So what are the important things to consider while defining the configuration of aircraft.
What are the important aspects of configuration concept?
1. Wing design.
2. Payload accomodation.
3. selection and arrangement of propulsive system
4. Arrangement of lift generating surfaces
5. Arrangement of control surfaces
6. placement of undercarriage.
Also there should be a way to test all this improvements that we promish with better configurations.
This can be done with DOC- Direct Operating Cost. This is of two variant for civil aircraft.
1. DOC for passanger aircraft.
cost /(Eb *np)= €/km/pax
2. DOC for cargo aircraft.
cost / (Eb* mp)=€/km/kg
Eb= range*nf
nf= total number of flights
range= the range of the flight
mp= mass of payload
np= number of passanger
For the Range we should know the formula.
the more popular formula for the range is Breguet Formula, which is:
R= 1/(SFC*g)*v*Ca/Cd*ln(Wstart/Wend)
where the formula composes of 3 different parts
1. Aerodynamics=Ca/Cd*v
2, Propulsion= 1/(SFC*g)*v
3. Structure= ln(Wstart/Wend)
Now we need to understand that the different criteria for an aircraft configuration are interconnected.
if we try to improve one quantity another quantity is affected and so on.
if we increase the aspect ratio of the wing to reduce induced drag.-> this increases the structural weight.
if we increase the bypass ratio of the engine for better propulsive efficiency -> this increases the structural weight and also interference drag.
if we improve the radar signature of the aircraft by suitable shaping -> this reduces the maneuverability and flight performance.
So all the points are interconnected and we should be careful in changing such characteristics.
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