Original Posted By: Clif Dawson
Thank You for Your Report (Community Watch)
Re: Re: Pietenpol-List: long cross country in an Air Camper
Original Posted By:> "Christian Bobka"
Well said, Chris.I owned a J-3 Cub for many years, and even though it is nearly as light as a Piet,its trim was very necessary. Elevator pressures on a Cub, with its USA35Bairfoil (nearly as much camber as a Piet) got uncomfortably high gliding at 50mph, if the trim was set for its 75 mph cruise.I have installed a trim system on my Pietenpol very similar to the one that MikeCuy installed on his. Neat, internal (no visible trim tabs), lightweight, andesily adjusted.Jack Phillips>
Well said, Chris.I owned a J-3 Cub for many years, and even though it is nearly as light as a Piet,its trim was very necessary. Elevator pressures on a Cub, with its USA35Bairfoil (nearly as much camber as a Piet) got uncomfortably high gliding at 50mph, if the trim was set for its 75 mph cruise.I have installed a trim system on my Pietenpol very similar to the one that MikeCuy installed on his. Neat, internal (no visible trim tabs), lightweight, andesily adjusted.Jack Phillips>
> Re: Pietenpol-List: long cross country in an Air Camper
Original Posted By:> "DJ Vegh"
> To: > Subject: Re: Pietenpol-List: long cross country in an Air Camper> > > With the exception of the rare use of a 100% symetrical airfoil (like on a> late pitts), every airplane will only be in trim at one airspeed for its CG> position. The 100% symetrical airfoil has no camber, hence no center of> pressure (CP) travel with changes in angle of attack (which is determined> directly by airspeed). As you add more and more camber, the fore and aft> center of pressure travel on the wing between high and low AOAs gets greater> and greater.> > The Taylorcraft uses the NACA 23012 airfoil and does not have as much CP> travel as does the Piet's airfoil which has a tremendous amount of camber.> An added trim system would make the aircraft more pilot friendly throughout> a large airspeed (AOA) range.> > However, as the first paragraph says, every airplane will only be in trim at> one airspeed for its CG position. If you plan to fly your piet at the same> CG location and at the same speed day in and day out, then the rigging of> the decalage angle between the wing and the horizontal stabilizer will take> care of the trim. You set these angles at time of rigging, tweaking them> throughout the testing period until you are satisfied the plane can fly> hands off at your favorite power setting and AOA.> > But if you plan to fly the aircraft long hours at many different, wide> ranging CGs, then a trim system is in order.> > There is nothing worse than a long flight in an airplane that you can't> trim.> > I believe that Mike C. has a simple bungie arrangement to give the stick a> little pull one way or another. This is used in many aircraft types and is> sufficient.> > Chris Bobka> > > ----- Original Message -----
> To: > Subject: Re: Pietenpol-List: long cross country in an Air Camper> > > With the exception of the rare use of a 100% symetrical airfoil (like on a> late pitts), every airplane will only be in trim at one airspeed for its CG> position. The 100% symetrical airfoil has no camber, hence no center of> pressure (CP) travel with changes in angle of attack (which is determined> directly by airspeed). As you add more and more camber, the fore and aft> center of pressure travel on the wing between high and low AOAs gets greater> and greater.> > The Taylorcraft uses the NACA 23012 airfoil and does not have as much CP> travel as does the Piet's airfoil which has a tremendous amount of camber.> An added trim system would make the aircraft more pilot friendly throughout> a large airspeed (AOA) range.> > However, as the first paragraph says, every airplane will only be in trim at> one airspeed for its CG position. If you plan to fly your piet at the same> CG location and at the same speed day in and day out, then the rigging of> the decalage angle between the wing and the horizontal stabilizer will take> care of the trim. You set these angles at time of rigging, tweaking them> throughout the testing period until you are satisfied the plane can fly> hands off at your favorite power setting and AOA.> > But if you plan to fly the aircraft long hours at many different, wide> ranging CGs, then a trim system is in order.> > There is nothing worse than a long flight in an airplane that you can't> trim.> > I believe that Mike C. has a simple bungie arrangement to give the stick a> little pull one way or another. This is used in many aircraft types and is> sufficient.> > Chris Bobka> > > ----- Original Message -----