Brodhead Pietenpol Association

Original Posted By: Kenneth Bickers
Subject: Pietenpol-List: Routed Spar weight

Original Posted By: mike Hardaway
I understand the need for jury struts, but was just wondering.Do wood strutshave the same vibration problem that metal struts do?Gary Boothe Cool, Ca. Pietenpol WW Corvair Conversion, Running! Tail done, Fuselage on gear, RIBS DONE!________________________________________________________________________________Date: Sat, 19 Feb 2011 17:21:10 -0800Subject: Re: Pietenpol-List: Harmonic Vibrations

Original Posted By: owner-pietenpol-list-server(at)matronics.com
Kenneth, thanks for the detailed report on this. It agrees pretty well withmy calculations on weight savings. I used =BE=94 spars without bevelled topsand routed the rear spars only, using a bullnosed router bit as youdescribed. By my calculations I saved 3.89 lbs by routing the rear sparsfrom =BE=94 down to =BD=94 in the middle. Obviously, using 1=94 spars you saved evenmore.This is the kind of good hard data that is useful to refute arguments.Jack PhillipsNX899JP =93Icarus Plummet=94Raleigh, NC _____

Original Posted By: owner-pietenpol-list-server(at)matronics.com
Yes. The only real advantage wood has over metal is that wood is notsubject to fatigue as metal is. But if you put the jury struts right in thecenter of the lift struts you can still set up devastating harmonicvibrations, where if you move the support point a few inches either way itdoes not allow such harmonics to develop.Jack PhillipsNX899JP "Icarus Plummet"Raleigh, NC _____

Original Posted By: Kenneth Bickers
Subject: Re: Pietenpol-List: Routed Spar weight

Original Posted By: Jim Boyer