panel, PPF.
For example, probably the most important quality in this application is how invisible the edge is and is it resistant to dirt buildup at the edges and lifting/peeling. However, since the area the pads rest on is pretty flat, it doesn't require a film that can go around sharp corners AND resist peeling/lifting. I'm sure some of the high-end films have a reputation for exactly that but in this application, it's not necessary.
Bikes take a huge hit to rang. Also roof box is better than bikes by a long shot. This is a picture with roof box, trailer basket and probably overloaded.
Attachments
Helicopter tape works great for protecting paint under bars as well as downtubes on bikes
As winter arrived I was excited to strap a roof rack on my Model 3 and take it to the mountains. I quickly discovered little information out there about how it would impact the range. Given the long cold uphill drive and variable weather conditions, I was determined to find the highest efficiency setup and characterize it for route planning. I started with a stock TM3 LR AWD, keeping as many variables constant as possible, and did 20+ runs up and down the highway gathering data. I tested with both the SeaSucker Monkey Bars and Tesla's Roof Rack, with various configurations of snowboards, carriers, and fairings.
Additional pictures, charts, and raw data: Model 3 Roof Rack Options - Comparing Efficiencies
TL;DR compared to stock TM3 LR AWD 18":
Test Procedure
- Tesla Roof Rack -- 1.6% range loss
- Tesla Roof Rack + Yakima FatCat 6 Evo -- 17.3% to 19.6% range loss
- SeaSucker Roof Rack + Thule 91725 Flat Top Ski Carrier -- 26.7% range loss
- Aero Wheel Caps Removed -- 5.4% range loss
I avoided traffic during the trials to not skew the data and threw out any significant outliers due to road conditions. I tried to test when the wind was at a minimum but this seemed to be the most significant variable I couldn't completely control.
- Get on the highway going 70mph with autopilot engaged and reset the trip meter.
- Drive 6.5 miles south, gaining about 130 feet in elevation.
- Log the Wh/Mi, disable autopilot, and get off the highway
- Get back on the highway going north and do the same thing again. This time losing about 130 feet in elevation.
- Average the north and south results together.
Controlled Variables
Configurations Tested
- 55-60°F outside temperature
- Dry highway road, minimal wind
- 70mph on autopilot
- HVAC off
- Radio @ 25% volume
- Tires @ 42 psi cold
- Baseline: Tesla Model 3 Dual Motor Long Range, 18” Wheels w/ Aero Wheel Caps
- Config 1: Aero Wheel Caps removed
- Config 2: SeaSucker Monkey Bars, Thule 91725 Flat Top Ski Carrier, 2 snowboards bindings down, Yakima Wildshield Fairing 46” [Picture]
- Config 3: Model 3 Roof Rack, Yakima FatCat 6 Evo T-Slot mounting, 2 snowboards bindings up (T-Slot mounts too low to put bindings down) [Picture]
- Config 4: Model 3 Roof Rack, Yakima FatCat 6 Evo standard mounting, 2 snowboards bindings down [Picture]
- Config 5: Model 3 Roof Rack, Yakima FatCat 6 Evo standard mounting, 2 snowboards bindings down, Yakima Wildshield Fairing 46”
- Config 6: Model 3 Roof Rack
Results and Real World Impact
At the end of the day I care about how much time I spend on the road. To that end I plugged the Wh/Mi figures for each config into ABetterRoutePlanner to see how they would impact the round trip driving time to my favorite ski resorts.
Wh/Mi Δ / Range Δ / Time Δ
1. No Aero Caps
+5.7% / -5.4% / +7 minutes
2. SeaSucker
+36.4% / -26.7% / +44 minutes
3. Tesla Rack + T-Slot
+24.4% / -19.6% / +28 minutes
4. Tesla Rack
+23% / -18.7% / +26 minutes
5. Tesla Rack + Fairing
+21.0% / -17.3% / +24 minutes
6. Tesla Rack Only
+1.6% / -1.6% / +2 minutes
Accuracy
For each config I did two or three round trip trials. On average the trials within a config varied by 2.2%.
Cabin Noise
I measured cabin noise for each config using the iOS app Decibel X. The absolute values are probably not too accurate, but the deltas are somewhat interesting. The baseline measured 83dB.
- Config 2 (SeaSucker) measured 84.5dB. Without the fairing the app measured lower but the sound was much more unpleasant. Likely due to the frequency of the noise and concentration at that frequency.
- Configs 3 and 4 measured 86.5dB and 86.1dB respectively. Config 5 (fairing) measured 86.7dB and was actually more unpleasant due to a small gap between the fairing and the rack+boards.
- Config 6 (Tesla Rack Only) measured 85.1dB but didn't sound too different from the baseline in practice.
Speed Impact
I repeated testing of Config 6 going 65mph instead of 70mph. The Wh/Mi decreased by 9.9%, causing the range to increase by 11.0%. No big surprises here, but always interesting to verify physics.
MOST INFORMATIVE POST EVER.. THANKS!!!! 5 GOLD STARS!!
moojimmy
Member
As winter arrived I was excited to strap a roof rack on my Model 3 and take it to the mountains. I quickly discovered little information out there about how it would impact the range. Given the long cold uphill drive and variable weather conditions, I was determined to find the highest efficiency setup and characterize it for route planning. I started with a stock TM3 LR AWD, keeping as many variables constant as possible, and did 20+ runs up and down the highway gathering data. I tested with both the SeaSucker Monkey Bars and Tesla's Roof Rack, with various configurations of snowboards, carriers, and fairings.
Additional pictures, charts, and raw data: Model 3 Roof Rack Options - Comparing Efficiencies
TL;DR compared to stock TM3 LR AWD 18":
Test Procedure
- Tesla Roof Rack -- 1.6% range loss
- Tesla Roof Rack + Yakima FatCat 6 Evo -- 17.3% to 19.6% range loss
- SeaSucker Roof Rack + Thule 91725 Flat Top Ski Carrier -- 26.7% range loss
- Aero Wheel Caps Removed -- 5.4% range loss
I avoided traffic during the trials to not skew the data and threw out any significant outliers due to road conditions. I tried to test when the wind was at a minimum but this seemed to be the most significant variable I couldn't completely control.
- Get on the highway going 70mph with autopilot engaged and reset the trip meter.
- Drive 6.5 miles south, gaining about 130 feet in elevation.
- Log the Wh/Mi, disable autopilot, and get off the highway
- Get back on the highway going north and do the same thing again. This time losing about 130 feet in elevation.
- Average the north and south results together.
Controlled Variables
Configurations Tested
- 55-60°F outside temperature
- Dry highway road, minimal wind
- 70mph on autopilot
- HVAC off
- Radio @ 25% volume
- Tires @ 42 psi cold
- Baseline: Tesla Model 3 Dual Motor Long Range, 18” Wheels w/ Aero Wheel Caps
- Config 1: Aero Wheel Caps removed
- Config 2: SeaSucker Monkey Bars, Thule 91725 Flat Top Ski Carrier, 2 snowboards bindings down, Yakima Wildshield Fairing 46” [Picture]
- Config 3: Model 3 Roof Rack, Yakima FatCat 6 Evo T-Slot mounting, 2 snowboards bindings up (T-Slot mounts too low to put bindings down) [Picture]
- Config 4: Model 3 Roof Rack, Yakima FatCat 6 Evo standard mounting, 2 snowboards bindings down [Picture]
- Config 5: Model 3 Roof Rack, Yakima FatCat 6 Evo standard mounting, 2 snowboards bindings down, Yakima Wildshield Fairing 46”
- Config 6: Model 3 Roof Rack
Results and Real World Impact
At the end of the day I care about how much time I spend on the road. To that end I plugged the Wh/Mi figures for each config into ABetterRoutePlanner to see how they would impact the round trip driving time to my favorite ski resorts.
Wh/Mi Δ / Range Δ / Time Δ
1. No Aero Caps
+5.7% / -5.4% / +7 minutes
2. SeaSucker
+36.4% / -26.7% / +44 minutes
3. Tesla Rack + T-Slot
+24.4% / -19.6% / +28 minutes
4. Tesla Rack
+23% / -18.7% / +26 minutes
5. Tesla Rack + Fairing
+21.0% / -17.3% / +24 minutes
6. Tesla Rack Only
+1.6% / -1.6% / +2 minutes
Accuracy
For each config I did two or three round trip trials. On average the trials within a config varied by 2.2%.
Cabin Noise
I measured cabin noise for each config using the iOS app Decibel X. The absolute values are probably not too accurate, but the deltas are somewhat interesting. The baseline measured 83dB.
- Config 2 (SeaSucker) measured 84.5dB. Without the fairing the app measured lower but the sound was much more unpleasant. Likely due to the frequency of the noise and concentration at that frequency.
- Configs 3 and 4 measured 86.5dB and 86.1dB respectively. Config 5 (fairing) measured 86.7dB and was actually more unpleasant due to a small gap between the fairing and the rack+boards.
- Config 6 (Tesla Rack Only) measured 85.1dB but didn't sound too different from the baseline in practice.
Speed Impact
I repeated testing of Config 6 going 65mph instead of 70mph. The Wh/Mi decreased by 9.9%, causing the range to increase by 11.0%. No big surprises here, but always interesting to verify physics.
Thank you very, very much for your efforts and for this incredibly helpful post. You’re a star!
moojimmy
Member
Did anyone successfully fitted the Thule XL (52') Airscreen? Curious if the width fits or too long.
If not, what's the current best option for the fairing?
If not, what's the current best option for the fairing?
For my Inno Surf Racks, I keep the T-bolt on the racks and just remove the surf rack itself (you hardly noticed the 4 bolts sticking out from the rails). This way, it's super easy to add/remove when I need to carry surfboards.
Based on his tests, it seems using t-slot mounting point and fairing will yield the best result if you rather just keep the accessories mounted to the rack at all times.
StealthP3D
Well-Known Member
I had to disagree because rack fairings generally INCREASE drag, not reduce it (as the provided testing shows). This is because they cause a large increase to the frontal area of the vehicle. It is possible they reduce whistling noises from attached accessories even as they increase the total drag.
But that's not what his chart shows. #4 and #5 setup are identical except his #5 configuration is with the Yakima FatCat 6 Evo rack mounted with standard mounting (not T-slot), 2 snowboards on it, with the fairing. He gained almost 1.5% efficiency from his test without the fairing with identical setup.
So based on his results, adding the fairing actually improved efficiency vs without it.
I did read it wrong on the T-slot though, and to me the I'm surprised with the results there. I guess the standard mounting for his FatCat was more efficient than mounting it with T-slots.
In my case, my rack sticks up another inch with standard mounting so I switched to a T-slot mount version.
StealthP3D
Well-Known Member
First, 1.5% is well within the margin of error one could expect for the methodology.
Secondly, that test had snowboards mounted with the bindings facing down. This is not comparable to a rack with rack accessories left on all the time (a snowboard is a very large wing).
Either way, with #4 and #5, all things are equal except for a fairing. If 1.5% error margin, since the 1.5% was BELOW the setup without the fairing, then it would simply mean adding a fairing doesn't affect the efficiency, not reduce efficiency as you stated.
But yes, I wasn't trying to say that it would be efficient to run with accessories on the rack all the time. That's precisely why I don't have mine on normally. As the chart shows and as one would expect, the efficiency with the bars alone, vs with the accessories mounted, is quite a difference.
My non-T-slot mounting surf rack was super quick to take off, but I didn't like how much taller it stood. So I settled with the T-slot mount and leave the T-slots on the rack and just unscrew the bolts that mount to these t-slots to quickly remove the surfboard rack when I don't need it.
StealthP3D
Well-Known Member
No. There are certain items you could attach to the bars that might cause the fairing to actually reduce the overall drag - but the fairing will not reduce the drag of bare bars (or bars with small attachments on it). I was under the impression that you were discussing leaving the fairing on all the time because it would result in lower overall drag.
Snowboards can dramatically increase the drag and small changes in the mounting position and angle, bindings up or down, etc. can dramatically alter the drag. But without such items on the rack the rack fairing generally adds quite a bit of drag. I run the Tesla Aero Bars on my Model 3 all winter long and the drag of the bar bars is very minimal but increases dramatically with boards mounted. Skis have a lot of additional drag, especially wide powder boards, but snowboards with bindings take the cake.
Biscuitman
Member
I leave my Tesla bars all year round as I like the look and don’t want to risk the roof cracking as has happened to several members here.
Winter is coming soon here in the great white north, so am looking forward to stepping my Yakima Fatcat 6 rack on and hitting the slopes in the not too distant future .
OP thanks for the great and detailed info. You have convinced me to go with the standard set up attachment and pass on the t slots.
Ski on!
Winter is coming soon here in the great white north, so am looking forward to stepping my Yakima Fatcat 6 rack on and hitting the slopes in the not too distant future .
OP thanks for the great and detailed info. You have convinced me to go with the standard set up attachment and pass on the t slots.
Ski on!
Do you have picture of the 46 Yakima fairing on the Tesla oem roof rack ?
I've to buy a fairing and I don't know whitch size will better fit.
Thanks
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