Key equations and terms Flashcards
Relationship between VT and VE
Vtas^2rho=Veas^2rho0
Best Cl
sqrt(cdo/K)
Taper ratio equation
3/2 Cr (y+1)/(y^2 +y + 1)
How to stop divergance?
Less aerofoil slope, reduce b, reduce c, move spans to increase 2nd polar moment of area, stiffness, ac and elastic axis closer
Volume box equation
dftcr
Thurst equation
= mdot(ve-vi)+(pe-pi)Ae
thurst and power equation
T=(p*efficiency)/v
Changing power at altitude
Pslpalt^2=Paltpsl^2
wing - > aerofoil coefficents
/0.95 /0.9
typical values for taper ratio and twist
0.3 -1.5 degrees
Piston engine, propellor or jet?
propellor
Vtip static ^2
vtip^2-Vc^2
w
vtipstatic*2 / Df
w -> N
60/ (2*pi)
Best L/D
tangential intersection from (0,0)
What unit should dCl/da be in?
radians
Why do we calculate load factor
To measure the severity of an manoeuvrer
What is the equation for load factor
L/W
Is an Electric engine prop or jet
prop
What is the disadvantages of electric engines
Batteries add weight and limited duration
disadvantage of parasole wing
adds additional weight
disadvantage of mid wing
has to cut through fuselage
disadvantage of low wing
gets heat and disturbed air of the runway but ground effect means its easier to take off.
Lowest drag wing combination
medium wing
Where do we want the aircraft gravity centre to be
close to the wing
Why is elliptic lift distribution what everyone aims for
Least drag for given span
aerofoil of tail needs to be [2]
symmetrical, less thick then wing
pusher engine why?
wings have clean air but then engine doesnt
puller
engine has clean air but then wings don’t
centripetal force
m v^2 / r
what is a spoiler
used in landing for reducing lift (secondary control decide)
in steady pull up, circular acceleration acts inwards or outwards
outwards
Breguet range eq
-V/c L/Dln(Wf/Wi)
linear matching plot equations
jet take off prop maximum speed
disadvantage of having more wings
more interference/ vortices
how to pick setting angle
the angle of attack at the cl ideal
what do you want cm to be
as low as possible
cli what
minum drag
dihedral what
improve stability
anhedral
improves roll manvourvability, especailly when its stable
how to you choose aerofoil
max lift coefficent for point but doesnt matter if its less
for lifting line theory what two things need to be true for it to be passable
Cl needs to be more than required and shape of graph need to be alliptal- highest point in the middle
cr and ct
ct=y*cr
ramjet
SuperJet engine, have to use it when its already going
under wing location what
clean air, decrease bending stresses, get debris going in the runway
why more engines
safer
why t tail
out of the flow at stall
why twin vertical tail
high directional controls
what is a Cruciform Tail
in the middle between t and convention
what are the two types of static aeroelastity
divergence and control surfaces reversal
what is the only type of dynamic aeroeleastity
flutter
What causes flutter
resonance speed of wind
