I didn't see Rhubarb Twist on Terry Atkinson's page! But I did find two similar blocks. Could it be Wheels or Whirligig?
Wheels is from 1976 (Progressive Farmer), and it looks like yours except that compared to it, yours is on point. It's in Barbara Brackman's
Encyclopedia of Pieced Quilt Patterns (#1278) and Maggie Malone's
5,500 Quilt Block Designs (p. 167).
Whirligig (from 1931) is more complicated because its triangles are in three pieces, but I can't really tell where all your seams are. That one's in Jinny Beyer's
Quilter's Album of Patchwork Patterns.
Whirligig instructions are on Marcia Hohn's Quilter's Cache, God bless her, although the colors aren't arranged like yours:
http://www.quilterscache.com/W/WhirligigBlock.html
Anyhoo, I'm sure you'll have fun with it, 'cuz it's a really pretty block.