Transcript Powerpoint Viewfoil Template

The 797: Boeing’s
New Regional Jet
Lawrence Stewart
AA 241B
March 16, 2006
Design Requirements
 85 passengers
 Takeoff field length of 6,500 ft
 Cruise Mach number of 0.8
 Range of 1,600 nm
Similar, Existing Regional Jets
Bombardier CRJ900
Embraer 175
number of passengers
86-90
78-86
takeoff field length (ft)
5,833
5,689
cruise Mach number
0.8-0.83
0.82
range (nm)
1,350
1,800
MTOW (lb)
80,500
82,673
wing area (ft2)
738.7
SLS thrust per engine (lb)
14,255
14,200
41,000 (maximum)
30,000 (initial)
cruise altitude (ft)
Baseline Design Estimates
 MTOW = 81,600 lb
 Sref = 740 ft2
 SLS thrust per engine = 14,200 lb
 Later changed to 12,240 lb
 Initial cruise altitude = 30,000 ft
Baseline Design, Cross-section
Baseline Design, Cabin Layout
Baseline Design, Top View
Baseline Design, Performance
 Takeoff field length = 7,072 ft
 Second segment climb gradient = 1.29%
 Range = 2,047 nm
 Landing field length = 4,586 ft
Baseline Design, Summary Chart
No feasible region
Optimization Process
Takeoff field length
Second segment climb gradient
 Reduce the TOW
 Increase the SLS thrust per engine
 Increase the takeoff flap deflection
 Increase the AR
 Increase Sref
 Reduce the takeoff flap deflection
 Increase the SLS thrust per engine
 Reduce the TOW
Optimization Process, Continued
By hand:
 Reduce the TOW
 Increase Sref
 Increase the AR
 Increase the SLS thrust per engine
 Increase the initial and final cruise altitudes
Then, select all of the design variables except cruise Mach number
and iterate 2,000 times.
Final Design, Summary Chart
Sref = 675 ft2, MTOW = 77,394 lb
What Changed
Baseline Design
Final Design
81,600
77,394
740
675
9
10.35
SLS thrust per engine (lb)
12,240
12,325
initial cruise altitude (ft)
30,000
32,751
final cruise altitude (ft)
30,000
33,501
0.36
0.315
MTOW (lb)
Sref (ft2)
AR
wing position
Performance Comparison
Baseline Design
Final Design
takeoff field length (ft)
7,072
6,358
second segment climb
gradient (%)
1.29
2.52
range (nm)
2,047
1,705
landing field length (ft)
4,586
4,419
Final Design, Top View
Geometry Comparison
Lessons Learned
 You have to start somewhere
 Look at similar, existing airplanes
 Estimate initial parameters
 Airplane design is an iterative process
 Everything is a tradeoff
Future Studies
 Reduce noise
 Reduce emissions
 Composites?