Why Airplanes Look Like They Do - AOE - Virginia Tech

41 Pages·2009·1.69 MB·English

Why Airplanes Look Like They Do
W. H. Mason
Aerospace and(cid:1)
Ocean Engineering(cid:1) collage from John McMasters
slide 1(cid:1)
9/4/09(cid:1)
(cid:1) A new capability
(cid:1) Technology
someone might
advances?(cid:1)
pay to have?(cid:1)
Designer(cid:1)
How to exploit
(cid:1)
technology for
capability?(cid:1)
Configuration
Concept(cid:1)
Airplane Shapes Have Changed to(cid:1)
Exploit Advances in Technology(cid:1)
Aerospace and(cid:1)
Ocean Engineering(cid:1)
slide 2(cid:1)
9/4/09(cid:1)
Configuration Concept:(cid:1)
• Payload(cid:1)
• Lifting surface arrangement(cid:1)
• Control surface(s) location(cid:1)
• Propulsion system selection(cid:1)
• Landing Gear(cid:1)
Wright Brothers:(cid:1)
• (cid:1) Innovative control concept (cid:1)
(cid:1) (more important than stability)(cid:1)
• (cid:1)“Light weight” propulsion(cid:1)
•(cid:2) Continual design evolution/refinement(cid:1)
Aerospace and(cid:1)
Ocean Engineering(cid:1)
slide 3(cid:1)
9/4/09(cid:1)
Basic Laws of Airplane Design(cid:1)
(cid:1)
• …
• Simplicity is the essence of true elegance—(cid:1)
- it can also save weight and/or reduce cost.(cid:1)
• If you can't build it, you can’t sell it.(cid:1)
• …(cid:1) from John McMasters, Boeing(cid:1)
Brewster P-33A (cid:1)
Example of an airplane
management decided was to
risky to build(cid:1)
courtesy Dr. George Inger(cid:1)
Aerospace and(cid:1)
Ocean Engineering(cid:1)
slide 4(cid:1)
9/4/09(cid:1)
Beauty is in the Eye of the Beholder(cid:1)
Aerospace and(cid:1) “Dream Airplanes” by C.W. Miller, (cid:1)
as shown in Fundamentals of Aircraft Design, by L.M. Nicolai(cid:1)
Ocean Engineering(cid:1)
slide 5(cid:1)
9/4/09(cid:1)
Good Aircraft(cid:1)
• (cid:1)Aerodynamically efficient, including propulsion integration (streamlining!)(cid:1)
• (cid:1)Must balance near stability level for minimum drag(cid:1)
• (cid:1)Landing gear must be located relative to cg to allow rotation at TO(cid:1)
• (cid:1)Adequate control authority must be available throughout flight envelope(cid:1)
• (cid:1)Design to build easily (cheaply) and have low maintenance costs(cid:1)
• (cid:1)Today: quiet, low emissions(cid:1)
Aerospace and(cid:1)
Ocean Engineering(cid:1)
slide 6(cid:1)
9/4/09(cid:1)
Themes in Design(cid:1)
• Efficient payload movement(cid:1)
• Speed/Maneuverability(cid:1)
• Field Performance(cid:1)
The NASA/Grumman Research Fighter Configuration(cid:1)
Aerospace and(cid:1)
Ocean Engineering(cid:1)
slide 7(cid:1)
9/4/09(cid:1)
Key Technologies(cid:1)
• Aerodynamics(cid:1)
• Propulsion(cid:1)
• Structures(cid:1)
in the late 70s:(cid:1)
• Flight controls(cid:1)
in the 80s and early 90s:(cid:1)
• Systems/avionics/observables & Manufacturing(cid:1)
today:(cid:1)
• the design process - (includes MDO)(cid:1)
Amazingly Tricky to Integrate Advances in Each Technology(cid:1)
Aerospace and(cid:1)
Ocean Engineering(cid:1)
slide 8(cid:1)
9/4/09(cid:1)
Conventional Subsonic - A Baseline(cid:1)
• Payload distributed around cg
• Longitudinal control power from tail (with moment arm)
• Vertical Tail for directional stability, rudder for control
• Wing/Fuselage/Landing Gear setup works
• Minimum trimmed drag at
near neutral stability
Aerospace and(cid:1)
Boeing 747-400, source: www.boeing.com(cid:1)
Ocean Engineering(cid:1)
slide 9(cid:1)
9/4/09(cid:1)
Configuration Options(cid:1)
•(cid:2) Where do you put(cid:1)
–(cid:2) the wings?(cid:1)
–(cid:2) the engines (in fact, what kind?)(cid:1)
•(cid:2) Where do you put the control surfaces?(cid:1)
–(cid:2) what options are available?(cid:1)
•(cid:2) Do you have room for the landing gear?(cid:1)
•(cid:2) Possible innovative designs?(cid:1)
Aerospace and(cid:1)
Ocean Engineering(cid:1)
slide 10(cid:1)
9/4/09(cid:1)