Brodhead Pietenpol Association

Original Posted By: Steven Dortch
Subject: Pietenpol-List: fluid dynamics of drag

Original Posted By:> owner-pietenpol-list-server(at)matronics.com [mailto:owner-pietenpol-li
I'm not sure that a streamlined tube on a 45 is any better than a round tube....although I'm sure one of you engineers will prove me wrong...GeneOn Jul 9, 2014, at 9:50 AM, "Jack Phillips" wrote:> Mike,> > In the interest of improving the =9Ccrash-worthiness=9D of my Pietenpol, I=99ve decided this winter to replace the cabane diagonals on mine, per William Wynne=99s suggestions after his experience. While my diagonal struts are plenty beefy, and the attach points to the front cabane struts are good and solid (see photos below),> > > > > > the weak point in the system is the turnbuckle fork that I used to allow for easy adjustment of the wing. In the event of a crash, any forward movement of the wing will likely buckle the turnbuckle fork shaft. I will remake the struts with the streamline tubing going all the way to the attach point, now that I have the wing where I want it.> > > > Wing movement in a crash is not much of a concern with a nose mounted tank (of course, having a tank full of fuel in your front passenger=99s lap might be something to worry about). But with a centersection tank like I have, it won=99t take much motion to rupture a fuel line and cause a fire.> > Another point to consider is that using streamline tubing produces much less drag than round tubing (there is almost no worse shape moving through the air than a round tube), but the round tube is much cheaper. Trying to reduce drag on a Pietenpol is pretty much a losing proposition.> > Anyway, this is a good discussion to have for those who are in the building process and making decisions on how to brace their wing structure.> > Jack Phillips> NX899JP> Smith Mountain Lake, Virginia>