Limitations Flashcards
GLF with higher wing loading
GLF increases
ULL of a jet transport a/c
3.75
CS 25- LF limit for a normal transport a/c
2.5g to -1.0g
CS 23 - LF limit for a utility a/c
4.4g - 1.75g
E.g heavy transport a/c
CS 23 - LF limit of a aerobatic a/c
6g to -3G - not economical
Graph for LF against IAS
V-N diagram
What happens to GLF with an increase in wing loading
GLF increases
What happens if you pass the curve lines on the v-n diagram
You will stall
What happens if you pass the NLL
You will overstress the a/c
What happens if you pass the ULL
You will cause structural failure
Relationship between VA and ULL
ULL will always be 22% higher than VA speed
Formulas for working out VA
Va= Vs1g x square root of the LF
Va = Vaold x square root of Wnew/Wold
% change in va = 50% change in weight
What happens to va with altitude
Va is higher at altitude
Vb vertical gust requirement
20,000 - 66ft/s
50,000 - 38ft/s - linear decrease
However this speed is too slow to fly at
Vc and vd gust requirement
Vc - 55ft/s
Vd - 25ft/s
Formula for working out change in LF with a gust
Use the usual LF formula but add the additional CL created to the lift part of the formula
Change in LF at high altitude
Due TAS increasing at altitude, the change in AoA is reduced due to the bigger speed vector
To work out LF at the stall speed
Square of the stall speed e.g 1.3vs=30%faster than vs
So LF = (1.3)2 = 1.69
Effect of aspect ratio on the change in LF with a gust
Increases LF change with an increase in aspect ratio
Effect on mass on the GLF
Lighter the a/c is the bigger the effect of the gust
The effect on wing loading on the GLF
The harder the wing has to work, the effect of the gust is decreased
The effect of wing area n GLF
Increasing the wing area, increases the GLF
The effect of GLF on increasing IAS
GLF will increase
Effect on increasing altitude on GLF
GLF will decrease
1.3g altitude
Height at which a 0.3g change in LF will not cause a buffet
Effect of wing loading on the change of lift in a gust
High wing loading = small change
Low wing loading = big change
Relationship between CL to AoA curve on the change in CL with a gust
Steep curve = big increase in CL Shallow curve (swept wing) = lower change in CL
What should be taken into account during the determination of VA
Limit load factor
What does VMCA depend on
Airport density altitude, location of engines on the a/c
What happens to the GLF when the wing area decreases
GLF decreases
What happens to GLF when the EAS decreases
GLF decreases
