Dave Jackson
10th Jan 2002, 07:58
This year, the German patent for the intermeshing helicopter rotor (Synchropter) is 100 years old.
The intermeshing Flettner FL-282 was the world's first production helicopter. At the end of World War 2, the only operational FL-282 that remained was sent to the United States where the Prewitt Aircraft Company evaluated it for the USAF intelligence department.
The following is the Prewitt's Report Summary, for those who are interested.
____________________
SUMMARY
Flight tests were made on the Flettner FL-282 Helicopter to determine the power requirements, control response, couple response between rudder and aileron, static stability, and the difference between a straight and a butterfly stabilizer.
The performance of the helicopter was found to be very high, due to a very low disk loading and to a comparatively high figure of merit.
The controls of the helicopter are relatively sensitive and substantially unaffected by rotor loading. The large size of rudder makes directional response more sensitive with increasing speed. Lateral control is one-half as sensitive as longitudinal control. Rudder control is one-half as sensitive as lateral control.
Fore and aft control and changes In throttle setting do not affect roll or yaw. There is, however, a coupling between fixed-stick rudder control and fixed-rudder stick control.
The lateral static stability is substantially neutral. There is, however, considerable damping to lateral roll and lateral control presents no special problem. Directional stability Is Influenced by collective blade pitch angles (good at high pitch, poor at low pitch). The helicopter has static longitudinal stability at between 10 and 80 mph. The longitudinal dynamic stability appears to follow the longitudinal static stability.
The tests show that there Is no observable difference between the straight and the butterfly stabilizers In either the control tests or stability tests.
The maintenance on the helicopter during the test period was nil.
The Inertia stick dampers were found to be very effective as was the rotor governor.
_____________
<a href="http://www.unicopter.com/0474.html" target="_blank"> Picture ++ </a>
The intermeshing Flettner FL-282 was the world's first production helicopter. At the end of World War 2, the only operational FL-282 that remained was sent to the United States where the Prewitt Aircraft Company evaluated it for the USAF intelligence department.
The following is the Prewitt's Report Summary, for those who are interested.
____________________
SUMMARY
Flight tests were made on the Flettner FL-282 Helicopter to determine the power requirements, control response, couple response between rudder and aileron, static stability, and the difference between a straight and a butterfly stabilizer.
The performance of the helicopter was found to be very high, due to a very low disk loading and to a comparatively high figure of merit.
The controls of the helicopter are relatively sensitive and substantially unaffected by rotor loading. The large size of rudder makes directional response more sensitive with increasing speed. Lateral control is one-half as sensitive as longitudinal control. Rudder control is one-half as sensitive as lateral control.
Fore and aft control and changes In throttle setting do not affect roll or yaw. There is, however, a coupling between fixed-stick rudder control and fixed-rudder stick control.
The lateral static stability is substantially neutral. There is, however, considerable damping to lateral roll and lateral control presents no special problem. Directional stability Is Influenced by collective blade pitch angles (good at high pitch, poor at low pitch). The helicopter has static longitudinal stability at between 10 and 80 mph. The longitudinal dynamic stability appears to follow the longitudinal static stability.
The tests show that there Is no observable difference between the straight and the butterfly stabilizers In either the control tests or stability tests.
The maintenance on the helicopter during the test period was nil.
The Inertia stick dampers were found to be very effective as was the rotor governor.
_____________
<a href="http://www.unicopter.com/0474.html" target="_blank"> Picture ++ </a>