Roof Hatches

While I was watching the races on tv the last few weeks, I noticed that the roof hatch on Robert Hights car was not latched during his runs. Does anyone think that having a roof hatch open could be considered a "vortex generator" as it could create a low pressure area behing the open part of the hatch, then create more down force on the deck?

 

Barry:

Most are not using latches anymore on the roof hatches. In our case even with a latch the pressure inside the body is blowing the hatch open at about 200 miles per hour (less than 1/2 track).

RG

 

Thanks Randy..I guess that what happens when you don't go to a race for a year or so..the "technology" moves ahead

 

Randy, does the high pressure in the drivers compartment 'push' the hatch open, or the giant low pressure void coming behind the vault of the air stream over the windshield 'pull' it open?
I would say the latter. But either way, it does come open on it's own. (Although, I have heard heavily intoxicated "experts" in the crowd tell me that the hatch comes open only when they shake the tires early in the run.)

 

Whether it's sucked open or blown open the same dynamics still exists, the pressure inside the cab is lower than the pressure outside on the roof.

I've seen better ESPN2 videos but they aren't on YouTube. If you watch this one at around the 2:30 mark and can pause it at the right moment you see the roof hatch inflating, even to the point where it pushes itself up between the hinges above the roof line in front before the latch finally pops.

Daniel Oliver Las Vegas round two/YouTube

RG

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It certainly is a phenomenon unique to these cars. I couldn't really tell what was going on at first. My car did not start to do it until I changed spill-plates. Then it started to do it every pass. You have to see it to really believe it.
However, I am still trying to figure the aero package of this;
http://www.buzzzmiller.com/cavein2.jpg

 

Are you sure? Fires typically get drawn in when there is firewall damage after a kaboom. Could it be that depending on the firewall configuration (when we mounted our body in the shop we installed a full firewall to help support the body, not the "V" shaped many others have) that the area in front of the firewall at the back of the engine may have higher pressure than the cab?


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