I am framing up a 77" Ziroli Stearman. The upper wing is ready to sheet on the forward and mid sections, but it seems too easy to twist at this stage. The plans show no shear webbing between the spars, but would it help? or is it unnecessary weight? Will the sheeting and covering add enough stiffness without the webbing?

Once that wing is sheeted all the twist will be gone.I think shear webbing is a way to save time and weight
so you dont have to sheet. The last one I fully sheeted was a Top Flight Mustang.Once it was done the covering just made it pretty. That wing was stiff as a board. If you havn't done sheeting before, be sure to use Elmers
to edge glue the sheeting together and not CA. later daveo

Thanks for the help, and you are the second person to mention Elmers over CA for sheeting. Why? That's one I missed somewhere in my learning.

The Elmers can be sanded, the CA will leave a high spot.Plus Monocoat dose not stick to CA very well.
later daveo

Doug, I've got one of those kits cut by The Aeroplane Works. I'm curious as to what engine you'll be using? I want to go with gas but I have reservations about how easily I'll be able to hide it with a dummy radial.
As for the shear webbing, it wouldn't hurt but is probably unnecessary.
Although, as I recall, it's only sheeted from the spar forward (like in D-tube construction) and not fully sheeted like the TF Mustang and similar planes, the fact that it's a bipe means that twisting will be resisted with all the cabanes and N struts tied together.
I really don't think shear webs resist twisting as much as they resist up and down flexing anyway...Not sure about that though.

Thanks for your response. My kit was cut by All-American, and the guy there was currently building a 77" Ziroli Stearman for himself. He was planning to use a dummy radial (I think he was talking about the Williams Brothers version) on a gas engine. I am using a G-38 gasser and plan on buying the dummy engine as well. Yes, I will have to cut out a couple of cylinders at the bottom for the gasser cylinder. I saw a Stearman with gasser and no dummy radial, and it was butt ugly. So, if I cannot succeed in installing a dummy radial around my G-38, I will switch over to Super-Stearman looks by adding a cowl. I added the shear webs, and it made a huge improvement in folding stiffness and some improvement in twist. Like you, I will count on the cabanes and maybe some flying wires for twist stiffness. Someone in another web discussion group has taken my question about the wing as an opportunity to trash Ziroli's Stearman as weak and unsafe. I try not to listen to radical posters on the web, but I thought the shear webbing could serve as a little insurance. Everyone else I talk to, have nothing but praise for Ziroli's plans.

I've come to the same conclusion about the Super Stearman being the choice if I can't convincingly blend the gassser in with a dummy radial. I corresponded with Gerry Yarrish about his and although I'd seen photos of his without a dummy radial to hide the gasser, he informed me that he did in fact hide his successfully with one from Bob Dively.