Original Posted By: "John Dilatush"
Is anyone running any washout in their wings? If so how much?DJ VeghN74DVMesa, AZwww.imagedv.com/aircamper________________________________________________________________________________
Pietenpol-List: Washout??
Re: Pietenpol-List: Washout??
Original Posted By: "DJ Vegh"
DJ,Here is a response I got from Chuck G. to the same question last year. Isaved it in my goodstuff folder.Bob B. - MissouriIn a message dated 9/6/03 8:40:23 AM Central Daylight Time, baileys(at)ktis.netwrites:>Bob,Washout is a twist in the wing, where the leading edge of the outboardportion of the wing is twisted to a lower angle of incidence than theinboardportion, causing the inboard portion to reach it's Critical Angle of Attackbeforethe outboard portion. Angle of incidence is the angle between the MeanAerodynamic 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 theangleof incidence is set with the difference in length of the cabane struts - thefront ones are 1" longer than the back ones, making about a 3 angle ofpositive incidence. The purpose of washout is to ensure the inboardportion of thewing is location where the stall begins, leaving the outboard aileronportionto be the last part of the wing to stall, thus maintaining aileron controluntil the entire wing is stalled.Now comes the kicker: On a hearshey bar wing - constant chord, straightwing-, the stall naturally occurs at the inboard portion of the wing, thereforewashout is not really required. Just rig the entire wing at the same angleofincidence as the inboard portion, where the cabane struts are, by the lengthof the lift struts. Although, it could be recomended to err the tips towardalower angle of incidence. The wing twists easily, till the lift struts &cables are installed. On wings where the leading edge is swept, or thetrailingedge is swept forward (tapered wings), or the entire wing is swept (like onjets) is where washout really is needed, because sweeping the wing backcausesthe tips to stall first.Chuck G.----- Original Message -----
DJ,Here is a response I got from Chuck G. to the same question last year. Isaved it in my goodstuff folder.Bob B. - MissouriIn a message dated 9/6/03 8:40:23 AM Central Daylight Time, baileys(at)ktis.netwrites:>Bob,Washout is a twist in the wing, where the leading edge of the outboardportion of the wing is twisted to a lower angle of incidence than theinboardportion, causing the inboard portion to reach it's Critical Angle of Attackbeforethe outboard portion. Angle of incidence is the angle between the MeanAerodynamic 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 theangleof incidence is set with the difference in length of the cabane struts - thefront ones are 1" longer than the back ones, making about a 3 angle ofpositive incidence. The purpose of washout is to ensure the inboardportion of thewing is location where the stall begins, leaving the outboard aileronportionto be the last part of the wing to stall, thus maintaining aileron controluntil the entire wing is stalled.Now comes the kicker: On a hearshey bar wing - constant chord, straightwing-, the stall naturally occurs at the inboard portion of the wing, thereforewashout is not really required. Just rig the entire wing at the same angleofincidence as the inboard portion, where the cabane struts are, by the lengthof the lift struts. Although, it could be recomended to err the tips towardalower angle of incidence. The wing twists easily, till the lift struts &cables are installed. On wings where the leading edge is swept, or thetrailingedge is swept forward (tapered wings), or the entire wing is swept (like onjets) is where washout really is needed, because sweeping the wing backcausesthe tips to stall first.Chuck G.----- Original Message -----