TWENTY YEARS AGO

A Pawnee By No Other Name?

by Bill Lavender

RIBEIRÃO PRETO, BRAZIL- During a trip to Brazil last summer, I was able to meet with José Paulo Rodrigues Garcia, simply known as Garcia, owner of Garcia Aviacao Agricola, Ltda. Garcia owns a Pawnee outiftted with winglets, that I was anxious to fly.

Like so many ag pilots, my first spray season in 1974 was flown in a Pawnee. My particular type Pawnee was known as a Hutcherson Pawnee with metal wings and fuselage, spring steel gear and a 250-horsepower engine (O-540 Lycoming with high compression pistons requiring 100 octane av gas). To me, the “metal” Pawnee flew better than the rag wing of that day. This was before the fuel cells were in the wings, but instead were installed in the fuselage between the hopper and the engine.

These early model Pawnees’ nose bowl was painted red. We used to make jokes (not very funny if it was you) that the red nose of the Pawnee was nothing more than the end of a match stick! Of course, this was because of the danger of the fuel bladder so close to the engine, with the red nose bowl striking the ground causing many times the aircraft to burst into flames, and the demise of the pilot, a widow maker.

Vortices are much smaller with the winglets…

...than without them.

Later in my ag aviation career (1980), one of the ag planes the company I owned (ironically called Ag Air) operated a Pawnee. So, I had several logbook pages recorded flying this aircraft. I basically knew what to expect from it. The last time I had flown a Pawnee was almost exactly a year ago when I was in Tucson, Arizona to make an evaluation flight of the Goddard Lift Kit mounted on a rag wing Pawnee.

Ernesto Franzen (AAU Latinoamerica’s Brazilian representative) and I arrived at Ribeirao Preto late in the afternoon. Garcia kindly picked us up at the airport. By the time we were at the airstrip, the sun was setting. During the evening Garcia made the awaited invitation to fly his Pawnee. I am always humbled when a long distance friend, one I’ve never even met, so graciously extends to me an invitation to fly his aircraft. Garcia only advised me that I would see an “ocean” of sugar cane once I was in the air. No precautions from Garcia about being careful, or any particularities to the aircraft.

The next morning, upon careful preflight of the D-model Pawnee, I found it to be in perfect condition. It had a SATLOC unit and a winglet system designed by Dr. Marcos Vileala and Garcia installed.

Questioning Garcia, he told me the winglets were designed through a trial-and-error method. A local fabrication shop built the molds for the fiberglass winglets. The installation is like other winglets that I’ve seen on U.S. ag aircraft, basically replacing the wing tip using screws to secure it. That these winglets looked like the Brazilian Ipanema should come as no surprise — Garcia and Dr. Vilela gave the design to Neiva due to the red tape involved in certification.

To me, the Pawnee has always been a fun ag plane to fly. It handles well empty. This morning I flew the aircraft empty, simply to determine how well it was trimmed in flight and not to evaluate its characteristics loaded. That is to be regretted, because most ag aircraft will fly well empty. It is when they are loaded that their handling characteristics are the most important. It was winter time and Garcia’s loading facilities had been disassembled for off-season maintenance.

Typical of an ag plane with winglets installed, the pilot will feel how yaw is kept to a minimum. Although this is not usually a problem with single engine ag planes, it is the feel of stability that this lack of yaw gives to the pilot. In the turns, the rudder is more responsive and the aircraft has a “tracking” feeling on its way back to the field.

The slower an ag plane becomes in the turns, the more rudder movement is required. If the turn is a climbing, nose falling through, turning back toward the field-type turn, the pilot can literally have the rudder pedals pressed to the floor. With winglets, this doesn’t seem to happen as readily. Without an accurate way of measuring the difference, it is a sensation of feeling that the aircraft has more capability to be pulled harder on the elevators and literally pointed back to the field. In less words, the winglet Pawnee turns even better than before winglets.

I did not witness a swath from this winglet Pawnee. However, I saw pictures showing a visible reduction of vortices. Admittedly, a better evaluation flight would have been with the aircraft loaded and a video taken of the swath, examining its make up. This particular flight was made without intention of such intense evaluation, only a simple early morning fun flight.

I don’t know if Garcia will pursue marketing the Pawnee winglets. Undoubtedly, they are an improvement to the aircraft. Garcia is a busy and successful ag aviation operator. He may just keep this luxury to himself!