so i was watching the Discovery show Mythbusters tonight, and they did an experiment on whether its better to drive with your tailgate up or down. the results suprised me alot. ill skip right to the good part now and explain why later. they saiy its better to drive with your tailgate up! i thought this would actually create alot more drag, but surprisingly, it is the exact opposite. they said with the tailgate up, the wind catches in the bed and forms a "bubble" right behind the cab at the bulkhead. this "bubble" keeps more air from entering the bed of the truck and creating drag. its hard to believe, but this bubble actually keeps the air out of the bed. on the other hand, when you put the gate down, or dont have one at all, that bubble is completely lost, and the fast moving air comes over the cab and pushes down on the bed creating more drag. im still a little skeptical about this one. they put a model, a ford truck mind you!, in a water tank and pushed the water with a boat propeller. then they dumped oats into the water and it showed the bubble they talked about, but its still just hard to believe. i thought id share that little bit of information with all you guys and see what you think. i always thought it was better to run gateless, but i guess i was wrong...i think?

 

i'll remember this next time i am going up slickrock at 2mph

thats awesome! cool info and i love that show!
seriously though, never thought of it like that!

EDIT... just curious but how did they figure out there is a bubble that is formed? some sort of wind tunnel?

-cutts-

 

still interesting, since I used to run with my tailgate down on long trips when I didn't have my toneau cover on..

 

Though it is a cool show, the only one I've ever seen blow up a cement mixer, take it with a grain of salt. They don't always cover all the angles or get very scientific. They had a whole show about myths that they botched. I do know for a fact that at least with semi dump trailers (I have my Class A CDL) an empty trailer pulls hard due to the drag of the tailgate, harder than an empty dropdeck or van.

 

Thread moved to " General Automotive Discussion" forum. This info would be useful to all truck owners.

 

sorry about that. i usually hang in the offroad forum and was so caught up in disbelief i forgot about the other parts of the forum. my apologies.

 

It makes sence, since the automakers design the truck from a standpoint of jsome efficiency to meet cafe requirements. I would expect that when they do drag tests in windtunnels to measure wind resistence they would have to preform this with the tailgate up. Just a thought

 

I've heard from many, many sources that it is more efficient to run with the tail gate up. And while the aero test that the mythbusters performed is not 100% realistic, remember that aerodynamic properties are considered fluid dynamics and aerodynamics tests can be simulated in water.

EDIT: They demonstrated air flow over a pickup using a model truck in a tank of water with a current. Oats were dropped in the water to show the flow over and around the truck.

 

Their testing uses what's known to us engineers as similitude. It's a valid method. They could have just as well used a model in a wind tunnel with smoke to illustrate the aerodynamics. Test like this are frequently done on things like cars, airplanes, boats, and spillways. Testing of this type is very cost effective; a model is cheaper than a prototype.

 

There is also a thread on this in the fuel mileage forum.

 

This is something we farmboys should have known years ago because we rode in the back of trucks and knew where to sit and to put the tailgate up so the we could smoke in the "dead air zone".