AE6005 Helicopter Theory, Fourth year, Department of Aeronautical Engineering, First and second Units Questions.
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PART A – (10 x 2 = 10 Marks)
1)      What is hovering?
2)      What are the advantages of Helicopter over an Aircraft?
3)      What is meant by Blade Loading
4)      What is ground effect?
5)      What is tip loss?
6)      What is ideal twist?
7)      Define blade element theory?
8)      Define momentum theory?
9)      Define solidity?
10)  What are the types of drag acting on a rotor blade and explain it?
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PART - B [80 Marks]

11)  From blade element theory, by using Rotor Figure of Merit, estimate the performance of a rotor.
(16)
12)   By using momentum theory show that υ = √ (T/2ρ ΠR2)                                                      (16)

13)  With neat sketches explain about advantages and disadvantages of different configurations of helicopter.                                                                                                                                (16)                                                                                                                                         
14)   A helicopter with gross weight of 1200kg, a main rotor radius of 4m, and a rotor tip speed of 200m/s has 250 kw delivered to the main rotor shaft, the tail rotor radius is 0.6m and the tail rotor is located 5m from the main shaft.for hovering condition at the sea level,compute the rotor disk loading, the ideal power loading, thrust and torque coefficient and the figure of merit and actual power loading. Also calculate the thrust and power required by the tail rotor for hovering conditions at 7500 ft and 12000ft.Assume that the figure of the merit of the tail rotor is 0.70.

15)   Consider a helicopter with the following features:
Weight of the helicopter =1.33*104 N; Main rotor radius =4.88m; Rotor disk area 74.7 sq.m; Rotor tip speed =213m/s; Rotor blade chord 0.3048 m; Number of blades=2; Profile drag coefficient=0.01; lift curve slope (a)=6(per radian).Assume the atmosphere conditions at sea level.
(i) Find the non dimensional pressure change (∆P/P∞)
(ii) Find the value ῳ of the induced velocity for below the rotor, according to momentum theory.
(iii) Find the local lift coefficient at r =0.5*R
(iv) Find the local blade pitch angle at r=0.5*R
(v) Find the ratio of profile power coefficient to the induced power coefficient.