Post on 13-May-2017
AERODYNAMIC DESIGN
HIGH SPEED SUBSONIC BUSINESS JET
What is a “Business Jet”?“Business jets are turbojet aircrafts weighing less than 100,000 pounds maximum gross Takeoff weight, with wingspans less than 100 feet that are used by companies to conduct their business” [GAO (Government Accountability Office USA), August 2007].
Motivation for the topicIn today’s corporate world long unexpected intercontinental flights are unavoidable. Though a luxury high speed private jets like our’s are the only solution.
It can also be used by sports persons, cases of medical emergencies etc
Mission Requirements ➔ Intercontinental(long range)
lightweight medium sized Business Jet
➔ High comfort of passengers
Technical Specification➔ 10 passengers(executive
arrangements)➔ 4 crew (Pilot, Co-Pilot and 2 flight
attendants)➔ Cruise Range 11000km➔ Cruise Mach no : 0.9
Mission Profile
First Weight Estimate
Second Weight Estimate
Third Weight Estimation
Criteria➔ Maximum CL/CD
➔ Maximum CL
➔ Maximum stall angle
➔ Minimum drag➔ Minimum
moment coefficient
Suitable airfoils➢ NACA 64(3)-618➢ NACA 64(4)-421➢ NACA 63(4)-421➢ NACA m9
NACA 64(3)-618• High Maximum lift coefficient• Very low drag over the range of operating conditions
• Optimized for high speed
GEOMETRY
FUSELAGE DESIGN
FUSELAGE
WIDTH = 2.4 m● 2 seats abreast● 0.7 m executive seat ● 0.8 m aisle width● 0.2 m pressure
cabin structure
LENGTH = 27 m
● Empirical relation● Coefficients from
plots
WING GEOMETRY
Wing Area (93.7 m2) ● From gross weight and wing loading
Aspect Ratio = 7.5
Wing span(26.51 m)● using wing area and AR
Taper Ratio (0.2)● to be efficient● reduction in root bending moment● decrease the structural weight
Sweep Angle(34o)● To delay Drag Divergence Root chord length = 5.89 m
Tip chord length = 1.178 m
TAIL GEOMETRY
The T-tail configuration
This is mainly to avoid the interference of the flow from aft mounted engine interfering with the tail.
Horizontal Tail Vertical Tail
Volume Coefficient 0.95
Aspect Ratio 5
Area 25.8
Span 11.38
Root chord length 3.03
Tip chord length 1.517
Volume Coefficient 0.0855
Aspect Ratio 1.2
Area 17.48
Span 4.58
Root chord length 4.08
Tip chord length 3.616
CONTROL SURFACES➔ AILERON● span =10.604● chord length =0.7068➔ RUDDER● span =4.12● chord length =1.335➔ ELEVATOR● span =10.24● chord length =0.796
STRUCTURAL LAYOUT
3D DIAGRAMS
Front View
Top View
Side View
Power Plant Selection
Engine SizingCriteria
➔ T/W Take-off = 0.269
➔ WO = 27094.28 kg➔ Max Thrust req = (36099.89 * 2) N
Aircraft Powerplant Maximum Thrust Bypass ratio
Cessna Citation X Rolls-Royce AE 3007 30 KN 4
Gulfstream G550 Rolls-Royce RB.183 Tay
62.8 KN 3.04
Citation longitude Snecma Silvercrest 49 KN 5.9
Dassault Falcon 200lx Pratt & Whitney Canada PW308C
28.6 KN 4.2
Bombardier Challenger 850
General Electric CF34-3B1 turbofans
42 KN 6
Engine Sizing
After Sizing➔ Length = 2.44m➔ Max Diameter = 1.11m➔ Dry Weight = 626.8 kg
Inlet➔ Pitot inlet is used taking advantage of
the transonic flow-->RAM EFFECT➔ Vanes are provided at inlet to induce a
vorticity which helps in compression➔ Inner lip radius is greater than outer lip
radius, useful for high angles of attack and sideslip
➔ The capture area was found to be 0.3 m^2
Drag Polar❖ Equivalent Skin Friction method➔ Cd0 using wetted area➔ e using sweep angle and aspect ratio
❖ Component Build up method➔ component form factor➔ component interference factor
Induced Drag➔ Leading edge- suction method
Drag Polar
Trim AnalysisTrim -> Obtained from equilibrium equations for forces and moments.
The trim obtained is subjected to stability analysis
Stability Analysis➔ The trim is subjected to small
perturbation analysis and the constraints for CG wrt Neutral Point is obtained (SM--Static Margin)
➔ The most aft location of CG is found to be 14.64m corresponding to a SM of 0.23 .This also determines the maximum elevator deflection.
CG Estimation
CG calculations➢ Approximate
Group Method Xcg = 15.86 m Zcg = 2.35 m
➢ Statistical Group Method
Xcg = 14.32 m Zcg = 2.5 m
Landing Gear - Tricycle/Nosewheel
➔ Stable design➔ Less demanding
on the pilot➔ Small angle of
attack➔ Better visibility
over the nose
FLAPS - SLOTTED FOWLER TYPE➔ Increased chord length➔ Slot to delay flow separation
Difficulties faced in Design
Suggestions for improvement
Winglets Noise Reduction - Nozzle redesign
Fuel Tank
Are the design requirements met?
Flight PerformanceThrust Required at cruise 10.38 kN
Vmin (Tr) 238.93m/s
Min Thrust required at cruise 10.152 kN
Vmin(Pr) 181.55m/s
Minimum Power Required at Cruise 2.13 MW
Max Range 13461 km
Sustained Turn Rate 3.51o/sec
Take Off distance 533.56m/s
Total Landing Distance 842.754m
Flight Performance
Long Range 11,000 km
Medium Size
Compact Geometry
Light weight 27,094 kg
Comfort