Landracing Forum
Tech Information => Steering - Suspension - Rear End => Topic started by: Jonny Hotnuts on September 06, 2007, 12:15:34 PM
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The MS class allows a 130" wheelbase and forward streamlining (ahead of and including the cowl).
I am thinking what I would like to do is stretch the wheelbase to 130" and move the 2 front tires closer (they are about 4' now and was thinking somewhere about 1.5-2').
I was wondering:
A-is this legal in my class to move the tires closer together
B-would moving the front tires closer adversely affect handling
C-will doing this much BS be worth the time and effort (the reasoning behind wanting to move the front wheels closer is because I can go crazy with streamlining the front end.....a benefit for me because the car is a mid engine and don't have to worry about engine fitment in the front).
Good idea.....bad idea???????
-JH
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The MS class allows a 130" wheelbase and forward streamlining (ahead of and including the cowl).
I am thinking what I would like to do is stretch the wheelbase to 130" and move the 2 front tires closer (they are about 4' now and was thinking somewhere about 1.5-2').
I was wondering:
A-is this legal in my class to move the tires closer together
B-would moving the front tires closer adversely affect handling
C-will doing this much BS be worth the time and effort (the reasoning behind wanting to move the front wheels closer is because I can go crazy with streamlining the front end.....a benefit for me because the car is a mid engine and don't have to worry about engine fitment in the front).
Good idea.....bad idea???????
-JH
Sounds like the rules are very similar to comp coupe. If so then I would think you could change the front track width and I would do it. There is no need to drastically narrow the front as the air will still see the car at it's widest point, but narrowing it some sure couldn't hurt and would give you the option of better directing the air that does go towards the body as you have talked about.
(http://purplesagetradingpost.com/sumner/temp-pictures/blowfish-1.jpg)
You could then also work on the front wheel openings and try to avoid them acting like parachutes. If you can totally cover them then the narrower track would be worth it right there. If not again look at the deflectors that Blowfish uses at the front of their wheel-well openings that deflect the air just enough that it reattaches right behind the wheel opening. Of course they used a wind tunnel to find the perfect solution. If you don't have a wind tunnel you might try Hooley's Okie wind tunnel. We use an air hose pointed at the part of the car in question and sprinkle baby powder into the air stream and see where it goes :-o .
The longer wheelbase should help with the handling and would help to move the CP rearwards (good). Now once the car is in a spin, hopefully you will avoid this, then the the long/narrow wheelbase might be a negative. I would really work on the CP/CG thing and get it right and get the weight in the car you need so that a spin is less likely to happen as a result of tire spin on the top end.
Is it worth it. Depends on much you want to hand that 250 mph time slip to Dan 8-) ,
Sum
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Has anyone built a competition coupe with front wheels in line or nearly so, ala the Teague, Costella, and other streamliners? There appears to be nothing in the rules prohibiting same.
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Has anyone built a competition coupe with front wheels in line or nearly so, ala the Teague, Costella, and other streamliners? There appears to be nothing in the rules prohibiting same.
Not to my knowledge, but wonder if it would help with a coupe as you still have the body. A streamliner can make their body any width they want.
c ya,
Sum
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What would Jack Costella do? I'd do that!!!!!!!!!!!!!!!!!!!
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Has anyone built a competition coupe with front wheels in line or nearly so, ala the Teague, Costella, and other streamliners? There appears to be nothing in the rules prohibiting same.
Not to my knowledge, but wonder if it would help with a coupe as you still have the body. A streamliner can make their body any width they want.
c ya,
Sum
It doesn't do anything to reduce the frontal area on Costella's 'liners, either, especially the V8 powered one. Frontal area isn't everything; the friction drag is reduced by reducing the skin surface area.
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The way I read the rule book on page,19 PP2.H Tread is defined as the measurement from the centerline of one tire to the centerline of the opposite tire of paired wheels.
The minimum tread dimensions for all vintage category vehicles is 44" front and 50" rear. Special construction vehicle are not subject to this rule.
JD or Dan W. need to clarify this for comp.coupe and MS
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The way I read the rule book on page,19 PP2.H Tread is defined as the measurement from the centerline of one tire to the centerline of the opposite tire of paired wheels.
The minimum tread dimensions for all vintage category vehicles is 44" front and 50" rear. Special construction vehicle are not subject to this rule.
JD or Dan W. need to clarify this for comp.coupe and MS
The way I read the rule book, the modified category, [5.D], is not part of the vintage category, [5.B].
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Already in the works for cars other than streamliners.
DW
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"Reading is FUNdamental. writing is elemental, and the results are sometimes astounding." (me):wink:
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Already in the works for cars other than streamliners.
DW
Even lakesters? Will minimum tread widths be 44" for all non-special construction classes?
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Has anyone built a competition coupe with front wheels in line or nearly so, ala the Teague, Costella, and other streamliners? There appears to be nothing in the rules prohibiting same.
Not to my knowledge, but wonder if it would help with a coupe as you still have the body. A streamliner can make their body any width they want.
c ya,
Sum
It doesn't do anything to reduce the frontal area on Costella's 'liners, either, especially the V8 powered one. Frontal area isn't everything; the friction drag is reduced by reducing the skin surface area.
Good point.
I wonder about the difference in the ratio of the width of the front of the car to the widest point on one of Jack's car to say using the same width of the front to the widest point of say a wider comp coupe car. Would the angle out to the sides and then the angle created where the front meets the body not be good. I don't know???
One thing about what we are doing is often opposite designs result in about the same results :-) .
I personally feel Jack's car's are successful for what isn't there. As Stainless likes to say you don't have to worry about the Cd of what isn't there, or something like that :|.
c ya,
Sum
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44" has yet to be mentioned.
DW
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You could then also work on the front wheel openings and try to avoid them acting like parachutes. If you can totally cover them then the narrower track would be worth it right there. If not again look at the deflectors that Blowfish uses at the front of their wheel-well openings that deflect the air just enough that it reattaches right behind the wheel opening. Of course they used a wind tunnel to find the perfect solution. If you don't have a wind tunnel you might try Hooley's Okie wind tunnel. We use an air hose pointed at the part of the car in question and sprinkle baby powder into the air stream and see where it goes :-o .
Using taped on tufts and a video camera would work too and is probably a cleaner way to do it , but I'm sure a bright green non-street legal Fiat attracts unwanted attention on the road!
Johnny,
Borrow a copy of "The Leading Edge" as there are some interesting things about nose sweep angles in it that seem to indicate narrowing the front in may not be advantageous. Maybe I can do a scan when I get home.
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Borrow a copy of "The Leading Edge" as there are some interesting things about nose sweep angles in it that seem to indicate narrowing the front in may not be advantageous.
I just won a copy of that book on Ebay,less than $6 including shipping.
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Borrow a copy of "The Leading Edge" as there are some interesting things about nose sweep angles in it that seem to indicate narrowing the front in may not be advantageous.
I just won a copy of that book on Ebay,less than $6 including shipping.
You got a deal. Most of it is over my head, but there is enough to be learned that it is the best book I've bought on aero and even at the list price could maybe save you a lot of money/mistakes.
Good to see you on here,
Sum
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tortise,
Lakesters DO fall under "Special Construction".
P.44, 2007 rule book.
JG
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No luck with poop bay, I could only find a new copy for 99$ or a used one for 179$ on Amazon (seriously the used cost more....go figure).
If anyone has a copy I could borrow....I will make it worth your while.
Or is someone has a copy they want to sell I would be interested if the price was decent.
I more I think about it I have to agree that a graduated from narrow front end is not the best idea. It would surely increase surface friction up the nose. I guess what I am trying to learn is what is the most efficient nose that can be built on a car 5' wide without the limitations of front wheels or engine.
The main reason why I want to move the front wheels closer is because I can still maintain a good amount of steering ability and still have the wells covered.
I really like the nose on the Blowfish and the late model Camaro but they are designed with the motor and wheels where they are. I am not saying they are not perfect....they very well may be but I have the ability to do anything to the front and what know if I can surpass their aero ability because I don't have a front engine and can add about 4' in length to the wheelbase. I am about to undertake major car surgery and don't want to be a pissen' and a moanin' next year because I did not get it right on paper and have to do it again.
Thanks for the comments.
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Check these auction numbers:
250069319858 $.99 + shipping
6913318403 $8.45 + shipping
Also check Half.com for books.
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All the info I have seen shows the lowest drag shapes at subsonic speeds have noses that are elliptical (look at the nose profiles of all the low speed passenger jets, bombers, and commercial jets).
Pointed only looks fast, and depending on your side profile will increase the sensitivity to off axis air flow (side winds).
Larry
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Knowing nothing about aerodynamics,I've often thought the front half
of a car (like /CC) should be shaped like the front half of an air foil.
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No luck with poop bay, I could only find a new copy for 99$ or a used one for 179$ on Amazon (seriously the used cost more....go figure).
If anyone has a copy I could borrow....I will make it worth your while.
Or is someone has a copy they want to sell I would be interested if the price was decent.
I more I think about it I have to agree that a graduated from narrow front end is not the best idea. It would surely increase surface friction up the nose. I guess what I am trying to learn is what is the most efficient nose that can be built on a car 5' wide without the limitations of front wheels or engine.
The main reason why I want to move the front wheels closer is because I can still maintain a good amount of steering ability and still have the wells covered.
I really like the nose on the Blowfish and the late model Camaro but they are designed with the motor and wheels where they are. I am not saying they are not perfect....they very well may be but I have the ability to do anything to the front and what know if I can surpass their aero ability because I don't have a front engine and can add about 4' in length to the wheelbase. I am about to undertake major car surgery and don't want to be a pissen' and a moanin' next year because I did not get it right on paper and have to do it again.
Thanks for the comments.
You have a lot of front overhang now in front of the wheels/tires. I don't thing the car has to be much longer just the wheelbase. Move the wheels/tires in so you can cover them like you suggested and then take the "idea" that the Blowfish front suggests and copy that.
Most opinions about the ideal shape is still the teardrop. Make the curve around the front side to side the shape of the bottom of the teardrop like was suggested in the post above. That will form the rounded shape you see on Blowfish. Then cut down into that from the cowl forward like they also did. That will get some of the air down the sides of the car and some over the top. I guess you will have to guess how much you want where.
They could have covered their tires and still be within the comp coupe rules, but I think style went before that decision. The little side flaps in front of the wheel-wells tried to overcome that, but still covering them would have been best and you can do that.
I'll try and find a picture I did for our Stude and the Yellow one and post it if possible. It is where I hope we end up eventually.
c ya,
Sum
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Ok some photoshop type work using Microsoft paint and another cheap program:
The Wash. yellow stude as it is (they are having too much down-force issues):
(http://purplesagetradingpost.com/sumner/temp-pictures/Stude-Wash-1.jpg)
What I might do with it if it was mine and personally is the direction I suggest you go in:
(http://purplesagetradingpost.com/sumner/temp-pictures/Stude-Wash-2.jpg)
What I'd like to see us do and it is hard to make out, but it would be similar to the yellow one and not come down quite as much as it appears, but would have more going to the sides:
(http://purplesagetradingpost.com/sumner/temp-pictures/974%20Nose-2.jpg)
Just ideas,
Sum
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JHN,
I don't have a picture but, maybe Sumner has a shot in his archieves of Mike Cook's Alfa. This car was originally built by Rich Manchen and run By Rich, Mike Manghelli and Lee Kennedy.
Take a look at the front end and wheel wells. Just my contribution to get you to the AA license.
DW
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This one ?
(http://www.alfacentro.com/features/bonneville/images/bonneville_0106.jpg)
Another Alfa:
(http://www.international-auto.com/images/originals/bonneville-big.jpg)
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I was able to obtain a copy of "The Leading Edge" at my local library. They didn't have it on the shelf, but were able to order it through the system. It took about a week.
When I 'finished' reading it I was sure happy that I didn't pay anything for it!
Way deep, and a lot of it would not apply to a lot of classes.
Great if you are building a human-powered bicycle I guess.
My 2-cents worth.
JGMagoo
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I was able to obtain a copy of "The Leading Edge" at my local library. They didn't have it on the shelf, but were able to order it through the system. It took about a week.
When I 'finished' reading it I was sure happy that I didn't pay anything for it!
Way deep, and a lot of it would not apply to a lot of classes.
Great if you are building a human-powered bicycle I guess.
My 2-cents worth.
JGMagoo
Yep it can mostly be applied to streamliners and lakesters, but what you can do with the front of comp coupes, mod. roadsters, etc.. can be helpful. I look at it from the point of view how much is it going to cost me to make the HP to overcome a dumb mistake that could have been avoided :wink:,
Sum
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The red one.
DW
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Wheelwell openings...If you are going to have wheelwells---go look at a new Corvette---not the Z06---notice how close to the outside of the car the wheels and tires are and how the wheelwell body panel goes flat surface to a flat surface behind---from what I have been told you want to get the tires and body sides in as flat a plane as possible---most classes allow you to radius the wheel wells--no reason not to stick those suckers out there.
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..........
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Panic,
The "coke bottle" shape of early supersonic aircraft is strictly related to only supersonic aircraft and does not have affect on land vehicles that certainly very "subsonic" like Corrvetts etc. The idea was to try to make the cross section area of the aircraft constant through out its length so the fuselage was narrowed in the area of the wings which gave the "coke bottle" shape to the aircraft.
The shape of an new Corvette is strictly to cover up the wide wheel/tire combination that they want to run.
On production based cars you want the air to go around the sides of the car and you want the wheel/tire outer edge to be inline with the body to prevent the air flowing past them from becoming un attached. Once the air becomes un-attached bluff body drag happens you go slow.
Rex
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JH, thanks for starting the thread on the Hot Nuts Effect!!!!!!!!!! It apatently has affected more cars that just yours -- thats for sure!!
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So, JH, will you be building to the new 27" minimum tread rule?
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So, JH, will you be building to the new 27" minimum tread rule?
"Front tread width may be narrowed a maximum of 12 in. less than OEM, but may not be less than 36 in. minimum. The entrant is required to provide the OEM front tread dimension."
27" is 9 more that could be legal.
After the tread width rule was implemented I was about 2 seconds away from building my front end using a forward canard to A.C. style wheel pants design. (Very similar to the Plymouth prowler but with covered wheels). If nothing more than to prove a blunt little rule change, aiming to make the class head into a generic direction, would not deter me from building a car could abided by the rules but very much not what the SCTA had in mind for the class and with the intent of the trac rule.
Let’s say I was talked out if it…..for no other reason to abide to the intent and not the possibility of what could be done, even if it was legal and in accordance with the rules.
Unfortunately, I have continued reservations about the rule change. I would like to see the MS class be more competitive to true sports cars but because in part of this rule change I could not see wider tracked sports cars like the Vett (minimum allowable is 51” [15” from 36]) and the Viper (minimum allowable 47” [11” from 36]) be made for MS. Even cars like the slim 911 will be giving up over 6” at 10’ to cars like the Berk, Fiat or the MG. This will IMO make only the cars with the most narrow stock track width desirable.
I would like to have seen a tread width number that ALL cars could run as apposed to “12” from OEM and no more than 36””. This would eliminate having to “provide documentation of OEM dimensions” and would also make the class competitive for cars other than tiny European 2 seaters….thankfully I have chose a Fiat long before this rule was proposed……don’t really have too much to complain about, certainly glad I didn’t opt for a Vett.
No more rants, but surprises to come…..
-JH
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I don't know what you are talking about. The revised rule takes all cars including Corvettes to 27". How narrow do you need to go?
DW
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Dan, welcome back, been on vacation? I was afraid you retired from the website....
JNuts, the previously proposed changes may have been changed, every now and then, drift back to the homepage, the current change was released and posted. As Dan said, looks like 27 is for everybody, no OEM or 12 inch language.
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Even cars like the slim 911 will be giving up over 6” at 10’ to cars like the Berk, Fiat or the MG. This will IMO make only the cars with the most narrow stock track width desirable.
Unless the rules allow the body to be narrowed, wide cars will always be at a competitive disadvantage in MS.
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"Streamlining ahead of and including the cowl, channeling, belly pan and skirts is allowed. Front tread width may be narrowed to a minimum of 27 in."
I don't see any body width restrictions in these two sentences from the rulebook.
DW
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I don't see any body width restrictions in these two sentences from the rulebook.
I'm talking about the body aft of the cowl. The entire modified category prohibits narrowed bodies.
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I just received a mail regarding this….
Must admit that I am MUCH happier about it for the reasons I mentioned before.
True that a narrower body will have an advantage, having a narrower front end (to a point) will too.
Good news for all in MS.
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Tortoise,
Now we're talking. Yes, the body must be stock from the cowl back. If it was my world it would be near OEM in front also but, I'm just a passenger.
DW
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If it was my world it would be near OEM in front also . . .
Ageed. One of the Bonneville Berkeleys has a stretched OEM nose, and it's actually pretty slick. Air dams should be allowed for safety, certainly. Too late now, I guess.
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Yep, too late again.
Jack and others will remember that at one time this class disappeared because of modifications that made the cars "one off" rather than based on a production body. Lufkin, White, Deeds and others made the class into gas streamliners.
Miler Mike Stewart and a couple of others resurrected the class to be a gas coupe type of thing. The cars then evolved, some would say devolved, into what we have today and the ones you didn't see that were proposed and rejected.
Oh well, that was then - this is now.
Less than a month and I don't have to worry,
DW
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Dan,
Have they found your replacement yet? I am in the process of building a new a wind screen for the Berkeley and I would like to get someone's sign off before I go through all the work.
-Jack
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Jack,
Use your committee contact, Jim Miller, section 17 of the rulebook. There will be no rules co-ordinator. Stuff will go through your committees.
DW
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who is the author of The Leading Edge thanks willie buchta
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TAMAI
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Book Description
The Leading Edge is the first book to summarize the aerodynamic design and construction issues of solar cars and ultralight land vehicles. Author Goro Tamai draws on his own experience in designing solar cars at MIT to produce a book for the ground-up streamlined land-vehicle designer or constructor, as well as for the solar/electric/ultralight vehicle enthusiast. As with any engineering problem, the "best" body shape for solar cars, HPVs, or Electrathoners is not the body of absolute lowest drag. The vehicle system, including the driver, chassis, and energy/drive system must work in concert to produce the maximum output. The Leading Edge will help designers quantify the trade-offs, and make logical decisions.
- Vehicles covered include solar cars, human-powered vehicles (HPV), solar bikes, electrathon racers, ground-up hybrid or pure electric vehicles, and fuel-economy record cars
- Numerous examples using specific race cars and teams, and how designers solved problems
- Full definition of terms, with equations and examples provided for determining key aerodynamic parameters
- All design and construction issues, from body shape, to wheels, to canopy integration, to solar panel sizing
- How to do in-the-field testing and diagnosis of aerodynamic performance
- Special overview section reviews the history of ultra-streamlined land vehicle development
"An excellent review of the problem of low-drag ground vehicle aerodynamics, filled with references and design examples. It allows the reader to understand the issues involved and quickly come up with a preliminary design, leaving time for the oft-neglected detail work and testing." Jacek Gromadzki, aerodynamicist, 1997 University of Waterloo Solar Car Team
"The Leading Edge is an extensive treatise on the aerodynamics of streamlined land vehicles...It is a valuable contribution towards advancing the technology in this important field." Mark Drela, Professor, MIT Department of Aeronautics and Astronautics
"I wish I had access to this book when I was designing human-powered vehicles. While I've read a lot of the same references, this book pulls them all together and I might have done things a little differently." Douglas Milliken, co-author of Race Car Vehicle Dynamics (SAE, 1995)
Hope this helps.