Compound curves (Veneer)

Well I have not tried the veneer method of making the plywood compound curves as of yet. i.e. By using narrow pieces of veneer edge glued over a form and built up to the desired thickness required that Achim talked about. I was thinking about building the forms one of these days when something came to mind. Since the tail section of the Siemens are made up of individual pieces as shown in many pictures, scarfed together....why would they do it that way if they made up the plywood using veneer. If I build a form that is the entire tail of the aircraft why couldn't I then build the skins much larger ? Say 4 pieces joined at the LE & TE ? It doesn't add up !

What do you all think ?

Mike Maddeford

Mike

I am very interested but am not quite sure of what you mean. Sorry- Im not familiar with Siemens practices. Are you speaking of having your parts come out "over size" by the thickness of your skin build up?

As I see it, Albatros fuselage had stock sheet plywood covering with scarfed joint at edges and virtually no compund curves (check any photo with a straight edge). Pfalz seems to have used a wraped method actually producing compound curve. The Nieuport strip method, ditto. Others seem to be variations of these basic examples.

BTW- I have a US government report from 1940 which details various and accepted wooden construction methods for aircraft industry. There is a very short section on forming parts from laminated veneers around, over and inside molds. Will make those portions availble for this discussion if there's any interest.
Charlie

[fltmech]

If you look closely at the shape of the SSW D.III/ D.IV from the cockpit back, it may be taken as a series of cones. In this case approximately 4. This would allow the use of sheets of plywood scarfed together, and give a faired shape.

Yes. The fuselage is a series of cones. Not perfect ones but cones. I'm talking about the tail section includeing the upper fin, tail skid fin and the tail plane. It's made up of a number of small pieces scarfed together. Some aircraft simply add the tail surfaces to the fuselage ( with or without root fairing) The Siemens surfaces are all built together. The skin on the fuselage is run down the side and then curves out onto the tail. I can't tell if the skin on the fuselage is wrapped right around with only the spars sticking through. And then the tail ribs put on and then skined and faired in ??? I don't think it was that way. I'm leaning towards skin on the surface only.????

Mike

[fltmech]

It appears the that there are separate fairing pieces,between the fin,horiz tail and the fuse. the easiest way to reproduce them would be laminated veneers. As far as the skin wrapping around, with only the spars sticking through, I would say no. Please look at windsock datafile 29 page 9 center photo. :