Comparative Analysis of the Vibrational Response of Different Main Rotor Blades of a Homemade Helicopter [1]

This paper investigates	 the dynamics of homemade helicopter wooden and aluminum	sheet	rotor	blades.	The	rotors	are articulated	and	their	blades	are	rigid. The	 main rotor	 implementation	 takes	into account flap, lag, and feather degrees of	 freedom for each of the equispaced blades as well as	their dynamic couplings. Transmitted vibrations due to the rotating	rotor	blades	on	the	body structure	(fuselage)	are	 studied. This work	presents an	aerodynamic	model of main rotor	blades	that allows	 us to analyse vibrational transmissions on	 the fuselage (body) of	 the craft. Vibrations	 in	 helicopters are a common problem which involves complex interactions between the inertial, structural and aerodynamic	loads, especially in homemade helicopters. The major source of	 vibrations	 in	helicopters	is	the	main rotor.	The	efficiency	and	stability of the main rotor blades	is	determined	by	the	magnitudes	of	the	predominant	frequencies	they produce. These	vibrations	 affect	 the functionality, durability of the engine component	 parts,	increase maintenance frequency	(cost),	and	cause structural failures.	The	aerodynamic model has been built up	 using blade element theory. The aerodynamic load	 creates vibrations	 on	 the homemade helicopter and	 these are analyzed	on	the	fuselage by	using a	short time Fourier	transform that brings out the vibrational	spectrum. The results	 of	 the analysis serve	 as	 a reference to	characterize the stability	and	efficiency	of homemade main rotor blade profiles.