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Old 10-27-2017, 08:04 AM   #41 (permalink)
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Originally Posted by Galane View Post
The Vixen is older and not as slick as the Navette. The great granddaddy of aero RVs is the GMC. Unfortunately those still ended up with plenty of 'warts' poking out where General motors didn't use parts custom designed to be low drag.
Vixen still better FE though

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Old 10-27-2017, 11:21 AM   #42 (permalink)
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Quote:
Originally Posted by Galane View Post
The Vixen is older and not as slick as the Navette. The great granddaddy of aero RVs is the GMC. Unfortunately those still ended up with plenty of 'warts' poking out where General motors didn't use parts custom designed to be low drag.
To my knowledge, the Vixen is the only one that ever went to a real wind tunnel in full size. (Bendix wind tunnel in Indiana if I recall correctly). I don't think I've seen an drag coefficient claims for the Navette, and the only GMC numbers I've seen were based on small models.
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Old 10-28-2017, 01:32 PM   #43 (permalink)
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All that work on the front and side skirts. I wonder what they did on the back?
I assume that you missed the detailed explanation on page 2.
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Old 10-28-2017, 01:35 PM   #44 (permalink)
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Originally Posted by ctmaybury@yahoo.com View Post
What kind of mileage improvement do you expect from a conventional setup? I have no idea what these things can get on a long haul.
The national average for a Class 8 truck in almost 2018 is still only aound 6.5 MPG.

With my last truck in 2012, the BulletTruck, we achieved 13.4 MPG coast-to-coast.

We expect to do better with the brand new StarShip, and we will be doing another coast-to-coast record run along I-10, in February.
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Old 10-28-2017, 01:38 PM   #45 (permalink)
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Originally Posted by Smitty View Post
CAN you make the rear of cab / front of trailer curved like a ball & socket joint? That way it can turn left or right with minimal flow interruptions & no crunch points.
Make the back of the cab half-a-ball shaped, & the matching socket curvature at the front of the trailer. Or I guess you could make it the other way as well
You're neglecting the electrical umbilical and air lines that go between the tractor and trailer that would surely get destroyed in such a configuration.
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Old 10-28-2017, 01:42 PM   #46 (permalink)
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13.4 is amazing. I can barely beat that with a 3/4 ton and a 7k lbs travel trailer. I'm hoping to top 20 with some eco mods.
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Old 10-28-2017, 09:55 PM   #47 (permalink)
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Quote:
Originally Posted by Smitty View Post
CAN you make the rear of cab / front of trailer curved like a ball & socket joint? That way it can turn left or right with minimal flow interruptions & no crunch points.
Make the back of the cab half-a-ball shaped, & the matching socket curvature at the front of the trailer. Or I guess you could make it the other way as well
One little problem with that. The center of the ball & socket has to be the hitch ball where the trailer attaches to the tractor. Turning left and right is easy. Not so easy is allowing the tractor to tilt up relative to the trailer (think pulling into an uphill driveway).
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Old 10-29-2017, 11:14 AM   #48 (permalink)
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Originally Posted by ctmaybury@yahoo.com View Post
13.4 is amazing. I can barely beat that with a 3/4 ton and a 7k lbs travel trailer. I'm hoping to top 20 with some eco mods.
A Class 8 OTR truck prolly does 98% highway driving. I'm sure that you do much less highway driving with your pickup.

The BulletTruck would do 17.5-18 MPG on dead-nuts level ground. On steep uphill grades, it would only do 2.5-2.9 MPG. Downhill it would peg the instant MPG meter at its upper limit, which is 256 MPG. So it was a combination of those climbing, level ground, and downhill grades that let us average 13.4 MPG for that 3043 mile coast-to-coast freight run from Farmington, CT to Tracy, CA.

Interestingly, hardware and software allowed us to log engine conditions in real time during any leg of a trip. We set the data log parameters and took a snapshot of the engine computer approximately every 60 seconds for 1998.2 miles from Illinois to Tracy, California. There were 2250 lines of data, one line for every minute, traveling from west of Chicago, IL to Tracy, California. For those 2250 minutes, we were coasting for over 500 minutes. To put it another way, for those 1998 miles, we were coasting for almost 500 miles. Proper kinetic energy management, and utilizing it correctly, is crucial to obtaining hyper-mileage.
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Old 10-29-2017, 05:34 PM   #49 (permalink)
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I log each tank. Don't have a scan gauge or equivalent to tell me the second to second mileage. I find the empirical data very interesting and necessary to design and test a system. Data logging is necessary. I can see the need to teach you how to drive. What really counts is the long term mileage like the tank or the week month or year.

Aero mods are clearly your best bang for the buck, but do you have engine mods on your truck too? Turbo diesel motors have many great mods available to reach their potential. My trucks now have some standard mods that many do, but the future will see some custom 1 of a kind mods to help with pumping losses and thermal losses. Best thing about the next round of mods is power, efficiency, smoke control and emissions all improve.
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Old 10-31-2017, 12:19 PM   #50 (permalink)
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Aero mods are clearly your best bang for the buck, but do you have engine mods on your truck too?
The Cummins X15 engine is basically stock. With our high visibility, we cannot do anything contrary to EPA regulations like modifying the engine. As a matter of fact, I had to sign an EPA/Cummins waiver to run our active grill system, as it needed a special ECM calibration. The stock Cummins sensors were not accurate enough for the active grill with the standard calibration. We also have a custom data-plate on the engine stating the EPA exemption for the custom calibration.

We do however have a very low restriction exhaust system. It is almost a straight-shot to the aftertreatment system. The OEM exhaust system of the brand new 2016 International ProStar that we used as a rolling chassis, had NINE, 90 degree bends in the exhaust system. Most of those bends were between the two different aftertreatment tanks of the OEM system. That old system was completely lame.

Additionally, the turbo is wrapped as is the complete turbo down pipe all the way to the aftertreatment tank. We still gotta plumb the intake, but I have been in contact with my partners at K&N Filters about engineering that system. So yeah, we try to get the air in and out of the engine as efficiently as possible. Airflow is so important, I named my company after the concept.

We also have a trailer roof solar array charging the 48 volt battery bank in the day time so our 48 volt Delco Remy alternator will have much less parasitic losses. And we have a way cool Horton Cooling fan viscous drive that is electronically tied into the ECM.

And of course I can't forget our special, super-duper, custom Shell Rotella engine, transmission, and differential oil for reducing driveline parasitic losses. We use special Shell "Witches Brew" (very appropriate on Halloween) blends of all of these oils. When we filled the differential with the new oil, it looked and flowed just like light golden beer. Very, very watery looking viscosity. But the Shell scientists tell us that it will protect the differential better than the OEM dark molasses looking and flowing, 85W-90 gear oil that we drained out.

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