Go Back   EcoModder Forum > EcoModding > Aerodynamics
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 12-06-2013, 07:28 PM   #21 (permalink)
EcoModding Lurker
 
Join Date: Dec 2013
Location: NA
Posts: 29
Thanks: 0
Thanked 2 Times in 2 Posts
More complete instructions under the "about" tab at Airtab: Aerodynamic fuel savers for truck, tractor, trailer, bus, RV. Not trying to spam or shill, I just figure they have a better explanation and I don't need to retype it here.

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 12-06-2013, 07:45 PM   #22 (permalink)
Master EcoModder
 
Join Date: Oct 2009
Location: Phoenix AZ
Posts: 547
Thanks: 4
Thanked 17 Times in 13 Posts
Well these are based on this:

Airtabs™ should be installed as close as possible to the back (trailing) edge of the vehicle. If the Airtabs must be moved forward to avoid rivet heads etc, keep the wide edges of the Airtabs within 12-18 inches of the back for optimum performance. Airtabs are effective shielding gaps or reducing turbulence entering undesirable areas. Any vehicle component with an edge that is 90 degrees to the airflow is a possible AirtabŪ location provided that location receives an adequate supply of relatively undisturbed airflow. Examples: forward of wheel wells, slung tool boxes, trailer skirts etc. Airtabs are also effective on roof trailing edges of automobiles with a rear window slope exceeding 30 degrees. For ALL applications, ensure that the leading (wide) edge of the AirtabŪ is absolutely flush with the mounting surface.
  Reply With Quote
Old 12-06-2013, 08:15 PM   #23 (permalink)
Master EcoModder
 
Join Date: Oct 2009
Location: Phoenix AZ
Posts: 547
Thanks: 4
Thanked 17 Times in 13 Posts
Also this

"Install Airtabs 3 per foot which is one every 4 inches on center. Airtabs are 4.76” long, 3.25” wide, and 1” high. Metric: 12cm long, 8.2cm wide, 2.5cm high. Spacing is 10.1 cm on center. Increase spacing to avoid rivet heads, lights, grab bars etc. Do NOT decrease spacing as this may decrease performance."

I rechecked and I need to put back a few...

I had so call expert tell me I had too many...and I removed every other one on the sides.

BUT I had been running them for a couple of years and with so small a improvement calmed could never tell if they or my extra ground effect add ons did ANY good.

I was hoping they would help the van...

Rich

Last edited by racprops; 12-06-2013 at 08:28 PM.. Reason: Checked tabs on Van.
  Reply With Quote
Old 12-06-2013, 11:44 PM   #24 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 14,147
Thanks: 3,480
Thanked 4,645 Times in 3,704 Posts
Try this:
Quote:
Issue: 646 Section: DIY Tech Features 30 April, 2013
Fitting vortex generators to a three-box sedan

Changing flow patterns
by Julian Edgar
AutoSpeed - Fitting vortex generators to a three-box sedan
  Reply With Quote
Old 12-07-2013, 12:23 AM   #25 (permalink)
Master EcoModder
 
Join Date: Oct 2009
Location: Phoenix AZ
Posts: 547
Thanks: 4
Thanked 17 Times in 13 Posts
Interesting a whole 3% improvement...he would have to done something like 20 test runs to prove so a small improvement and I would then as him to remove the generators and retest 20 to prove that the 3% went away with out them.

NOT worth my time to even bother with them.

Rich
  Reply With Quote
Old 12-07-2013, 12:24 AM   #26 (permalink)
EcoModding Lurker
 
Join Date: Dec 2013
Location: NA
Posts: 29
Thanks: 0
Thanked 2 Times in 2 Posts
Quote:
Originally Posted by racprops View Post
BUT I had been running them for a couple of years and with so small a improvement calmed could never tell if they or my extra ground effect add ons did ANY good.

I was hoping they would help the van...

Rich
Yeah, they only claim a 2% to 4% improvement in fuel economy, not very noticeable on most commuter cars or especially low mpg vans and trucks, but it adds up quick on OTR tractor/trailer rigs running over 100000 miles a year.

If it were my van, I'd run the column straight up from the front edge of that side marker light, about as many as I could fit without spacing them too close together. Of course it isn't mine, so do as you see fit.
  Reply With Quote
Old 12-07-2013, 12:29 AM   #27 (permalink)
EcoModding Lurker
 
Join Date: Dec 2013
Location: NA
Posts: 29
Thanks: 0
Thanked 2 Times in 2 Posts
Quote:
Originally Posted by racprops View Post
Interesting a whole 3% improvement...he would have to done something like 20 test runs to prove so a small improvement and I would then as him to remove the generators and retest 20 to prove that the 3% went away with out them.

NOT worth my time to even bother with them.

Rich
I figure a little here, a little there, but keep on gunning for those double digit improvements.

That's three percent on an already aero car, a boxy van would probably do a bit better. But it'd still be hard to notice right away.
  Reply With Quote
Old 12-07-2013, 12:47 AM   #28 (permalink)
Master EcoModder
 
Join Date: Oct 2009
Location: Phoenix AZ
Posts: 547
Thanks: 4
Thanked 17 Times in 13 Posts
Well as I still have them I will replace them in the missing spaces.

Can't hurt.

Rich
  Reply With Quote
Old 12-07-2013, 01:25 PM   #29 (permalink)
Master EcoModder
 
Join Date: Mar 2008
Location: USA
Posts: 560
Thanks: 1
Thanked 67 Times in 53 Posts
Vortex generators are known to improve lift on aircraft wings, enabling lower takeoff and landing speeds, better climb rate, while reducing stall speed. So, using this technology, for a given acceptable stall speed, they would enable an otherwise smaller wing, which in turn would mean higher cruise speed. This happens due to better attached flow over the wing.

Julian Edger shows some improvement in fuel economy, attached flow on the rear glass and deck, and perhaps less noise. Noise is a good indicator of turbulent and detached flow, so less noise would be consistent with smoother air flow.

Vortex generators can be make for virtually no cost: Using two-sided adhesive tape such as carpet tape, and bent bits of aluminum, one could make small VGs out of, say, a used beer can. Just cut ~1" X ~1" rectangles, bend 90 degrees at centerline for an L shape, then trim one corner (which will be the leading edge) to rounded shape with a fingernail clipper. (If a beer can skin is too thin, use thicker material from a hardware store such as aluminum ducting for furnaces and chimney flues, etc.) Attach two-sided tape to the untrimmed side of of the L, and stick to the car surface at ~15 degrees off of flow direction, making V shapes with sets of VGs.

Google (http://www.microaero.com/ImageGaller.../ig_index.html) for vortex generators for airplanes, and see how they are attached at normally turbulent flow areas, such as inside the angle of horizontal and vertical fin, wingroot, etc.

On a car, one might imagine tuft testing of VGs where ever there is detached flow, such as various places on the hood, roof, rear glass, in front of and behind wheel wells, on undertray (Securely attached GoPro camera would be good for this.), etc..

So, for less than a dollar's worth of carpet tape, a used beer can, some yarn tufts and bits of scotch tape to attach, and with a buddy in a chase car with a camera, you could do all sorts of testing.

Consider: Edger's 3% fuel economy improvement may not be much in itself, but then he only applied VGs to a tiny portion of his car--the rear window. What would happen if he'd gone whole hog and tested everywhere the tufts showed bad flow? One might imagine 3% here, 2% there, 1% someplace else, and pretty soon we're talking about significant fuel savings.

Last edited by Otto; 12-07-2013 at 01:35 PM..
  Reply With Quote
Old 12-07-2013, 01:33 PM   #30 (permalink)
Master EcoModder
 
Join Date: Oct 2009
Location: Phoenix AZ
Posts: 547
Thanks: 4
Thanked 17 Times in 13 Posts
I agree they work great when used correctly and wind tunnel tested and all the science and math is done and specially on air craft flying at over 100 MPH..

But like those silly wings stuck on many cars they do not work at normal legal road speeds. (Under 100 MPH)

I think I would have better luck with a wrap around air wing that pulls air into the back of the van, like those old rear window cleaners used on station wagons, they help fill the hole behind the back end.

Rich

  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com