An idea
In your now closed thread
Back door approach for VTOL design you were considering the possibility of an ultralight fixed wing VTOL. You have also considered the possibility of electric flight.
Here is an idea, or to be more exact, modifications to the previous submitted idea on post #2 of the above thread, in which the suggestion was made to use pre-stored compressed air as the means of assisting the engine during a vertical take off.
The modifications consists of 2 parts;
1/ Replace the proposed gas engine with electric motors. Electric motors are now very light and they are capable of providing 2 to 3 times their rated power for a short period of time. The time of additional power is only limited by the fast increase in the motor's temperature.
2/ Release some of the compressed air through the coils of the motors. This expanding air should have a significant effect in pre-cooling and during-takeoff-cooling of the motors.
Here is a motor for consideration. 20 hp out of a 4.2 lb motor!
Plettenberg ~ Predator 37
Just an idea to provoke thought.
Dave
PS.
This side-by-side electric rotorcraft is a somewhat similar idea that is currently being 'fleshed out'. This craft would be extremely risky but it might provide man's first flight in an electric helicopter.