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To Jay's point, I said a while back if you want to improve intrusion protection add some tubes in the typically wide open spaces in the cockpit area.
An accident like Jay's is a heck of a lot more likely to happen than a halfshaft coming through the side of the car. Just my very humble opinion.
That said, my Citation has no wide open spaces between tubes in the cockpit area.
It is by far the strongest and safest car I have driven.
I was trying to stay out of this thread but you baited me with aero talk ;) Frontal area is definitely not the largest component of drag!! It's the tires!! For almost all formula cars tires are the #1 source of drag by far, and in FC tire drag is about 50% of drag for a car with a proper aero effort. That it is down to frontal area is simple not true.Quote:
Originally Posted by S Lathrop
That "everyone still has the same tires so that leaves everything else to work on" is also false in my view. I've spent a lot of time trying to reduce tire/wheel drag on various types of cars and always have some measure of success. If someone was willing to really push the boundaries of the rules (I'm usually not), then I am sure there'd be much bigger gains left, not only in reducing tire drag but reducing tire lift, which negates the need for so much downforce generation, reducing drag further ;) So tires should be [and are] an open area of aero work, and the gains can be as big as the gains made in cooling (i.e., still small, but hardly zero!)
And regarding the frontal area statement, a nicely faired sphere can have the same frontal area as a flat plate cut to match it in area, but the flat plate will have more than 10 times the drag (if we're talking road cars speeds)!! I've designed wings that [IIRC] have a higher frontal area than the current crop but less drag, because its ultimately the pressure distribution on the surface that dictates drag, and that distribution has been more carefully manipulated with modern aero techniques. A chassis can have the same frontal area but one throws off undesirable vortices or has separation, it will have higher drag! I'm not discounting that less frontal area is a good thing, I mean to say that the goal should be a low frontal area and proper shape, with shape being the more important of the two.
Cooling will account for some drag surely, but with a good design effort that will a few percent . . . in general I think the current crop of Formula cars have a lot of work to and/or bigger gains to find elsewhere before focusing on cooling drag. Bigger aerodynamic fish to fry, so to speak.
I think, at least aerodynamically, that this is a bad thing. It seems like not only the formula for aero but also the formula for the methods behind aero design are decades behind. Not just for FC, but for small formula car design in general. I'm not sure what went into the design effort of most current cars, and I certainly don't mean to belittle anyone as it was probably done in a different era, but in comparison to modern cars it looks like zero analysis went into them at all. I only say that because I have run high fidelity CFD on current cars and identified many improvements. Now an excuse may be that CFD or vortex panel codes, or advanced wind tunnel testing didn't exist back then, and that's valid, but at the same time it's been 20 years, and they sure as hell exist now!Quote:
We build cars to a formula and the formula for FC has been unchanged since the late 80's.
And just to be clear, I don't limit "improvement" to mean just lift and drag, but sensitivity to yaw or ride height, larger range of adjustment, more predictable behavior, etc.
I think the old formula of either copying other successful cars (wing profiles for example), or simply sketching the cars up with knowledge or experience is highly outdated. Modern CFD and wind tunnel methods have moved past the rules of thumb from the 80's and 90's, and the idea that anyone could just "know" the right answer in their head is a little crazy to me. I could definately draw up a design that works, maybe even well, but I would absolutely need CFD to capitalize on the interactions between components, which are WAY to non-linear and difficult for any mortal to simply guess or predict (the front wing and rear tire for example, have a relationship more complicated than most marriages!)
For example, F3000 and Champ car and other airfoils are sometimes used as a trusted benchmark designs, but in reality are actually compromised designs, sometimes thicker or less cambered than they should be for rules or structural reasons. When simply re-using these designs because those series are respected or high visibility, the design is actually compromising the performance of the new car!
Either very accurate wind tunnel testing on numerous designs (prohibitively expensive), or proper, professional level CFD (NOT floworks, CFDesign, etc.) is required for a good aero design, and while totally unfeasible in the past, it is now wholly possible and affordable, though not easy to find people who can do it and certainly not easy for them to do it. But I think the motorsport engineering community should really be pushing that down to lower series. Really I think to keep a series competitive against others we should be bringing down as many advancements in safety, suspensions, composites, and aero as can be done without increasing cost, but that's a wider discussion that's probably been had here many times before.
FYI, this is all in my opinion and based of my experience, and others' may certainly vary. I'd like to believe that I'm pretty good at this stuff though, so please word any conflicting views softly, us geeky aero folk are pretty sensitive :kiss:
RPerry, there you go clouding the issue with facts. You will be reprimanded harshly for your non-conformists words. No soup for you!!!
Quote:
Originally Posted by jimh3063
Exactly what facts did rperry introduce? Especially since the last thing he wrote is "this is all in my opinion."
It looks like more of the same from the Radon guys.
For the 100th time. I own a Van Diemen.
Why is that so hard to get your head around.
I'm for introducing new technology to the class. If that makes me a radon guy then I guess I am.
Come on folks hop in the time machine and jam it in reverse.
Wren what are you say rperry stated that is incorrect, please tell us how and why.
I apologize for not being more artful in how I phrased my points. I always thought tires were part of the frontal area of a formula car.Quote:
Originally Posted by rperry
I was taking the tires as a given in both aerodynamic and mechanical terms of cornering potential.
The only point I wanted to make is that the designs of FF/FC cars may appear to be static but are evolving continuously. Over time it becomes necessary to do a "new car" more to allow for continued development than because what one has is outdated.
But if you change the rules then you certainly can get the design of cars to change. I believe I was accused of not having done a thing for the last 15 years.
Given your list of modern tools available to the designer, why do we need to change the rules? You should be able to improve FC by simply correcting all the errors I and others have made through ignorance and oversight. But modern seems to be reinterpreting the rules vs. doing a better job of the basics. Cost is always an issue and we all do the best with the resources we have.
I am sorry to offend you.
I said that as a matter of politeness. Quite a few facts are posted if you're willing to read it all, rather than rudely dismiss it all. Do you dispute any of it? That drag is not mostly frontal area, that tire drag is not "fixed" and that tire drag is the biggest factor are all aerodynamic facts for f1, irl, f2k, etc. Are you going to claim they're false? On what basis?Quote:
Originally Posted by Wren
I think darrin and I have been quite informative in this thread, so if that's considered "more of the same" I'll take it :-D
Mr. Perry, I agree with much of what you have to a say WRT modern technology & methods such as CFD, FEA etc. Having managed a big race program including a great deal of CFD work I must say that these tools, when properly implemented, are invaluable in the design & development of any race car & open wheel FC is no different & the opportunities for improvement are pretty decent IMHO. However I suspect that you know, (based on some of your comments), that the resources required to do truely functional & correlatable CFD work is way beyond the capabilities of most small formula car manufacturers.
Now I use CFD for my designs & have done so since 2005, I must say that my work is TOTALLY uncorrelated to anything except track data & race wins. I would also mention that I could do CFD runs forever & use up all the computer resorces that are available to me & never build another race car. So my method is to do as much as I can within my resource limitations & actually BUILD the car.
I would love to have the resources to do more & I am ABSOLUTELY CERTAIN that every other builder of small formula cars would like to do the same. However there is the matter of the $$$ investment required to make that happen & then getting your customers to pay the extra $$$ for all that work.
I applaud those who can do it.
Thanks ... Jay Novak
They are, but tires are only a portion of frontal area but the majority of the drag! My point was that less frontal area /= less drag, and it seems like we're in agreement there :thumbsup:Quote:
Originally Posted by S Lathrop
Well I don't think I changed any rules, and I've always thought the aero rules were good and didn't need to be changed or expanded. And the COA seems to agree, because there's nothing really magnificent about the design; it's a winged car with a conventional diffuser, sidepod, etc. I just spent a lot of time fine tuning them all to work together. To be honest, the aero rules are great as they are and I never felt the need to push the boundaries or change them.Quote:
Given your list of modern tools available to the designer, why do we need to change the rules? You should be able to improve FC by simply correcting all the errors
I actually appreciate the civil tone, too many of these threads have gotten hostile.Quote:
I am sorry to offend you.
Well, I think that's finally starting to change. I build computing hardware myself, which saves a ton of money, and use open source software, without which would have put CFD out of almost everyone's grasp. The way I've done it, and at least so far I'm probably the first, it's within the capability of a lot of manufacturers, and as that becomes more widely known I think we'll see CFD spread. Ten years ago CFD in F1 was in it's infancy but now look where it is! And I think it's great for the sport as IMO aero is the biggest bang for your buck.Quote:
Originally Posted by Jnovak
But that's all moot because the real point of aero, of course, is to look cool :p
Well it's great to see the technology expanding, and I think as costs continue to drop you'll find it more and more useful. Good luck with it and have fun!Quote:
I would love to have the resources to do more & I am ABSOLUTELY CERTAIN that every other builder of small formula cars would like to do the same. However there is the matter of the $$$ investment required to make that happen & then getting your customers to pay the extra $$$ for all that work.
It's not the cost of the software, as you say there is a lot of low cost CFD available & I have friends in the business. The low cost stuff is not as user friendly as the big $$ software. The real issue is the man hours required to make it all happen. When you are a very small builder your time is your money. So as much as all of us love to do the design/analysis work you have to remember what the customer will pay as well as TRYING to pay yourself.Quote:
Originally Posted by rperry
Thanks ... Jay Novak
I was referencing rperry as saying more of the same from the radon guys, not you.Quote:
Originally Posted by jimh3063
all about how archaic FC is and how no one else is really trying hard enough.
Again, you are just trolling.Quote:
Originally Posted by jimh3063
Let's review what I said:
Quote:
Originally Posted by Wren
I didn't say that he was wrong about a single thing. Why do you keep trying to make up things that I have never said? It's trolling.
[FONT=Verdana]Steve,[/FONT]Quote:
Originally Posted by S Lathrop
[FONT=Verdana]I haven’t seen any info on the Euro FF standards & I’m not sure what the objectives are. I’m no expert on this, but if it is to pass an FIA style test, then energy absorption & minimizing peak loads (g force) is the objective. In one test, a truncated 25 degree cone is pressed through a test plate to measure this. A frame with lots of tubes & subsequently small openings would not have to have as thick a panel, nor would that panel need to be attached as well as a it would to a frame with larger openings. [/FONT]
[FONT=Verdana]This is a total guess, but I would think it would take a minimum of about 1/8 inch of a decent ballistic fiber laminate to make most current chassis much safer. That would be about 12 plies of a 5 oz material, or much fewer plies of a heavier weight material. I do believe 8 plies (.080 in.) would certainly be beneficial. It would take at least ¼ inch of a Kevlar-like material to be strong enough to span a large area.[/FONT]
[FONT=Verdana]Regarding the Kevlar question, this is something that SCCA should consider changing the wording on. Kevlar is a registered trademark of DuPont & I believe there is some liability in using a trademark without proper acknowledgement. The proper generic name is “para-aramid fiber”( Kevlar is easier to say). Companies like Teijin make very similar versions that cost about half as much. There also lower cost fibers like Innegra, that are used in ballistic applications in conjunction with para-aramid to reduce cost. Para-aramid fibers have pretty decent tensile strength, but are not so good in compression. I saw some data that indicated a 50/50 blend of KevlarTM/Innegra was as effective as 100% KevlarTM. [/FONT]
[FONT=Verdana]Zylon is some cool stuff. It is as stiff & strong as most regular carbon fibers, but has incredible elongation. F1 requires 6.2mm, which I am told is added as a “chicken panel” because they don’t trust the teams to run the same tub they certified. This makes passing the peak g-force test much more challenging, as the panel can pretty much pass the test by itself. I was also told the IRL just doubled the F1 requirement, which makes the peak g test even more difficult. [/FONT]
Quote:
Originally Posted by Jnovak
[FONT=Verdana]I agree with the followup post that said the Citation is probably the safest chassis out there. That probably has a lot to do with the fact that it is constructed with “legal” sized transverse tubes which are welded, not brazed (aka Van Deimen). Every crash is different, and it is virtually impossible to predict with certainty how a particular car will react when hit by another. I have seen some pretty exotic crash analysis software tools that do a fantastic job, but they can only analyze one of millions of scenarios.[/FONT]
[FONT=Verdana]I do know that for the Radon, FEA analysis of several chassis designs was performed & the tube frame made with the same material as the roll hoop (per the GCR & similar to the Citation) was about twice as stiff torsionally, than the carbon panel construction used on the Rn.10. Aluminum panels were also analyzed & they were slightly stiffer than the carbon panels. However, in side impact, the carbon panels were roughly 200% stronger than a “legal” tube frame & 250% stronger than a Van Diemen. The Radon roll cage also meets the FIA standards WITHOUT the carbon panels installed. The steel tube frame of a car like the Van Diemen or the Citation is highly optimized for torsional rigidity and the resistance to side impact is just whatever it turns out to be, which can obviously be pretty decent. [/FONT]
[FONT=Verdana]Even in a T-bone type crash, a stationary car is not an immovable object. What energy that is not absorbed in the crash is used to accelerate the other car in a direction other than what was intended. In a blunt side impact, the ideal frame would absorb the blow by "giving" a bit rather than being perfectly rigid (think about jumping stiff-legged onto a concrete floor as opposed to one covered with a 2" of rubber). At the same time, you want the ultimate strength to be very high. That presents a challenge for a conventional steel tube frame, which relies on the geometry of the tubular construction for strength, and where you have very little control over the stiffness in side impact. (If you have lots of room in the sidepods and are allowed to use carbon fiber construction, like F1, you can take a different approach, where you make the monocoque as stiff as possible and rely on external components to absorb impact.) [/FONT]
[FONT=Verdana]However, the mechanism for absorbing energy in a metal tube frame requires significant deformation. There is plenty of room in a stock car for that, but when you are sandwiched firmly between those tubes (ala FC), that will hurt a lot. You are better off being shoved out of the way, which induces deadly high g-forces. If rigid composite structures are impacted, they tend to fail internally, absorbing much more energy in much less space. That is one reason you will start to see more & more composite structures used in automotive structures (street cars).[/FONT]
[FONT=Verdana]Okay, enough of the composite infomercial. Sorry for the long-winded response. I am not attempting to argue the legality of the Radon chassis; just relating some things we all learned along the way. I will say that anything we can do to keep the sport cost effective while improving safety is a good thing for everyone![/FONT]
[FONT=Verdana]There are lots of ways to solve a problem & plenty of bright people who come up with them. As my fortune cookie said last night:[/FONT]
Darrin;
Thanks for your reply. Your contributions to this thread have been very enlightening.
Two tidbits to note:
1. The drawing in the GCR for FC body rules is the drawing from decades ago. The heavy black lines at the outer side edges and at the front bulkhead represented crush panels of aluminum honey comb.
2. The Zylon panels added enough stiffness to the IPS chassis that it was necessary to changes the chassis setups.
This thread is like the car accident in the other lane that you cant help but look at... It's embarrassing! If you don't feel side intrusion protection as outlined by the GCR is adequate, drive something else.
John
John:
I actually did. I ran a Stohr for a while that I felt had great side protection. Now I remember the reason why I changed, it costs almost 2 times as much to run a season.
It's all coming back to me now.
Jimmy
rperry,
Off the top of your head how do we improve the drag from the exposed wheels?
Brian
Rperry
Won't bargeboards help direct flow behind the front wheels, reducing the wake drag created by the front wheels?
Jimmy
What is a chicken panel?
Brian
Quote:
Originally Posted by Hardingfv32
Looks like Jim beat me to it ;)Quote:
Originally Posted by jimh3063
The quick answer is to either raise the pressure behind the wheel or lower it in front (duh). This can be done with the front wing, but it's tricky on FC cars because the front wing rules are a bit restrictive.
That is untrue. Baldwin and Firman were lying to you if they told you that. There are only three full-scale test rigs in the UK, and the RFR was not tested on any of them. No surprise, it is horrifyingly expensive.Quote:
Originally Posted by S Lathrop
Of course, it is (remotely) possible that they tested outside the UK, but I find that extremely unlikely. If that is the case, I am sure they would publicise the test results.
Is there a net positive drag gain from the increased frontal area and added surface drag of the bargeboard vs the improvement of the wake behind the front wheel?
Why is this not common practice in low power classes?
Brian
It was done in France, if I remember correctly, and paid for by the FIA. Up until that test, the FIA was trying to get all of the lower formula classes to switch to composite tubs, and the test results showed that that was not necessary.Quote:
Originally Posted by asw
Most of the lower classes have rules against "forward facing openings" in the bodywork (for things other than feeding the radiators, shocks, and engine), so barge boards as we know them would most likely be ruled illegal.Quote:
Is there a net positive drag gain from the increased frontal area and added surface drag of the bargeboard vs the improvement of the wake behind the front wheel?
Why is this not common practice in low power classes?
Quote:
Originally Posted by John Walko
HAHAHAHA I've been saying this every time I click on the link. It's hard not to look. I'm kind of disappointed it hasn't turned back into a serious name calling thread.
If you don't like the side protection on a VD, don't even glance at the cockpit of a DB-6...
On a side note, do you think the Carters would make a sections on apex for controversial topics that would be unfiltered? Just a straight up bash fest? These 6 page technical threads get boring for those of us with ADD and actual lives....
I think I would still rather have a side impact than a hard front impact. My legs are so wedged in a DB6 that my knees are hard against the shocks at all times. I don't think that a hard front impact would end well at all.Quote:
Originally Posted by Cole Morgan
In my defense, almost all of my posts here have been while I was waiting on an aircraft to come on range or get fixed or while a cnc machine was running.Quote:
actual lives....
I have a copy of the 2010 FIA technical regulations. I haven't figured out how to attach a pdf file to this thread however if anyone would like a copy I would be happy to send it to anyone who PM's me.
SteveO
We had to flip the bolts on the top mount for the dampers so that my knees would stop bleeding after sessions. I have to replace right hand gloves often too from holes getting worn on the backside of my hand from shifting. It's a tight fit for me (6' 2'' 195lbs) with virtually no seat or anything else to hold me in place besides frame rails.Quote:
Originally Posted by Wren
The car has the track record in FC at almost every track in the SEDIV, so the real lesson from this thread is that "unsafe" is really fast.
Carry on with your normally scheduled boringness.
New cars are the only thing that can save our class. Let's all try to work positivlytogether to save FC
Cole,
What you may have proven is that, as Mr. Perry implied, aero is pretty damn important when you only have about 150 HP. The Swift makes about the smallest hole in the air as any FC.
We need new cars in the series or it will die. The only interest seems to be in the Radon or the Furman.
There is a pent up demand that the current offerings don't seem to be satisfying.
There have been very few new cars enter the class in years. We need to have a flow of new cars.
Great, where can we see the results?Quote:
Originally Posted by R. Pare
Luckily, a good friend of mine works for the FIA and after speaking to him no one at the FIA seems to know anything about it. Are you sure that you are not mistaken? Is this the same France that is in Europe and not some one's garden shed?
Why the smart ass post asw? Are you just trolling for a fight? If you have useful information then post it.
Baldwin and Firman indicated that such a test had been performed on a Van Diemen frame during a meeting at Runoffs last September. If you doubt the truthfulness of the report then call those guys. Perhaps they will confess that they lied to us Yanks.
I question as to why Richard and others continue to post information on this forum only to have their integrity impugned. This forum is quickly taking on the same characteristics of the old Formula Ford Underground...it starts with baby steps. :thumbsdown:
John
[QUOTE=John Walko;279163]This thread is like the car accident in the other lane that you cant help but look at... It's embarrassing! If you don't feel side intrusion protection as outlined by the GCR is adequate, drive something else.
john,
you said what i was thinking.
the cars we drive have awesome safety records.
if you want to take all the risks out of what we drive, maybe it would be better if you just sit on your couch and watch racing in the safety of your house.
btw john, i returned you email last week but it bounced back to me as a address problem.
mark d
Quote:
Originally Posted by John LaRue
Quote:
Originally Posted by John LaRue
[FONT=Verdana]Mr. LaRue,[/FONT]
[FONT=Verdana]I apologise if I offended you, it was not my intention, I should have [/FONT]
[FONT=Verdana]included a smiley face or two after my garden shed quip![/FONT]
[FONT=Verdana]Mr. Pare and Mr. Lathrop appear to be claiming that tube frames are as [/FONT]
[FONT=Verdana]safe as carbon tubs based on a test of a tube frame under FIA [/FONT]
[FONT=Verdana]supervision (the "information" that you accuse me of impugning). [/FONT]
[FONT=Verdana]However, no one at the FIA seems to know anything about any such test, [/FONT]
[FONT=Verdana]nor do my colleagues who are involved in crash test safety research.[/FONT]
[FONT=Verdana]Since we do like to mislead you Yanks, it may be that Mr. Firman was [/FONT]
[FONT=Verdana]pulling everyone's leg. :)[/FONT]
[FONT=Verdana]There also are some inconsistencies in the claims, are there not? You [/FONT]
[FONT=Verdana]say that "Baldwin and Firman indicated that such a test had been [/FONT]
[FONT=Verdana]performed on a Van Diemen frame" while Mr. Lathrop claimed that the new [/FONT]
[FONT=Verdana]RFR frame (not a Van Diemen) had been "crash tested."[/FONT]
[FONT=Verdana]If such a test has been performed, then the data would be of great [/FONT]
[FONT=Verdana]interest to everyone concerned with tube frame safety. Perhaps one of [/FONT]
[FONT=Verdana]you who is acquainted with Mr. Firman could ask him to post it here?[/FONT]
[FONT=Verdana]Cheers.[/FONT]
That more like it ASW... They will shut this thread down.
And then what?
No such claim was made by either of us. The reason behind the statement was only that tube frames have indeed passed certain FIA F3 crash test requirements. Exactly what the requirements were at the time for side panels, I do not know, but the results of the squeeze test were within the F3 requirements.Quote:
Originally Posted by asw
Ralph just called me a few minutes ago to clear this up. The test was on their F1600 Van Dieman 2 or 3 years ago, and performed at the Cranfield facility. Their current RFR car is basicly the same chassis, designed to the same standards.Quote:
Originally Posted by asw
Memory of specific details often is inversely related to the quantity of gray hair. :DQuote:
Originally Posted by asw
Since you seem to have some position in this area, maybe you could look up those tests for us and post the results yourself.Quote:
Originally Posted by asw
I am wondering if ASW is a Radon Guy?
Really? Designed to the same standards? Isn't the new RFR car the oneQuote:
Originally Posted by R. Pare
with a raised nose and no structural floor pan protecting the driver? I
see no similarity between an older Van Diemen Formula Ford (at least the
ones we see at circuits over here in the UK) and the new RFR F2000 car
except they are both made from tubular steel.
Again, you seem to know Mr. Firman quite well, perhaps you can get a
copy of the test results from him directly? I think it would be very
useful. I don't know Mr. Firman nor do I have any contacts at RFR.
Quote:
Originally Posted by R. Pare
Are you sure? See quote below from your self.
Quote:
Originally Posted by R. Pare
It seems to me that a lot of these posts appear to be all about creating the impression that the tube framed FC cars are not sdequate from a saftey standpoint.
I also note that several very functional ideas have been put forward by several people on how to improve crash protection on existing FC chassis (within the current rules) that have simply been ignored by many of the participannts of this forum.
I have an IDEA. Let's start another thread that is focused on improved saftey of FC chassis (within the existing rules).
I also have another IDEA and that is that those who want to change the rules WRT the chassis design rules should start another thread on an ACTUAL RULES PROPOSAL.
Thanks ... Jay NovaK