ME Flashcards
Definition of an absolute ceiling?
The highest altitude at which an aircraft can maintain level flight.
Max thrust available = thrust required = total drag at minimum drag speed
RoC and AoC equals 0
Definition of a service ceiling?
The highest density altitude at which an aircraft can, in clean configuration and at Vy, sustain a climb at 100ft/min
What is happening when an ME aircraft lose an engine?
The aircraft yaws and rolls towards the inoperative engine.
Because the operative engine creates more thrust, it induces a yaw. Being faster, it also creates more lift, inducing the roll. The induced flow of the operative engine also adds lift, increasing the roll.
If not feathered, the windmilling prop of the inoperative engine greatly increases drag, increasing the aforementioned effects.
What should you do to get a zero side slip in the event of losing an engine?
Rudder + light roll towards the operative engine
Ball centered on the left or right line (halfway out of the center cage)
Definition of the critical engine?
The engine whose failure would most adversely affect the performance or handling qualities of the aircraft.
On a PA27, which one is the critical engine?
Left one
Explain why, on a twin-engine which both engines turn CW, the left engine is the critical engine.
At high angles of attack, due to P-Factor, the descending blades are creating more thrust. The thrust moment of the right engine (from the centerline of the aircraft) being bigger, the right wing tends to go faster.
If on top of that you lose the left engine, that’s where you’ll have to apply most rudder (to counteract a greater yawing moment).
Definition of the Vmc?
Velocity of minimum control / Minimum control speed
The minimum speed at which it is possible to retain control of the aircraft and maintain straight flight, through the use of maximum rudder deflection and not more than 5° bank angle.
What happens if a twin-engine aircraft goes below Vmc?
There may be no sufficient rudder authority to counteract the yawing movement and maintain directional control of the aircraft.
What are the factors affecting Vmc?
- Bank angle
- Propeller
- Power setting
- Altitude
- Weight
- C of G
- Flaps
- Gears
How does the bank angle affect the Vmc?
Too much bank angle adversely affects the performance. As much as 3kts per degree of bank. Keep a low bank angle to avoid enter a sideslip.
How does the propeller affect the Vmc?
A windmilling propeller creates a lot of drag. Remember to feather it as soon as you have confirmed the inoperative engine.
How does the power setting affect the Vmc?
A low power setting will decrease the adverse effects of losing an engine.
However, going on a too low power setting also decrease overall performance!
How does the altitude affect the Vmc?
At high altitudes, air being less dense, the power will decrease, reducing the effects of running on one engine.
Vmc will therefore decrease with an increase in altitude or OAT. But it could go below the Vs, which is not good.
This also means that if you lose altitude, your Vmc will increase (and you will be able to keep it above Vs)
How does C of G affect the Vmc?
An aft center of gravity will increase the Vmc, as the arm through will the rudder acts will be shorter.
