mark manda

mark manda

Well Known Member
anybody leave out the post in the center? (on a slider canopy rollbar) view would be greatly improved.

The 4's just have a rollbar.
 
No I think it is a bad idea

The lateral stability of the roll bar is dependant on that strut. With out it your primary rollover protection could just fold over.

You bring up RV-4 roll bars. I guess I see where you are driving. First the roll bar BTW do have diagonal struts to handle fwd/aft loads and deflection. I guess my first comment is the RV-6/7/9 does not have a roll bar to compensate. The back of the fuselage is not going to cut it.

I would call Van, but it is your backside. You are the builder and can modify it, but I do personally think (with out analysis but a good understanding of loads, geometry and flip-over event) it could be fatal.

Another wrinkle is this, insurance. Consider this not too far fetched scenario. You flip over and you or the passenger or both are hurt or worse. Lets say the roll bar folded back and you elected to not follow the kit manufactures plans and left of a structural member. The accident report comes out and this is mentioned, "builder elected not to install part of the roll bar structure". DO you think they will pay the medical, liability or death benefits to the survivors? This is not far fetched with similar legal precedence. Of course you could be sued. I always say build it to plans, light, simple and straight as you can.

I hate to be grim but flying is dangerous and I think Van installed the strut for a reason, design loads. I am smart but not that smart that I think I can design a better plane than Van. Again I would call the factory. I am sorry for getting dogmatic but when I hear about structural mods it gets my attention. George
 
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George sometimes likes to wax poetically and is certainly correct, but the short story ( :D ) is that that brace is a structural brace... period. You don't want to mess with structure.

Paint it light Gray (or better yet, Sky Blue), and you'll never notice it again.
 
Getting Out

Mark, that center post is a mighty fine grab for hoisting your tired butt out of the seat.

And you could hang a compass from it.

And it closes a triangular section with the top of the firewall to help stiffen that up besides stabilizing the roll bar (sort of a co-dependence thing).

Lindbergh didn't even have a windshield to look through. That center post will be invisible to you, especially when you're focused on the cow.

John Siebold
 
And from flying with Kahuna in his -6A slider before he finished the -8, I can tell you that this brace makes a great "Oh S$#@" handle. :D
 
I havn't built that part of the plane yet but.... If I'm correct the only thing holding the forward bottom part of the windscreen in is some metal tabs. It's not actually screwed to the cowl. So without that strut in an extreme case the windscreen could come out if the roll bar is pushed back just a bit. In the very least I would think the vibrations alone would present a problem with the fiberglass that is used to fillet in the windscreen.


I can see it now.... flying along and you hit a big bird... (no not the tall yellow one) The impact causes the roll bar to angle back. The windscreen pops out at the bottom. The wind catches it and it departs the plane. Now the back half of the canopy is a huge wind catcher and it takes full power to maintain altitude. Then it departs the plane and takes out the VS. And you get the idea. I can go on and on here. I'm just thinking out loud here but I think it's a good idea to leave it there.

;)
 
thanks for all the excellent input. Sure looks good without it. might argue the increased visibility warrants not using it. But like I said, all the advice is noted.

112305032nobar0qv.jpg


1123050402yn.jpg
 
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sweet

Looks sweet. Your right it would be really nice witout it. Too bad there is now way to make a clear brace. What was that on the Star trec movie with the whales.... transparent aluminum?
 
Sounds like another reason to build a tip-up.

Sorry, I just had to say that.

This is kind of like roll bars in cars. Back in the hay day's of Triumphs, MG's, AH 3000's, Sprites, Jag's, etc. they used to install single hoop roll bars. In fact, you can still buy them them for Miatas. Including the "style bars" that have two hoops behind the driver's head. I know of at least one Miata roll over where the "style bar" bent forward killing the driver.

For track use the SCCA requires roll bars to have at least one diagnel member and supports, usually streaching towards the back of the car.

Don't remover the forward bar or you might be eating the cross bar in a roll over.
 
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Yep I'll install it.

The next thing you'll be telling me is I have to cut a 1" hole in my glareshield vinyl. :(
112305047glareshieldlealf3tm.jpg
 
darn it. I cut my slot a 1/4" too long. thanks for all the advice I wonder if I should do the whole thing over again. :eek:
120105038rollbarbracein8qj.jpg
 
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