In order to detect the presence of defects in the composite structure of helicopter rotor blades, combined neutronand X-ray radiography investigations were performed at the Budapest Research Reactor. The rotor blades were about 10 m (or 6,5 m) long, and therefore the images were taken in several segments, and a special program was developed to reconstruct the entire radiographic image from the ...

Active/passive optimization of helicopter rotor blades for vibration reduction and performance enhancement at high advance ratios is studied. Dynamic stall is the dominant source of high vibration levels for this flight regime. In the active/passive approach, active control of vibration and required rotor power is implemented with partial span trailingedge flaps operating according to a closed-...

Analytically, uneven (modulated) spacing of main rotor blades was found to reduce helicopter noise. A study was performed to see if these reductions transferred to improvements in subjective response. Using a predictive computer code, sounds produced by six main rotor configurations: 4 blades evenly spaced, 5 blades evenly spaced and four configurations with 5 blades with modulated spacing of v...

Abstmcf: Flight testing of a fully-instrumented model-scale unmanned helicopter (Yamaha R-SO with loft. diameter rotor) was conducted for the purpose of dynamic model identification. This paper describes the application of CIFER' system identification techniques, which have been developed for full size helicopters, to this aircraft. An accurate, high-bandwidth, linear state-space model was deri...

The effectiveness of surrogate based optimization of helicopter rotor blades for vibration reduction using kriging global approximations is investigated. The search for the optimal design is conducted using two methods: (1) the “one-shot” approach in which the surrogate is optimized directly and (2) a method based on the expected improvement function which seeks to find optimal designs while re...