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 Post subject: Re: Say for instance..
PostPosted: March 15, 2014, 11:35 pm 
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jazz2561 wrote:
I have a question. Say for instance that if I were to design a locost designed to seat four people, what size tubing and wall thickness do I use for the chassis?


It's a simple rudimentary engineering calculation.

You have a 600kg weight that you want to increase by 200kgs (2 people, chassis and seats) so you engineer to a 33% strength increase. A 1.25" tube is 200% stronger. I maintain that 1.25" should be the base tube for a Locost anyway.

But wait, we are also going longer by 40%, hmm lets see, a 24" length of 1.25" x 0.065" will support 1/12 of 800kgs at 0.15" deflection, increase that length by 40% to 35" and you will need 1.75" at 0.16" deflection to maintain similar strength but allowing for buckling strength I would go to 0.080" wall and have 0.014" deflection.

Problem solved, use 1.75" x 0.080" for your primary structure and diagonals for scaled up chassis boxes or 1.00" diagonals if you add an extra box (which would be my preference).


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 Post subject: Re: Say for instance..
PostPosted: March 16, 2014, 12:08 am 
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Joined: November 11, 2013, 2:11 pm
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Location: Frankfort, KY(for now)
So basically I can go to 2 X 2 .95 wall tubing to be safe


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 Post subject: Re: Say for instance..
PostPosted: March 16, 2014, 12:20 am 
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Location: Cedar City UT
jazz2561 wrote:
So basically I can go to 2 X 2 .95 wall tubing to be safe


imho i would use 1.75 x .095" round DOM ... best compromise for dent-resistance

however, i guess a .95 wall tube will not dent anyway :P :lol:

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 Post subject: Re: Say for instance..
PostPosted: March 16, 2014, 12:25 am 
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Location: Frankfort, KY(for now)
Sounds like a plan


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 Post subject: Re: Say for instance..
PostPosted: March 16, 2014, 3:27 am 
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jazz2561 wrote:
So basically I can go to 2 X 2 .95 wall tubing to be safe


No, you go to 1.75" x 1.75" x 0.080" to be overly safe, more than that is based on other factors.

If you use 2.00" x 2.00" there is no reason to go more than 0.065" wall which is 30% stronger than 1.75" x 1.75" x 0.080".


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 Post subject: Re: Say for instance..
PostPosted: March 16, 2014, 3:30 am 
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Location: Frankfort, KY(for now)
I gotcha


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 Post subject: Re: Say for instance..
PostPosted: April 12, 2016, 2:15 am 
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Location: Frankfort, KY(for now)
I'm back, and I kept my promise. The build tread will be starting soon. I dropped my wb down to realistic size, which come from my exterior styling inspiration, a 1937 delage d8 120s pourtout aero coupe. Its wheelbase is around 132 inches. Mines is between 133 and 134.


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 Post subject: Re: Say for instance..
PostPosted: April 12, 2016, 2:29 am 
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Joined: November 11, 2013, 2:11 pm
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Location: Frankfort, KY(for now)
I also have a very serious question I must know this immediately. Does anyone have a ballpark figure of how wide the survival cell(driver, passenger, and occupants) is, and how wide is the car overall from tire to tire, front and rear measurements?)


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 Post subject: Re: Say for instance..
PostPosted: April 13, 2016, 12:53 am 
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Why ballpark? Why not just choose a donor, google it, do a little math, and have an accurate answer? Find the track and subtract the width of a tire to get inside tire-to-tire width, or add the width of a tire to the track to get the overall width. The "book" Locost chassis width is 42", but it seems modern Locost widths are generally set by the rear axle of the donor; the inside tire-to-tire width of the donor, minus an inch or two for tire clearance .

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 Post subject: Re: Say for instance..
PostPosted: April 13, 2016, 8:31 am 
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JackMcCornack wrote:
Why ballpark? Why not just choose a donor, google it, do a little math, and have an accurate answer? Find the track and subtract the width of a tire to get inside tire-to-tire width, or add the width of a tire to the track to get the overall width. The "book" Locost chassis width is 42", but it seems modern Locost widths are generally set by the rear axle of the donor; the inside tire-to-tire width of the donor, minus an inch or two for tire clearance .


Jack,
I thought our cars were getting bigger because it's nearly impossible to fit a modern American into a book chassis. :lol:

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 Post subject: Re: Say for instance..
PostPosted: April 13, 2016, 10:44 am 
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Quote:
The "book" Locost chassis width is 42", but it seems modern Locost widths are generally set by the rear axle of the donor; the inside tire-to-tire width of the donor, minus an inch or two for tire clearance .
That is good premise for a solid rear axle. IRS opens up a lot of variables (and sins). I thought US Locost widths were set by our insatiable "need" V6 and V8 engines. And, as Toobusy stated incompletely, our modern American a$$es.

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 Post subject: Re: Say for instance..
PostPosted: April 15, 2016, 12:57 am 
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Joined: November 11, 2013, 2:11 pm
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Location: Frankfort, KY(for now)
Thanks for the replies. I do plan on using a irs, was just torn over the idea about tire-frame clearance. I have a exterior design and the chassis design is almost done. I just want to make sure that the tire-frame clearance is right to prevent tire rub or worse.


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