Chapter 0: Service reuirements Flashcards
What are/discuss the 5 design factors/considerations for aircraft?
- Types of services
- Speed
- Altitude
- Range
- Operation hours
What is the meaning range in design factor?
It is the point to point distance travelled
Discuss speed in Design factors
The higher the speed, the higher the skin temperature
Discuss altitude in Design Factor
Decreasing air density, temperature and pressure with altitude
Discuss Operation hours in design factors
Number of flights per day, total hours per flight and maximum time between maintenance
Discuss Types of services in Design factors
Civilian, military and reconnaissance
What are types of mechanical properties for property requirements
Strength, fatigue, toughness and stiffness
What are the types of physical properties in property requirements
Reflectivity, conductivity, density and melting point
Metallic materials are made up of grains. List 2 methods how the grain size can change/vary
- Cold working
2. Heat treatment
What is microstructure insensitive properties and give all example.
Microstructure insensitive properties are properties that are not affected by the change in grain structure. Density, Melting point, Conductivity and Reflectivity
What is microstructure sensitive properties and give all examples.
Microstructure sensitive properties are properties that change and is dependent on the grain structure.
The composition of the material can be studied by the use of
Scanning Electron Microscopy –
Energy Dispersive X-Ray Spectroscopy or SEM-EDX
State two main criteria used for ranking suitable materials for aircraft construction
- Specific strength: Strength/Density
2. Specific Stiffness: Young’s modulus/Density
In the mode of operations, What are the properties of a Civil flying object?
- Lower stresses compared to military
- Good fatigue behaviour requirement
- Must be cost-effective
In the mode of operations, What are the properties of a Military flying object?
- Able to handle high loads
- Functional material
- Cost less of an issue
- Weight less of an issue
Contrast the material requirements for the wings
Expectation - Highest and complex stress
- Cantilever maximum bending moment at the root
- Hang down due to self weight, fuel and engine
Requirements - Resistant to compression
- High static tensile strength
- Resistance to fatigue
Contrast the material requirements for the landing gears
Expectations
-High stresses on taking off a full load of fuel
-Greatest during landing; whole aircraft weight on
touchdown
-Retract during flight
Requirements
- Highest possible static strength
- Low cycle fatigue strength
- High fracture toughness
- Minimum volume
Contrast the material requirements for the control surfaces
Expectations
Lightly loaded
Requirements
Adequate stiffness High cycle fatigue
The ASTM standard to calculate the ASTM grain size number is based on the magnification of
100 X
Can you use the formula 2^n-1 if the magnification is 200 X
No. That formula only applies for 100 X
The temperature at 35000 ft is?
-55 degree Celius
The formula for temp increase (in Kelvin)
V^2/87^2
V = airspeed in knots
If V = 500 kts and the Skin temperature = -55 + 33 = -22
what is it?
Not critical for commercial airlines
If V = 1400 kts or more and the Skin temperature = -55 + 259 = 204
what is it?
Critical skin temperature for military jets
