(second in the 'chuck' series of 5 ).
The 'chuck' series consists of : Babychuck (6pcs), Woodchuck (24 pcs), Papachuck (54pcs), Grandpapachuck (96 pcs), and GreatGrandpapachuck (150 pcs)
As Pentangle puts it, "The Chuck Series could be described as a family of puzzles which vary both in size and degrees of difficulty. Based on a design by Ron Cook they are the 'original' Pentangle puzzles"
( "A second cousin to the woodchuck 'series' and one step up from the Squirrel Cage" ) . . . . . 38 pieces
Also known as Poison on Bits & Pieces online catalog; although similar-looking from the outside, I'm not sure if the internal structure -- or pieces -- are the same . The solution for Lunatic can be viewed here .
A high-quality coordinate-motion puzzle .
. . . partially opened