A nose for all occasions (a crazy idea)

[Sumner]

...............The problem with some neutral downforce designs is that a little change in angle of attack, like from a bad bump, could put you into lift.

 

This picture is from 2006, but this year they put a splitter at the bottom of the front and had that problem.  One run it would push the body work into the tires and then next it would want to lift the front-end.  I think they are a good idea in NASCAR, but hard to predict in LSR.  We get so few runs to try things it is hard to work from that angle.

We have stops that will stop the body from getting into the tires.  It isn't good to have stops that the suspension will bottom on, but it is worst to put the body into a tire and the disaster that can come from that.

c ya,

Sum   

[Unkl Ian]

Take a look at the fast Streamliners.

[Jonny Hotnuts]

The problem with some neutral downforce designs is that a little change in angle of attack, like from a bad bump, could put you into lift

How I am hoping this will work is that the space under the nose that air can get under will create pressure and lift because of the reaction with the ground. The counter pressure is dependent on the diverter under the nose. In the case of hitting a bump that raises the front, the diverter under the nose will loose its seal and not be able to create pressure and any lift that is being generated will disappear. I know that by a bump that has a reaction of the front rasing....even slightly will put the body in a position for the front to lift. It is not my intent to create a perfect 50/50 match but more in the lines of 60/40. At 60/40 there would still be progressively higher downforce on the nose but would hopefully eliminate any chance for a bump to cause the front to lift and still provide some aero equalization (and would not have to worry about getting it in a wind tunnel to get the balance perfect.

Take a look at the fast Streamliners.

After taking a look a Toms (and the a few others) steamliner it looks like there are two schools of front end design. The one like Toms, the Socal, Banks and others that allow for some counter pressure on the nose....and the others like the Costella that start at a tiny front end and gradually progress to the body and not allowing any air under the nose. It makes sense to me that with a tiny front nose that graduates to a larger area you would not want air under the nose because the downforce pressures are dissipated over a longer area and would not need something to counter it.

This brings a question to mind of what is better, increase surface friction of dissipating the air over a longer graduated area up the nose or to have a nose that has controls the air flow in the first 2 feet and generates progressively higher downforce the faster you go.
IMO Burkland built this nose to equalized the pressure on the top and bottom. The question is will it work for a car that is 2x as wide as it is tall without causing adverse affects and a million dollar wind tunnel budget.

[Unkl Ian]

The big buck twin engine diesel streamliner team spent a bunch of money of CFD modeling of the air flow off the tires,and across the bottom of their streamliner.

It was in one of the English race tech magazines recently.

[interested bystander]

I don't want to irritate all the experts that have been posting advice but, the nose thing-see my Sept 10 post- is such a case by case basis (read the part about making my brain buzz) that I feel it's irresponsible to offer advice on how to shape one without strong aero knowledge of what goes on BEHIND the nose-hence the reference to the Summers car- and you can use Burkland or the limey diesel or Cobb. etc. too.
It relates to the whole package.
Off my soapbox!

[Glen]

How come no mention of the Vesco Terminator. It's a very effective car. Or How about Al Teague

[interested bystander]

Yes, Glen, my point exactly, those vehicles were a complete nose to tail design.
Glueing a similar nose of any of the low-drag LSR streamliners onto a Pinto, fiat X19, Studebaker, '32 Ford, Mercedes CTS, whatever, does not assure it would work to keep the car from doing something embarrassing
We all watch NASCAR and they talk about minuscule improvements that can change a car from  push to loose aerodynamically with a subtle change.
AGAIN, it's the whole package!

[Sumner]

How come no mention of the Vesco Terminator. It's a very effective car. Or How about Al Teague

Believe me when my lakester is done it will have a lot of "Al Teague" influence in it, especially as the car looked when it ran as a lakester before morphing into a streamliner.

No, I would never put that nose on a Stude or Johnny's car.  Right IB the whole package and where you need the air to go on that particular application is dead on and since none of us (at least most of us) don't have the money for a wind tunnel it is a lot of guessing with no way to prove our point.

Let's also remember that the air does not flow over the car, the car goes thru the air that was sitting there right before the car got to it.

c ya,

Sum

[JackD]

From the drivers position forward, Teague's car took it's shape from a Norton bike liner.
There is a MS running around that is really pretty slippery until you get to the roll cage that looks like a scaffold system for a 2nd floor addition.

[Sumner]

From the drivers position forward, Teague's car took it's shape from a Norton bike liner.
There is a MS running around that is really pretty slippery until you get to the roll cage that looks like a scaffold system for a 2nd floor addition.

     



Very nice in my opinion and well proven,

Sum

[sockjohn]

Two pages later and I think I've lost track of the original problem...

Is this really a CG versus CP problem or the nose producing lift? 

Since this is a rear engined car, have you actually put the car up on four scales to check the CG?  The Busa motor should be light enough to easily ballast back to where it needs to be.

This should be a close to free fix if you can borrow the proper scales, since ballast should be cheap or free.  I would do this prior to changing the nose unless I'm missing something.

If the nose is the problem, the dilemma is that to do it properly need a wind tunnel ($$$) or computer software which while a cheaper options is still pricey and takes a somewhat skilled operator.

I think you're best bet is to keep it simple and do some tuft testing.  "Bullet" cameras are small and cheap and would disrupt the airflow at a minimum if they had to stick out.  Mos have analog outputs that plug into most video cameras, if you buy a video camera for this purpose, make sure it supports analog inputs.  Place them carefully and they shouldn't effect the measurement.

[JackD]

It is time to reissue the picture of the CG and CP that you did the simple way.
Add lines to indicate what you would get from wind tunnel generated smoke trails to the picture you have and see what you come up with,
then modify it and look again

[Jonny Hotnuts]

Don’t think that I don’t appreciate everyone’s help on this topic but this for me is clearly a case of “ask 10 LSR guys what the answer is and you will get 10 different responses and 9 will be correct”. In this case I ended up with more questions that I did not feel comfortable with as there was too much information, conflicting information and many variables that needed to be resolved to effectively apply them to my application.

I will say that I am now being helped with the nose/ frontal design by an authority and legend in LSR who I will not mention by name.

Here is an overview of what is to come:


The nose section, while not finalized in design, will be the class length maximum of 130”. The section will also be balanced aerodynamically as originally questioned in this thread and based on a gradually tapering design with a narrow front track or inline front wheels. The frontal section will have a rounded lower surface to allow pressure to bleed and not the more common flat bottom that is common to longer tapered frontal sections.

I will update with more info when I have more time.

-JH


-JH

[JackD]

It sounds like you are on your way.
Look at the fastest and ask yourself why, and then don't be shy to ask them why.

[tortoise]

The nose section . . .  will be  . . .with a narrow front track or inline front wheels.

In the "Re: Wheelbase, spacing and handling" thread, Dan Warner tells us a minimum track dimension (unspecified) is "Already in the works for cars other than streamliners."