Estimation of component-wise drag coefficient and Planform Visualization of CG for Various Sub Components

The aim of this report, is to present an application of the preliminary design procedure followed in the course entitled “Airplane design(Aerodynamic)”. A 150 seater jet airplane cruising at M = 0.8, at 11 km altitude and having a gross still air range(GSAR) of 4000 km is considered.

Taper ratio is 0.3 for all Wing, Horizontal Tail and Vertical Tail.

Nacelle Flow Interference Factor (Q)
Flow interference factor Q is usually between 1.03 and 1.06.In this case it is assumed to be 1.03 for all the components.

Total Drag Coefficient
Total drag coefficient is the addition of all the CD0 values of the respective components.

Total CD0= 0.014398347 Excrescence Drag
Excrescence Drag is usually considered to be 1% of the total drag coefficient.So, we multiply CD0 by a factor of 1.01 to get the total drag.

Limitations:
The current Cdo-total of the aircraft does not account for the landing gears and flap deflection.Also, the value of density and dynamic viscosity is assumed to be at the cruising altitude of 11000 m (36000 ft) and the aircraft velocity is at cruising speed that is, 0.85 Mach.Pylons are not considered in this calculation because they account for very insignificant drag value as compared to the nacelle.So, increasing the nacelle drag by a bit was a better option to compensate for the pylons.The drag due to the anti-shock bodies is not considered.

INDUCED DRAG
Induced Drag Factor k is calculated as follows: From this Formula, e= 0.87 But as the planform shows, there are winglets present which decrease the induced drag by 5-10%.
Therefore, the final efficiency factor after considering the winglets will be slightly more than the calculated one.
Assume that due to winglets there is a 7.5% increase in efficiency factor e.
New efficiency factor e= 0.87+0.075*0.87=0.936.The value of CD 0 is slightly on the side because the size of aircraft is very large.The value is still under the acceptable limits for the provided amount of thrust.

Nacelle
t/c= 0.127 i.e Aerofoil has 12.7% thickness.Nacelle is assumed to be a cone with Diameter 3.6 m and Length of 7.2 m.Wetted area is calculated according to the surface area of cone.Multiplied by 2 since it's a twin-engine aircraft.Average Skin Friction Coefficient (CF)Average skin friction coefficient CF for any aircraft component like wing, fuselage, nacelle etc. is a function of Reynolds Number.Form Factor (k)Wing/Horizontal Tail/Vertical Tail Angle-29.7 o xt= Chordwise distance in meters from leading edge to max thickness point on MAC.

Mass of Operationally Empty Aircraft = 255152.394 lbs CG of Operational Empty Aircraft = 104.984068 ft =105 ft Operationally Empty Mass from Previous Session = Empty Mass + Associated Crew Mass =101000+8940 kg= 109940 kg= 242376.195 lbs Percentage Difference in Both Values = 5% i.e ACCEPTABLE Percentage Fraction of Component to Operationally Ready Empty Aircraft Operationally Ready Empty Weight = 255152.394 lbs
• Empty Weight and Operationally Ready Empty Weight are different.Empty Weight does not have the Associated Mass added due to the cabin crew.• Technology factor of 0.75 has been used to scale down the component weight found from databases like Roskam, Nicholai, Raymer who have used metal as the base material unlike now when more advanced light weight composites are used.• Slight manipulation in extra mass has been done to keep it under the acceptable limit.• Number of Cabin Crew = 22 • Amenities' weight has been assumed for a long-haul flight (Transatlantic Flight) with 4 meals and drinks with some extra snacks.