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AVIA 245 Exam 2026-2027 BANK QUESTIONS WITH
DETAILED VERIFIED ANSWERS EXAM QUESTIONS
WILL COME FROM HERE (100% Latest Already Graded
A+
QUESTION 1
The specific impulse of a rocket engine is most accurately defined as:
A) The total thrust produced per unit mass flow rate of propellant
B) The ratio of exit velocity to the vehicle's current velocity
C) The thrust coefficient divided by the characteristic velocity
D) The product of chamber pressure and nozzle area ratio
Answer: A
Explanation: Specific impulse (Isp) is the thrust per unit weight flow rate
of propellant, which simplifies to exhaust velocity divided by standard
gravity (g0). In physical terms, it is the total impulse delivered per unit
weight of propellant consumed, making it a direct measure of
propulsion efficiency. Option B is incorrect because it describes a
velocity ratio unrelated to Isp. Option C defines the thrust coefficient
(Cf) divided by c*, not Isp. Option D describes a rough approximation of
thrust, not specific impulse.
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QUESTION 2
Which thermodynamic cycle is most commonly used to model ideal
turbojet engines?
A) Otto cycle
B) Brayton cycle
C) Rankine cycle
D) Diesel cycle
Answer: B
Explanation: The Brayton cycle is the ideal thermodynamic cycle for gas
turbine engines, including turbojets, turbofans, and turboshafts. It
consists of isentropic compression, constant-pressure heat addition,
isentropic expansion, and constant-pressure heat rejection. The Otto
cycle (A) applies to spark-ignition piston engines, the Rankine cycle (C)
to steam power plants, and the Diesel cycle (D) to compression-ignition
piston engines.
QUESTION 3
In a convergent-divergent nozzle, the Mach number at the throat under
choked conditions is:
A) Exactly 1.0
B) Less than 1.0
C) Greater than 1.0
D) Dependent on the chamber temperature
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Answer: A
Explanation: Under choked conditions, the mass flow rate through the
nozzle reaches its maximum for the given upstream conditions. At the
throat, the flow velocity equals the local speed of sound, so the Mach
number is exactly 1.0. This is a fundamental requirement for achieving
supersonic flow downstream. The Mach number cannot be less than 1
at the throat if the flow is choked, nor can it be greater than 1 because
that would imply the throat is downstream of the sonic point. The
chamber temperature affects the speed of sound but does not change
the Mach number at the throat under choked conditions.
QUESTION 4
The stagnation temperature in an adiabatic combustor is:
A) Lower than the static temperature
B) Equal to the static temperature
C) Higher than the static temperature
D) Unrelated to the static temperature
Answer: C
Explanation: Stagnation temperature is the temperature the fluid would
reach if it were brought to rest isentropically. In a flowing gas, the static
temperature does not include the kinetic energy contribution.
Stagnation temperature equals static temperature plus the kinetic
energy term (V²/(2cp)). Therefore, for any positive flow velocity,
stagnation temperature is higher than static temperature. In an
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adiabatic combustor, the stagnation temperature remains constant if
no work or heat is added, but static temperature can vary with velocity
changes.
QUESTION 5
The primary function of a diffuser in a gas turbine engine is to:
A) Increase airflow velocity
B) Decrease static pressure
C) Convert kinetic energy into pressure energy
D) Mix fuel with air
Answer: C
Explanation: The diffuser, typically located downstream of the inlet and
upstream of the compressor, decelerates the incoming airflow, thereby
converting kinetic energy into static pressure rise. This pressure recovery
is essential for efficient compressor operation. Option A is the opposite
of the diffuser's purpose; it decreases velocity. Option B is incorrect
because the diffuser increases static pressure. Option D describes the
function of the combustor or fuel injection system.
QUESTION 6
The pressure ratio across a normal shock wave is accompanied by what
change in Mach number?
A) Mach number increases through the shock
B) Mach number remains constant
AVIA 245 Exam 2026-2027 BANK QUESTIONS WITH
DETAILED VERIFIED ANSWERS EXAM QUESTIONS
WILL COME FROM HERE (100% Latest Already Graded
A+
QUESTION 1
The specific impulse of a rocket engine is most accurately defined as:
A) The total thrust produced per unit mass flow rate of propellant
B) The ratio of exit velocity to the vehicle's current velocity
C) The thrust coefficient divided by the characteristic velocity
D) The product of chamber pressure and nozzle area ratio
Answer: A
Explanation: Specific impulse (Isp) is the thrust per unit weight flow rate
of propellant, which simplifies to exhaust velocity divided by standard
gravity (g0). In physical terms, it is the total impulse delivered per unit
weight of propellant consumed, making it a direct measure of
propulsion efficiency. Option B is incorrect because it describes a
velocity ratio unrelated to Isp. Option C defines the thrust coefficient
(Cf) divided by c*, not Isp. Option D describes a rough approximation of
thrust, not specific impulse.
,2|Page
QUESTION 2
Which thermodynamic cycle is most commonly used to model ideal
turbojet engines?
A) Otto cycle
B) Brayton cycle
C) Rankine cycle
D) Diesel cycle
Answer: B
Explanation: The Brayton cycle is the ideal thermodynamic cycle for gas
turbine engines, including turbojets, turbofans, and turboshafts. It
consists of isentropic compression, constant-pressure heat addition,
isentropic expansion, and constant-pressure heat rejection. The Otto
cycle (A) applies to spark-ignition piston engines, the Rankine cycle (C)
to steam power plants, and the Diesel cycle (D) to compression-ignition
piston engines.
QUESTION 3
In a convergent-divergent nozzle, the Mach number at the throat under
choked conditions is:
A) Exactly 1.0
B) Less than 1.0
C) Greater than 1.0
D) Dependent on the chamber temperature
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Answer: A
Explanation: Under choked conditions, the mass flow rate through the
nozzle reaches its maximum for the given upstream conditions. At the
throat, the flow velocity equals the local speed of sound, so the Mach
number is exactly 1.0. This is a fundamental requirement for achieving
supersonic flow downstream. The Mach number cannot be less than 1
at the throat if the flow is choked, nor can it be greater than 1 because
that would imply the throat is downstream of the sonic point. The
chamber temperature affects the speed of sound but does not change
the Mach number at the throat under choked conditions.
QUESTION 4
The stagnation temperature in an adiabatic combustor is:
A) Lower than the static temperature
B) Equal to the static temperature
C) Higher than the static temperature
D) Unrelated to the static temperature
Answer: C
Explanation: Stagnation temperature is the temperature the fluid would
reach if it were brought to rest isentropically. In a flowing gas, the static
temperature does not include the kinetic energy contribution.
Stagnation temperature equals static temperature plus the kinetic
energy term (V²/(2cp)). Therefore, for any positive flow velocity,
stagnation temperature is higher than static temperature. In an
, 4|Page
adiabatic combustor, the stagnation temperature remains constant if
no work or heat is added, but static temperature can vary with velocity
changes.
QUESTION 5
The primary function of a diffuser in a gas turbine engine is to:
A) Increase airflow velocity
B) Decrease static pressure
C) Convert kinetic energy into pressure energy
D) Mix fuel with air
Answer: C
Explanation: The diffuser, typically located downstream of the inlet and
upstream of the compressor, decelerates the incoming airflow, thereby
converting kinetic energy into static pressure rise. This pressure recovery
is essential for efficient compressor operation. Option A is the opposite
of the diffuser's purpose; it decreases velocity. Option B is incorrect
because the diffuser increases static pressure. Option D describes the
function of the combustor or fuel injection system.
QUESTION 6
The pressure ratio across a normal shock wave is accompanied by what
change in Mach number?
A) Mach number increases through the shock
B) Mach number remains constant
