Jeep Cherokee "Aeromatics" (Kammback / partial boat tail)

[Piwoslaw]

I am impressed at what you're doing with a Jeep!

Good luck with the A-B-A testing. I can't wait to see the results.

BTW: If you have the time, try to sqeeze in an extra 'B', so your testing is A-B-A-B.

[comptiger5000]

This definitely gives me inspiration. Jeeps are such practical, fun vehicles, but the MPG sucks. If there's a way to at least fix the highway mpg a bit, then that makes it even better!

[XJguy]

When addressing aerodynamics to my Jeep, I look at all the research and developments being done in commercial trucking, since they too are boxes on wheels, albeit much larger.

Check this idea:

Trailer Innovations: Aerodynamic Enhancement Products for Tractor Trailers

[aerohead]

Originally Posted by XJguy

When addressing aerodynamics to my Jeep, I look at all the research and developments being done in commercial trucking, since they too are boxes on wheels, albeit much larger.

Check this idea:

Trailer Innovations: Aerodynamic Enhancement Products for Tractor Trailers

I anticipate that they will be very disappointed with their results.They should have proved it out before they smelled green.
Also,they should have done a more thorough patent search,as this form has already been investigated,if not already within a patent application.

[JeepNmpg2]

Sorry guys, I didn't have the time or money to spend on the gas to do some proper testing last week. But I've got a full tank and plenty of time on saturday to try it out again. I'll post the results here as soon as they are finished.

[aerohead]

Originally Posted by XJguy

When addressing aerodynamics to my Jeep, I look at all the research and developments being done in commercial trucking, since they too are boxes on wheels, albeit much larger.

Check this idea:

Trailer Innovations: Aerodynamic Enhancement Products for Tractor Trailers

Edgar L. Keedy of Liberty Center,Ohio received this Utility patent in Mar.24,1981,for a very similar invention.

[FastPlastic]

Defiantly not stealthy, but from the initial testing you may just fly by my numbers in a matter of no time.

[ShadeTreeMech]

I would suspect he's done his turn with "B" testing. (AKA "beforehand" testing)

let him catch up with a few "A" tests.

[JeepNmpg2]

Ok, I'll admit I got derailed this weekend, but it isn't over yet. I have still some time tonight to get that test in. But in the meantime, wanted to bring up something, mostly usefull for us "hatchies" but for everyone else out there that just wants to haul some stuff that's oddly shaped. I picked up a hitch carrier on Craigslist for $20 a few months back and it has been integral in my initial aeromod designing, as well as simple utility.

Today is a prime example: I wanted to pick up an 80lb computer desk/hutch, and while I drive a box, it's not a very large box.



That carrier gets itself right behind the bumper, and doesn't really affect the airstream, and as long as nothing protrudes beyond the profile of the vehicle, it's almost like nothing is there, except for the added weight. Notice in the photo below that tbe desk in all of it's ratchet-strapped glory sits about eight inches above my roofline. had to drive 40 miles to get the thing so--- here's the results:

going to Seattle FE: 25.1 (almost my best ever)
coming from Seattle FE: 23.5 (not too shaby)

While this is not conclusive, it is demonstrating one thing to me: my normal pulling a trailer FE ONLY on the freeway is between 16-20. This is much better, as it only affects one leg of the trip, and even then, for much less of a penalty.

Ok, I'm getting ready to head out in a minute, strap on the kamm, and get some testing done.

[JeepNmpg2]

Ok, so this was my methodology for these tests so I can control everything as much as possible:

1. accelerate to 50 mph holding the throttle at 16% open the whole time
2. use gps/scangauge to keep speed as even as possible (49-51) and keep foot even and steady (TPS on scangauge and listening to the engine).
3. 4 mile course, no traffic, no wind, two turns but nothing to slow down for, very little elevation change
4. prewarmed/driven vehicle

The course is 4 miles out, check fuel, turn around, reset, 4 miles back.... rinse repeat

So here's my results for this 50 mph test (in gallons of fuel used per run):

First A Sets (Kamm attached):

.17
.15
.16
.15
.16
.14
.16
.14

Average: .15375 gallons for 4 miles or 26.02 MPG

B Sets (no Kamm):

.17
.16
.17
.16
.17
.15
.17
.16

Average .1625 gallons for 4 miles or 24.62 MPG

Second A Set (Kamm back on):

.16
.15
.16
.15
.16
.14
.16
.15

Average: .15375 gallons for 4 miles or 26.02 MPG... again

In conclusion, there is a difference, but I doubt it would normally be this great at 50 MPH. I need to find a longer test track where I could maybe go ten miles and get more accurate fuel usage/run data. This data shows a 5.6% increase in FE with Kamm on versus Kamm off. When compared to what the EPA average is for this vehicle of 15MPG, 1.4 MPG extra is 9.3%. Also, I know this aeromod should perform better when comparing it at 60-65 MPH, where aero is more of a factor.

Bottom line: there are improvements to be made to my design, especially in the neighborhood of transitions. I'm thinking for starts - a second layor of 6 mil plastic, attached with black tape and heat shrunk to fit right might improve a lot of places.

I'm worn out, and going to bed. I probably didn't explain myself clearly enough on everything tonight, so post a question and I'll get back to you tomorrow.

BTW: I'm still rocking that ratchet strap to hold on the top of the kamm. I managed to hide the bulk of the mechanism a lot better from the wind this time though.