Landracing Forum

Tech Information => Aerodynamics => Topic started by: RebekahsZ on November 15, 2015, 08:59:09 PM

Title: Roof rails-how important?
Post by: RebekahsZ on November 15, 2015, 08:59:09 PM
I am seeing a lot of landspeed cars (coupes and sedans) with angle aluminum formed to follow the roof line along both sides of the roof...what is that for?  And how effective is it?  I will be making windshield and back glass retention tabs, and I often see these sections of aluminum incorporated into the window tabs....good idea, or keep it simple and just make some simple tabs?
Title: Re: Roof rails-how important?
Post by: Glen on November 15, 2015, 10:04:48 PM
Rule book says required
Title: Re: Roof rails-how important?
Post by: jimmy six on November 15, 2015, 11:53:08 PM
You don't say what you are building. There are 2 questions here. 1. If you don't have a rule book....get one. 2 this is lesser known, go to the SCTA-BNI web page an look under forms to print an inspection form so you will know the minimum that will be checked when you bring your to inspection. It references where in the book each item is....

I was an inspector for over 25 years and I still check off my car as if I've never seen it by going down the list. Good luck...
Title: Re: Roof rails-how important?
Post by: jl222 on November 16, 2015, 01:09:55 AM
   The roof rails are there to spoil the air flow over the roof if you get sideways and prevents the car from lifting off the ground.
   I would use tabs in case you ever need to replace the wind shield.
   I spun on a wet track at Bviile at 260+ mph and stayed flat. Guess they helped some.

      JL222 :cheers:
Title: Re: Roof rails-how important?
Post by: Finallygotit on November 17, 2015, 08:33:22 AM
  The roof rails are there to spoil the air flow over the roof if you get sideways and prevents the car from lifting off the ground.
   I would use tabs in case you ever need to replace the wind shield.
   I spun on a wet track at Bviile at 260+ mph and stayed flat. Guess they helped some.

      JL222 :cheers:

Thank you, I have been waiting for that explanation.   :cheers:
Title: Re: Roof rails-how important?
Post by: SPARKY on November 17, 2015, 10:18:00 AM
They function as spoilers do on a glider/sailplane wing 
or as tires do on top of mobile homes---- they kill lift by creating turbulence
Title: Re: Roof rails-how important?
Post by: redhotracing on November 17, 2015, 11:09:45 AM
We retained the windshield and back glass separately then laid the roof rail edges over those. Roof rail material is "generally" thinner gauge than the tabs (i.e. 1/8" vs 1/4") but of course that depends on whether you're using lexan (with frames) or stock-style laminated glass. We utilized the windshield wiper stalks as our bottom tab mounts then tied the top into the body.
Title: Re: Roof rails-how important?
Post by: RebekahsZ on November 17, 2015, 04:00:35 PM
Thank you fellas-I have an ECTA rulebook and have passed tech twice without them, perhaps I'm just too slow (in several ways).  I didn't even know what to call those aluminum "thingies."  So roof rails it is!  Now I will go do some more research now that I know the proper term to search.  Thank you.  redhot-I'd love to see specifically what you mean by tying into the windshield wiper posts.  Thanks for being so helpful. 
Title: Re: Roof rails-how important?
Post by: RebekahsZ on November 17, 2015, 05:59:51 PM
Never in a million years would I have guessed the rails were for safety-I figured they were a form of streamlining.  I knew what the window tabs were for.  Thanks again.
Title: Re: Roof rails-how important?
Post by: dw230 on November 17, 2015, 11:08:37 PM
The roof rail rule came directly from NASCAR at the suggestion of Bill Ward in the 80s.

DW