Flat Deck vs Drop deck

[XRNone]

bloomquist is back to a drop deck in his new car. What are the advantages/disadvantages?

[TheJet-09]

Did you see that from an in-car camera at Bristol? I noticed it, but also thought the car looked old. The air filter was even bent up on it.

I have a hard time wrapping my head around aero stuff. I know back when you could have the area right behind the hood open, it would help pull air out from under the front of the car. Bloomquist even ran a "belly pan" under the entire nose back then (which I believe is also illegal now).

One thing we all know, is nothing he does is by accident. After the "window net" race at Eldora, I looked at his car in the pits and noticed he had the LF fender bent at the top in a way that created a Gurney Lip for the majority of its length. How that wasn't illegal is well beyond me, but I couldn't cite what rule it violates.

He himself said air can't follow more than a 7 degree pitch, so I've also wondered how disruptive a straight drop behind the hood could be beneficial.

[MasterSbilt_Racer]

So aero laws changed is why they went drop deck, flat, and now he's back to drop?

[Peanut Butter Falcon]

I saw that also. And did you notice the Warrior car Ryan King is driving had a dropped deck.

[Ghopper]

If you want insight into the pressures above or below the deck.... Nearly any hole in the deck causes air to go from outside to inside, reducing the downforce of the body. Oil coolers on the deck have flow from outside to inside, a very effective passive system to move air across the heat exchanger. However, it costs total downforce numbers. Drop deck removes volume under the body, that could help peak downforce, but if you cut a bunch of hole in the deck it doesn't matter.

https://www.totalsim.us/simulating-a-dirt-late-model-in-cfd/

https://www.totalsim.us/dirt-late-model-revisted-spoiler-or-rear-wing/

[TheJet-09]

I'm not sure who implied aero laws changed, as I'm the first to admit I don't know why he would do that. But I do feel he's the master of "red herrings" so maybe it's nothing more than that.

[MasterSbilt_Racer]

I'm not sure who implied aero laws changed, as I'm the first to admit I don't know why he would do that. But I do feel he's the master of "red herrings" so maybe it's nothing more than that.

No one did. But, I felt it was implied that Scott Bloomquist was always right.

[ZERO25]

No one did. But, I felt it was implied that Scott Bloomquist was always right.

He's never wrong........he was just testing! lol

[XRNone]

Now the 2 coulter car is at Bristol with a completely flat deck and windows like it’s 1999. I can’t keep up!

[JustAddDirt]

You guys do understand that Bloomquists father was and, and still is in the aviation industry. So that gives him a very good insight on the way air works, and the way that air moves around things. Drag, lift, forces of air around things. How many of you guys remember him racing the car he called “Airplane” at Eldora? The roll cage was made out of teardrop shaped moly tubing that was used in construction of airplane wings. As much as people hate to admit it, the guy is pretty smart!

[ZERO25]

He raced that car at Speedweeks. I was fortunate enough to have seen it!

At GIS, he even had airfoils made outa plexiglass riveted to the front a posts. He had competitors scratching their heads! lol

[JustAddDirt]

He was and still is good at making people scratch their heads. Sometimes in a good way, others not such a good way. Wander what ever became if that car?

[ZERO25]

If you want insight into the pressures above or below the deck.... Nearly any hole in the deck causes air to go from outside to inside, reducing the downforce of the body. Oil coolers on the deck have flow from outside to inside, a very effective passive system to move air across the heat exchanger. However, it costs total downforce numbers. Drop deck removes volume under the body, that could help peak downforce, but if you cut a bunch of hole in the deck it doesn't matter.

https://www.totalsim.us/simulating-a-dirt-late-model-in-cfd/

https://www.totalsim.us/dirt-late-mo...-or-rear-wing/

After reading it a couple of times, I noticed the author said the flow onto the back of the deck could be improved.

Any suggestions?

[MachineMasters]

Would holes in the surface of the deck not help to suck air out from underneath the deck?
Faster air moving across the surface of the deck vs slower air underneath...?

I noticed the dropped deck that Zero had at Bristol had a long sideboard running down the rightside of the driver's compartment. Wouldn't put it past Scott to opt for the drop deck just for the additional ~3ft sideboard.

[billetbirdcage]

Would holes in the surface of the deck not help to suck air out from underneath the deck?
Faster air moving across the surface of the deck vs slower air underneath...?

I noticed the dropped deck that Zero had at Bristol had a long sideboard running down the rightside of the driver's compartment. Wouldn't put it past Scott to opt for the drop deck just for the additional ~3ft sideboard.

High pressure tends (lol) to flow to low pressure so high pressure on top of deck will flow to underneath. I suppose if the hole had a tube on it sticking up (to get to the high flow rate air) then it might but on the deck surface for the car to make down-force the top has to be moving slower then the bottom.

PS: Not an Aero engineer