Helicopter Flying Qualities Sensitivity Analysis with Respect to Aerodynamic Configuration

An improved helicopter flight dynamic model suited to evaluate the flying qualities of a single rotor helicopter was built for UH-60A, including trim calculation and stability and controllability derivatives. On this foundation, the open-loop flying qualities of the UH-60A helicopter were studied by using MIL-F-83300. According to the requirement, the change of the UH-60A dynamic response and the control characteristics were computed and compared when some typical aerodynamic configuration parameters were adjusted, the influences of the aerodynamic configuration parameters on flying qualities and the sensitivities of flying qualities with respect to the parameters were analyzed.

Defect Structure of MEV Si Implantation in GaAs

ABSTRACTThe defect and atomic profiles for MeV implantation of Si in GaAs were investigated using He++ channeling, TEM, and SIMS. Doses of 1–10 × 1015Si/cm2 at 1–3 MeV were used. MeV implantation at room temperature rendered only a small amount of lattice disorder in GaAs. Upon annealing at 400°C for 1 h or 800°C for 30 a, we observed a ‘defect-free’ surface region (- 1 μ for 3 MeV implant). Below this region, extensive secondary defects were formed in a band which was 0.7 μ wide and centered at 2 μ for 3 MeV implant. These defects were mostly dislocations lying in the [111] plane. SIMS depth profiles of Si implants showed the Si peak to be very close to the peak position of the defects. The experimental profiles of Si were compared to the TRIM calculation; generally good agreement existed among the peak positions.