Limitations Flashcards
Load Limit Is
Max load expected in services
Ultimate Load Limit
Failing of a structure 1.5 times to load limit
Load Limit for CS25
2.5G
Load Limit for CS23 commuter
3.8G
Load Limit for a CS23 utility
4.4G
Load Limit for CS23 aerobatics
6G
Manoeuvre Envelope
Referred to as the Vn diagram (load factor against EAS)
The set out envelope we fly within
Stall Boundary in the Vn graph is where
Left had side of the envelope below the va speed
Vd
Design speed - used by engineer to structural will be the speed at which ac structure fails if falls outside this
Vibration and flutter likely
Va
Design Manoeuvre speed
Highest speed at which sudden full up elevator can be made without exceeding limit load factor
Va - Design Manoeuvre speed varies with
Mass - higher mass gives us a greater va
Altitude - va increases with altitude
Vc is
The design cruise speed
Faster than vb to cope with inadvertent speed increases by turbulence
Must be 32% more than VB
Vb
Design speed for max gust intensity
Vmo
Maximum operating speed
MNO
Max operating speed at altitude when flying with a Mach number
VLE
Max landing gear extended speed
VLO
Max speed when extending landing gear
Speed lower than VLE
VFE
Maximum flaps extension speed
Reduces max load factor
Vra
Turbulence penetration speed
Must be 35kt below vmo
Vne
Small aeroplane never exceed speed
Set at 0.9 VD
Red radial line on ASI
Small margin
VNO
Maximum structural cruise speed
Cannot be faster than VC
0.89 of Vne
Gust Loads
Sudden extra load felt through turbulence vertically
How do you cope with a gust load
Maintain altitude and allow ac to respond naturally to severe up/down droughts
Gust loads what to do with speed and altitude
Fly close to Vb and descend if near aerodynamic ceiling
Altitude on gust load factor
Low altitude means higher gust load factor
Higher altitude means lower gust factor
Mass on load factor
Higher the mass the lower the load factor
Lower the mass the greater the load factor
Wing loading on load factor
Low wing loading has a higher load factor
High wing load has a lower load factor
Airspeed on wing load
Higher airspeed has a higher load factor increase
Lower airspeed has a lower load factor increase
Load factor is proportional to
Wing area
AOA
EAS
Wing load is inversely proportional to
Wing loading
Mass
Altitude
Where does the gust load factor envelope start for speed and load factor on the graph
LF - 1
VS - 0
Vb Gust load factor
+-66FPS
Vc gust load factor FPS
+-50fps
VD gust load factor fps
+-25FPS
Resonance
Mass/stiffness determine natural frequency of oscillations
Flutter - mass balancing and putting mass in front of hinge line
What needs to be taken into account when determining Va?
The Limit Load factor
How do you calculate Va from VS1
Find limiting load factor (4.4/2.5g etc)
Use three step method to calculate VA from limiting load factor a load factor at 1G
VNo must not be greater than what of VNE
0.89
Large transport ac VC to VD negative load factor limit
VC -1
VD 0
MMO VMO applies to
CS23/S25
VNO and VNE apples to
CS23
Load Limit of a CS25 AC with flaps extended
2.0g
Design speeds and design gust values are
EAS
