Bob,
I started building a Pitts and can verify that Betty Skelton's L'il Stinker had a M-6 airfoil. The airfoil was not symmetrical. That airplane also had ailerons on the lower wing only. Betty's Pitts was powered by a Lycoming 65 (Continental?). By the 1960's people were using 180HP and then 200HP Lycomings.
In the 60's the symmetrical airfoil Pitts came using 4 ailerons. The M-6 airfoil versions was flown by many including Mary Gaffney, Bob Herendeen, and Don Pittman. I flew a Breezy to the 1969 EAA fly-in in Rockford IL. (The last one in Rockford). Gene Soucy and his father had 3 airplanes. One older version Pitts (N8J) with the M-6 airfoil, a newer version Pitts (N9J) with the symetrical 4 aileron wings, and a Senior Aero Sport. (N89J) 2 place version of the PJ260, painted like the two Pitts Specials.
The famous "Red Devils" flew for the 1st time with a quickly made up routine, and were introduced as the "Red Angels". Bob Heuer and Gene Soucy flew the red Pitts and Marion Cole flew Mary Gaffney's Yellow and Black Pitts. Before the end of their flight they were renamed the "Red Angels".
The "Red Angels" evolved into the team of Gene Soucy, Tom Poberezny, and Charlie Hilliard. They later flew the Christen Eagles.
Doc,
The nonsymetrical airfoils were in many airshow airplanes, including Stearmans, Wacos, PJ 260's. Cap 10s and on and on. Inverted flight required a larger angle of attack.
Bill Byles can add much more on the flight characteristics, since he flew air shows for many years.
Hi Tom,
Curtis Pitts designed the first Pitts Special (the S-1) in 1944 using an M6 airfoil, which is very close to being a reflexed Clark Y airfoil. The Clark Y is often called a "flat-bottom" airfoil, however it is only flat from about 30% aft of the leading edge. The M6 airfoil is cambered on the bottom surface for about the last 35% to the trailing edge as well as being cambered on the bottom from the leading edge aft for about 30%. It performs pretty well in negative "G" maneuvers for a non-symmetrical airfoil. In inverted flight it does fly at a higher angle of attack than a fully symmetrical airfoil.
The second Pitts Special Curtis built was also an S-1 with an 85 hp fuel-injected Continental engine, and that airplane was the one ultimately bought by Betty Skelton and the one in which she won the 1948, 1949, & 1950 U.S. Female aerobatic championship.
The S-1C is an evolution of the S-1 with ailerons on the lower wings only and having an M6 airfoil, being designed for more horsepower (from 100 to 180 hp) and was the original amateur-built version.
The S-1D, also an amateur-built version, is a further evolution of the S-1C, and began using symmetrical airfoils although some continued to use the M6. This version has four ailerons. Plans were made available for this version in the early sixties.
(Skipping a couple of versions here.)
The S-1S is the factory-built version with symmetrical airfoils, four ailerons and spades, and has the Lycoming AEIO-360-B4A aerobatic engine. I have quite a bit of time in this version and it is really fun to fly. Factory production of this version was begun in the early 1970s (the one I flew was a 1974 model.)
The S-1T is also a factory-built airplane with an AEIO-360-A1E aerobatic engine and had some airframe reconfiguration to accommodate the additional weight of the bigger engine. It has a fully symmetrical airfoil with four ailerons and spades on the lower ailerons to assist with stick force reduction in the roll mode.
Beginning in the late sixties a two-seat Pitts was produced and became the S-2 and subsequent versions of the two-seat design. It has a slightly larger airframe than the previous single-seat Pitts and was produced with both a 200 hp Lycoming four-cylinder engine and a 260 hp six-cylinder, 540 cubic inch engine. Of the Pitts I have flown the Pitts S-2B with fully symmetrical airfoil, four ailerons with spades, and the AEIO-540 using a composite three-blade propeller is my personal favorite. You can take a passenger in this one & it has great performance in both the climb and roll rate capability.
The early S-1's with two ailerons and M6 airfoil are great fun and are capable of doing pretty much all of the IAC schedule maneuvers. However, the
S-1S, S-1T, & S-2B with the big engines, fully symmetrical airfoils, and four ailerons with spades do it all easier & better.
While Pitts was far from the first to use fully symmetrical airfoils he did begin using them in the early sixties with good success.
Topic: Airfoils (Read 20091 times)