Roll Bar Adjustment

[mfleming]

The -7 roll bar is one springy piece of metal

The roll bar is 7/32" too wide. So like a lot of other builders I got down to the job of adjusting the bar.

Currently, by squeezing the bar in by 3"... I've gained about ⅛".

My question is - how much can I squeeze the bar? Will it fail?

Roll Bar persuader.

[wirejock]

That's a pretty creative method.
To answer the question, it will fail but no idea when.
I can't remember how much I squeezed mine but it was scary. It took lots of tries. Each was about an inch more. I used a come along at the base flange so it could be released gently. First attempt was a wratchet strap. It actually made it wider when it snapped loose.

[mfleming]

Originally Posted by wirejock

That's a pretty creative method.
To answer the question, it will fail but no idea when.
I can't remember how much I squeezed mine but it was scary. It took lots of tries. Each was about an inch more. I used a come along at the base flange so it could be released gently. First attempt was a wratchet strap. It actually made it wider when it snapped loose.

Scary is right...I'm not sure how much a replacement bar cost but its probably expensive (Van's doesn't show a WD-641 on the web).

Another roll bar question...The plans don't appear to give a dimension for placing the roll bar on the fuselage for and aft. They mention 7/32" a gap between the fuselage side and the outer edge of the bar but no dimension for and aft.

[wirejock]

Yes, it's there. Not the easiest thing to find.
Look at DWG42, View C-C
By the way, don't make abfinal trim on the roll bar brace till you finish the canopy. That way you can shimbit to match the forward bow. I had mine perfectly square then the bow was not square and it looked stupid. Had to order a new brace.

[Tdeman]

Originally Posted by mfleming

Scary is right...I'm not sure how much a replacement bar cost but its probably expensive (Van's doesn't show a WD-641 on the web).

Another roll bar question...The plans don't appear to give a dimension for placing the roll bar on the fuselage for and aft. They mention 7/32" a gap between the fuselage side and the outer edge of the bar but no dimension for and aft.

Bottom left of DWG 42, View C-C, shows a dimension for fore/aft positioning of the roll bar. (EDIT: Doh! Wirejock beat me to it)

I had about 3 ratchet straps cranked WAY down on mine, then stood it up on its side and gave a few good pushes on the other end with gravity's help to try and narrow it up.

Unstrap, re-measure, repeat. Thats a seriously substantial piece of 4130, I wouldn't be too concerned about it letting go before you get to your final dimension. The ratchet straps on the other hand....

[Maxrate]

Hey Michael, I?m right behind you waiting on the finish kit to arrive. Please keep posting on your progress. Would love to see how you finally achieve squaring that thing up!

[mfleming]

Originally Posted by wirejock

Yes, it's there. Not the easiest thing to find.
Look at DWG42, View C-C
By the way, don't make abfinal trim on the roll bar brace till you finish the canopy. That way you can shimbit to match the forward bow. I had mine perfectly square then the bow was not square and it looked stupid. Had to order a new brace.

View C-C...Hiding in plane sight

Thanks for the tip about having the roll bar square...I'll wait until the slider is in place before finalizing the roll bar brace

Originally Posted by Tdeman

Bottom left of DWG 42, View C-C, shows a dimension for fore/aft positioning of the roll bar. (EDIT: Doh! Wirejock beat me to it)

I had about 3 ratchet straps cranked WAY down on mine, then stood it up on its side and gave a few good pushes on the other end with gravity's help to try and narrow it up.

Unstrap, re-measure, repeat. Thats a seriously substantial piece of 4130, I wouldn't be too concerned about it letting go before you get to your final dimension. The ratchet straps on the other hand....

I tried that after you mentioned it...no joy, I guess I'm weight challenged...couldn't get it to budge

I just kept winding up that strap until it was right. BUT, I noticed after test fitting the bar that I had gone backwards .
I then realized the fuselage sides were moving (when I leaned on them) more than I was trying to correct for.
Soooo, I installed most of the forward upper fuselage assembly and things quit moving around.

Originally Posted by Maxrate

Hey Michael, I?m right behind you waiting on the finish kit to arrive. Please keep posting on your progress. Would love to see how you finally achieve squaring that thing up!

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Success The roll bar is drilled (pilot holes) and in place. Man that's scary bending that bar

The forward brace is just propped up, not installed yet.

[wirejock]

Michael
Maybe not an issue but I clekoed the top skin for all that work just to be sure. Maybe nothing will move but I sure don't want a rude surprise later. It's hard enough to cleko in place when all the holes fit!

[mfleming]

Originally Posted by wirejock

Michael
Maybe not an issue but I clekoed the top skin for all that work just to be sure. Maybe nothing will move but I sure don't want a rude surprise later. It's hard enough to cleko in place when all the holes fit!

Yes, I thought about the top skin ( in the middle of backdrilling the pilot holes).
Tomorrow I plan on cleko?ing the top skin on and lookin things over. Being only the pilot holes are currently drilled, I should be able to bias the install one way or the other when upsizing the holes.....I hope

[mfleming]

Installed the forward top skin and everything still fit properly.

Here's the roll bar cleo'ed on and the top skin in place...I couldn't resist putting the canopy frame in place just for grins.