Pietenpol-List: 4th of July
Posted: Fri Jul 04, 2014 12:50 pm
Original Posted By: Robert Bush
nBill,Those are some very clear and useful drawings, a good reference point, and I wouldbe very interested to read about what the incidence of any flying Ribblettairfoiled plane is. 4.1 degrees on that airfoil is a lot. People miss how many kits use Ribblett airfoils,even things like Zenith 601XLs. I am pretty sure the same airfoil usedon the Piet is also on modern Kitfoxes, and they don't have anywhere near thatkind of incidence, even when you factor in the speed and wing loading difference.With 6% camber, this airfoil will still produce lift even if the incidence is loweredto 0 degrees. If the plane is trying to fly with the fuselage angled down3 or 4 degrees in flight, the often forgotten part on trimming is that it isalso adding this to the down thrust of the engine and subtracting it from theincidence of the stabilizer.Was anyone else at Brodhead about 10 years ago when a plane flew in that had thecabanes reversed? I recall a plane flying around the pattern with the nose about4 degrees up. I have seen some rigging errors before, but that one standsout in my memory, and I have no explanation why the builder might have thoughtit was OK. -ww.Read this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: 4th of July
nBill,Those are some very clear and useful drawings, a good reference point, and I wouldbe very interested to read about what the incidence of any flying Ribblettairfoiled plane is. 4.1 degrees on that airfoil is a lot. People miss how many kits use Ribblett airfoils,even things like Zenith 601XLs. I am pretty sure the same airfoil usedon the Piet is also on modern Kitfoxes, and they don't have anywhere near thatkind of incidence, even when you factor in the speed and wing loading difference.With 6% camber, this airfoil will still produce lift even if the incidence is loweredto 0 degrees. If the plane is trying to fly with the fuselage angled down3 or 4 degrees in flight, the often forgotten part on trimming is that it isalso adding this to the down thrust of the engine and subtracting it from theincidence of the stabilizer.Was anyone else at Brodhead about 10 years ago when a plane flew in that had thecabanes reversed? I recall a plane flying around the pattern with the nose about4 degrees up. I have seen some rigging errors before, but that one standsout in my memory, and I have no explanation why the builder might have thoughtit was OK. -ww.Read this topic online here:http://forums.matronics.com/viewtopic.p ... ___Subject: Pietenpol-List: 4th of July