Gas mileage ?

All about towing and tow vehicles

Postby Mojave Bob » Thu Jul 21, 2011 11:44 am

CarlLaFong wrote:I'm really amazed by the folks that have managed to defeat an empirical scientific fact. They have managed to get something for nothing. They should invent a perpetual motion machine next.


I think it is more complex than that. It is true that more weight and more rolling resistance equates to more gas, assuming all other things are equal. However, adding a trailer also significantly changes the aerodynamic profile of a vehicle, and at highway speeds, aerodynamics plays a larger role than weight. So, if the trailer actually improves airflow around the vehicle, the gain in aerodynamic efficiency can actually increase gas mileage more than the weight decreases it, resulting in a net gain in observed mpg. Or, it can break even. However, as you can see from the posts, it usually works out to be a net loss. It will vary for every vehicle/trailer combination.
Mojave Bob
Teardrop Master
 
Posts: 147
Images: 7
Joined: Wed Jul 13, 2011 8:19 am
Location: Northern Indiana

Postby emiller » Thu Jul 21, 2011 5:29 pm

Bob I don't know where you came up with that hopefully your not driving that fast with a trailer that you are getting a arrow push. I know the best mileage I ever got was in California doing 55 on the freeway flat land and when I get into Arizona sometimes in a hurry to get home I have done 75 to 85 flat land and my mileage drops quite a bit.
User avatar
emiller
Donating Member
 
Posts: 3421
Images: 157
Joined: Sun Jun 13, 2004 11:00 pm
Location: Arizona, Phoenix

Postby Roly Nelson » Thu Jul 21, 2011 9:56 pm

My 4 banger Camry gets 2 mpg less when I am towing my 500 lb 1/2 Nelson Woody. However, when I hooked up the 6 foot long 245 lb "Stacker", I filled the gas tank until it was overflowing, drove 300 miles to the Colorado River and filled it up again until it overflowed..........it took exactly 10 gallons, which is the same as if I had left the TD at home. It's kind of like just having an extra person in the car with me........and I love it.
8) :shock: :thumbsup: Roly
See the little 1/2 Nelson Woody constructions pics at: http://gages-56.com/roly.html
User avatar
Roly Nelson
L'il Ol' Woody Builder
 
Posts: 2966
Images: 13
Joined: Sun Jan 30, 2005 12:45 pm
Location: Wildomar, Calif
Top

Postby jhanlon » Thu Jul 21, 2011 11:44 pm

So now take the 40 x 48 and build a foamie. Trailer weighs 98 pounds. add foam and you will have to take gas OUT at every fill up.

I expect to get same mileage with my 40 x 48 foamie chuck wagon/ external A/C unit for my van. "You pulling a trailer?"

John the Vanner.
John the Vanner - now with 41 X 48 HF trailer
User avatar
jhanlon
Teardrop Advisor
 
Posts: 66
Joined: Fri Jul 08, 2011 12:08 pm
Location: Sioux City, IA
Top

Postby Deryk the Pirate » Fri Jul 22, 2011 7:23 am

Now with the pt cruiser I averaged 26mpg mixed city/highway with the lil vardo on I got about 19 mpg but its not aerodynamic, like bob's barn lol. Im hopein to do about the same with my rav4 since it gives me around 21mpg. Gonna lose some with the high flat sides but what are ya gonna do lol. But the engine is much more powerful and its twing is 3500lbs. Will be finding out in a few weeks lol once it gets built!
Build Thread lil vardo 1: http://tinyurl.com/baqe6py
Build Thread lil vardo 2: http://tinyurl.com/b3rwffm
User avatar
Deryk the Pirate
500 Club
 
Posts: 809
Images: 158
Joined: Tue Aug 18, 2009 11:03 am
Location: Parlin NJ
Top

Postby Mojave Bob » Fri Jul 22, 2011 7:46 am

emiller wrote:Bob I don't know where you came up with that hopefully your not driving that fast with a trailer that you are getting a arrow push. I know the best mileage I ever got was in California doing 55 on the freeway flat land and when I get into Arizona sometimes in a hurry to get home I have done 75 to 85 flat land and my mileage drops quite a bit.


A general rule of thumb is that 50% of an average car's energy is used for just pushing through the air at a rate of 55mph. The less energy it takes to push through the air (aerodynamic drag coefficient), the less gas will be consumed. With a FEW car/trailer combinations, the drag coefficient is better with the trailer than without. With a VERY FEW car/trailer combos, the coefficient is so much better that gas mileage actually increases minimally, in spite of the extra weight and drag of the trailer.

I'm not an aerodymanics engineer, but I would expect that the vehicles most likely to be affected in this way would be boxier ones with poor trailing-edge airflow. Just guessing.

Again, these are the exception rather than the rule, and I'm not saying "Tow a trailer to save gas". For nearly all of us, our gas mileage will go down when we tow.
Mojave Bob
Teardrop Master
 
Posts: 147
Images: 7
Joined: Wed Jul 13, 2011 8:19 am
Location: Northern Indiana
Top

Postby stevem50 » Fri Jul 22, 2011 9:53 am

i totally agree with bob, i have studied aero and fluid dynamics, and found the overall shape of the object you are pushing through the air determines how much energy is required to do it.

the tear or waterdrop shape ( rounded at leading side tapering to the rear) is the most efficient shape, and if you are driving something squared at the rear, like a van or wagon, you can theoreticly get better mileage when towing... assuming your trailer is not too heavy.

in my case, with a small hatchback, with low power, i have no loss in mileage on flat ground, but i do lose 2-3 mpg when it get hilly.

overall 32-35 mpg towing is not bad
User avatar
stevem50
Teardrop Master
 
Posts: 150
Images: 15
Joined: Tue Jun 29, 2010 8:07 pm
Location: Bel Air, MD
Top

Postby slowcowboy » Sun Jul 24, 2011 9:06 pm

problem with a teardrop built out of foam.

when the wind blows in wyoming its not going to be on the highway.

it will blow over in the barrow ditch in to seconds.

this will happen when the road report says."high winds. NO LIGHT TRAILERS>"

heee! need wood trailer and teardrop in the state of wyoming due to wind force!!!!!!!


I found last weekend on a trip to nebraska to bring home a round baler I bought.

that its mostly weight and wind restince on gas milage.

I got driving a f-150 pulling a empty 20 foot gooseneck flat bed trailer.

175 miles to a tank of gas.

same truck same trailer.

loaded with round baler.

round a baler sticks up high in the air.

I know it was eating a lot of wind due to all the bugs stuck to the round a balers front end when I got home.

gas milage pulling round baler and 20 foot flat bed on same truck f-150.

100 miles to a tank of gas at the most.

I lost 75 miles to a tank of gas due to wieght of load and wind restince.

speed on big hills on 1 25 out of cheyenne coming in to casper around douglas was dropping down to like 40 mph.

speed out of casper was around 60. could have pushed it to 65 but didn't due to no spare blown in oglala, nebraska.

I am conveived wieght and wind restince is a major factor on gas milage when towing.

round baler was square and tall was at least 3 to 4 feet above the cab of the f-150 truck.

lots of wind resitance.

wieght went up by like 2 tons.

I had close to 5000 in towing weight from a empty like 2400 pound goosekneck flat bed trailer.

lost 75 miles to a tank of gas.

so conserder the extra weight and wind restince when your pocket book cant stand the bite on gas when you want to say no teardrop for me.

Slowcowboy.
Plans. there was supposed to be plans to be followed when I built this thing. Opps! AH, gee, tum,tee tum. I think I forgot about the plans 2 years ago. ------Tow vehicles, 1995 ford explore, 1994 ford ranger, 1993 ford F-150, 2009 4x9 Off road teardrop, on harbor freight greatly modified frame.
User avatar
slowcowboy
6000 Club
6000 Club
 
Posts: 6912
Images: 165
Joined: Tue Feb 09, 2010 12:25 am
Location: pavillion, wyoming.
Top

Postby stevem50 » Sun Jul 24, 2011 10:03 pm

the weight issue has been bouncing around in my head lately, more so as i read more about mike's giant foamy. i'm trying to shave lbs off my 4x10 woody to ease strain on my car climbing mountain roads. i'm only at 1100lbs fully loaded, but think how much better the mileage and performance if i could have another 2-300 lbs lighter...
User avatar
stevem50
Teardrop Master
 
Posts: 150
Images: 15
Joined: Tue Jun 29, 2010 8:07 pm
Location: Bel Air, MD
Top

Postby Constrictor » Mon Jul 25, 2011 8:40 am

stevem50 wrote:the weight issue has been bouncing around in my head lately, more so as i read more about mike's giant foamy. i'm trying to shave lbs off my 4x10 woody to ease strain on my car climbing mountain roads. i'm only at 1100lbs fully loaded, but think how much better the mileage and performance if i could have another 2-300 lbs lighter...

In my opinion gas mileage while hauling a trailer is mostly the footprint it makes in the wind, resistance. my 6x12 box trailer gets the same mileage empty as with a load.
User avatar
Constrictor
Teardrop Builder
 
Posts: 30
Images: 16
Joined: Fri Jul 04, 2008 12:44 am
Location: 65802
Top

Postby stevem50 » Mon Jul 25, 2011 8:56 am

i'm not really thinking i can boost the fuel consumption much, but if i put my woody on a diet, it will be easier on the car while towing it.. lighter can't hurt when the hills start coming
User avatar
stevem50
Teardrop Master
 
Posts: 150
Images: 15
Joined: Tue Jun 29, 2010 8:07 pm
Location: Bel Air, MD
Top

Postby Ron Dickey » Fri Aug 19, 2011 1:15 am

It all really is what are you driving. but Teardrops and Tinny Travel trailers do not add that much pull to a engine. So it is more is up hill, flat, sea level or at 5000 ft., paved or dirt, 2 wheel or 4 wheel drive, Are you a fast driver or do you drive by what the signs say to drive.

All in all you do not loose that much unless what you put in it for the camp is more then you should.
121377.............134179.........134805
both side walls are up...cabinet needs stain.......ongoing 2.5 yr bld build as i find time..... Cross Bow in Build Journals....viewtopic.php?f=50&t=54108
User avatar
Ron Dickey
Silver Donating Member
 
Posts: 2930
Images: 701
Joined: Tue Apr 20, 2004 5:56 pm
Location: Central Coast, CA
Top

Postby slowcowboy » Fri Aug 19, 2011 4:35 am

only drop in milage I have seen is trowing something big and bulky full of wind resitance on the roof rack on the teardrop

like a jon boat.

other than that I get the same milage as not pulling the teardrop.


the only real cure to worrys about gasoline is to get the dang goverment to lower the gas price to what there citizens and ecomomy can afford with out killing prudutivity and economic growth.

and untill that happens. Teardrops will be in demand.

slowcowboy.
Plans. there was supposed to be plans to be followed when I built this thing. Opps! AH, gee, tum,tee tum. I think I forgot about the plans 2 years ago. ------Tow vehicles, 1995 ford explore, 1994 ford ranger, 1993 ford F-150, 2009 4x9 Off road teardrop, on harbor freight greatly modified frame.
User avatar
slowcowboy
6000 Club
6000 Club
 
Posts: 6912
Images: 165
Joined: Tue Feb 09, 2010 12:25 am
Location: pavillion, wyoming.
Top

Postby StandUpGuy » Fri Aug 19, 2011 6:22 am

slowcowboy wrote:..milage as not pulling the teardrop.


the only real cure to worrys about gasoline is to get the dang goverment to lower the gas price to what there citizens and ecomomy can afford with out killing prudutivity and economic growth.

....
I think this sort of thinking has gotten us where we are now. I do not want the government to control the price of anything. That is socialism. I want the government to back off of regulations and allow for greatly increased drilling for oil in the USA.
User avatar
StandUpGuy
1000 Club
1000 Club
 
Posts: 1060
Joined: Sun Mar 27, 2011 6:15 pm
Top

Postby starleen2 » Fri Aug 19, 2011 8:29 am

Mukilteo wrote:I don't want to know the mileage I'm getting towing the trailer. I might get depressed and not go anywhere.
What kind of fun sitting at home be?
Some times you have to throw caution to the wind and say "The heck with it, let's hit the road. :D "

+1 :thumbsup:
User avatar
starleen2
5th Teardrop Club
 
Posts: 16256
Images: 48
Joined: Sat May 12, 2007 8:26 pm
Location: Pea Ridge ,AR
Top

PreviousNext

Return to Towing and Tow Vehicles

Who is online

Users browsing this forum: No registered users and 1 guest