Forces In Descent Flashcards
What is the descent angle
Angle between ac path through the air and local horizontal
Symbol y (gamma)
Pitch angle + AOA
What is the pitch angle
Angle between longitudinal axis and horizontal (shown on attitude indicator)
Pitch angle is less than the descent angle
Given as a negative value
Forces in descent parallel to flight (power on)
Drag = Thrust + W Siny
Thrust
Drag
Wsiny
Steeper descent will have a
Larger descent angle
Shallowest descent is at
VMD
Engine failure you will fly at…
Vmd for shallowest descent
Vx
Best angle of climb
Steepest climb angle
Operate most efficient at heigh
Slow speed
How do we manage drag
Speed and spoilers
Depressurisation what speed should you fly at
VMO for most excess drag
Drag in a descent formula
T + weight x siny = drag
WSINY =
Drag - Thrust
——————
Weight
In a glide descent forward component is what to drag
Equal as no thrust
Calculating glide range
X lift by the range altitude
Convert ft to nm (6080ft in 1nm)
Gliding with head wind
Range reduces
Gliding with tailwind
Range increases
Mass impact on glide range
Does not affect in still air heavy ac will simply just reach ground quicker in same location
Heavy A/C in headwind glide range
Will be in air less time therefore less effected so slightly better range than a lighter ac
Tailwind and mass
Light a/c will have greater range due to being in air longer
X2 Factors effecting glide range
Flaps - reduce L/D ratio and glide range
Speed - flying faster or slower than vmd
Glide endurance speed is
Vmp (0.76 vmd)
Useful for gliding over sea
Vmp is the minimum speed for power
AOA is always expressed as
A positive number of degrees
Pitch angle is always
Negative
In steady power off descent which force drive ac down descent flight path?
Weight
CDFA Is + advantages
Continuous descent final approach
Certain power setting all the way down the descent saves fuel/reduces engine wear and reduces air and noise pollution
Glide angle of descent is the ratio of
Height lost to the horizontal distance travelled
Best glide gradient factors
Vmd
Best L/D ratio
CLMAX/CD
Formula for descent angle
Pitch Angle + AOA
(Always negative) (always positive)
How does calculating angle of descent differ from calculating angle of climb
Angle of descent uses = siny = drag - thrust
—————-
Weight
Angle of climb uses = siny = thrust - drag
——————
Weight
Calculating drag/weight or descent angle in powered off glide
Siny = drag
——-
Weight
Glide range formula
Height x L/D ratio
Glide range formula with winds
Glide range in still air x ground speed/original TAS
Mass on glide range
Heavy ac will glide same distance if both fly at Vmd
More induced drag on heavier so has to fly faster vmd so will reach ground quicker
Flaps and landing gear on glide range
Reduces due to increased drag
Steeper glide path and reduced endurance
Headwind will do what to glide range
Reduce distance covered over the ground
Does not effect rate of descent
Tailwind on glide range
Increase our speed
Cover more distance
No effect on endurance
Shallowest glide angle is achieved when aircraft is gliding
At the speed which equates to best L/D ratio
Which force drives ac down the descent angle in power on and off descent?
Weight
Driving factor for an aircraft down the descent flight path
On a drag polar curve where is VMP to VMD
VMD is always below VMP on a CL/CD graph
