SimplePlanes doesn't have battery powered engines, so I made my own using Funky Trees.

The controls are pretty easy, and a large display in the cockpit makes learning how to operate this helicopter straightforward. As power is drained, the battery percentage will drop, turn on the generator to regain power. With just the props on, the generator will almost perfectly match the draining, however the booster engines draw more power, so throttle back to 48% to maintain even charge. If the battery runs out completely, all engines will shut off.

Use caution on landings, because if the throttle is below 5%, the heli blades risk breaking. So to land, keep the throttle above 5% and use the VTOL slider to adjust vertical speed. Once landed, the throttle can go down to 0%.

AG1: Generator
AG2: Boosters
AG3: Canopy
AG8: Gyroscope

Feel free to make changes, this is just a concept aircraft to demonstrate "electric" engines.