[DeTomaso] Gr4 Pantera at Le Mans video / aerodynamics at high speed

Wed Feb 3 20:49:27 EST 2021

You forgot to mention frightening, Charles!
Memo to self: Remember to load the nose by braking a bit while entering 
a hump bridge at 155.
Hahahahahaha...
Dave

On 2021-02-03 5:32 p.m., Charles Engles wrote:
> Dear Larry,
>
>             Your postings are the most informative Pantera aerodynamic practical research that I have seen.  Very impressive.  In the absence of a wind tunnel session with various aero aids and suspension mods, I think this is outstanding.  Well done, sir.
>
>                          Warmest regards, Chuck Engles
>
>
>
> -----Original Message-----
> From: DeTomaso [mailto:detomaso-bounces at server.detomasolist.com] On Behalf Of Larry Stock
> Sent: Wednesday, February 03, 2021 6:14 PM
> To: Rich Hoppe
> Cc: DeTomaso at server.detomasolist.com; Dan Courtney
> Subject: Re: [DeTomaso] Gr4 Pantera at Le Mans video / aerodynamics at high speed
>
> We make and sell a NASCAR Type rear blade spoiler, we also developed a rear center diffuser, and we have a race lipped front air dam that will develop about 500 pounds of front down force at 150 MPH, plus the we then added a underside wing to go under that spoiler. (at the Pony Express we got her airborne going over a bridge for about 175 feet, we actually came down slightly nose heavy at 155 mph) With another 7 weeks of foam and fiberglass underside shaping and side skirts we were getting about 4700 pounds of down force from shaping the underside with only the blade rear spoiler above the centerline. The side skirts made all the difference in the world. At Pahrump’s 2.4 mile technical road course we shaved off 6 seconds with and without the side skirts with all the other enhancements afore-mentioned installed. So if you are running a Silver State for speed, no skirts for minimum drag, for a Road course run the side skirts to suck it into the pavement. Since we were  creating so much down force we actually had to set the chassis up with Positive Camber to get the tires to heat evenly. We were actually sucking the Pantera down about 3 inches at 140 MPH. We measured less than ¼” of clearance left at the rear crossmember by the amount of fiberglass left on our rear diffuser. We were pulling up the asphalt pebbles, depositing them on top of the deck lid, so much so I had to repaint the deck lid 2 or 3 times as they would pile up in front of the rear blade spoiler and just grind away the paint.
>
> Larry
>
>   
>
> From: Rich Hoppe <richbhoppe at gmail.com>
> Date: Wednesday, February 3, 2021 at 2:38 PM
> To: Larry Stock <larrys at panteraparts.com>
> Cc: Dan Courtney <dan at excaliburre.com>, "DeTomaso at server.detomasolist.com" <detomaso at server.detomasolist.com>
> Subject: Re: [DeTomaso] Gr4 Pantera at Le Mans video / aerodynamics at high speed
>
>   
>
> Larry
>
> I ran the pizza car with a front spoiler or splitter 165 mph at silverstate for the last 20 miles straight without a problem.
>
> I think I hit that speed again at the texas world speedway on the main straight.
>
> The car is pretty stable at that point, but I would like to buy a nascar rear blade if someone has one.
>
> I really dont want to find the aero limit by trial and error.
>
> At Apex motor club track that I run on they put a chicane on the long straight that holds my speed to maybe 140-150.
>
> They may have a day where they take the chicane out and let you go down a 3800 ft straight.
>
> I think I could hit at least 180mph.
>
> When I run it out in forth gear it hits about 167mph at peak HP 8000 rpms.
>
> Then there is 5th which has been changed to the taller gear in the transaxle.
>
> I have never  shifted to 5th and let it climb yet the road is always too short.
>
> So I am not sure when I really need the blade but the situation will happen sometime.
>
> Rich
>
>   
>
> On Wed, Feb 3, 2021 at 3:15 PM Larry Stock <larrys at panteraparts.com> wrote:
>
> At speeds beginning at 120 the US DOT raised ride height Pantera's front end will start to float. If you lower the Pantera to Dallara's originally designed ride height with the A-Arm's flat and parallel with the road surface, and with a short and well clearanced GTS fiberglass or a short blade type front spoiler, we can get to 155 MPH when it's all you can do is hold on to it in two lanes of traffic as I experienced at the Silver State. With a group 4 or group 5 front spoiler you are good up to about 180 MPH when the roof and deck lid design will begin to lift the roof and unload the rear of the Pantera so you need a rear spoiler and diffuser to break up the rear lift to hold it down. A wing will do the same, but you probably won't have the HP to be able to get there with most wings, and it then it will become rear heavy and unbalanced. So if you were to get air under the front end where you end up like Junior Wilson and/or the Audi Prototype car at Le Mans 10 years ago, going a spectacular 70 feet in the air going end over end until final impact. A simple Nascar type blade spoiler to break the lift without adding much drag is about all you need. Mike Cook told me with the aluminum front hood skin, that at about 185 MPH, it was pushed (crushed inward) in from the frontal air pressure just above where the vented hood vents would have been. So at speed, the typical radiator front hood vents would probably be putting more air under the Pantera aero design, further destabilizing it. Now let all that data settle in.
> Larry Stock
>
> On 2/3/21, 1:20 PM, "detomaso-bounces at server.detomasolist.com on behalf of dan at excaliburre.com" <detomaso-bounces at server.detomasolist.com on behalf of dan at excaliburre.com> wrote:
>
>         Regarding the aerodynamics at high speed, when Cook Sr. built "The
>         Beast" in '71 he used rubber thongs on the vented fiberglass front deck
>         lid, which allows it to float at high speed.
>
>         On the rear deck lid he installed a huge stainless steel wing, like
>         something off a B-52.
>
>         The wind didn't appear to help enough.
>
>         On one infamous Silver State Challenge the rear of "The Beast" was
>         lifting above 170 mph.
>
>         About 1/2 way through my run "The Beast" stabilized and started holding
>         the road again.
>
>         After arriving at the finish line someone asked me what happened to my
>         rear deck lid (now fiberglass and without the B-52 wing) and I realized
>         it was gone.
>
>         I'm guessing it flew off at the same time the car stabilized.
>
>
>         Dan
>
>
>
>         Dan Courtney
>
>         La Jolla, CA
>
>         (858) 337-7019 cell
>
>         Dan at excaliburre.com
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