What day of the week was May 24, 1940?

The day of the week May 24th, 1940 fell on was a Friday.

Igor Sikorsky performs the first successful single- rotor helicopter flight. Acting on the orders of Soviet leader Joseph Stalin the NKVD agent Iosif Grigulevich orchestrates an unsuccessful assassination attempt on exiled Russian revolutionary Leon Trotsky in Coyoacán, Mexico.