[DeTomaso] Cobra / Shelby Club Race at Willow Springs / Rear DeckLid Needed

[John Taphorn]

Aerodynamic research by Dr. Andrew Wortmen has evidenced poor aerodynamic performance around the rear decklid exacerbated by the sugar scoop design.  He champions that a tremendous improvement in Aero could be gained by a cover that encloses it.  He also supports the idea of a belly pan.  

We are all experiencing this problem and it affects us with greater drag, lower top speeds and poorer feul economy to name a few.  Your car has simlpy had adequate tie downs that has kept you oblivious to the problem.  Which makes my point.

JT
  ----- Original Message ----- 
  From: Garth Rodericks 
  To: John Taphorn ; detomaso at realbig.com 
  Sent: Wednesday, May 14, 2008 7:15 PM
  Subject: Re: Cobra / Shelby Club Race at Willow Springs / Rear DeckLid Needed


  What poor performance???  My point is that no one else is experiencing this problem, so 
  not likely that it's a "compromised design," unless of course you're referring to the 
  design/lay-up quality of the CF decklid.

  John Taphorn <jtaphorn at kingwoodcable.com> wrote:
    Garth

    I appreciate your passion, but bigger straps doesn't interest me.  It is obvious that it needs to be tied down better.  It is clever to improve the airflow such that it would stay in place without any tie-downs.  Bigger hammer, larger clamps, more horsepower, can overcome a lot of compromised designs and mediocre driving skills.  I'd rather address the cause of poor performance.

    JT


      ----- Original Message ----- 
      From: Garth Rodericks 
      To: dfcex at pacbell.net ; detomaso at realbig.com ; John Taphorn ; Mike Drew ; kenn_green at yahoo.com 
      Sent: Wednesday, May 14, 2008 6:05 PM
      Subject: Cobra / Shelby Club Race at Willow Springs / Rear DeckLid Needed


      Uh, aren't we all missing the point here?  The rear decklid should NOT come off, 
      regardless of whether or not there's a front spoiler or airdam, or the trunk tub is in place or 
      not. MD and others consistently run at Silver State at super-illegal speeds without losing 
      their rear decklids. And I've never heard of anyone else losing their rear decklid on the track. 
      And there's also the guy who holds a land speed record at 209+ mph in his stock bodied 71 
      Pantera with no wings or spoilers, and he's never had the rear decklid come off.

      Is this a case of the carbon fiber just not being stout enough at the hinge mount points? 
      Surely if it cracked at one of the hinge points, that would be enough for the lid to lift into the 
      airstream enough to be grabbed like a parachute and ripped right off. Perhaps it's time to 
      bond some steel into/across that mounting point so it doesn't separate from the hinges or 
      flex enough to allow the wind grab it.

      I also recall one of the silver state guys running with the rear decklid unlatched; it 
      supposedly raised up a few inches in the back and stabilized there. I don't recommend this 
      though, especially on a track and if you're racing through twisties as that will put a lot of 
      lateral force on the decklid (probably not allowed for safety reasons too), and one spin at 
      speed would surely remove it again.

      I think you have to figure out why it's coming off in the first place before you bother making 
      expensive aero mods to depressurize the engine compartment/trunk area. Just my 2-cents.

      Cheers!
      Garth