Date: Thu, 19 Feb 1998 12:06:55 +0000
From: Mike Drew {[email protected]}
Subject: Re: Re[2]: Wrecked Pantera in HOT ROD
To: Multiple recipients of list {[email protected]}

The deck lid unlatched?????

}}}Right.  Junior discovered that there is an area of high pressure that forms 
underneath the decklid (and/or low pressure on top of the decklid) that causes 
rear-end lift at speed.  His solution was to remove the decklid struts and 
latching mechanism, and allow it to aerodynamically position itself in a 
neutral position.  He reported that at the type of speeds he was seeing (200 
mph plus), the decklid would 'float' about six inches open. 

That works fine when you're pointed into the relative wind.  But when you spin 
around at that speed, the unlatched decklid suddenly seems like not quite such 
a great idea! :}) 


Date: Mon, 23 Feb 1998 20:40:24 +0000
From: Mad Dog Antenucci {[email protected]}
Subject: Re: Fw: Bellypan vs. Plexiglass
To: Multiple recipients of list {[email protected]}

} }}The bellypan is a good idea and would probably only be needed at the
} }}back of the car assuming you did an effective job of getting air
} }}around the car with an airdam and skirts. I have a couple concerns
} }}with added heat without additional cooling because air does enter from
} }}underneath the car and air will still go up through the A/C condensor
} }}screen (Mike Anderson's Wind Tunnel Tests proved that out!) so what
} }}air pressure there is underneath the decklid might be better
} }}eliminated in other ways!

} }Don't forget that air is sucked in the rear grill for the A/C (I have
} }actually tested this with yarn strips - starts at about 35 mph). Therefore
} }there is a low pressure area in the engine compartment that may be coming
} }from under the car.  Maybe the low pressure area above the deck lid is just
} }greater at high speed.  This would indicate that a belly pan would not help
} }(maybe even make the lift greater).

Getting some interesting feedback on this subject. . .  Ted, you are correct 
about the air entering the rear grill for the A/C. . .but, I've been told by a 
few folks (Junior Wilson, Bobby Byers and Mike Anderson to name a few)  that 
their tests supported air flow reverses back out the rear grill at +- 150mph 
without the belly pan! 

I don't know the answer either but it seems reasonable to assume if that was 
the case then blocking off the grill may not be necessary. However,  if  the 
air does NOT reverse then it seems reasonable to me (anyway) that just 
blocking the grill would reduce the problem.  Bobby and Junior both have said 
that the increase in heat with the modified belly pan (A-arms & rear only) 
wasn't discernable. 

What Bobby did was just add a pan under the front A-arms and again at the rear 
of the car (didin't cover the water tubes) and he believes that goes a long 
way in reducing the air pressure problem under the back end...ASSUMING you 
also add the front air dam with side skirts to get air "around" the car. 

I also think several folks made a good argument to support reducing the sugar-
scoop air turbulance problem but after talking to some of our experts I have 
concluded that at high speed that isn't as much a problem  - as equalizing or 
minimizing the front end and rear end lift/pressure problems. 

Bobby and Junior start to differ in opinion at this point in a big way on the 
need for a front air dam (Bobby yes - Junior no!) and the rear spoiler at the 
high end stuff. Junior definately believed his rear spoiler was/is needed at 
speeds above 175+ mph on a stock bodied car. Bobby on the other hand believes 
if you equalize the air under the car and the problems with pressure/lift. . . 
then very little rear spoiler is required. In fact he believes you can very 
easily dial in too much down force with a rear spoiler. I'd like to see some 
other opinions/idea's on this subject??? MD 


Date: Tue, 24 Feb 1998 21:07:52 +0000
From: [email protected]
Subject: Wind Tunnel Tests of a Pantera
To: Multiple recipients of list {[email protected]}

This has already been done by Ford many moons ago.  Even have photo's of it.
The event was photographed and placed in a book called "Style Auto #29".  We
have been over this before.

The test results showed that the Pantera had a front end lift and total drag
only slightly greater than a racing GT40.

Results:

Vehicle     Air Speed             Lift                          Drag
HP required
(Kmph)     Front   Rear   Total              (Kg)
due to drag
------------------------------------------------------------------------------
---------------------------------------
260          136      51      187               252
238
225          104      39      143               193
159
Pantera      190            77       28      105               142
100
160            52       22        74                 99
58
130            34       15        49                 63
30
------------------------------------------------------------------------------
---------------------------------------
260           120     -14      105                231
217
225             92     -11       81                177
146
GT 40        190             68     - 8        60                130
92
160             44     - 5        39                  91
54
130             27     - 3        24                  60
28
------------------------------------------------------------------------------
---------------------------------------
260           254     -75      179                344
324
Mustang    225            194    -57       137                263
217
Boss 302   190            143    -42       101                193
137
160              99   -29         70                 137
81
130              60   -19         41                   89
42
------------------------------------------------------------------------------
----------------------------------------

There you have it.  Fords own results from their testing.  The wind tunnel 
tests were carried out on the original prototype Pantera.  It was yellow, 
thats why the tests are so good.  Other colors on the car did not fair so 
well. 

This book is extremely rare.  If you ever find a copy, buy it!  I paid over 
$200 for mine in the late 1980's. 


Date: Wed, 25 Feb 1998 15:12:21 +0000
From: Mad Dog Antenucci {[email protected]}
Subject: Wind Tunnel Tests
To: Multiple recipients of list {[email protected]}

Here's another po'boy race tip that Mike Cook shared with me for you guys 
running the slower top end speeds at SS, Pocono and elsewhere. 

Use your out-of-the-box luggage tray "in Place" when you run your cars!!!  It 
helps deflect half or more of the rear  air pressure under the rear end!!! 


Date: Wed, 25 Feb 1998 17:19:59 +0000
From: Mike Cox {[email protected]}
Subject: Re: Wind Tunnel Tests
To: Multiple recipients of list {[email protected]}

} Here's another po'boy race tip that Mike Cook shared with me for you
} guys running the slower top end speeds at SS, Pocono and elsewhere.
}
} Use your out-of-the-box luggage tray "in Place" when you run your
} cars!!!  It helps deflect half or more of the rear  air pressure
} under the rear end!!!

Sounds like the luggage tray will sort of work like a belly pan. At higher 
speeds will it start to "lift" or float around under the decklid? Mine just 
sets in, there are no clips or buttons to hold it in place... 

I did notice at 70'ish speeds (going to Willow Springs a couple of months ago) 
with no luggage tray and no engine screen I could see the decklid momentarily 
float up against the latch and then drop down. 


Date: Wed, 25 Feb 1998 17:33:11 +0000
From: "Ted A. Mitchell" {[email protected]}
Subject: Re: Bellypan vs. Plexiglass
To: Multiple recipients of list {[email protected]}

There isn't any "data", the pictures showing the directions the yarn is 
flowing IS the data.  As for location, cover every 3 or 6 inches across one 
side and half of the top (hopefully both sides of the car flow the same) with 
the yarn taped at the end toward the front to flow toward the rear.  If you 
don't have enough yarn or energy to do the whole car, cover some parts of 
interest to you, e.g.. the front end, air dam, front fender and hood. BTW use 
a color of yarn that contrasts well with the color of the car so that it shows 
up good in the photographs. 

As we get more and more of this data, I will publish the pictures both on the 
net, and in POCA Newsletter. 


Date: Thu, 26 Feb 1998 23:51:06 +0000
From: DtomasoCat {[email protected]}
Subject: Wind Tunnel results repaired!
To: Multiple recipients of list {[email protected]}

I am trying it again, due to an e-mail from Mad Dog talkin' about the 
possibility of his sweet cheeks rubbin' asphalt if he didn't have this 
information.  I converted all the metric info on the former posts to pounds 
and miles per hour. 

I a nutshell, the "slicker" a car is to the wind, the less friction it makes 
and therefore the less power it needs to go faster.  The more a car is shaped 
like a brick the more power it needs to go fast. 

You can see from the chart, that a Boss 302 needs 86 more horsepower than 
Pantera to go the same speed.  If a GT40 and a Pantera are both traveling at 
162 miles per hour, the Pantera needs 21 more horsepower than the GT40 just to 
push it through the air. 

I know this oversimplified, but so am I.

Results of Wind Tunnel tests:
Pantera - At a wind speed of 162 mph, it has 300 pounds of lift on the front, 
112 pounds of lift on the rear, and has a total drag of 554 pounds.  The 
horsepower required due to drag at that speed  is 238. 

At a wind speed of 140 mph, it has  229 pounds of lift on the front, 85 pounds 
of lift on the rear, and has a total drag of 425 pounds.  The horsepower 
required due to drag at that speed is 159. 

At a wind speed of 118 mph, it has 169 pounds of lift on the front, 62 pounds 
of lift on the rear, and has a total drag of 312 pounds.  The horsepower 
required due to drag at that speed is 100. 

GT40 - At a wind speed of 162 mph, it has 264 pounds of lift on the front, -31 
pounds of lift on the rear, and has a total drag of 508 pounds.  The 
horsepower required due to drag at that speed is 217. 

Mustang Boss 302 - At a wind speed of 162 mph, it has 559 pounds of lift on 
the front, -165 pounds of lift on the rear, and has a total drag of 757 
pounds.  The horsepower required due to drag at that speed is 324. 


Date: Wed, 27 May 1998 15:31:46 +0000
From: [email protected]
Subject: Re:  Speeding on Hwy 318 (was:Re:  SS Tech Questions)
To: Multiple recipients of list {[email protected]}

{{However, in their europhic speed-induced intoxication {grin}they forgot all
about my warnings. As they went around Curt's and my cars, I think they said
something about my warning had as much credibility as your rain gutter-removal
speed improvement modification idea! but I could be wrong! :-]  MD}}

The thread about rain-gutter removal suggestion was intended to quiet air
blast noise during Jon's windows-down driving, but I think it'll help at least
as much as your 2-rolls-of-duct-tape streamlining of all body cracks etc.
Recommend talking to Mike Cook re his Bonneville experiences & rain-gutter
removals. BTW, did your car get noticibly quieter when you taped up the seams
last year?