021 01 Airframe & Systems

The vapour pressure is the term used to indicate the ambient pressure at which the fuel vaporises. A high vapour pressure indicates that fuel vaporises at high atmospheric pressure.

When aviation gasoline is stored and has a chemical interchange with air, hydrocarbons vaporise.The fuel can oxidise. Two of the biproducts of this oxidation are soluble gums and insoluble black particulates. The particulates and gums can block fuel filters or clog up carburator jets and narrow bore pipes.

Pascal's Law is a principle in fluid mechanics that states that a pressure change at any point in a confined incompressible fluid is transmitted throughout the fluid such that the same change occurs everywhere.

P = F / A and P₁ = P₂ and Volume = A * D

F₂ = 60 N

D₂ = 20 in 

 

Health precatutions to avoid contact with the fluid.

• must flow with minimum resistance
• must be incompressible
• must have good lubricating properties
• must inhibit corrosion and not attack seals
• must not foam in operati

With open center systems, multiple hydraulic actuators are supplied simultaneously.

With closed center systems, hydraulic actuators can only be used one at a time.

• Active: pressure is cont. generated by a pump
• Passive: pressure is only generated, when the hydraulic operating unit is used, e.g. wheel brake.

Variable displacement pump (piston type)
used between 1500 and 6000 PSI.

Gear type pump.

Ideal up to 1500 psi.

No, there is a relief valve, which is closed by a spring in normal operation mode and letting the oil flow through the filter material (micronic element). In case the filter becomes clogged up and the differential pressure overcomes the spring force, the relief valve openes and the oil can bypass the filter material. 

By using hydraulic fluid to compress air (the oil & air separated by a synthetic rubber bladder), the compressed air can transfer energy back to the hydraulic oil in case of sudden pressure loss. 

Sudden increase in the applied force

• Continual reversal of loading
• The structurewill fail at a lower load compared to the maximum static load designed for at the beginning of its life 

\(Zündwinkel= {{ 720°} \over { Number \space of \space cylinders} }\)

•  Optimale Kraftverteilung
• Kraft kann in Strukur aufgenommen werden --> Fail Safe
• Negativ: Kein Platz

• Timber Frame/Fachwerk
• Monocoque
• Semi-Monocoque

• Carries all the forces: Skin, Bulkhead
• Parts used: SKin, Former, Bulkhead
• Can absorb forces 
• Has space for pax and cargo
• Negativ: If structure is damaged, it is weakened and can ben

• "Advanced" Monocoque
• Stringers strengthen the skin. They are riveted on to the skin
• Longerons further strengthen the skin in longitudinal direction
• Force is absorbed by: Skin, Bulkhead, Stringer, Longeron, Former

Main Parts:

• Spar
  • Caps
  • Web
• Torsionbox
• Formers
• Stringers
• Ski

• Integral
  • Everything out of one part
  • If something breaks the whole thing has to be replaced
• Differential
  • Single members form one part
  •  Members can be replaced if damaged
  • Members break as seperately

An A/C has a defined minimum number of flying hours or cycles which should elapse before a major structuralfailure occurs

• Multiple load Paths --> Loads are shared by additinal members
• If one part fails the load is carried by the adjacent member for a limited period of tim

EAA:

• CS25, Big A/C
• CS23, Small A/C

FAA

• FAR25, Big A/C
• FAR23, Small A/C

1. L_max (Last cycle), maximum Load, Designlimit
2. Proof Load (no Deformation), L_max * 1.125
3. Ultimate Load (below that no failure), L_max * 1.

• Dehnung
• If acting force is string enough to change the shape of the object

Condition        Probability         Effect

Minor              Frequent            Normal Operation

Minor              10^-3                    Operating limits, Mergency Procedures

Major              10^-5                    Difficulties for Crew

Hazardous      10^-7                    Extended Workload, Serious or fatal injuries in small numbers

Catastrophic   10^-9                    Total Hull Loss, Multiple death