ISA
What is the approximate air density at 5500m altitude?
Approx. half of density at sea level: 1.225/2=0.6125kg/m3 (exact value= 0.5694)
What is the slope of the CL-αlpha curve of a flat plate?
2pi.
Name four types of aircraft engines.
Turbojet/Turbofan, Rocket Engine, Combustion Engine, Turboprop.
Name the formula for Aspect Ratio.
AR = b2/Sref
On what date will the EvV1 exam take place in 2026?
March 4th, 2026.
Name the four main gases of which the atmosphere consists of.
Nitrogen, Oxygen, Argon, Carbon-Dioxide
What is the Reynolds Number and name the formula.
It’s a nondimensional parameter that compares inertial to viscous forces and predicts laminar & turbulent flow (Re=(ρ⋅V⋅l)/μ).
Define SFC and SEP.
Specific Fuel Consumption and Specific Excess Power.
What is a Canard Airplane and what does Canard mean?
Canard is French for duck, the aircraft have their horizontal stabiliser in the front (forewing).
Would a reindeer sleigh fly more in the subsonic or supersonic range?
Sure Subsonic - otherwise presents gone ☹
How does the true airspeed change if an aircraft climbs with constant Mach number?
TAS decreases as speed of sound decreases (M=v/c) (at least until Tropospause)
What is the critical angle of attack?
The specific angle at which a wing first experiences a large loss of CL and rise of CD due to flow separation.
Name the limits in an aircraft’s flight envelope.
Structural, Service Ceiling, Stall Limit.
Where does stall occur first when having rectangular wings?
Near the wing root.
Grandpa asks at Christmas: “How can you fly a sailplane, what do you do when there suddenly is no wind anymore?”
You pour Grandpa another glass of wine and tell him about Thermals and why wind is not useful.
How do Density, Pressure and Temperature vary with increasing height?
1.Pressure ↓ (exp.), Density ↓ (exp.), Temp. ↓ (linear until Tropopause)
Which aerodynamic function do winglets have?
Reduce edge vortices → less induced drag → lower consumption
How does the flight altitude influence the generated thrust?
Decreases due to lower air density and mass flow rate.
What percentage of a jet airliner’s MTOW is approximately empty weight?
Around 40%.
Grandmother asks at Christmas: “How can an airplane ever fly upside down? Does it not generate lift downwards then?”
You pour Grandma another glass of wine and tell her about lift generation through AoA and control devices.
Tropopause (weather): ~10km, Stratopause (ozone layer): ~45km, Mesopause (meteors burn within): ~80km
Why are symmetrical airfoils rarely used in commercial aircraft construction?
Curved profiles generate more lift with the same drag.
What defines the aircraft performance in an OEI case?
One-Engine-Inoperative: Engine Power, Controllability, remaining Range, Take-off is critical.
Why do short-range aircraft like the A320 typically have a smaller aspect ratio than long-range aircraft like the A350?
Missions: LR longer cruise flight (high AR→less Cdi), Weight: high AR → high WRBM → higher mass: for LR this pays off for fuel savings over long distance, Airport infrastructure (SR: ICAO Code C, b<36m) (A320 AR=~9.5, A350 AR=~10.4)
Why does fuel drip from the SR-71 when it is on the ground?
In extreme temperatures in flight (Mach 3+) titanium structure expands considerably → the gaps and joints at the fuel tanks only close completely at operating temperature