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  #1  
Old 02-22-2018, 07:24 AM
olyolson's Avatar
olyolson olyolson is offline
 
Join Date: Dec 2009
Location: St Louis, MO
Posts: 691
Default RV-4 Rollbar

My Rollbar is getting a bit chipped so I decided to take it off and repaint it. Then I thought, what the heck why don't I have it powdercoated. Then I remembered seeing some guys with a really nice curved rollbar on their -4s but I don't think I can tackle a project like that since I don't know how to weld. Checked with some local A&Ps and some car guys but haven't had much luck yet.

I have the standard RV-4 rollbar and have never liked the basic slap it together look. If a new one was made it could be widened a bit at the top to follow the canopy contour closer. The wider curved bars clean up the cockpit a bit which would probably allow better videos without so much tubing in the picture.

So does anyone know how those guys made this cool looking rollbar? If you are one of those guys please e-mail or PM me. Looked online and couldn't find any pictures. If someone has some good pics perhaps I could take it to a muffler shop and have them make one with the curved top for "an off road vehicle".
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Last edited by olyolson : 02-22-2018 at 08:34 AM.
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  #2  
Old 02-22-2018, 09:03 AM
fixnflyguy fixnflyguy is offline
 
Join Date: Jan 2006
Location: Winston-Salem, N.C.
Posts: 879
Default A couple things to keep in mind

I was going to do mine curved, but talked myself out of it. The purpose is to be a roll (flip-over) bar, and the factory design likely transmits those loads better than any other design with the straight tubes. The curved top bars are equally effective, only if the tubing is of adequate steel. I doubt a muffler shop can do much..(inferior steel and large radius benders), but many of the race car shops can if they build roll cages. It is a very tight bend for the tubing size. Many RV off field landings end in flip-overs..I certainly want mine as robust as possible.
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  #3  
Old 02-22-2018, 09:46 AM
SJordan SJordan is offline
 
Join Date: Sep 2016
Location: Scottsdale, AZ
Posts: 142
Default

I spend countless hours trying to pull off the curved roll bar, lets just say its not possible if you want to stick with safe size and gauge 4130. That tight radius is just not possible. I ended up make a semi round one with 4 different segments cut at lower angles and tig welded together. I would just powdercoat what you got.
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  #4  
Old 02-22-2018, 10:06 AM
rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 7,555
Default

Quote:
Originally Posted by olyolson View Post
My Rollbar is getting a bit chipped so I decided to take it off and repaint it. Then I thought, what the heck why don't I have it powdercoated. Then I remembered seeing some guys with a really nice curved rollbar on their -4s but I don't think I can tackle a project like that since I don't know how to weld. Checked with some local A&Ps and some car guys but haven't had much luck yet.

I have the standard RV-4 rollbar and have never liked the basic slap it together look. If a new one was made it could be widened a bit at the top to follow the canopy contour closer. The wider curved bars clean up the cockpit a bit which would probably allow better videos without so much tubing in the picture.

So does anyone know how those guys made this cool looking rollbar? If you are one of those guys please e-mail or PM me. Looked online and couldn't find any pictures. If someone has some good pics perhaps I could take it to a muffler shop and have them make one with the curved top for "an off road vehicle".
Quote:
Originally Posted by fixnflyguy View Post
I was going to do mine curved, but talked myself out of it. The purpose is to be a roll (flip-over) bar, and the factory design likely transmits those loads better than any other design with the straight tubes. The curved top bars are equally effective, only if the tubing is of adequate steel. I doubt a muffler shop can do much..(inferior steel and large radius benders), but many of the race car shops can if they build roll cages. It is a very tight bend for the tubing size. Many RV off field landings end in flip-overs..I certainly want mine as robust as possible.
^^^^^^^^^
Correct

The roll over bar is an engineered part.

If you change it, it would be a good idea to do some reverse engineering and make sure your new design is equivalent.

A roll bar with a curved shape and no gussets at the top is going to be much more susceptible to collapse in compression than the triangular shape, if the same size and wall thickness tubes are used.
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  #5  
Old 02-22-2018, 10:26 AM
SMRacer SMRacer is offline
 
Join Date: Feb 2012
Location: Leesburg, VA
Posts: 392
Default Roll bar

Mine was done by a race shop.

The curve at the top was too severe to be made with a single bend using the proper diameter and wall thickness tubing. So we made it in
two pieces and then sleeved it at the top. Even then it was about an inch shorter than the stock roll bar.

Based on the experience of the shop that did the work (the region's most well regarded cage builder), and the dynamics of the cages in the cars I drove, I'm quite convinced that the curved top provided equal or superior protection for rollover.
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  #6  
Old 02-22-2018, 10:57 AM
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fl-mike fl-mike is offline
 
Join Date: Jul 2005
Posts: 912
Default

Showplanes has a pre-bent rollbar piece.
Check their website.
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  #7  
Old 02-23-2018, 12:24 AM
Jetj01 Jetj01 is offline
 
Join Date: Mar 2005
Posts: 316
Default Love my curved rollbar in my RV-4

Found a race shop that makes roll cages online. There are several. Look for the radius and metal you want ready made. It will come U shaped and you simply lay it next to your factory rollbar and cut both to fit your symmetrical desires. It is a tighter radius than any shop in Dallas could fashion. I went a step further and in the two joints to be welded slid another metal bar inside to line up my soon to be attached point. Had it professionally tig welded, powder coated and flying now nine years! Stronger than factory��
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Last edited by Jetj01 : 02-23-2018 at 12:27 AM.
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  #8  
Old 02-23-2018, 08:06 AM
Whitman Whitman is offline
 
Join Date: Oct 2010
Location: 2R4
Posts: 198
Default

While you’re at it; move that roll bar back a few inches for added comfort!!
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  #9  
Old 02-23-2018, 08:51 AM
olyolson's Avatar
olyolson olyolson is offline
 
Join Date: Dec 2009
Location: St Louis, MO
Posts: 691
Default RV-4 Rollbar

I checked out the Showplanes website but I’m out of town this weekend so I can’t measure my rollbar to compare. Just looking at the picture it looks like I could cut my rollbar off just above the cross support where the shoulder harness attaches. Then trim the Showplanes one to fit the canopy and weld it onto the top of mine.

Anyone done this on a standard -4 rollbar?

Any pictures for sharing?
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Last edited by olyolson : 02-23-2018 at 08:54 AM.
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  #10  
Old 02-23-2018, 09:16 AM
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SMO SMO is offline
 
Join Date: Oct 2007
Location: Salmon Arm, BC
Posts: 927
Default

This pic shows my roll bar. I had a shop in Calgary make the bends for me. They used a thick wall mild steel, said a thinner wall would not make the bend. Added ~15 lbs to the plane as compared with the stock setup.

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