Doubling up Aluminium Sheet

[rwtalbot]

By this stage in the project I should probably know the answer to the but here goes anyway. I am wondering if there are any specific rules for doubling up material.

I am trying to fabricate the F-7109 plate. This is the stiffener that holds the smaller roll bar brace that goes in the middle of the windscreen on the slider.

Van calls out to make the doubler from 063 material. Unfortunately I don’t have any. I do have some 040 and 032 material I could use. Is it acceptable to do this? I suspect it is but I cannot find a reference to it in any of the publications I have. This is a structural area so I would like some peace of mind before I do it.


Thanks
Richard

 

[Wicked Stick]

Perhaps other 7 builders can verify this, but I would have thought Van's would have included a piece in your kit to use for this. Especially since it's called out for in the plans.

 

[rwtalbot]

Hi Did

I only found out after I used it for something else. Van has a habit of providing a stack of material in certain sizes rather than marking out what it is for all the time.

Richard

 

[jsharkey]

Don't stack material to get the correct thickness called for on the drawings. The structural properties, in anything but direct tension, are completey different for two stacked pieces of .062" compared with one piece of 1/8". Try bending them!
Jim Sharkey

 

[Yukon]

It's not rocket science

Two pieces will work fine. Look at the wing spar. Is it one big chunk? Besides,
if you don't like the stiffness when it's done, order a new piece!

 

[mgomez]

I do have some 040 and 032 material I could use. Is it acceptable to do this? I suspect it is but I cannot find a reference to it in any of the publications I have. This is a structural area so I would like some peace of mind before I do it.

I wouldn't. It would take a lot more rivets that the drawing calls out to make those two pieces as stiff and strong as one. I had the same problem...I must have used the piece that Van's supplied for something else. Fortunately, I had a big sheet of 0.063" that I bought for my center console, so I just made it from that.

And now I'm waiting for the 1/8" angle that rivets onto F-7109, because I seem to have used that for something else, too!

So if you want my advice, just order another sheet of 0.063" and never worry about it again.

 

[jsharkey]

Two pieces will work fine. Look at the wing spar. Is it one big chunk? Besides,
if you don't like the stiffness when it's done, order a new piece!

The wing spars are designed from the get go as laminated beams.