Ethanol
Generally regarded as low toxicity compared to methanol, while still retaining adequate catalytic reactivity with platinum glow plugs. These desirable attributes make ethanol a potential replacement fuel for methanol glow engines. It also has higher energy density than methanol, leading to a longer flight time.
An attempt was made to power a Hirobo SDX 50 on denatured ethanol (5% methanol). In this youtube video the SDX 50 can be seen performing a brief hovering followed by a full collective climb.
Isopropanol
Isopropanol generally does not perform well with glow engines because of its limited reactivity with platinum in standard glow plugs. However, it has low toxicity, and an energy density of about 77% of that of gasoline. Our study suggested that it is a viable fuel for spark-ignition engines particularly in applications requiring long endurance.
This youtube video shows a demonstration in which a 3-cylinder four-stroke engine running predictably on isopropanol.