Instrumention and Aircraft Tech Flashcards
How does temperature affect LSS?
As temp decreases, LSS decreases.
What are the ASI/Mach Meter indications for a blocked Pitot and or static port?
A blocked static line means that the static pressure in the ASI/Mach Meter remains the same.
What are the forces acting on an aircraft in flight?
Drag, thrust, lift and weight.
What is direct lift control?
The elevator, stabiliser produces direct lift control.
What are high lift devices?
Trailing edge flaps, leading edge flaps, slots.
Define two major types of drag…..
Profile and induced drag. Together they equal total drag.
What are high drag devices?
Landing gear, trailing edge flaps, spoilers, reverse thrust, breaking parachute.
How do you prevent span-wise airflow on a wing?
Fences, vortex generators.
What is the purpose of fences and vortex generators?
To reduce span-wise airflow and thereby reduce its effects.
What are winglets and how do they work?
Winglets are aerodynamically efficient surfaces. They are designed to reduce the effect of span wise airflow and reduce induced drag by dispensing the the airflow from the upper and lower surfaces of the wing.
How does a forward centre of gravity affect the stall speed?
A centre of gravity forward of the centre of pressure will cause a higher stall speed.
What are the advantages of a swept wing?
High Mach cruise speed and stability in turbulence.
Where does a swept wing stall first?
A simple swept or tapered wing will stall at the wing tip first.
Explain speed stability…..
It is the behaviour of the speed of the aircraft after a disturbance at a fixed power setting.
What is a Mach number?
Mach number is a true airspeed indication, given as a percentage relative to the local speed of sound.
What is Mcrit?
Mcrit is the critical Mach Number. It is the speed at which the airflow over the wing becomes sonic.
What is Mach Tuck?
It is the nose down pitch moment an aircraft experiences as it passes its critical Mach number.
What is the purpose of a Mach trimmer?
A Mach Trimmer automatically compensates for Mach tuck above Mcrit.
What are the effects of compressibility?
The effect of air being compressed onto a surface resulting in an increase in density and thus dynamic pressure rises above its expected value.
What changes the aircrafts angle of attack at the stall?
The movement of the centre of pressure point at the stall causes a change in the aircrafts angle of attack.
What happens to the stall speed at very high altitudes?
Mach number compressibility effect on the wing results in a higher EAS. Compressibility error on the IAS increases the stall speed.
What is a super stall?
It is a stall from which the aircraft is unable to recover.
What is Dutch Roll?
It is an oscillatory instability. It is a combination of yawning and rolling motions.
What causes Dutch Roll?
Swept wings.
What are the three purposes of spoilers?
Roll control, air speed brakes, ground lift dumpers.
What are Kruger flaps?
Krueger flaps are leading edge wing flaps used to increase the wing camber.
How does the use of flaps affect take off ground run?
A higher flap setting within the take off range will reduce the ground run required.
What is the purpose of yaw and roll dampers?
To prevent Dutch Roll and coordinate turns.
What are the four reasons for a variable incident tail plane?
To provide a balancing force for a large CofG range, cope with large trim changes, provide balancing force for a large speed range and reduce elevator trim drag.
What is a mass balance?
It is another form of aerodynamic balance control on a control surface.
What are active controls?
A surface that moves automatically/actively in response to non-direct inputs.
What is engine torque?
A force causing rotation.