From: "Marvin Kaye" <marv@lancaironline.net>
Subject: Re: [FlyRotary] FD rads & Evap Cores Take 2
To: flyrotary
Date: Mon, 09 Feb 2004 02:02:29 -0500
Message-ID: <web-2983564@logan.com>
In-Reply-To: <20040209010135.KTMB2425.fed1mtao06.cox.net@smtp.west.cox.net>
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Posted for Dale Rogers <rogersda@cox.net>:
  
Leon <peon@pacific.net.au> wrote:

> You are touting that 2 Evap cores as being able to cool better than 
> an FD rad (plastic tanks aside),  but having less drag.  So should I 
> throw away the FD core (with alloy tanks) in the race car and 
> replace it with 2 evap cores? 
> 
> Will I then have less drag???  Will the race car then go faster,  or 
> have better fuel economy at the same speed (a very important 
> factor in endurance racing)?  

Leon,

    It is true that there is very little empirical evidence 
- as yet.  Moreover, even when we get more data on aircraft 
operation, it won't necessarily apply to race cars.  The 
modes of operation have enough significant differences to 
warrant caution.

    How often do you race at 10,000 feet, where the air is 
typically 20*C cooler than at sea level?  There is a 
difference in the requirements to push a 2000# airplane 
offering maybe 9 sq.ft. of frontal area at ~190 mph, as 
compared to a 3000# car offering 15+ sq.ft. at what? maybe 
~140?  Changing your radiator will have much less impact on 
your total drag.  

    I suspect Tracy's situation in an air race is not 
comparable either. How much of the time are you actually 
running at WOT?  In an air race, contestants are typically 
operating on the ragged edge of WEP.  That is so stressful 
that at the top end - the warbirds - engines a frequently 
good for only a single race.

    With two birds due to be finished this spring, we'll 
be getting more data to work with.

Dale R.
COZY #1254
Still on Ch. 3