Teardrop aerodynamics

[Modstock]

I draft trucks when I can. Usually when it's real windy but ya have to be careful which ones you pick. The "independents" have more power and the "box store" trucks will slow you down.

I first did this in a soft top jeep. When I would get to the sweet spot , the jeeps top settled down and quit rattling around.
Haven't noticed a difference (on my end) with the wings/flaps on a semi.
It's an art and I have it down pat.



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[booyah]

Great topic! I am wondering about the wings I see sticking out of the back of truck trailers these days and the panels down low on the sides of trucks at the side space between the front and back wheels. I have to assume these devices are helping fuel economy. Not sure how extending the trailer on the rear cuts drag (unless there is suction there that is moved away from the trailer. On that note I have seen many drivers drafting off the truck in front of them so I tried it for a short distance and I could see my mileage go up when I was close.

The panels on the side reduce the turbulance underneath, and the tails on the back are much like a boat tail on a bullet. Both go a long way to increase effeciency


"Side skirts are used to prevent air flow from entering the under-trailer region. In recent years, these have been widely adopted and are commonly observed on many trailers. Fuel consumption reductions on the order of 3-7% have been reported."

Overall its actually fairly interesting to read about
https://www.tc.gc.ca/en/programs-polici ... buses.html

[Sparksalot]

Great topic! I am wondering about the wings I see sticking out of the back of truck trailers these days and the panels down low on the sides of trucks at the side space between the front and back wheels. I have to assume these devices are helping fuel economy. Not sure how extending the trailer on the rear cuts drag (unless there is suction there that is moved away from the trailer. On that note I have seen many drivers drafting off the truck in front of them so I tried it for a short distance and I could see my mileage go up when I was close.

The panels on the side reduce the turbulance underneath, and the tails on the back are much like a boat tail on a bullet. Both go a long way to increase effeciency


"Side skirts are used to prevent air flow from entering the under-trailer region. In recent years, these have been widely adopted and are commonly observed on many trailers. Fuel consumption reductions on the order of 3-7% have been reported."

Overall its actually fairly interesting to read about
https://www.tc.gc.ca/en/programs-polici ... buses.html

I just posted this on another for almost the same question.

What the big rigs are doing is a modern version of what's called a Kamm Tail. 50 years ago, many race cars where designed around this. Kamm did aerodynamic research on the true teardrop shape, then modified it by cropping the tail of the teardrop. He found you can significantly shorten the length of your vehicle, while maintaining the low drag, if you start the teardrop, then crop it.

Probably the most famous example is the Shelby Daytona Coupe.

[tony.latham]

Here's the real deal.



But that would be awful to camp in.

Tony

[Squigie]

I've been ending up with a 'Kam Back' on nearly every design due to constraints imposed by the materials and components that I've chosen to use. Perhaps I should incorporate a spoiler -- make it look like something that belongs in a Fast and Furious film...

Here's the real deal.
(image redacted)
But that would be awful to camp in.

Tony

That's where the AN-2 comes in as a compromise: Antonov AN-2
More drag. But also more room for activities!

I see that Wikipedia now has a little blurb on my favorite thing about that plane: It has no official stall speed. It is capable of maintaining a level orientation while 'parachuting' itself out of the sky, and is one of the most survivable designs to come from our communist comrades. (The majority of fatalities were CFIT.)

A bad translation of the flight manual, which I read about a decade ago and will never forget: "If plane is bad for flying, pull the wheel for the most up and cowboy to the ground."

[tony.latham]

A bad translation of the flight manual, which I read about a decade ago and will never forget: "If plane is bad for flying, pull the wheel for the most up and cowboy to the ground."

Damn funny.

The last one I saw was sitting with two flat tires on an airport ramp in Mexico. I was looking at it when the Federales showed up in a taxi to check us out.

You could see the brush strokes in the paint from the factory.

It may be still there and that was fifteen years ago.

Tony