Aircraft Design and Optimisation
Bombardier
Challenger 650
Initial Estimation of Thrust to Weight ratio (T/W) and the Wing Loading (W/S) of a Business Jet
Contents
01
Aircraft Overview
Baseline specifications and fundamental parameters
02
Thrust-to-Weight Ratio
T/W calculation and comparative analysis
03
Wing Loading Analysis
W/S calculation in metric and imperial units
04
Thrust Matching
Cruise analysis and aircraft sizing validation
05
Stall Speed Verification
CLmax calculation and takeoff configuration
06
Takeoff & Landing
Distance analysis and field performance
07
Climb & Turn Performance
Rate of climb and maneuverability metrics
08
Design Validation
Key insights and performance summary
Praveen Tiwari
Aircraft Overview
Maximum Takeoff Weight
Metric
21,315 kg
Newtons
209,100 N
Imperial
46,991 lbs
Wing Reference Area
Metric
45.4 m²
Imperial
489 ft²
Engine Configuration
2 × GE CF34-3B Turbofans
Each rated at 41 kN thrust
Total Installed Thrust
82 kN
Fundamental Design Parameters
T/W
Thrust-to-Weight Ratio
Section 5.2
Formula
T/W = TSL / W0
Determines climb performance and acceleration capability
Critical for takeoff field length requirements
Higher values enable steeper climb angles and better obstacle clearance
Business jets typically require higher T/W than commercial transports
W/S
Wing Loading
Section 5.3
Formula
W/S = W0 / S
Influences stall speed and landing distance
Affects cruise efficiency and fuel consumption
Lower W/S improves altitude capability and ride quality
Business jets often use lower W/S for enhanced performance
Design Context: These two parameters form the cornerstone of preliminary aircraft design. They are interrelated and must be balanced to achieve optimal performance across all flight regimes - from takeoff and climb to cruise and landing. The Challenger 650's design reflects careful optimization of both parameters for its business aviation mission profile.
Abhishek Lakhera
Thrust-to-Weight Ratio Calculation
Calculation
Parameters
Total Installed Thrust:
82,000 N
MTOW:
209,100 N
Takeoff
T/W = 82,000 / 209,100
T/W = 0.392
Comparative Analysis
Challenger 650
0.392
Jet Transport (Typical)
0.25
Difference
+56.8%
Design Implications
Superior Climb Performance
Higher T/W allows steeper climb angles, reducing time to cruise altitude
Short Field Capability
Enhanced acceleration and obstacle clearance for operations at smaller airports
Mission Flexibility
Business jets prioritize performance over pure efficiency, for diverse operational scenarios
Dantu Phani Surya (22AE30006)
Cruise
T/W = 1/(L/D) = 1/12.75
T/W = 0.0784
Wing Loading Analysis
Calculation in Unit Systems
Metric System
Formula
W/S = W0 / S
Substitution
= 209,100 N / 45.4 m²
Performance Benefits
Lower wing loading enables higher cruise altitudes, improving fuel efficiency and ride quality
Better maneuverability and control during approach and landing phases
Lower wing loading provides smoother ride in turbulent conditions
Raymer Reference: Table 5.5 indicates typical jet transport W/S of 120 lb/ft². Business jets like the Challenger 650 operate with lower loading to maximize altitude capability and passenger comfort.
Priyangshu (22AE10048)
Wing Loading (W/S)
4,606 N/m²
Significance : This reduced loading enhances performance by improving altitude capability for more fuel-efficient cruise, providing a smoother ride in turbulent air, and supporting superior low-speed handling for operations at smaller airports.
Comparative Context
Challenger 650
96.1
lb/ft²
vs
Jet Transport Typical
120
lb/ft²
Difference
-19.9%
Lower Loading
≈ 96.1 lb/ft²
Thrust Matching: Cruise Analysis
Cruise Conditions
Altitude
37,000 ft
(11,277 m)
Cruise Speed
Mach 0.80
(235.7 m/s)
L/D Ratio
12.75
Cruise Weight
~97%
of MTOW
Estimated Cruise Weight: 202,827 N
Thrust Required Calculation
Raymer Equation
Substitution
= 202,827 N / 12.75
Cruise Thrust Required
15,908 N
Sea-Level Equivalent Thrust
Thrust Lapse Ratio: High-bypass turbofans at 35,000+ ft typically produce only 20-25% of sea-level rated thrust
Calculation (using 0.25 thrust lapse ratio)
Equivalent Sea-Level Thrust Required
63,632 N
Validation Result
Installed Thrust
82,000 N
Cruise Requirement
63,632 N
Margin
+28.9%
Ganjare Aavishkar (22AE30010)
Stall Speed Verification
Source Data
Stall Speed (Takeoff Configuration)
145 kt
= 74.6 m/s
CLmax Verification
Raymer Equation 5.6
Vstall = √(2(W/S) / ρCLmax)
Solving for CLmax
CLmax = 2(W/S) / (ρ × V²stall)
= 2(4,606) / (1.225 × 74.6²)
= 9,212 / 6,817
Maximum Lift Coefficient
CLmax ≈ 1.35
Configuration Analysis
CLmax ≈ 1.35 Interpretation
This value suggests the 145 kt stall speed corresponds to a clean or low-flap takeoff configuration, not maximum lift configuration
Typical CLmax Values
Clean configuration:
1.2 - 1.5
Takeoff flaps:
1.6 - 2.0
Landing flaps:
2.0 - 2.5
Operational Significance: The verified CLmax value confirms the aircraft's stall characteristics align with expected performance for a business jet in takeoff configuration, validating the design's low-speed handling qualities.
Sanjeev(22AE30011)
Takeoff Distance Analysis
Takeoff Parameter (TOP) Calculation
Raymer Equation 5.9
TOP = (W/S) / (σ × CLTO × T/W)
Assumptions
CLTO (takeoff flaps):
1.6
σ (sea level):
1.0
Substitution
= 96.1 / (1.0 × 1.6 × 0.392)
= 96.1 / 0.627
Takeoff Parameter
TOP ≈ 153
Ground Roll Estimate
Raymer Figure 5.4 Reference: For twin-engine jet with TOP = 153
Estimated Ground Roll
~2,500 ft
(~760 m)
Source Data Comparison
Source Specification
1,720 m
(5,643 ft)
Source value represents Balanced Field Length (BFL) - the critical decision speed where accelerate-stop distance equals accelerate-go distance with one engine inoperative
BFL Components
1
Ground Roll
Lift-off distance
2
Safety Margins
Engine failure scenarios
3
Obstacle Clearance
35 ft screen height
Conclusion: The difference between estimated ground roll (760 m) and source BFL (1,720 m) reflects regulatory safety requirements, not performance discrepancy.
Jenish Patel (22AE30014)
Landing Distance Evaluation
Distance Definitions
Landing Ground Roll
Distance from touchdown to full stop using brakes and thrust reversers only
FAR 23 Landing Distance
Total distance from 50 ft obstacle height to full stop.
The Landing distance modeled by Raymer for FAR23 landing. (Raymer Equation 5.1)
Raymer’s Model
Where,
(W/S) : is the Wing Loading at the Landing
: is the ratio of density
: is the maximum Coefficient of Lift
: is the Obstacle Clearance Distance [for Business Jet (General Aviation) = 600 ft]
Dheeraj (22AE30009)
Landing Distance Evaluation
Dheeraj (22AE30009)
Source Data
Landing Distance (Source)
732 m
2,400 ft
Assumptions
Landing Weight:
85% MTOW
(W/S) Landing:
0.85 x 96.1 = 81.7 lb/ft²
CLmax (full flaps):
2.2
Sa (approach):
600 ft
Calculation
= 80(81.7)(1/2.2) + 600
Estimated Landing Field Length
~ 3,571 X 0.66 (Thrust Reversal) ~ 2357 ft
(~ 718 m)
= 2,971 + 600 = 3571 ft
Calculations For Bombardier Challenger 650
Calculated (Using Raymer’s Model)
Landing Distance
718 m
2357 ft
Rate of Climb & Turn Performance
Rate of Climb
Specific Excess Power Method
(Derived from Raymer Eq 5.28)
Assumptions (Sea Level)
Climb Speed:
170 kt (87 m/s)
L/D :
12.0
T/W :
0.392
Calculation
= 87(0.392 - 1/12)
= 87(0.309)
Rate of Climb
26.9 m/s
(~5,290 ft/min)
Turn Rate
Sustained Turn Rate Formula
Assumptions (Cruise)
Turn Load Factor:
2g (60° bank)
Cruise Speed:
236 m/s
Gravity:
9.81 m/s²
Calculation
= 9.81√(4-1) / 236 = 9.81(1.732) / 236
Turn Rate
0.072 rad/s
(4.1°/s)
Performance Validation: The high thrust-to-weight ratio of 0.392 underpins the Challenger 650’s strong climb performance (26.9 m/s) and its competitive turn capability (4.1°/s). Together, these characteristics reflect a design well suited to business aviation missions that demand rapid climb to cruise altitude and enhanced operational flexibility.
Kumar Ashmit Ranjan(22AE30016)
Key Insights &
Performance Summary
Superior T/W
0.392
56.8% higher than typical jet transports, enabling exceptional climb and field performance
Optimized W/S
96.1
Lower wing loading enhances altitude capability and ride quality for passenger comfort
Validated Design
100%
All performance calculations confirm design optimization for business aviation missions
The Bombardier Challenger 650 exemplifies business jet design philosophy - prioritizing performance, flexibility, and operational versatility. Every calculated parameter validates the aircraft's capability to execute diverse missions while maintaining the highest standards of safety and efficiency.
Meet Raju Meshram (22AE30019)
Image Sources
https://www.aerotime.aero/articles/bombardier-challenger-australia
Source: aerotime.aero
https://bombardier.com/en/aircraft/challenger-650
Source: bombardier.com