Greetings,
So I used the AST and placed it over my RAV4 EV. Then I went ahead and used mspaint to measure the pixels within the image and recorded the placements for Length. The RAV4 EV is 180 inches in length, so I used that as a guide line.
In the picture the front end of the bumper ends at about 1.23.
In the picture the rear end of the rear bumper ends at about 6.09.
That is a 4.86 pixel difference.
Rav4 Ev Length/Pixel Value=Value per Pixel in "inches".
180/486=0.37037037"
Once I had this value then I measured the space between the end of the rear bumper to the very tip edge of the aero stream template.
The tip of the aero stream template was at 9.65.
Tip of Aero Template-End of rear bumper=Pixel space between said points
965-609=356
Pixel Space Value for Boat Tail Length*Pixel Point Value for Rav4 Ev= Possible Inches in Length for Boat Tail
356*0.37037037=131.85185172"
Boat Tail Inches/Inches Per Foot=Boat Tail Length in Feet.
131.85185172/12=10.98765431'
So, basically about 11 feet long unless I made a mistake. That seems like an awfully long boat tail! I'm not sure how I would be able to drive it around town. The longest vehicle I've owned was a 2004 Chevrolet Express Normal Wheel Base which was 224 inches long. I never really have any trouble parking it. However, there was a long wheel base version of 244" which is what I originally wanted.
If I were to only make the boat tail half the size it would be 5 feet 6 inches. In other words... 66 inches in length. Rav4 EV is 180 inches plus 66 inches = 246". So, it would be 2 inches longer than a 2004 Chevrolet Express Long Wheel Base. Which I think is cool! But, that is only half the size of a full size boat tail, and I really want a full size boat tail. I do feel that the length of a 2004 Chevrolet Express Long Wheel Base would be the longest I'd want to drive around in the city.
Also, isn't there a legal limit to how long a vehicle can be before it needs some sort of special permit?
Vehicle Lengths It appears to be 40 feet total vehicle length? Which is 480 inches?
So I'd guess I will still be in the green if I do decide to make the boat tail 11 feet long? 180"RAv4 Length+ 132" Full Boat Tail =312 Inches long or a 26 feet long vehicle lol?
Can I even make safe lane changes on the freeway with something like this? If something happens... it'll be my fault isn't? Yeah, no pressure driving around that submarine on the hwy LOL.
So basically the boat tail needs to be 73.333333333% the length of the Rav4 EV. Is that the common average % for a full size boat tail around here?
180/100=1.8
132/1.8=73.333333333
Quote:
Originally Posted by aerohead
Most modern cars will achieve Cd0.13 with a full tail.
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So this beast of a boat tail should bring down my Rav4 EV's drag to Cd0.13 from Cd0.30?
Quote:
Originally Posted by aerohead
I ran the profile out with some minimum constants for cooling system drag ( 0.011 ),'features drag'( gaps,cut lines,door handles,antenna,wheel openings,etc.) ( 0.007 ),and then subtracted out 0.015 for a complete wheel fairing set using data from the Sunraycer.
It appears that if we do everything 'right',we could get a car down to a conservative Cd 0.126,at 80 % of the template length.
The last bit of drag would be insignificant,residing within the 'phantom' tail.
Running the tail out to 100 % would only get the Cd down to 0.123.
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Reading this bit... does this mean 80% of the template length would be just as good? I don't need to go full size? (Or retard :P)
If I made a mistake on the template please let me know! Or a mistake anywhere for that matter. Hopefully that could make the boat tail shorter! Here is the picture with template:
