John:
The Taz is a very funny little "Qualifier" heli-roc.
Sanding Airfoils on rotors and Glider wings is one of those skills that takes a little time to develop.
As Mark said layout the high point of your airfoil and always sand with a sanding block, the longer the better really. The High Line should be about 1/4 to 1/3 of the rotor or wing width.
To that end I generally us a 12" or 18" block to "T" bar depending on the length of the Rotor or wing.
I've also found one of the most important tools as a solid sanding surface. I use an 12" x 24" piece of 3/4" Plate glass as a dead flat surface the doesn't move easily and doesn't flex at all
To keep the rotor or wing in place while sanding I use a strip of Double faced masking tape that has been somewhat de-tac'ed to hold firmly but will release the sanded piece with the help of a Plastic pallet knife.
Align the edge of the rotor with the front edge of the glass. Sand the leading edge first then pop the rotor up with the pallet knife and reverse on the glass to sand the tailing edge leaving the line almost intact. this can then be eased with fine grit paper after the piece has been removed for the tape. another thing is to sand in one direction only, keeping constant pressure on the block. this will take a little time to perfect but once you've sanded a couple rotors you'll get the hang of it
Tasmanian devil isn't a great performer no matter how well built or what scale, I have a 13mm model and two different micro models that get nearly identical flight times on 13mm A's and Micro motors! it's amazing!!! Funny as all gee-wiz also LOL