The Basics & Derivation of Lift Flashcards
What is newton’s first law?
a body will continue in rest or motion unless acted on by an external force
What is newton’s second law?
the rate of change of momentum of a body is proportional to the applied force, and takes place in the direction in which the force acts
what is newtons third law?
to every action there is an equal and opposite reaction
In a stationary body it is … that is a measure of its resistance to change
mass
In a moving body it is … that resists change of motion
momentum (mass x velocity)
work done is…
force times the distance moved in the direction of force
power is …
the rate of work done
Energy of a moving body (kinetic energy) is proportional to …
mass times velocity squared – 1/2MV(squared)
boyles law…
at fixed temp increasing pressure will decrease the volume and thus increase density
Charles’s law …
at fixed pressure increasing temp will increase volume and thus reduce density
Pressure law …
at fixed volume increasing temp or pressure will increase the other factor
Air density is roughly half the sea level value at … (653 g/m3) and a quarter the sea level value at …
20 000ft
40 000ft
formula for mass flow through a convergent duct =
area x speed x density
equation of continuity =
(flow through convergent duct)
K = A x V x Rho
K is a constant
Symbol for dynamic pressure?
Q
equation for dynamic pressure?
½ x rho x Vsquared
How does dynamic pressure vary with speed?
proportional to the square of the true airspeed
density decreses with increasing altitude so to maintain lift at altitude what must increase?
TAS
V in the lift equation must increase because density has reduced but all other factors in the equation remain equal
Lift is defined as the component of the total reaction acting … to the relative airflow, and in level flight is the force supporting the weight
perpendicular
what is an indication of 1/2 rho Vsquared?
IAS
what is the lift formula?
CL x 1/2Rho x Vsquared x S
what is CL formula?
lift / 1/2Rho x Vsquared x S
Thickness of a wing is often defined as a …, usually expressed as …
thickness/chord ratio
a percentage of the chord
compared to symmetrical aerofoils, a cambered aerofoil will have a greater CLmax and critical alpha will …
decrease

