Welding

Hello my drive into work is about an hour, which gives me far more time to think than I probably should have. Diving in this morning I was thinking about differnt ways that might be possible to build the fuselage of an RV. One idea was welding the fuselage skins to the longerons. I figure that there would be a problem due to vibration causing cracks in the welds, but what do I know. Any comments on the idea of welding?

You mean like the Eclipse?

The skins are 2024 and the longerons are 6061. I don't think welding is recommended on 2024, so that may be a limimting factor. Besides both the skins and longerons are heat treated to a t-6 condition, and welding would definitely affect that.

Just another opinion in a sea of opinions...

Regards,
Merle

Dustman,
Merle is correct. Welding is not allowed on 2024-T3 due to the copper in the alloy. Welding will change the properties of the alloy for the worse.
Charlie Kuss

Get a shorter commute

and forget about it!

Ignoring the compatibility factor...

1) Extra weight
2) Resale value..Personally I'd run a mile
3) its prepunched..what do you do with all those holes?
4) Riveting works..if it ain't broke don't fix it.
5) airframes flex, will the welds crack?

Spot welding

The only way I'd see it done properly is spot welding (same as auto makers use). It has absolutely no added weight, in fact it would be lighter than rivets. It allows some flex (basicaly like rivets) yet it also allows to add strength where needed (welding spots next to each other). The only problem is that you would have to fabricate all parts from stock (non prpunched) and from weldable alloys. So no way you could justify this other than high number serial production.

Ya gotta post heat-treat any aluminum weldments. There's a reason boeing, etc don't do it.

Dustman,

I feel your pain. When it came time to drill and countersink all the longeron holes, I was not looking forward to that chore. Once it was over, I wondered what the big deal was.

The bigger issues is fitting the top skins over the outer skin and then securing that one. This means you would have to either rivet the top skins on while holding them in place. This assumes you could weld it up. Clecos do a great job of holding the skin in place so you would still be stuck with filling all those holes.

Take a look forward, I think your plans call for some keep rivets to hold the longerons in place while you fit and rivet the upper skins.

think outside the box

You could pretend you are Howard Hughs and use epoxy glue. It worked on the spruce goose. keep those new ideas coming, who knows something might just click.