Came across another great article .... here is a snip ...
John Miller was the first individual to purchase a Pitcairn PCA-2 autogiro, Serial No. 13, in 1931. That number had been offered to but turned down by Amelia Earhart. Two years later, Earhart received national recognition for making a transcontinental flight in an autogiro–although Miller had accomplished the same feat two weeks earlier. I made it out and back, he mused after the flight. She crashed it on the way out, then totaled it on the way back!
Miller honed his autogiro flying skills while performing incredible feats–such as loops and rolls–at airshows across the country, including the National Air Races in Los Angeles and the International Air Races in Chicago in 1933.
I was the only one who ever did loops and rolls at airshows [with an autogiro], Miller declared. Other pilots thought I was crazy. But I wasn’t crazy–I was an engineer! A 1927 graduate of Pratt Institute in New York City, Miller knew the autogiro could withstand the maneuvers, and he meant to prove to everyone that it was a safe aircraft.
John also said (in article printed, or re-printed, in the PRA magazine) that he would only do inverted maneuvers in a winged autogyro with aerodynamic controls, such as his PCA-2.
He was, indeed, a degreed engineer. He recognized that ailerons and elevators work normally, regardless of pos G, zero G or neg G.
Otoh, direct cyclic controls, with a teeter hinge, lose their power to rotate the airframe at low G. They reverse at neg G.
The loss of control power with our "modern" controls is tolerable for short durations, as long as the airframe has no other moments or forces trying to rotate it (draggy undercarriage, body pod, uncorrected prop torque, high thrustline, etc.). Things go to hell very fast if such moments exist and you do a low G maneuver in a direct-control-with-teeter hinge gyro.
No such trip to hell occurs in the type of gyro that John flew (and looped).
The early Autogyros with conventional "airplane control surfaces" were still airplanes, and had to be flow as such to maintain three-axis control. All the main rotor did was prevent the aircraft from stalling.
Gyros with ailerons and elevators still control their rotors by cyclic pitch. You tilt the whole airframe (bringing the spindle with it) instead of tilting only the spindle, or using a swashplate, as we do now. Tilting the frame sends a cyclic pitch change to the rotor (via the spindle and flap hinges, same as a Bensen type), and the rotor responds.
You can do vertical descents in this type of gyro. It won't stall as a FW plane will. In fact, John Miller pointed out that Amelia Earhardt failed to recognize that the "giro" could flare to zero mph. She leaned on fixed-wing experience, trying faster "wheel" landings, leading to her crack-ups.
The aerodynamic surfaces do lose effectiveness at slow speeds unless energized by propwash. Ailerons that extend all the way to the wing root might help a bit in this regard, as long as the engine is running.
I had an awesome opportunity to spend a day with Johnny Miller in 2005 while I was flying my gyro to all 48 states in the Continental US. I had arranged to meet Gyro record holder Andy Keech and when I arrived he told me we were on tap to drive to meet Steve Pitcarin owner of the Miss Champion gyroplane and Johnny Miller. It was a day I will never forget being in company with so many gyro legends. There are a few more pictures on my website at: http://gyroamerica.com/Gyro Legends.htm
I stayed in some touch with Johnny after I first met him and he told me so many wonderful stories about his barnstorming days and other adventures. He was still instructing into his 90's. His email address was jennystojets as he had started his career flying Curtiss JN Jenny biplanes and finished up flying jets for the airlines- (PanAm I think). He watched Lindberg take-off. On his first solo flight he was only supposed to be doing taxi practice but as the trees approached he figured he better try to fly rather than slam on the brakes, so he hauled back on the yoke. He tried several times to land but kept overshooting the small farm pasture so he laneded in someone else's larger pasture. The landowner asked if he gave rides- so he said sure and took a passenger up on his second flight. In his early 90's he was President of the Bonanza society and flew to their annual meeting from his home in NY to New Orleans. He landed on instruments in IMC and went in to the FBO to pick up his rental car- they told him he was too old and would not rent him the car despite having just landed on instruments. He told me how he raced Amelia Earhart across the US in a gyro, flew a gyro from the top of the Philadelphia post office every day for a year to prove the concept of airmail. He also told me how he barnstormed across the US and would send out penny postcards to every house in town advertising flights on the weekend, then on Monday he would be off to the next town.
What a treasure he was!