Author details

Constantin Rotaru<sup>1</sup> \* and Michael Todorov<sup>2</sup>


## References

more tail rotor thrust to maintain the directional control. The increased tail rotor thrust takes away a power from the engine, and therefore will have less power available to the main rotor, which produces the required lift. Some helicopters have a critical wind azimuth limits and the manufacturer presents maximum safe relative wind chart. If the helicopter operates above these

When developing performance charts, aircraft manufacturers make some assumptions about the operating helicopter conditions and the pilot's ability. It is supposed that the helicopter is in good operating condition and the engine is able to develop its rated power. It is assumed that

With these assumptions, the manufacturer develops performance data for the helicopter taking into account the flight tests. But the helicopter is not tested under all conditions shown on the performance chart. Instead, an evaluation of the specific data is performed and the remaining

Generally, the charts present graphics related to hover power: in ground effect (IGE) hover ceiling vs. gross weight, and out of ground effect (OGE) hover ceiling vs. gross weight. The exact names of these charts may vary by different helicopter manuals. These are not the only charts, but these charts are perhaps the most important charts in each manual—they help to understand the amount of power which the helicopter have to have under specific operating

In this chapter, an analysis for defining the helicopter's performance was performed. It has been shown that the performance characteristics can be derived by using simple models as the momentum and blade elements theories. The impact of weight and altitude on the required power and the available power has been presented. The effect of near the ground operation on the helicopter's performance is discussed. Also, the case when the engine stops in flight and the main rotor performs autorotation is presented. Some elementary analysis of the stability characteristics has been done. The impact of different helicopter parts on the stability has been

considered. Finally, it has been shown how the helicopter can be controlled.

\* and Michael Todorov<sup>2</sup>

\*Address all correspondence to: rotaru.constantin@afahc.ro

1 "Henri Coanda" Air Force Academy, Brasov, Romania

2 Technical University of Sofia, Bulgaria

the pilot performs normal operating procedures and he has average flying abilities [2].

limits, it can cause a loss of tail rotor control [2].

46 Flight Physics - Models, Techniques and Technologies

data are obtained in mathematical way [2].

conditions (altitude, gross weight, and temperature).

8.5. Performance charts

9. Conclusion

Author details

Constantin Rotaru<sup>1</sup>


Provisional chapter
