My iPad kneeboard is hinged at the bottom with a folding spacer allowing it to tilt up about 30 degrees for better viewing. Ram slider-mount, though even a couple Velcro pads work ok. Secured to my leg with a simple wide elastic strap with Velcro on the ends.
Like to rest my cyclic arm on my thigh though, so prefer the mounted powered versions like you see from progressive helicopter manufacturers replacing the old approach plate holders.