1.If thrust loading is 0.65 then, find the power loading of a prop aircraft. Consider propeller is idle.
a) 846.15/V
b) 846.15
c) 650
d) 6.5
Explanation: Given, prop aircraft, thrust loading T.L. = 0.65
Since propeller is idle, propeller efficiency ƞ=1. Here, velocity is not mentioned so we will substitute it as V.
Now, thrust loading is given as,
T.L. = T/W = (550*η / V)*(hp/W)
Hence, power loading W/hp = PL = 550*η / (T.L.*V) = 550/(V*0.65) = 846.15/V.
2.If a turboprop is cruising with 2275kg of weight, then determine power loading. Given power = 190hp.
a) 12
b) 5
c) 10
d) 25
Explanation: Given, weight at cruise W = 2275kg, power = 190hp.
Hence, power loading = W/hp = 2275/190 = 11.97 = 12.
3. An aircraft is cruising with lift coefficient of 2.5 and thrust loading of 0.6. Find drag coefficient of the aircraft.
a) 1.5
b) 2.5
c) 2.6
d) 2.59
Explanation: Given, lift coefficient CL = 2.5, thrust loading T/W = 0.6.
Now, thrust loading at cruise is given by,
T/W = CD / CL
0.6 = CD / 2.5
CD = 0.6*2.5 = 1.5.
4. Thrust loading is defined as ____________
a) ratio of thrust produced by an engine to the weight of the aircraft
b) ratio of lift to thrust
c) ratio of drag to thrust
d) ratio of lift to weight
Explanation: Thrust loading is nothing but the thrust to weight ratio. It is defined as the ratio of thrust produced by the engine to the weight of the aircraft. Thrust loading will vary from aircraft to aircraft. It can be between 0.2-0.6 typically.
5.What is thrust matching?
a) Comparison of the engine’s available thrust at cruise to the estimated drag of aircraft
b) Comparison of the engine’s available thrust at cruise to the estimated weight of aircraft
c) Comparison of the engine’s available lift at cruise to the estimated drag of aircraft
d) Comparison of the engine’s available power at cruise to the estimated drag of aircraft
Explanation: Thrust matching is nothing but the comparison of an engine’s available thrust at cruise to the estimated drag of aircraft. It is used for better initial estimation of the thrust to weight ratio.
6. At idle cruise condition, thrust loading is equal to ______
a) drag to lift ratio at cruise
b) drag to power ratio
c) lift to drag ratio
d) aerodynamic efficiency
Explanation: At idle cruise condition, lift = weight and thrust = drag. Hence, thrust loading T/W = D/L = Drag to lift ratio at the cruise. Aerodynamic efficiency is the ratio of lift to drag. Thrust loading at cruise is inverse of aerodynamic efficiency.
7. For an aircraft cruise aerodynamic efficiency is 10. Find the thrust loading at cruise.
a) 0.1
b) 0.01
c) 0.4
d) 0.5
Explanation: Given, Aerodynamic efficiency L/D = 10
Thrust loading at cruise T/W = 1 / (L/D) = 1/10 = 0.1.
8. A typical jet airliner has cruise thrust to weight ratio of 0.5. Determine at which aerodynamic efficiency this airliner is flying.
a) 2
b) 3
c) 4
d) 5
Explanation: Given, Thrust loading at cruise T/W
Thrust loading at cruise T/W = 1 / (L/D)
Hence, Aerodynamic efficiency (L/D) at cruise is,
L/D = 1 / (T/W) = 1/0.5 = 2.
9. A jet aircraft has maximum lift to drag as 12. Find the value of the thrust loading at the cruise.
a) 0.096
b) 0.0069
c) 0.96
d) 0.0096
Explanation: Given, maximum lift to drag = 12.
Thrust loading at cruise T/W = 1 / (L/D at cruise)
For, jet aircraft cruise lift to drag = 86.6% of maximum lift to drag = 86.6% of 12 = 0.866*12 = 10.392
Now, thrust loading at cruise,
Thrust loading at cruise T/W = 1 / (L/D at cruise)
= 1/10.392 = 0.096.
10. Power available for prop will vary with density.
a) True
b) False
Explanation: Power available is affected by the density at a given altitude. Based on density ratio power available decreases with increasing altitude given that the engine is not supercharged.