twisted rail fence with double helix fabric
 

I'm needing help with direction of helix placement. Should I keep the helix aligned so that it is always running vertically or make half running horizontally?

Does this quilting pattern seem to be suitable for the design of the double helix fabric or would you have another suggestion for a beginner?

Also for a 70 X 70" quilt, how much yardage of each of the four fabrics would be needed if the twisted rail fence is the selected pattern?

here's a tut i found. seems pretty easy to follow. it states to place the 'eye' in the same position on all.
http://exuberantcolor.blogspot.com/2...-tutorial.html
HTH

I love the pattern made with only 4 fabrics. It's downright stunning.

I am not a beginner and would hesitate to use any directional fabric with this particular pattern. It's going to require that you figure out how you are going to place the blocks before you even sew them. I would just go ahead and substitute another fabric. As for how many yardage. This is how I calculate it...others may do it differently.

finished size 70" x 70" = 4,900 square inches
one yard 36" x 40" = 1,440 square inches
divide sq yd into finished inches 4900/1440 = 3
Because you are going to lose some to seams, I would buy about 1 yard of each fabric. I don't think this would allow enough for the binding, but am not sure.

I am so glad you asked about this pattern. For the guild I belong to, our challenge this year is Black & White and red all over. There can be other colors added to. This is going to be the one I make.

How will the quilt be used? If it's a wall hanging, then I would make the helixes all run the same way. If it's going to be used, like a throw etc, then letting them run in both directions will make it so there's no right side up. Which ever edge you grab, half the pattern will be right!
Barb in Louisiana's calculations are correct, however, the assumption in the calculations is that you are going to use the entire piece of fabric.
To provide a good estimate, we need to know how wide you are going to cut your strips. I don't know if the tutorial link provided by QuiltnNan is the one you are going to use, but if you cut 3" strips, then your strata is going to measure 10", and so you would cut 10" squares. The width of fabric is normally assumed to be 40", so you will get 4 squares with no waste.
If you cut your strips 3.5", your squares will be cut at 12", you will only get 3 squares per strata and lose 4".

I love this quilt! I've never seen it before, but wow that twisting is wonderful! Thanks for sharing.

And Barb in Louisiana and Paper Princess you guys are amazing with your calculations. I'm no mathematician but when I get ready to make this there will be no way I'll remember how to find this thread so if I plan to do this I would have to get into my stash and do it super scrappy. Do you think the twist would be lost if so?

I was thinking scrappy, too, but changed my mind. The pattern was specific to use colors light to dark and scrappy might be difficult to pull off.

Very cleaver way to calculate; I never thought of it that way. Good luck with your challenge quilt!