The Underbody (flat belly pan is suboptimal - explanation & solutions offered)

[Xist]

Hey, I have a degree in Spanish and have had training in driving a school bus and fuel supply\driving a fuel truck. I am also an Eagle Scout. All that I have done is remove the crossmembers on my roof rack, but I read over and over about Hucho using wind tunnels.

I am going to believe the guy that used wind tunnels until someone else uses one and disproves him.

[jime57]

Originally Posted by Xist

Hey, I have a degree in Spanish and have had training in driving a school bus and fuel supply\driving a fuel truck. I am also an Eagle Scout. All that I have done is remove the crossmembers on my roof rack, but I read over and over about Hucho using wind tunnels.

I am going to believe the guy that used wind tunnels until someone else uses one and disproves him.

It's the approach most aero designers take when they can't actually reduce the problem to simulations or equations. In the end, everyone with resources tests in the wind tunnel anyway so may as well ask about the "smoke" right away.

[MTrenk]

For the hood with the directional vents, you could pop some air temperature (or pressure) sensors across the back of the hook in a lane (maybe even two or three rows for a nice plot) and that could net you some useful data. They'd have to be nice ones though!

freebeard that car is quite gorgeous. The back transition straight into the ground doesn't look like it would do much good, but I do enjoy the attempt to make the entire front end of the car a massive airfoil. That is a big part of my designs.

[MTrenk]

For the hood with the directional vents, you could pop some air temperature (or pressure) sensors across the back of the hook in a lane (maybe even two or three rows for a nice plot) and that could net you some useful data. They'd have to be nice ones though!

[UltArc]

I am not trying to disagree, but I can NOT believe everyone who has done a belly pan is just imagining the results. I will trust that the theory on improving the belly pan is accurate, or plausible, but to say that a belly pan does nothing? I can't believe that one bit. Too many people have done too good of testing for me to believe that a belly pan is worthless unless it has dimples or whatever.

And a flat belly pan is used to slow the cars down? I can't believe they would do anything to slow the car down. They have breaks, if they want to get into the lead, they need to get their the fastest, hold the turns well. If they wanted to make aero slow downs, it could be Bugatti style with flaps, which has been around for years. What is your take on the Ford GT underbody? That is what I want to build for my vehicle. Sub optimal?

Is that picture from Gran Turismo? I love that simulator

[MTrenk]

The flat section is to lower top speeds so the driving is less dangerous because for a while there the speeds there were achieving were too high for natural human response time to be adequate to maneuver the cars.

In the first page of the forum, oil pan 4 stated that many people were achieving only small gains from such a big project as a flat belly pan, where as you could get the same percentage improvements from just an air dam (a less extensive project). A flat underbody may be more efficient than all the bits that hang down from you car just in the wind, but if you want to see big, meaningful improvements, you really have to go for an airfoil shaped bottom, or dimple the sucker if you have to do a flat pan.

The passenger vehicle world is not the best place to look to for innovative designs. Their designs make money, and aren't always engineered to perfection. Some of the best cars out there, like the Tesla Roadster, and the Aptera, will never make money, but they are engineering to die for. Tesla is an electric car done properly, Aptera is real life eco car design.

freebeard, most cars aren't designed to be aerodynamic in the side direction I think what you speak of is a good example of how to achieve overall good aero performance in the real world: a windy highway.

[UltArc]

I didn't see the post about not knowing where it came from, struggling on a mobile phone for this.

So do you have a view point regarding the bottom of the Ford GT?

Flat underbellies are not visible on the road. They also don't scrape the road or bumps or hills. They shouldn't be affected by winter snow, and may improve slightly from crosswinds. I see what you are saying about price and work compared to payoff, but there are serious limitations. I will have to look at those things later from the wiki.

I thought the vehicles were now governed in the 22 or less range. And top speed doesn't matter in racing, if everyone is equal in top speed. Getting there should be important. Camaro vs Prius would lose to 5 mph, I believe, but say 50 or beyond, I would guess the Camaro.

[UltArc]

220 mph range, sorry for repost

[slowmover]

Originally Posted by UltArc

220 mph range, sorry for repost

No, apology not accepted . . you had me into the not distant not-far future of a tremendously limited number of vehicles -- the only ones still extant -- running saponified fats. Soylent Green done correctly

[jime57]

Originally Posted by slowmover

Soylent Green done correctly

Only old guys can remember that classic movie