Original Posted By: "Gene Rambo"
I haven't started construction so I'm spending a lot of armchair time withthe plans.My question is; what is the correct amount of washout and how do youestablish it? Is it done when the putting the ribs on the spars or whilemating the wings to the fuselage? Also what serves as a reference point?Bob B. - Missouri________________________________________________________________________________
Pietenpol-List: Wing washout
Re: Pietenpol-List: Wing washout
Original Posted By: "baileys"
I'm not sure the Piet starts out with washout. If it needs any, though, youadjust the strut lengths to give it any washout necessary. Believe me, thewing is flexible enough to accomodate any twist you need without making anyalterations to the ribs themselves.Gene----- Original Message -----
I'm not sure the Piet starts out with washout. If it needs any, though, youadjust the strut lengths to give it any washout necessary. Believe me, thewing is flexible enough to accomodate any twist you need without making anyalterations to the ribs themselves.Gene----- Original Message -----
Re: Pietenpol-List: Wing washout
Original Posted By: Rcaprd(at)aol.com
Subject: Re: Pietenpol-List: Wing washoutIn a message dated 9/6/03 8:40:23 AM Central Daylight Time, baileys(at)ktis.net writes:>Bob,Washout is a twist in the wing, where the leading edge of the outboard portion of the wing is twisted to a lower angle of incidence than the inboard portion, causing the inboard portion to reach it's Critical Angle of Attack beforethe outboard portion. Angle of incidence is the angle between the Mean Aerodynamic Chord (MAC) of the wing, and the longitude 0 of the fuselage - on thePiet it's the top of the longerons at the cockpits. On the Pietenpol the angleof incidence is set with the difference in length of the cabane struts - the front ones are 1" longer than the back ones, making about a 3 angle of positive incidence. The purpose of washout is to ensure the inboard portion ofthe wing is location where the stall begins, leaving the outboard aileron portion to be the last part of the wing to stall, thus maintaining aileron control until the entire wing is stalled.Now comes the kicker: On a hearshey bar wing - constant chord, straight wing -, the stall naturally occurs at the inboard portion of the wing, therefore washout is not really required. Just rig the entire wing at the same angle ofincidence as the inboard portion, where the cabane struts are, by the length of the lift struts. Although, it could be recomended to err the tips toward alower angle of incidence. The wing twists easily, till the lift struts & cables are installed. On wings where the leading edge is swept, or the trailingedge is swept forward (tapered wings), or the entire wing is swept (like on jets) is where washout really is needed, because sweeping the wing back causesthe tips to stall first.Chuck G.________________________________________________________________________________
Subject: Re: Pietenpol-List: Wing washoutIn a message dated 9/6/03 8:40:23 AM Central Daylight Time, baileys(at)ktis.net writes:>Bob,Washout is a twist in the wing, where the leading edge of the outboard portion of the wing is twisted to a lower angle of incidence than the inboard portion, causing the inboard portion to reach it's Critical Angle of Attack beforethe outboard portion. Angle of incidence is the angle between the Mean Aerodynamic Chord (MAC) of the wing, and the longitude 0 of the fuselage - on thePiet it's the top of the longerons at the cockpits. On the Pietenpol the angleof incidence is set with the difference in length of the cabane struts - the front ones are 1" longer than the back ones, making about a 3 angle of positive incidence. The purpose of washout is to ensure the inboard portion ofthe wing is location where the stall begins, leaving the outboard aileron portion to be the last part of the wing to stall, thus maintaining aileron control until the entire wing is stalled.Now comes the kicker: On a hearshey bar wing - constant chord, straight wing -, the stall naturally occurs at the inboard portion of the wing, therefore washout is not really required. Just rig the entire wing at the same angle ofincidence as the inboard portion, where the cabane struts are, by the length of the lift struts. Although, it could be recomended to err the tips toward alower angle of incidence. The wing twists easily, till the lift struts & cables are installed. On wings where the leading edge is swept, or the trailingedge is swept forward (tapered wings), or the entire wing is swept (like on jets) is where washout really is needed, because sweeping the wing back causesthe tips to stall first.Chuck G.________________________________________________________________________________