Building
 

A good FLAT sturdy table is hard to beat. Go to the local lumber yard/Home Depot and buy an untexured ceiling tile (2x4 ft) for a couple of bucks to use for a building surface. If the wing ribs have an undercamber, you may have to shim the trailing or leading edge with scrap balsa as per the plan. Built that way, you shouldn't have any warps.

Building wings on jig or Tabletop?
 

I jig. Having said that, I would also say that the real potential for wing problems is bowing rather than twisting. A sagging, bowed wing panel will probably sag forever, but a moderate twist is not hard to straighten out, especially in open framework. In fact for a lightly constructed wooden glider wing, holding a wing panel by one corner will probably allow it to twist out of shape under its own weight... the covering can easily correct the condition and hold it true. The jig will keep you safe from bows whether it's aligned flat or not.

That being the case, I'd rather build a twist in with a jig that's sitting funny than buid a bow in with a board that's got a dip or a hump.

(Downside: a jig takes a little setup work and usually a lot of mental buildup... a flat board takes less setup, but more care when you're actually building. Either method will produce an outstanding wing if you're careful.)

Building wings on jig or Tabletop?
 

I guess the bowing I've seen did come from bad spars that should have been corrected or replaced prior to building... but twisting I always check for anyway, so I guess I've been slow to worry about it.

The eliptical dihedral description reminds me of the Windfreak, but I think that was a smaller beast than yours... it sounds like a challenging project!

Building wings on jig or Tabletop?
 

I've never used one inch foam but have used drywall extensively and also 2 ft by 4 ft ceiling panels. The foam would be more tolerant of water though which will cause problems with both the drywall, which will swell, and with composition ceiling panels which will warp. Water is not normally a problem in most building environments and I have never had problems with high humidity, so I'll stick with what I have used in the past. Good idea though.

Both composition ceiling panels and drywall work very well and will lay flat on a flat table top or work bench. The ceiling tiles are a bit easier to pin parts onto, but if you are into designing and scratch building, you can drawn the plans right on the drywall on a drafting table and then build the aircraft on them on the work table. Making copies of the plans is a real bugger though as the drywall does not feed through the copy machine well, so it's a process that works best with one-off designs. =)

I tend to buy my wood in larger quanties to save money and then store them packed, stacked and level in old glider kit boxes, most of which accomodate 3X36 inch wood very well. By the time I get around to building something, the wood is all well aged, unwarped, has a constant moisture content and builds very well. The local humidity where I live is normally 10-30% so this probably works better for me than it would for someone who lives in a very humid environment or worse, where there are large fluctuations in humidity.

Wood should be stored level or else you will get more moisture accumulating in the lower ends of the wood. Same goes for wood props although this is more of a full scale aircraft concern than an R/C concern.

I like building on a table as creating or setting up a jig can be as much work as building the wing itself. My one full scale aircraft project (a Monnett Moni motorglider) took nearly as much time to build the wing cradle (that was placed on top of a level work table) as building the bonded and stressed skin aluminum wing itself. The hangar fell on my aircraft and on the Cessna 210 I shared the hanger with during a tornado last year and I am now faced with building a new cradle in order to rebuild the wing. It's dismal prospect. If you know of a pair of full scale Monnett Moni wings someone wants to sell, let me know. =)