2 - 3 DoF Ground Resonance Derivation

Br. Marius
Administrator

Posts: 126

2 - 3 DoF Ground Resonance Derivation Apr 28, 2015 18:53:00 GMT

Quote

Post by Br. Marius on Apr 28, 2015 18:53:00 GMT

Derive the ground resonance equations for a three-degree of freedom system: Cyclic lag (ζ_lc, ζ_ls) and pitch motion (α_y).
\(\newcommand{\dd}{\; \mathrm{d}}
\newcommand{\sstar}{\;\star\star}
\newcommand{\Star}[1]{\stackrel{\star}{#1}}
\newcommand{\SStar}[1]{\stackrel{\sstar}{#1}}
\newcommand{\ihat}{\boldsymbol{\;\hat{\imath}}}
\newcommand{\jhat}{\boldsymbol{\;\hat{\jmath}}}
\newcommand{\khat}{\boldsymbol{\;\hat{k}}}\)

Last Edit: Apr 29, 2015 1:13:24 GMT by Br. Marius

Br. Marius Administrator Posts: 126	2 - 3 DoF Ground Resonance Derivation May 3, 2015 17:31:47 GMT Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by Br. Marius on May 3, 2015 17:31:47 GMT This is what I got, though I left the rotor moment in terms in F_z because the case is so general. Attachments: HW11 P2.pdf (203.66 KB)

trdodge New Member Posts: 6	2 - 3 DoF Ground Resonance Derivation May 3, 2015 23:24:57 GMT Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by trdodge on May 3, 2015 23:24:57 GMT What you have makes sense, I think though that S*_zeta is unitless already and doesn't need to be normalized. I could be mistaken though.

Br. Marius Administrator Posts: 126	2 - 3 DoF Ground Resonance Derivation May 4, 2015 19:13:41 GMT Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by Br. Marius on May 4, 2015 19:13:41 GMT Just realized that the pitch forcing term should have a cosine attached to it...it's not just the individual blade moments, but it needs to be the blade moments in the pitch direction.

matthorr Administrator Posts: 87	2 - 3 DoF Ground Resonance Derivation May 4, 2015 22:30:05 GMT Quote Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by matthorr on May 4, 2015 22:30:05 GMT ENAE-633-HW11.pdf (124.93 KB)I've attached what I got. A bit different - I followed 6.3.5 from the notes but assumed that flapping (other than \(\beta_0\)) was zero.

ENAE633 (et al) Forum

2 - 3 DoF Ground Resonance Derivation

Post by Br. Marius on Apr 28, 2015 18:53:00 GMT

Post by Br. Marius on May 3, 2015 17:31:47 GMT

Post by trdodge on May 3, 2015 23:24:57 GMT

Post by Br. Marius on May 4, 2015 19:13:41 GMT

Post by matthorr on May 4, 2015 22:30:05 GMT

Quick Reply