Shape of teardrop and affect on gas mileage etc

[Lokahi117]

I am wanting to build my teardrop or rather tiny trailer very soon. But for my purposes I really won't need a kitchen or anything that requires the hatch to open. I will be pulling it behind a 2014 Honda Accord the v6 version, but I am wondering what kind of mpg drop I can expect from pulling this. And also if I make the trailer teardrop or just pretty well rectangle with a slight slope facing towards to the towing vehicle. Will that have any measurable effect on the mpg.

I will driving this for good long road trips and it will be used for utility not for leasure. I need something like this for work and it would be my own little home away from home.

Also will making it wuser than the towing vehicle really affect the mpg or tow ability?

Looking forward to getting it going and will post pics n stuff once it's under way.

[Socal Tom]

Making it wider or taller than the vehicle will have more impact on mileage. The Accord is a pretty aerodynamic shape, so its hard for me to say what the impact would be. The lower and smoother the transition from the back of the car to the front of the trailer the better. If the trailer gets lower and narrower at the back it would help reduce wind drag ( cars create a "vacuum" behind them that trys to pull them back). Perhaps someone else with an small car can help with the estimate. I've got a Jeep wrangler, so its a different story.
Tom

[pchast]

Hi,

I've checked both the wife's car and my pickup and lose about 1/3 of the
expected gas mileage on either. Ours is a 4X8, narrower, and 42 inches tall, so
slightly taller than the car. The pickup has no cap.

[aggie79]

Hi,

I've checked both the wife's car and my pickup and lose about 1/3 of the
expected gas mileage on either. Ours is a 4X8, narrower, and 42 inches tall, so
slightly taller than the car. The pickup has no cap.

We get similar results when towing our teardrop with our F150 and when we had a Honda CRV - about 1/3 less gas mileage. Our teardrop is 5x10, 4 feet tall.

[woodywrkng]

Pulling mine with a 2008 Scion xB reduced mileage from 32 to 24 mpg. The Scion was pretty tall, and a real brick in the wind so to speak. Generally for good aerodynamics you want your trailer to be shaped like a raindrop, or even, a Teardrop. The radius on the front of mine is 24", while the rear is 36". If I were to do it again, I'd increase both of them a bit.

Making it wider than your tow vehicle will create some real vision problems from your side view mirrors, and may be frowned upon by the local Gendarmes. Square edges should be avoided if possible. Smooth and curved is best.

[tony.latham]

I tow with a Tacoma that has a shell over the bed. It has a Scangauge that records current and tank MPG (and several other clumps of data). Without our 5x10 teardrop, I get 22 MPG. With the teardrop, I get 19 at worst. This is only if I keep the speed under 60. Anything above that the mileage drops exponentially –especially if I'm towing. (I'm three hours from the nearest Interstate or serious traffick, thus keeping my speed down isn't a challenge.)



My wife is a serious downhill skiier. She no longer keeps her ski rack on top of her Honda Fit in the winer. It eats mileage. She hauls the skis inside. Any front mass that protrudes above or to the side of your tow vehicle will increase your drag. The rear shape of the trailer is also important. A flat rear will cause seperation drag. There is nothing that induces drag more than a square box. (front and rear). Except maybe a parachute.



Tony

[Socal Tom]

Like I said, I tow with a Jeep Wrangler 4 door. On the highway at 65ish I get about 19 to 20 mpg. Towing I get 15 to 16. My TD is about the same width, height as the Jeep, so mine ends up looking most like the sphere with a fairing in the pic above.
Tom

[Ron Dickey]

a lot of this will depend on how you drive. I own a prius and when I drive it I drive it like I am riding a bicycle. I do not pull the trailer with it but I can get 50 mpg if I watch it with the prius and so goes true with your puller. reducing drag, knowing how fast you need to go up a hill if there is no down hill on the other side vs a hill with a down side on the other end (where you will get it back).

Trailer I pull with a carolla and if I do no drive aggressively I do well.

My new trailer as you can see below curves left to right. I wrote Camp in where the build both types and they said the Raindrop gets a little better MPG. so that is the way I am going. The trolley top may but that a little yet to see.

but the less you have sticking out on you puller and trailer the less drag the better mpg.

The Austrians put a screened stone blocks at the tung to cut back on air hitting the front of the trailer. I see it a cutting the air if angled right.

they see it as: ... Q. What are the advantages of a stone guard and are they worth the money?

There are 2 main reasons to fit a stone guard. i) to prevent stones and rocks from chipping the paint on the leading edges of your trailer and guards and ii) to prevent rocks bouncing off the front of the trailer and into the back window of the towing vehicle. Stone guards need to be angle downwards and back so that they deflect rocks back down to the road and away from the vehicle.


takes allot of thought and experimenting Ron

[Socal Tom]

they see it as: ... Q. What are the advantages of a stone guard and are they worth the money?

There are 2 main reasons to fit a stone guard. i) to prevent stones and rocks from chipping the paint on the leading edges of your trailer and guards and ii) to prevent rocks bouncing off the front of the trailer and into the back window of the towing vehicle. Stone guards need to be angle downwards and back so that they deflect rocks back down to the road and away from the vehicle.


takes allot of thought and experimenting Ron

Back when I was younger I camped out of a Ford van with a 460 engine. I built a big ole bumper for it, and for giggles I put and aluminum "cattle catcher" under it because I could. It turned out that my silly cattle catcher saved me about 1 mile per gallon, which was roughly a 10% improvement. I was really surprised at the impact. I never thought about doing something like that on the front of a TD, but reducing the airflow under it does improve drag.
Tom

[Supernaut]

I will say the shape of the trailer will have a huge impact on MPG.

I have used my ol' Pontiac Sunfire to tow motorcycles many times in the past. I tow them on a 4x8 flat trailer and when rolling down the highway they don't seem to pose much of a load on the car or hinder it much from rolling at highway speed. One time I bought a chest freezer that was not too large, light enough that I could lift it inside the box on my own with minor difficulty. I would imagine the package weighed maybe 60 pounds or so. I brought this home on my flat trailer, and I have to say it did seem like a bit of a struggle on the highway. I thought it bizarre, I can haul a 600 pound motorcycle down the highway and hardly notice it's there, but this 60 pound freezer feels like towing a small parachute.

The difference is the shape. I would imagine the difference in wind resistance between a rectangular trailer and a small tear drop would be very substantial.

Another big thing is speed. I believe I once read that to double your speed requires 4 times the power to fight wind resistance. More physics educated folk may say I'm wrong but it would seem to me that vehicles pass through some kind of wind resistance threshold when they get up to around highway speeds. For example, many expensive sports/exotic cars will have a spoiler that deploys around 70mph (112km/h) because they don't have much useful effect below that speed. A patient person willing to drive slow, say 90km/h or 55mph can experience a big saving in fuel and less strain on the towing vehicle. I once drove a long trip (no trailer) keeping my speed under 90km/h and was surprised to see the ol' sunfire returned about 6mpg better than it is originally rated to do.