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Bending The Longerons

RudysRV7

Member
The fuselage kit will be order in a few months. I am dreading, bending the longerons. Sine I have the AA6-125 longeron angles, is there any reason that I could not work on that now?
I would have to print the PDF template out, since I don't have the physical plans yet. But other than that....

Thoughts? PS. I may call Vans, but like to jump on this forum as well.

Cheers
 
You can do it now. Its intimidating, but once you start you'll see that it's really not that hard.

Just clamp in a vice, apply downward pressure and hit it with a rubber mallet, then measure. If it twists use a wrench to straighten it out. You'll go through the process a few times, but eventually it will be bent correctly.
 
Dies

I borrowed some dies and it was really easy to get a precise bend. Now after the fuse has been assembled, I realized how important it is to get this right; I would recommend you borrow a set of the dies.

But i too stressed about this, but it was straight forward and not worth the grief.
 
Bending the longerons is not something to dread. My solution was to take a hydraulic bottle jack (10-20 tons would do) and build a poor man's press using angle iron at the bottom and top connected with readi-rod and nuts. I clamped both longerons back to back, and made a hardwood "bending shoe" (with a slot in the middle for a close fit around the longeron flanges) to fit over the jack ram. At the upper end, the two cross bolts of the angle irons had pipe around them as spacers to these served as the other two contact points of the longerons. I used the full size drawing of the longeron curve to make an aluminum checking template. Using the hydraulic jack made it very easy to "creep up" on the amount of curvature without kinking or overbending. Yes you can print the PDF drawing out by taking it to a blueprint place, just be careful to check that the final scale is right.

Of more importance, and a PITA is the "sharp downward bend" that you have to put in the longerons to match the side skins on assembly to the front fuselage. This was where I reverted to the dead blow hammer suggested in Vans instructions. Each longeron was clamped individually to the bench, the initial bend/twist was put in by hand, but the final "sharp" part of the bend was with the dead blow hammer. It really took some hammering to get this profile right. Again, the top profile of the side skins is the guide here. If you don't get a sharp bend in the longeron, you may find the rivet pattern has insufficient edge clearance in the longeron flange, so it pays to keep checking this before calling it "good".
 
The bending of the longeron was one of the the easiest task in my RV8 built. They came out perfect from the bench vise. I think the all the noise about this operation was caused by people making the mistakes when they bend in the wrong direction and ruined their longerons.

What I did was to buy a couple of short length aluminum angles from Home Depot, about 12" long. Mark these LEFT template and RIGHT template.

From the drawings, transfer the directional arrows from the plan to the LEFT and RIGHT template and mark with "ARROWS" with left/right/up/fwd depending if the template is on the LEFT or RIGHT.

Transfer this directional template to your longerons so you will not bend the real longerons the incorrect direction. The process of bending the longerons is a simple whack of a hammer. You will arrive at the correct angle mostly with one strong blow or a couple of softer blows of the hammer.
 
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I used the dies and it really isn't that hard. I actually did them twice as a few other folks have done. A big Cresent wrench helps with the twisting too.
 
Longerons

Lots of ways to skin that cat as others mentioned but make sure the bend is in the right place and matches the part like the canopy deck and tthe down slope of the forward skin. The paper is handy but you won't be riveting the paper.:D
 
Thanks PhatRV, sounds simple. I like the idea of buying the templates from Home Depot.
Say, What size does the DWG come in from Vans, that has the actual scale of the bend?
I am hoping to print this DWG out, prior to getting the fuselage kit.
 
DWG

Thanks PhatRV, sounds simple. I like the idea of buying the templates from Home Depot.
Say, What size does the DWG come in from Vans, that has the actual scale of the bend?
I am hoping to print this DWG out, prior to getting the fuselage kit.

There should be a full scale drawing in the kit.
However, you won't be riveting the paper so don't quit till you use the actual parts to compare the bends. Especially the downward bend that matches the side skin.
 
Draker - Thanks for sharing your mistake. I can see how is something I would have done.
Hope all is well in Livermore. I am originally from Modesto, CA. (where I built the wings and empennage.

Cheers
 
Thanks PhatRV, sounds simple. I like the idea of buying the templates from Home Depot.
Say, What size does the DWG come in from Vans, that has the actual scale of the bend?
I am hoping to print this DWG out, prior to getting the fuselage kit.

The paper drawing is not full size. If you measure the bend locations as noted in the plan, the longerons will come out perfect. You need to make the mark before you make the bend. Some people clamp both longerons to keep them in symmetry. I bended one longeron at a time and both came out in symmetry as well. I found this is easier to whack it with a heavy mallet without have to worry about hitting the opposite longeron.
 
Dont stress about it...just go slowly

Just take your time....mine worked out fine with just a vice and rubber mallet. If you want, get some cheap angle form the hardware store and practice the bends on a short piece to get the feel for how it goes...
 
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