What is the limitation of current engine design?

A)
Expansion fan only
B)
Flow velocity over wing
C)
Turbine inlet temperature
D)
Inlet flow velocity reduction limitation

Correct Answer :   Turbine inlet temperature

Explanation : Turbine inlet temperature is one of the biggest obstacle of current engine design. For best Thrust and efficiency it is desirable to use stoichiometric air fuel ratio of 15:1. However, this generated tremendous high temperatures. Such high temperatures are beyond the limits of materials used for Turbine.

Recently Updated in Aircraft Design Questions
Determine the propeller efficiency if propeller velocity is 300ft/s and thrust of 1320 lb. Given bhp is 800.
A)
0.03%
B)
0.09%
C)
0.895%
D)
90%

Correct Answer : Option (D) :   90%

Explanation : Propeller efficiency = (thrust*velocity) / (bhp*550) = 1320*300/ (550*800) = 0.9 = 0.9*100 % = 90%.

Determine the required thrust coefficient to produce thrust of 1000N. Given diameter is 1.2m and n=22 rps.
A)
0.1
B)
0.32
C)
0.489
D)
0.813

Correct Answer : Option (D) :   0.813

Explanation : Thrust coefficient = Thrust / (density*diameter4*rps2) = 1000 / (1.225*1.24*222) = 0.813.

If a propeller has bhp of 700 and diameter as 1.2 ft. and rotating with 20 rps then, determine power coefficient. Consider sea level density.
A)
1.8
B)
15.8
C)
30.2
D)
40

Correct Answer : Option (B) :   15.8

Explanation : Power coefficient = 550*bhp / (density*diameter5*rps3)
= 550*700 / (1.225*1.25*203) = 15.8.

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