Share Pics of People Hauling or Towing Something Wrong

[dodge man]

Talking of thing floating out of your pick up, years ago I picked up a washer and dryer about 50 miles away. Brand new and boxed up. I had a strap pulling them up against the front of the bed against the cab. This was a regular cab truck so the washer and dryer were right behind us.

Going down the interstate about 65 mph out of the corner of my eye I saw one of the boxes start to float up out of the bed. It only lifted a few inches but my buddy looks at me and I say "did you see that". He says yes. We pulled over and added another tie down. A dryer is pretty light compared to a washer but I still wouldn't have believed it could have lifted up like that.

 

[Oldpath05]

Probably the main reason why that pickup had to many pallets on it is, that it's a result of Larry Curly and Moe saying, there's always room for one more. Sometimes I say the same thing when I'm getting out firewood.

 

[Diamondpilot]

Talking of thing floating out of your pick up, years ago I picked up a washer and dryer about 50 miles away. Brand new and boxed up. I had a strap pulling them up against the front of the bed against the cab. This was a regular cab truck so the washer and dryer were right behind us. Going down the interstate about 65 mph out of the corner of my eye I saw one of the boxes start to float up out of the bed. It only lifted a few inches but my buddy looks at me and I say "did you see that". He says yes. We pulled over and added another tie down. A dryer is pretty light compared to a washer but I still wouldn't have believed it could have lifted up like that.

Ok, I will get all technical on you guys. The cab of a truck is working like the wing of a airplane.

The way a wing works is its basically flat on the bottom and curved on the top. Imagine a molecule of air hitting the leading edge and splitting in half then rejoining on the trailing edge. The half of the molecule on top of the wing has to travel farther so it must travel faster then the half going under the bottom. This creates a pocket of low pressure above the wing that literally "sucks" the wing up. This is how lift is created and how a airplane flies.

Same thing is happening with your trucks. Imagine the doghouse, cab, and bed as the wing. The low pressure being created on the top side is sucking things out of the bed.

Chris

 

[s219]

I remember one time about 25-30 years ago driving back to school after a break, on I-91 north in CT near the MA border, a full sheet of plywood blew off a truck in front of me and I drove under it while it was still floating in the air. I actually saw it come off and followed it up and over my car looking through the sunroof, then saw it come down on the road behind me (through the rearview mirror) and break into chunks. Lucky there wasn't an accident, as I-91 was always been rife with them in those days with all the perpetual road construction at that time.

 

[sixdogs]

Ok, I will get all technical on you guys. The cab of a truck is working like the wing of a airplane.

The way a wing works is its basically flat on the bottom and curved on the top. Imagine a molecule of air hitting the leading edge and splitting in half then rejoining on the trailing edge. The half of the molecule on top of the wing has to travel farther so it must travel faster then the half going under the bottom. This creates a pocket of low pressure above the wing that literally "sucks" the wing up. This is how lift is created and how a airplane flies.

Same thing is happening with your trucks. Imagine the doghouse, cab, and bed as the wing. The low pressure being created on the top side is sucking things out of the bed.

Chris

OK, good comment. Now, is truck mileage better with the tailgate up, down or the same both ways?

 

[aczlan]

Same thing is happening with your trucks. Imagine the doghouse, cab, and bed as the wing. The low pressure being created on the top side is sucking things out of the bed.

You can see this if you have a little loose hay or woodchips in the bed of your truck and you drive down the road.
They will loop around in the back of the truck.

Aaron Z

 

[bcp]

They loop around, not sucked quickly out. Turbulence, not suction.

Bruce

 

[Diamondpilot]

OK, good comment. Now, is truck mileage better with the tailgate up, down or the same both ways?

Actually better with it up.

With it up the flow is more laminer. With it down the air churns just behind the cab creating induced drag.

The gain is minimal, about 3% if I remember correctly from the wind tunnel test we did 20 plus years ago.

Chris

 

[Fallon]

Actually better with it up.

With it up the flow is more laminer. With it down the air churns just behind the cab creating induced drag.

The gain is minimal, about 3% if I remember correctly from the wind tunnel test we did 20 plus years ago.

Chris

Mythbusters has done this one at least twice. The only way to improve on stock is with a tight tailgate net if I remember. Same airflow stuff as tailgate up & a bit lighter.

 

[aczlan]

They loop around, not sucked quickly out. Turbulence, not suction.

There is suction to lift them off of the floor of the bed and lift them above the level of the bed sides. Some escape, but most recirculate following the pattern shown at: John VerSteeg's CFD Project

Aaron Z