Building a car for the salt...
Moderator: Team
I got out there as a spectator, and got drafted to help crew on a car the day before we got rained out. Both of us got out there for Speed Weeks as spectators.
This year was a "research year". I may be ready to run something next year but I'm just taking things one step at a time, and if it works out it works out.
I figure on at least spending 5 years to get a car built and at a competitive condition.
The 150 club should be no problem for me, if I get the time and money to put a suitable roll bar/cage in my car, but a purpose built car for the salt will take a bit longer.
Larry
This year was a "research year". I may be ready to run something next year but I'm just taking things one step at a time, and if it works out it works out.
I figure on at least spending 5 years to get a car built and at a competitive condition.
The 150 club should be no problem for me, if I get the time and money to put a suitable roll bar/cage in my car, but a purpose built car for the salt will take a bit longer.
Larry
Hear you. Saw your post about Nascar cages. I am not interested in getting crunched any more than the next guy and unfortunately someone does occasionally get killed. I knew John Beckett from ECTA and was there that year. However when you think of folks driving with no equipment the max their cars will do on some highway (we have discussed some of those 160+ cars before) I feel somehow more safe in a fully caged car at speed on the salt. Maybe foolish of me. I did think, however, that if I ever rolled my liner in a ball sometime it was going to bite me bigtime. It never showed bad manners and they guy who now owns/drives it has not only upgraded the cage but did have a front tire blow at speed. Just made lot of flopping/shredding noise and he stopped easily and safely. My current car is a caged Firebird that have gone maybe 135 at Maxton and hope to do more and feel comfortable in it. Anyway, hope to be on Salt next year ( getting close to starting my engine first time and then have to mothball it for the winter) and look forward see you there.
Jack
Jack
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bill jones
- Guru
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-At speedweek we tested the roll cage on the Roger Griffiths 71 Camaro at about 236 mph----and if there had been a passenger he surely would have been better off being a little person.
-the car got just a little sideways and the air picked it up----stood it up on it's nose and did a half turn and dropped down onto the right front fender and back right rear corner of the cage.
-Basically it flattened both right side corners into a straight line from the headlight area.
-The front of the car never got off the ground---quite possibly because there is about 1000# of ballast in front of the spindle centerline.
-That was about as easy a blowover as a person could want to be involved with----then it slid basically in a straight line for about 3/4 of a mile.
--Doug Griffith was driving the car and he said it involved only one major jolt and that was when he was upside down.
-The cage structure virtually ripped the "x" joint area in the center of the upright tubes behind the driver and right above driveshaft tunnel.
-Both right side corners of the cage took a serious hit and were severely damaged by one hard hit----so attention to forces at speed look to need some pretty serious study.
-the one thing missing at Bonneville that all other tracks have is there is nothing to hit---no walls---no other cars---no guardrails----no curbs---no nothing---- to absorb and waste away any of the hi-speed energy---so all the energy is 100% asorbed by the components of the car.
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-One thing that was an eyeopener was: there was two stacks of ballast plates bolted thru the floor where the rear seat foot area is.
-these steel plates were about 12 to 14" square by about 3/4" thick---with one plate on the under side of the floor and maybe 5 plates on top.
-These were held together with a large bolt--maybe 3/4" or 1" in diameter.
-The forces from that crash landing nearly ripped the entire thin tin floor metal and there was evidence of the energy by the way all of this weight looked----as if it could have broken away and it would have seriously bashed the drivers back.
-the car got just a little sideways and the air picked it up----stood it up on it's nose and did a half turn and dropped down onto the right front fender and back right rear corner of the cage.
-Basically it flattened both right side corners into a straight line from the headlight area.
-The front of the car never got off the ground---quite possibly because there is about 1000# of ballast in front of the spindle centerline.
-That was about as easy a blowover as a person could want to be involved with----then it slid basically in a straight line for about 3/4 of a mile.
--Doug Griffith was driving the car and he said it involved only one major jolt and that was when he was upside down.
-The cage structure virtually ripped the "x" joint area in the center of the upright tubes behind the driver and right above driveshaft tunnel.
-Both right side corners of the cage took a serious hit and were severely damaged by one hard hit----so attention to forces at speed look to need some pretty serious study.
-the one thing missing at Bonneville that all other tracks have is there is nothing to hit---no walls---no other cars---no guardrails----no curbs---no nothing---- to absorb and waste away any of the hi-speed energy---so all the energy is 100% asorbed by the components of the car.
-----------------------------------------------
-One thing that was an eyeopener was: there was two stacks of ballast plates bolted thru the floor where the rear seat foot area is.
-these steel plates were about 12 to 14" square by about 3/4" thick---with one plate on the under side of the floor and maybe 5 plates on top.
-These were held together with a large bolt--maybe 3/4" or 1" in diameter.
-The forces from that crash landing nearly ripped the entire thin tin floor metal and there was evidence of the energy by the way all of this weight looked----as if it could have broken away and it would have seriously bashed the drivers back.
I've been playing with some small models of roll cages and sometimes the things they do as you apply forces to them are not what you expect.
One of the lessons from the models is that the "A" post bars and the front windshield bar are much weaker than any other part of the cage due to relatively long spans and their geometry. For example if the front "knee" of the "A" post bar is not firmly supported by the fire wall it drastically weakens the top of the A post bar as that peak angle flattens out that upper bend.
As that angle between the roof bar and the part of the "A" post bar that runs down the side of the windshield flattens out, the forces pushing back on the main hoop through the roof bar and down on the "Knee" of the A post bar go to infinity.
I'll try to post up some of the pictures of the model tests when I get a minute here.
Models were made from 1/4 inch Polyethylene tubing, cemented segments together with hot melt glue.
This allows quick assembly and the joints are both tough and flexible so they behave like a welded joint.
To straighten out the 1/4 poly, you need to boil it in water for a couple minutes then slide it on a piece of welding rod to cool.
scale factor for 1 3/4 tubing in a real cage is 6.5:1 so the model is large enough to work with but still table top size.
To make main hoop and side hoops, I made a form and put the boiled poly tube in the form to cool so it took the shape of the form like a bent tube.
Its a fun and very educational exercise.
One of the most interesting lessons is that as you add braces you do not eliminate cage distortion, you simply move it to a different part of the cage, and increase the amount of force required to cause the distortion.
That means the cage needs to be viewed as a system, just adding braces here and there can lead to unexpected results. In one of my first models I made the main hoop very rigid, as a result all the cage distortion got moved to the weaker parts of the cage.
Larry
One of the lessons from the models is that the "A" post bars and the front windshield bar are much weaker than any other part of the cage due to relatively long spans and their geometry. For example if the front "knee" of the "A" post bar is not firmly supported by the fire wall it drastically weakens the top of the A post bar as that peak angle flattens out that upper bend.
As that angle between the roof bar and the part of the "A" post bar that runs down the side of the windshield flattens out, the forces pushing back on the main hoop through the roof bar and down on the "Knee" of the A post bar go to infinity.
I'll try to post up some of the pictures of the model tests when I get a minute here.
Models were made from 1/4 inch Polyethylene tubing, cemented segments together with hot melt glue.
This allows quick assembly and the joints are both tough and flexible so they behave like a welded joint.
To straighten out the 1/4 poly, you need to boil it in water for a couple minutes then slide it on a piece of welding rod to cool.
scale factor for 1 3/4 tubing in a real cage is 6.5:1 so the model is large enough to work with but still table top size.
To make main hoop and side hoops, I made a form and put the boiled poly tube in the form to cool so it took the shape of the form like a bent tube.
Its a fun and very educational exercise.
One of the most interesting lessons is that as you add braces you do not eliminate cage distortion, you simply move it to a different part of the cage, and increase the amount of force required to cause the distortion.
That means the cage needs to be viewed as a system, just adding braces here and there can lead to unexpected results. In one of my first models I made the main hoop very rigid, as a result all the cage distortion got moved to the weaker parts of the cage.
Larry
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BillyShope
- Pro
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- Joined: Thu Apr 14, 2005 9:15 am
- Location: Orlando, FL
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The only car for which I have accurate force required data is the '60 Valiant. And, this demonstrates the improvements aerodynamically which have allowed more modern cars to achieve their improved fuel efficiency. The Valiant would require 175 horsepower to go 130 mph.
(A bit of trivia: When we were anticipating the 1960 compact car race to be held on the road course circuit at Daytona, we (those of us at Chrysler) became alarmed when we heard that the Falcon was so much "cleaner" than our Valiant that it would only take 145 horsepower to match the the 195 horsepower we were getting from our detuned 170 cubic inch slant six. Much to our relief as we watched the race on television, the Valiants had no competition from either the Falcons or the Corvairs. Later, the Falcon was tested at the Chrysler Proving Grounds and was found...much to everyone's surprise...to have more aero drag than the Valiant. With those large "eyebrows" on the Valiant fenders, who woulda thunk it??!!!)
(A bit of trivia: When we were anticipating the 1960 compact car race to be held on the road course circuit at Daytona, we (those of us at Chrysler) became alarmed when we heard that the Falcon was so much "cleaner" than our Valiant that it would only take 145 horsepower to match the the 195 horsepower we were getting from our detuned 170 cubic inch slant six. Much to our relief as we watched the race on television, the Valiants had no competition from either the Falcons or the Corvairs. Later, the Falcon was tested at the Chrysler Proving Grounds and was found...much to everyone's surprise...to have more aero drag than the Valiant. With those large "eyebrows" on the Valiant fenders, who woulda thunk it??!!!)
Billy -- interesting information. I guess that just goes to show how important grill area is and how aero behavior is sometimes not obvious.
I think it is worth considering the effect of aerodynamics on the roll over behavior of a car at speed. Sometimes they float (ie NASCAR flying car wrecks).
--- but --- The opposite condition is also possible!
If the condtions are right and the body turns to a high drag configuration at the right point in time, it could get "body slammed" into the surface by aero forces. Sounds like that might have been what happened to the camaro. Stood up on its nose then presented its full bottom to the wind and got slammed back down onto the salt.
Larry
Bill Jones wrote:-the car got just a little sideways and the air picked it up----stood it up on it's nose and did a half turn and dropped down onto the right front fender and back right rear corner of the cage.
I think it is worth considering the effect of aerodynamics on the roll over behavior of a car at speed. Sometimes they float (ie NASCAR flying car wrecks).
--- but --- The opposite condition is also possible!
If the condtions are right and the body turns to a high drag configuration at the right point in time, it could get "body slammed" into the surface by aero forces. Sounds like that might have been what happened to the camaro. Stood up on its nose then presented its full bottom to the wind and got slammed back down onto the salt.
Larry
I'm new to this site so I don't know if it's OK to bring back old threads, if not please except my apologes.
The Speedweek event at the Bonneville Salt Flats is about ready to start (Aug. 11 thru the 17)but mother nature is keeping us guessing right now as the track is currently under water at some points. If you get the chance this is a huge event with over 500 entrys this year, come see anything from '29 Ford roadsters to needle nosed streamliners running at speeds from 200 to 400+ MPH! If you check the SCTA/BNI.org website you will see if the event will go forward, they should know for sure by Monday.
The Speedweek event at the Bonneville Salt Flats is about ready to start (Aug. 11 thru the 17)but mother nature is keeping us guessing right now as the track is currently under water at some points. If you get the chance this is a huge event with over 500 entrys this year, come see anything from '29 Ford roadsters to needle nosed streamliners running at speeds from 200 to 400+ MPH! If you check the SCTA/BNI.org website you will see if the event will go forward, they should know for sure by Monday.
Michael LeFevers
www.mitechengines.com
Lifetime Member of the Bonneville 200 MPH Club
Frist Stock Bodied Car to Exceed 300 MPH
"Aerodynamics are for people who can't build engines" Enzo Ferrari
www.mitechengines.com
Lifetime Member of the Bonneville 200 MPH Club
Frist Stock Bodied Car to Exceed 300 MPH
"Aerodynamics are for people who can't build engines" Enzo Ferrari