EFM - Turn Performance Flashcards
Define turn rate
Rate of change of nose position in deg/s
Max turn rate for a given airspeed is at CLmax or airframe limit
Define turn radius
Distance from the centre of the TC to the flightpath
Usually measured in ft
Min turn radius for a given airspeed also achieved when flying to CLmax
Energy provides the capability to climb, decease turn radius and/or increase turn rate. Alternatively, too much energy can degrade performance. What are the two sources of energy that must be managed?
Kinetic (1/2 mv2)
Potential (mgh)
What is specific power?
A measure of the ability of an aircraft to change energy state or to trade energy for turn performance
Specific power = Specific energy/Time
I.e. a larger energy change and/or over a shorter time = Greater specific power
A measure of the delta of PE and KE
What is specific energy?
Specific energy = Total energy/Aircraft weight
I.e. more KE or PE and/or lighter = Greater specific energy
What are the 3 energy states that can be adopted in BFM?
Bleed
Sustain
Regain
What speed is assumed to corner speed for best RATE on Texan and what is the speed band we aim for when looking for best RATE?
240 KIAS best rate corner speed
210-240 KIAS band
Provides approx. 22 deg./sec instantaneous turn rate
What turn rate does a sustained, level MRT provide?
Energy bleeds to approx. 155 KIAS, giving approx. 15 deg./sec
When is bleeding energy commonly used in EFM/BFM?
Transitioning from a rate to a radius fight
To tighten a turn when defensive to give angle and closure problems to the hostile
Moving from the kill picture to a weapons solution
What is assumed to be the best turn radius speed?
110 KIAS, achieved by tickling further in to the stick shaker at 16 AoA
When would you regain in EFM?
Can use it if you’re slower than you want to be and the tactical scenario allows.
Most commonly used when the fight type changes (radius to rate) or when taking LAG to preserve range prior to repositioning for a kill
How do you regain energy?
Use height + full pwr + unload off the SS
Put your LV one ‘coke can’ BELOW the hostile as a good guide of how far nose down you should go to regain
Explain the ‘combat egg’
1g of gravity assists over the top, aircraft pulls 4g but the radial is that of a 5g turn, opposite on pull up.
Therefore, the radius is less over the top and greater on the pull up in to the vertical.
Slowing down over the top towards best radius speed (110) further accentuates this.
The ‘combat egg’ will have an effect on any turn where your LV is above or below the horizon. Closer the manoeuvre to the true vertical, the more marked the effect.
How does the combat egg effect you if your LV is BELOW the horizon?
Increased turn rate for a set speed + g (low yo-yo)
May accelerate
How does the combat egg effect you if your LV is ABOVE the horizon?
Decreased turn rate
Will probably slow down
Could use to convert from rate to radius??
Used for a high yo-yo
