[Land-speed] Fwd: Downforce vs Ballast Question

[Jane McMeekin]

Begin forwarded message:

> From: Jane McMeekin <mcmeekin at columbus.rr.com>
> Date: June 10, 2007 6:00:54 PM GMT-04:00
> To: Dick J <lsr_man at yahoo.com>
> Subject: Re: [Land-speed] Downforce vs Ballast Question
>
> Dick,
>      We just finished aero testing on the 240sx and discovered some  
> stuff that was not anticipated. For instance, we added a 3/8"  
> wicker bill to rear spoiler and experienced an additional drag  
> factor of 5+ hp (+.005cd), but at the same time, went from 230lbs  
> lift, at 200mph, to a lift of 91lbs with this change. As you can  
> see the trade off in drag for down force is very favorable with  
> this modification. The point is, it's not an easy call in many  
> instances and may be even be more difficult without scientific  
> data. What ever you decide to do, my advice is to pay attention to  
> developing the best possible shape, while at the same time, take  
> advantage of low penalty aero tricks that aid in the development of  
> down force at a reasonable cost in additional drag.
>      Don
> On Jun 10, 2007, at 3:30 PM, Dick J wrote:
>
>> Which is better?  It would seem that if you add, say 500 pounds of  
>> ballast, it's a simple addition.  If you add a spoiler designed to  
>> add 500 pounds of downforce, then you are adding the effective  
>> weight, plus additional drag.  No?
>>
>>   DickJ
>>   In East Texas
>>
>>
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