AE6005 Helicopter Theory,
Fourth year, Department of Aeronautical Engineering, First and second Units
Questions.
Answer ALL Questions
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?
Answer ALL Questions
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.
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