Gravity Shielding:
There isn't much data online for research but the following is true:
In the 1920s, Italian physicist Quirino Majorana measured a decrease in gravity inside spherical shell containing mercury that had been subjected to electric current.
The ratio of input energy to weight loss was found to be impractically large to be able to develop any useable antigravity mechanism.
But even if it didn't result in flying cars today, imagine what this would do for Aeronef science.
Anyone else got an idea for unusual engines?