A/C SYS 2017

1. the distribution of thrust on the propeller disc is not uniform
   1. Most of the thrust is generated in the outer part of the blade (rotational velocity component is higher)
   2. The energy lost in these tip vortices corresponds to the mechanical work needed to overcome the induced drag of the blades.
2. Other sources of energy loss are the parasite drag of the rotating blades, of the spinner and of the hub, and the angular momentum of the slipstream behind the propeller.

\(\pi*n*D\)

• n = propeller speed in revolutions per second
• D = propeller diameter in meters

the advance ratio J and the blade angle \(\beta\)

When the propeller pitch is set to a value that reduces drag to a minimum (in the event of an engine failure)

the fuel lower heating value [J/kg]

• A small fraction is used to overcome internal friction in the engine and to drive accessories, such as the fuel pump and the oil pump.
• The rest is left in the exhaust gas thermal energy. Indeed, the exhaust gas temperature of this engine at maximum static thrust was higher than 1000C.

A jet engine with no compressor and turbine

• sometimes called engine feed pumps
• are used to boost the fuel pressure in the engine feed lines. One of the reasons for this is to prevent aeration and cavitation at high altitudes

the presence of air bubbles in the fuel lines that could cause an engine flame-out

• the combination of low pressure, relatively high fuel temperature and high engine demand causes the formation of vapour bubbles in the fuel
• drastic reduction in fuel flow to the engine
• can cause a flame-out
• For this reason, engine manufacturers usually impose the requirement that the fuel feed pressure must remain at least 5 psi above the true vapour pressure at all times.

generation, control, transfer and utilization

- excellent power to weight ratio;
- high power transmission efficiency;
- flexibility in installation;
- resitance to overload conditions;
- high reliability;
- fast response;
- precise position and load control.

\(P = {F \over A}\)

F= Kraft

A= Fläche des actuator

\(P = {W \over t} = {F*d \over t} \)

F= Kraft

d= Distanz

\(A = {\pi *r^2}\)

\(TSFC = {m_f \over F}\)

\(spec. thrust = {F \over m_0}\)

The theoretical Otto cycle comprises an isentropic compression (process 1-2), a constant volume heat addition (process 2-3), an isentropic expansion (process 3-4) and a constant volume heat rejection (process 4-1).

2*s*n

Structure, vehicle system, avionic system

- complex and integrated set of structural components
- supports the mass of systems and PAX
- carries loads and stresses
- also known as the “platform”

- also known as general or utility system
- enables the A/C to fly safely
- provides an adequate environment for crew and PAX

provides information, control and communication functions that enable the aircraft to fulfil its operational role

- nowadays usually a Fly-by-Wire (FBW) system
- pilot control input is elaborated on the basis of air data, A/C attitude etc. to issue the proper control surface deflections that will effect the desired aircraft motion

in most recent aircraft a Full Authority Digital Engine Control (FADEC) system

provides airspeed, altitude, air temperature, rate of climb or descent information

provides information on pitch, yaw and roll angles, rates and accelerations

provides electrical power for flight and engine control computers, air data system, attitude systems, hydraulic servo-valves and (on some A/C) electrically driven hydraulic pumps

provides motive power for the actuators that move the flight control surfaces, or the engine thrust reversers

The functions whose loss would reduce the capability of the A/C or its crew to cope with adverse operating and environmental conditions (i.e. loss of cabin pressurization or loss of the anti-icing system)

Functions which could cause the loss of the aircraft or fatal injuries to the occupants (i.e. a complete loss of engine power)

The severity of a failure condition must be inversely proportional to ist probability

- Effects on the airplane
- Effects on the crew members
- Effects on the occupants

1. Probable: occur one or more times during the entire operational life of each A/C
2. Remote: may occur several times when considering the total operational life of a number of airplanes of this type
3. Extremely Remote: may occur a few times when considering the total operational life of all airplanes of this type
4. Extremely Improbable: not anticipated to occur during the entire operational life of all airplanes of one type

Probable: 10^-5 to 10^-3
Remote: 10^-7 to 10^-5
Extremely remote: 10^-9 to 10^-7
Extremely Improbable: lower than 10^-9

- Safe-Life
- Fail-Safe
- Fault-Tolerant

systems or components will survive a specific design life with no failures