Have a new project, and it is one that is a lot of fun, because it sure seems to work!! Thanks to all of you who post at ecomodder, it is you who have spurred me on to do this.
There is an article at recumbents.com that says that says that 15% of the energy used to push your vehicle down the road is lost in the driveline, 25% by the rolling resistance of the tires, and 60% (!) from air drag.
Until recently, have mostly concentrated, over several years, on improvements in the other two areas, and left aero alone. Have done many smaller things to a 2005 GMC Duramax (ideal high MPG candidate, huh?!), and most worked, some did not. Yes, even "dope" most every tank of fuel. No, that is not a big deal, when you only do it once a month.
Now am looking at aero, and other than a canopy, done some time ago, have done little.
That 60% is broken down in a pic posted at ecomodder, and it is below.
You can read a bit about aero modifications for vehicles at
Car Aerodynamics 101 ,
and they have a picture of some very large Vortex Generators there. Mine are a LOT prettier, and probably a bit less efficient, but they are easy to do, unobtrusive, and inexpensive.
They have been in use forever on aircraft, Spruce has them at:
Pilot Supplies, Avionics, and Homebuilt Aircraft Parts from Aircraft Spruce and Specialty Co. , and then type in vortex .
You can spend several thousand dollars for airplane vortex generators.
There are three or so different kinds of metal tape available for aircraft, but it is also expensive!!
About halfway down the page at:
Vortex generator - Airtabs - CleanMPG Forums , there is a group of links that show what gains can be made, and what was measured.
Have received permission from a VERY knowledgeable, principal aerodynamics engineer, Mr. Barnaby Wainfan, who works for the Grumman Advanced Design organization (I flew Grumman OV-1 Mohawks for the US Army from 1967-1982), to use the clearest information on vortex generators I have ever read. He recently wrote it as an article for Kitplanes, and also have permission from Kitplanes to use some excerpts.
You can go to Mr Wainfan's website, it is
Wainfan Home Page . Kitplanes is
KITPLANES The Independent Voice for Homebuilt Aviation . Thanks to both of them!! (Yes, am a subscriber to Kitplanes, also)
The discussion in the Kitplanes article is about airflow separation, and ways to fix it. Most of you already know that a re-design is not so practical for most of us with vehicles,(or airplanes!), and an add-on fix that can "re-attach the flow" is most desirable because it can fix the problem without great expenses.
"One such fix is called a vortex generator (VG). These are small, low-aspect-ratio blades that are mounted perpendicular to the skin of the airplane.
The vortex moves air that is near the airplane skin up away from the skin while at the same time moving air from the outer flow down closer to the skin. When separation is imminent, the air in the boundary layer right near the skin is out of energy. It is moving very slowly, and will soon stop and reverse direction, causing separation. The air in the outer flow is moving fast. The vortex created by the vortex generator(s) moves some of this high-energy air down into the tired boundary layer, and moves some of the tired air away from the surface. This increases the speed of the air in the boundary layer and delays separation of the flow."
In a motor vehicle on the ground, if we do this, it can reduce air pressure on the vehicle, and reduce drag. Because we don't have to worry about stalling a wing, we do not have to have the vortex generators as tall, which has a benefit in lessened drag, and greatly lessened cost. And, if we have inexpensive ones, we can add more, and maintain that smooth airflow, which helps fuel economy!
If you still have a little trouble with this, this explanation may help. Imagination those millions of air molecules are like a huge crowd of people pressing in on an area. Then imagine that there is a burly policeman/crowd-control officer at each of those points, saying "All right everyone, there's nothing to see here, move along, move along..."
You can search ecomodder for articles; there are several, but nobody uses inexpensive tape, because we are just now starting to make it!!
Here are the early results:
Have been getting 20-22 MPG most of the time, with a 2005 GMC Duramax, 6-speed stick-shift, with EFI Live, Scan Gauge of course, and some other modifications. Have spent some time (and money!) getting the most out of it over the years, (With diesels it is MONEY, just like airplanes!!!!), and just over 100,000 miles, re: fuel economy, and have not gone after the aero drag (other than the canopy, which is worth about 4% better fuel economy), until now. (Yes, a person who keeps their vehicle tires aired at 65 PSI is a bit anal!!)
Put aero tape on the outer (huge!) rear-view mirrors, on the front bumper toward the top, toward the back of the front bumper before the transition to the grille, at the front of the transition from the cab to the canopy, and on the sides of the windshield.
Then drove 45 miles, with a stop/shutdown at Summit, maybe six lights stopped at or slow roll, max speed 65, most of it 45-55, 26.6 mpg average. (plus or minus 2 for gauge error, etc.) About a one hour drive.
(And the return trip, with a stop at Carton Service, and at the Post Office, showed 25.5.)
Yes, I agree with others, in town one can actually get BETTER fuel economy!
Got back, added tape at the back of the front bumper underneath, and at the back of the canopy.
Then drove 6 miles each way on the I-84 freeway, East of Portland, between 65 and 70 mph: 25.1 out, 23.4 back. Was disappointed that there was not more difference.
Then added the aero tape in front of the windshield, and in front of the separation between the cab and the canopy.
Same drive: 26.3 out, 24.8 back.
Could I have "fudged" that much?? Yeah, maybe, but I did not. How do you"fudge" a lot on an 8,000 pound pickup?!
And, a NOTICEABLE difference is the much quieter cab inside.
The old numbers would have been 20-22 indicated, but may have driven a little more anally, which could account for most, if not all the gain. Would be very happy with even 5%!
Did not have a tailwind, and had about a 200 foot total elevation gain. Seems like it gains speed a little easier with a little less throttle.
Besides the mirrors, did the transition from the front bumper up onto the grill, and from it to the hood. Also did the sides, from the windshield around the corner to the side glass.
Am just about certain it is a winner.
Did the transition from the back of the hood to the windshield, and the back of the canopy to the back.
Have read the largest gain is around the back of the canopy (a kammback without doing it?!).
Not bad for an 8,000 pound pickup, eh? (Yup, a little light on fuel, about 8,500 with me and a full load <about 120 gallons> of fuel, about 7,500 empty of fuel and without me.)
The last was 130 miles, or 65 miles each way, from Portland, to The Dalles and back on I-84. Going, at 65-70 (mostly 70), 23.6, with my foot, and coming back at 65, with the cruise control, 23.2.
Yes, I also agree with others, you can do better with your foot, most of the time, than with the cruise control!
Am very happy, overall, with the results to this point.
Aero tape is what the pic shows on the Rear view mirror pic that is attached.
You peel the backing off, and stick it on.
Have black, yellow, red, blue, woodgrain(!), orange, and green at the moment, and 24 feet of tape (about 3/8" wide), is $29.95, shipped, 50 states, or add $4 for USPS "hurry-up". That is enough to do a pair of outside rear-view mirrors, and three or four passes or so in front of places where there is a 30 degree or more change in airflow direction.
If you want to read about me, I am xxxxxxxxxxxxxxx on eBay, and have been there ten years or so, mainly selling diesel engines. You can also google utterpower (my friend George's website, and powersolutions or PS, which is also me.
The highest air pressure is at the front of a vehicle, and the front half of the hood, and you can read about changes at the links earlier provided. I also have added it at the rear of the canopy, just ahead of the transition from the cab to the canopy, and from the back of the hood before it transitions up to the wipers and windshield, etc. (but that is a low pressure area, so did not expect a lot of gain)
If you achieve a 1% gain using it, it will save you its cost (a 100% annual return) every year. If you achieve a 10% gain in fuel economy, you will get a return of around $25 per month, based on driving averages, MPG averages, and $2.50/gallon fuel.
My best guess is; 10% for me. Would be happy with 5%.
And you don't need to do anything after it is on.
Apply to a clean, dry, warm surface, and press firmly. It will "bend" around pretty sharp corners very well when it is warm. It is UV resistant, waterproof, and should last a long time.
It is also 100% money-back guaranteed. If you try it, and think it is bs, why strip it off and send it back, and I'll even refund $2 for the return shipping. No, don't wait six months to do that, thirty days maximum, please!!
Additional colors within a week or so are, white, and may have some wider grey. (Yes, am told gray is a color, and grey is a colour, but have always spelled it 'grey'.
Can tell you also that, when it is on, it just "disappears", almost like pinstriping. That is using black and grey, on my silver pickup.
I do not think it will come off, there is no indication of that. It is modern, and very sticky!!
The main benefits are, it works, it is cheap, and it is easy to put on, with no maintenance afterward.
If you want to try it, please paypal my email address, listed below. Yes, you can use a credit card for this, and paypal does not send me any personal info, other than what you WANT to send. Please make sure your address is good, and we almost always ship within 24/48 hours. (except Saturday/Sunday)
Oh, if you want to stick it on, and take it off after a while, and are not sure how good your vehicle's paint job is, you may want to exercise caution. If that concerns you, please do not try it. Removed a one foot piece on the front of the hood that had been on about 48 hours, and it came off fine, but after a month or so, it may not want to come off at all!! (after removal, the weather/sun changes the residual glue, and it just wipes off very easily.
About a week later, have positive proof it works; 1000 bugs don't lie!! Finished about a 400 mile trip, lots of farms and bugs, and speeds generally from 55, all the way to 110 MPH. Drove it MUCH harder, and from sea level to just over 4,000 feet elevation. 21.8 MPG overall.
The Duramax is MUCH quieter at higher speed, and the pic of the bugs on the front Buck Stop bumper shows what happens from where the tape is.
Yes, we have some 1/16", and 1/8" thick, thicker tape also coming, if you want to try it. Add $10, and the colors will only be black/grey. It may not last as long, or stick as well, and may deteriorate in bad weather, sorry. I am Joel, and my cell is xxxxxxxxxxxxxxxx. Please don't call me at odd hours, 8AM to 6 PM works best. We are on the Pacific Coast, and at 65 years of age, like our night time sleep! You can always email me at: xxxxxxxxxxxxxx (Yes, change the (at) to an @)
(added pics, had to re-size them tiny, and tried to place them where I wanted them, but alas!, am old and slow, and some of this is a problem for me, sorry.
