December Racecar Engineering Magazine and Vees

[hardingfv32-1]

Larry

How did you measure the drag?

Brian

[hardingfv32-1]

Robert

The Boeing guys know what they are doing. I think they were just validating the stall point. The models in the wind tunnel are never 100% representative of actual flight conditions. You can bet the flight software is going to raise hell before it lets the pilot steer into a stall.

The Vee aero articles are very good at pointing out trends.

Brian

[brian]

I know that Bill Noble participated in the wind tunnel tests and both he and Lisa were on the tapes. I'd call Lisa and see if she knows where you can get the tapes. The ones I saw came from Ronnie Chuck.

My readings have indicated that due to our slow speeds, frontal area is the most critical with air management second. Real narrow cars with a bulge in the middle are not the answer. A visit to the US Bobsled website is a great place to see a perfect shape for low speeds. Admittedly, we don't have to push and jump in, so the back half isn't too informative.

[DanRemmers]

...we don't have to push and jump in...

Now THAT would make for an interesting start to a race.

[hardingfv32-1]

Frontal area (Fa) and drag coefficient (Cd) are of equal importance in the drag equation. A sleek body (low Cd) that requires a little more Fa can get you the same drag as a less sleek car that is going for min Fa. I would say the DB1 vs a Van Dieman is a good example.

With the wheels providing 65% of the drag, gains with the main body aero are going are going to have reduced significance.

Brian

[Ed Womer]

The article did state the fairings caused more drag than none. But like others mentioned properly built ones should reduce the drag. Remember that if the flairings are attached to the bodywork then they are considered bodywork not wings.

Ed

[hardingfv32-1]

Nice thought, but that will not fly. Many front wings are/were molded to the front nose. Now if you want to amend that proposed rule to: Considered a wing if said device has an adjustable angle of attack. Maybe this would be better. Just allow wings, what is the harm?

Brian

[Ed Womer]

I disagree with that Brian. The side pods along with the nose on the Citation are the shape of a wing or a streamline if you chose to call it that. They have been using that design for many years and it is legal or never challenged. Many people including me have used stremlining flairings on everything exposed to the air and no one has raised a fit about it. So if you streamline something as part the bodywork it should be OK since the pratice has been going on for ever.

Ed

[brian]

I agree with Ed. Citation, Lynx and many cars have enclosed the h-beam with aero shaped bodywork for years. As long as it does not go outside the uprights, its been considered legal. Used to be the rear axles were off limits but that to has passed. I know of several cars that have covers breaching the span between the rear axle and trailing arms.

[hardingfv32-1]

Of coarse "never challenged" or "common practice" hold no sway with the stewards. Why should stewards/tech be responsible for knowing all the common practices of every class or the history of all protests (which have no common library). No, it has to be in clear black and white print in the GCR.

Only the front of the front side pod (past the centerline of the beam) is controlled by the 31.75" demmension.

Also, there is no mention in the rules that this 31.75" is associated with the shock uprights. The 31.75" does not have to be centered. Does it even have to be one piece? What about two sections that total 31.75"? Can't wait for RA!!!

Brian

[robert]

I at first I found it hard to swallow that the beam fairings added drag and lift . . . .

So I actually read the article. It no longer seems unreasonable. The beam and suspension shoves a lot of air around.

I stand by my belief that the beam and front suspension are aero nightmares, and that the beam can be enclosed to reduce drag.

It would have been nice if the article had shown a smoke plume that tried to pass through or below the beam, rather than smoothly passing over it. Reminds me of the occasional car ad on TV that shows the smoke happily passing through the air about a a foot above the car.

[Bill_Bonow]

If you notice the Citation's side pod has a flat top surface and a curved lower surface.

Brian,

You gotta get out more often. The Citation hasn't had that configuration since the WSU wind tunnel test 15 to 20 years ago. Althought Citation (Campbell) hasn't built an FV for better than 7 years, the "pods" were an equal curved surface top and bottom as shown here on the last Citation. They have had this configuration from about '90 on.

[ external image ]

As for the "never challenged" portion of your statement, check the history of when the Lynx "pontoons" and the Citation 84v came out. I think you will find that both were challenged and that is how they came to be "common practice".

I say bring your wacky "split wing" up to RA. I'm sure you'll be the "bell of the ball".

Reminds me of the occasional car ad on TV that shows the smoke happily passing through the air about a a foot above the car.

Robert,

You mean like this?

[ external image ]

[hardingfv32-1]

I stand corrected on the current Citation side pods. They look perfectly shaped top to bottom.

I stand by my statement about "common practice". Exactly where do I or the stewards find the documented history of FV written?

Brian

[Bill_Bonow]

Exactly where do I or the stewards find the documented history of FV written?

How about starting with Terry Ozment VP of SCCA Club Racing in Topeka, KS. I'll bet she can direct you to the right person with historical documents. I would think that one would want to get that information in hand before challenging 20 to 30 year old precedents. If not, one could look a little foolish, you know...not being prepaired.

[Speedsport]

The 31.75" applies to the bodywork in front of the beam, but there is also a rule indicating no bodywork can extend wider then an imaginary line connecting the vertical centerline of the front and rear tires. Without looking at a car again, I recall that exceeding the 31.75" dimension directly behind the beam in any usefull manner is difficult due to the required tire clearance for turning.

[hardingfv32-1]

And exactly what do you think SCCA has documented? More precisely for what reason would "common practices" be archived.

I can understand protest appeals being archived by Nat, but are all protests retained at the Nat level? As a practical matter how does a steward gain access to such information (if it exists) while at the track trying to make a ruling?

You have a over simplified view of the situation. Your assuming Fred Clark is going to be at every Vee protest. This is unrealistic.

SCCA says protests and appeals are archived by event, not by category. No way to search this archive.

Brian

[hardingfv32-1]

So you might be able to get something in front of at least 1/2 a front wheel?

Brian

[brian]

My experience has been that records regarding rulings do not exist. The dated Frank Schultise book was used years ago as a bible but it's not very timely now. For a fee, you can get a ruling via the non-penalty protest process in the GCR.

[problemchild]

Question: Were the Brewer side pods ever homologated for the Citation FV?
Sometime at the Runoffs (late 90s) when the tech guys were making people cut off any "wing-type" fairings, the Citations (Brewer pods with 1" Gurneys) were spared the trouble because they were homologated body panels ..... which I never knew to be true .... or relevent. Just wondering .....

[hardingfv32-1]

I know this is against the principle of why there is a homologating system, but does the GCR does say you can modify a homologated car.

Are homologating documents public record for competitors to review?

Brian

[robert]

Bill,

yeah . . something like that. The lights in the background that I guess are meant to back light the smoke, obliterate the cockpit area, but at least it is clear that the smoke is turbulent behind the car.

The smoke is pretty cool, but tufts of yarn all over the car would provide lots of information. THe points of interest to me would be the front beam and suspension, the cooling scoops, and all the open area around the motor.

Wait 'til you see my pregnant guppy . . .

[hardingfv32-1]

Do you expect the air stream to look very organized after the beam, suspension, and front wheels? What would be its incentive to smooth out and reorganize? Then it starts all over with the engine and rear wheels.

Brian

[Bill_Bonow]

Question: Were the Brewer side pods ever homologated for the Citation FV?
Sometime at the Runoffs (late 90s) when the tech guys were making people cut off any "wing-type" fairings, the Citations (Brewer pods with 1" Gurneys) were spared the trouble because they were homologated body panels ..... which I never knew to be true .... or relevent. Just wondering .....

When Larry bought the Citation FV program, the homologation was still for the original car (84v) and that was the body molds he got. He offered both the Brewer or Falcon body as options, but I'd bet nobody ever had their car re-homologated for the other bodywork.

[Bill_Bonow]

You have a over simplified view of the situation.

And that's why I am the "Mayor of Simpleton".

There are no records, I just enjoy winding up springs and letting them go. Just ask Robert.

[Ed Womer]

I could be wrong on this but I think the homo process is geared towards making sure the CHASSIS is build safely. I haven't done the homo process since the 80's but I never r- homo'ed my car when I made changes to the bodywork. As long as you met the rules for bodywork how you do the bodywork is up to you. Even a streamline shape that is "nuetral, no lift or down force" is still an airfoil, so technically a wing.

So if you think anything streamlined is a wing then a lot of cars would have problems which is not the case as of now. Like Brian McCarthy mentioned most of these things are considered acceptable and because of that we all LEAVE IT ALONE. Anyone doing wings for down force will suffer a huge drag penalty and in our class will slow you down. So if you want to go ahead, I won't object.

Ed