Chassis tubing question

[LittleLiner]

I am trying to decide if I want to go with 1 5/8 inch by .120 wall DOM round tubing for the frame and driver area in my streamliner or to go with square tubing for the frame (like the Neb Therom III uses).  Of course I'll use the round tube for the cage.  However I wonder if someone can tell me what is considered safe (and will pass tech) as far as size and wall for square tube to support the cage and enclose the driver area?  Any help will be appreciated.

[John Bjorkman]

The roll cage structure is considered for safety to extend from in front of the drivers feet to befind the drivers head. The use of square tubing is allowed if you can show it meets the minimun strength requirements. The square tubing should have a Section Modulus, Moment of Inertia, and Cross Sectional Area equal to or greater than 1 5/8 diameter x .12wall round tubing.

[gearhead]

i emailed you also but just found out who makes the program for tubing strength. i got it from www.tonyfoale.com go to free software. there are some interesting things here and some other things that may be helpful. by the way its called something like sections or section stiffness.

[LittleLiner]

Thanks Jon and gearhead.  You have given me a starting point to figure this out.

[gearhead]

hey little liner one more thing. they have another program at the same site that im sure you could use. you were talking about problems cutting the round tubing and i wanted to let ya know that they have a program for that also. you type in the angle you need and size of pipe and it calculates and prints out a pattern. then you cut out the pattern and trace it on the pipe and then you cut. Ive used this and it works pretty good. a good way to get a really good joint. just another thing that may help

[John Burk]

LittleLiner - A fishmouth joint in end view is a radius - Viewed from the side it's two straight lines , even if it's a three way joint .

[willieworld]

for round and square tubing  example  1 in round and 1 in square  the distance around a 1 in square tube is 4 in  --the distance around a 1 in round tube is 3.1415 in ---the square tube will have more material as the round tube of the same size  if they have the same wall thickness   just a thought  willie buchta

[interested bystander]

Look at Sum's build in case you aren't a believer in square tubes!

Musta been a carpenter at one time.

He's done GREAT work, by the way.

Yrs truly's just been in the (mostl y) round world since '55 or so .  But, whatever's appropriate for the application!

[Joe Timney]

Come to Townsend, DE and get a free demo on fitting tubing!!!
joe 302.378.3013