Wichita Falls, Texas: Wednesday, March 3, 1999.

FLIGHT TESTS CONTINUE AT SHEPPARD AFB

On Saturday, February 20, CARTERCOPTERS L.L.C. resumed flight testing of the CarterCopter at Sheppard Air Force Base (Wichita Falls, Texas). Don Farrington flew the aircraft for 0.5 hours total flight time. Testing was then cancelled due to strong crosswinds gusting to 30 MPH and a problem with the left muffler.

Both of the aircraft's mufflers, made from 304 S/S and located inside the engine compartment, had been wrapped with new insulation following the flights on February 6 & 7. The insulation was necessary to prevent heat damage to nearby electrical components. The new insulation appears to have contained exhaust temperatures inside the exhaust system so effectively that extreme heat build-up caused metallurgical failure in the muffler. The baffles wadded - choking the exhaust. The sudden constriction caused exhaust gases to separate the muffler's flanges.

The exhaust system was totally rebuilt during the following week. The mufflers were eliminated. The exhausts from the headers were merged into a single 321 S/S pipe on each side of the engine that was run directly to the outside of the cowling. The pipes were wrapped with insulation. The exposure of engine components to the high exhaust temperatures is now minimized without greatly increasing external noise levels.

This past weekend, February 27 & 28, Don Farrington again flew the CarterCopter - adding 2 additional hours of flight time. The engine was using more oil than expected and horsepower had dropped off slightly, so flights were again limited to the length of the runway. Other than that, the aircraft performed flawlessly both days. As in past flight tests, the testing was halted every 3-4 flights and all flight-critical aircraft components and controls were checked.

PLANNING THE NEXT STEPS WHILE CRITICAL COMPONENTS ARE CHECKED.

The objective Saturday was to collect more data on the CarterCopter's flight characteristics. The aircraft's test weight was slightly more than 3100 pounds. Takeoff speeds of 50-60 MPH consistently used less than 150 feet of runway. Numerous repeatable data points were collected on stabilized flights down the runway at 90-100 MPH with varying combinations of cyclic, collective, and horizontal stabilator angles. Rotor-blade pitch was varied in flight from 0 to 5 degrees (8 degrees of a maximum 12 degrees was used during short field takeoffs). Different combinations of collective and forward speeds for given rotor RPMs, stick forces, and stick shake were investigated. Some stick shake and increased stick forces were encountered upon reaching 100 MPH, so flights were limited to this speed. Telemetry data showed that the aircraft would have steadily accelerated through this speed if permitted to do so.

It was decided that before attempting to fly faster than 100 MPH, the distance between the blade teetering axis and the blade spar would be increased. The closer the teetering axis is to the rotor center of gravity (CG), the less stick shake will occur due to blade flapping. To reduce the stick forces, the spindle tilt axis will be moved closer to the rotor aerodynamic center -- which also happens to be very close to the rotor CG. To make these changes, some of the rotor head components must be rebuilt. The new rotor head assembly may require 2 months to design, detail, and build. It can then be installed in a week. The portion of Phase II flight-testing that explores the speed range between 100-150 MPH will be delayed until this rebuild is completed.

With exploration of the higher speed ranges put on temporary hold, the objective Sunday was for Don Farrington to begin preliminary Phase III testing. This plan included slowly developing the techniques needed for zero roll takeoffs and landings.

Everything went as predicted. The preliminary jump takeoffs required rolls of only 25 feet with speeds of 20-30 MPH. Beginning with a reduced over-speed rotor RPM at the start of the takeoff roll, the collective was gradually increased from zero to 8 degrees in 3.5 seconds. Once airborne, flight speeds of 50 MPH were reached in 6 seconds. Landing speeds of 20 MPH were obtained by flaring the aircraft with the use of collective. By the time flight-testing ended, Don felt comfortable with the control system and aircraft performance.

HERE WE GO AGAIN ! (Top Right)

After examining the data gathered this past weekend, we feel relatively confident we will achieve our design goals for zero-roll takeoffs and landings. We hope to return to the 5,000 feet runway at Olney, Texas, during the Week of March 15^th to resume the Phase III testing begun this past Sunday. In the interim, we will tear down the engine for a complete inspection. We will increase the horsepower rating from 225 hp to 300 hp by installing new pistons to increase compression from 8.8:1 to 11:1. Even with the increased horsepower rating, the engine will remain de-rated from its designed potential. We will also remove the front landing gear extension in expectation of doing full zero roll takeoffs and landings. Without the extension, we will have the option of raising the landing gear in flight for the first time. If "power-off" landing tests from 100 feet altitude proceed as expected, then with confidence that the engine is OK, we will feel comfortable to fly airport patterns. We will be finished with Phase II testing when we have flown between minimum safe slow speed flight and 150 mph at varying combinations of cyclic, collective, and horizontal stabilator angles. Testing will continue until we fully understand how the aircraft is flying; i.e. our analytic analysis agrees with actual flight data. Once this milestone is complete, we can start work on zero-roll take-offs/landings; phase III flight testing. Phase IV flight testing will determine the maximum safe forward airspeed that can be attained at the lowest rotor RPM possible.

ONE OF MANY FLIGHTS DOWN THE RUNWAY.

STAN CLINES AND MARK ROBINSON INSPECT ALL MAJOR FLIGHT COMPONENTS.