NACA issues initial report on the analysis of ground resonance

Description

Ground resonance is an interaction between the rotor and the airfame, when on the ground, that can lead to catastrophic failure.

R.P. Coleman of NACA documented the early analysis that would lead to an understanding of ground resonance for rotorcraft.

The reference is provided below,

Coleman, R. P.: Theory of Self-Excited Mechanical Oscillations of Hinged Rotor Blades. NACA ARR 3G29, July 1943

(Note: Only the month and year of the report are valid)

It should be noted that there is evidence to suggest that the fundamental understanding of ground resonance had already been developed by the german mathematician Gigling who was working under Heinrich Focke (see " Gottinger Monograph N: A Historic Document is Back", Berend van der Wall, DLR, paper presented at AHS Forum 72, West Palm Beach, FL, May 2016, Page 16).

Source: "Milestones in Rotorcraft Aeromechanics", Johnson W., NASA/TP-2011-25971, May 2011, Page 10