WW1 and CNC

[franzkait]

I guess 3 phase is correct .

[jumpinjan]

Originally Posted by j ferguson

How were you able to find correct geometry for the fuselage and then correct the bulkheads? How did you decide which dimensions were correct?

I mentioned that I used an averaging technique to get a smooth profile. Yes, it took awhile to get it just right.
The drawings would make it look wavy, so thats not right. I actually found drawing errors that were seriously wrong. If you were using those drawings, you would be throwing hundreds of dollars of plywood in the camp fire.
Jan

[John McKenzie]

Jan,
Interesting to know ,..exactly which [set of ] Alb drawings you did use .
Thanks .

[John McKenzie]

Originally Posted by jumpinjan

..... replicating all the Albatros D.III's bulkheads. .... In the drawings, I found many mistakes including dimensional & drafting errors (just drawn wrong).





Picture of the averaged loft to make the body smooth, and not to follow the bulkhead's exact dimensions.

http://gwaero.com/uploads/September_2010.pdf

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Certainly it look now , nothing like if any original Albatros drawing was ever used .
You miss completely , the design idea behind the "original" DIII shape by a mile , especially in the nose part ,...in your smoothed out fantasy drawing !

[j ferguson]

JM,
The thing I get hung up on after looking at two Albatros projects is that the skin panels look like they cannot be bulged (stretched? deformed?). They have to be either cylindrical or conical surfaces where they are not flat. There are two challenging panels between the horizontal and vertical stabilizers that do look like they need to be pressed to shape after steaming. Maybe other skins are steamed so that they can be stretched over "bulged" bulkheads.

Of course what Jan had to do was deal with drawings which really did have bad dimensions - nothing new there, unfortunately

[Jeff Brooks]

Originally Posted by j ferguson

JM,
The thing I get hung up on after looking at two Albatros projects is that the skin panels look like they cannot be bulged (stretched? deformed?). They have to be either cylindrical or conical surfaces where they are not flat. There are two challenging panels between the horizontal and vertical stabilizers that do look like they need to be pressed to shape after steaming. Maybe other skins are steamed so that they can be stretched over "bulged" bulkheads.

Of course what Jan had to do was deal with drawings which really did have bad dimensions - nothing new there, unfortunately

After reading the NASM book about restoring the albatross http://www.amazon.com/ALBATROS-D-Va-...N%3D0874746337
they theorize that the plywood skin is created in a cement mold, and the plywood is glued then put in the mold and pressed with some sort of plastic or fabric with water used to weigh it down while it conforms to the shape, and the glue dries.

[j ferguson]

Wow, Jeff.

This would make building one of these things a real bear. Although if you had say a 4X8 Gantry Mill you could do the shapes with CAD, then cut plugs with the mill and use them to form concrete moulds. Maybe not that hard after all assuming you can get real geometry off the drawings.

It would be interesting to see how many 1:1 Albatros kits could be sold with all ribs cut, all bulkheads and the engine mounts, the spars and tail-feather pieces AND the formed skins. Not exactly a shake and bake, but certainly with a lot of the really vexing part of the work out of the way. Not to forget that the last 15% of any project takes half the time.

Jeff, thanks for sharing this.

[John McKenzie]

JF ....Probable answer is None ! .

You still have to make the jigs to hold the fuselage in correct positions for every operation of fitting Top Bottom & 2 sides etc.etc....in order to complete it as not distorted with empennage also correct alignment .

All longerons must have filler pieces added & shaped with the bulkheads also to have the correct bevel .....Some places at rear are double ply skin .

Fuselage nose shape is not a smooth continuous curve into the rear shape , as if the cockpit hole does not exist ...this is (only) one area of fantasy of so many people who make incorrect drawings & "corrections".....Too many assumptions made ,...and not only for this Albatros !

Just to say that these Alb' tail end panels are steam pre-formed in moulds similar to as Jeff did sugest .
Similar steamed panels is found here also for this place on SSW DIII/IV and some others .

Some other machines may use the method of 2 layers of strip ply Cold-Moulded , for some areas as in boat work .( and of course for whole fuselage as eg earlier Roland & the Pfalz 's )

All this original shape , curves & dimensions for the final correct shape is made on the prototype formers , by skilled "hand & eye" craftsmen with the designer with use of wood laths etc.....The whole is then completed by drawing/lofting to allow construct of all identical , required number of production jigs / tools etc.

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[William]

http://www.westsystem.com/ss/assets/...k%20061205.pdf

Worth reviewing these fellows experiences laying up hulls and a variety of other structures using veneers and West system epoxy. It would be work but perhaps not as massive an undertaking as is first imagined. I suspect that many of the original manufacturers workforce had experience from boat and carriage building.

[j ferguson]

John McKenzie, It wasn't clear to me how skins were made for Albatros. Did they press plywood in the forms described elsewhere - maybe with steam or did they build up the laminations in the forms like a Pfaltz was done except panels instead of fuselage halves. Maybe the answer is in Koloman's threads.