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These topics will be presented both from a pilot's perspective ("What are the implications of this for flying the airplane?") and from an engineer's perspective ("How do we design an airplane that can do this better? Might that make the airplane worse in some other way? How can we come up with a design that balances and optimizes these competing needs?") so as to shed as much light as possible into how every kind of airplane is designed the way it is: from single-engine recreational airplanes to airliners and fighters, today and throughout history. Things like the materials and configuration of the structure, the shape and moving parts of the wing, the size and gearing and compression ratio of the engine, etc., are all carefully chosen in different airplanes whose different missions require different compromises between these factors.
Full list of topics to be covered:
1: Lift (Wings)
- How wings work
- Multiple ways to think about (i.e. to model) the mechanisms behind lift generation: Bernoulli, Euler-N, Coanda, Newton's 3rd Law
- Dynamic pressure and the relationship between air density (temperature and altitude), airspeed, and aerodynamic forces. Pitot tubes and indicated airspeed.
- Understanding the stall; when and why it happens, how to delay and manage it. The CL-versus-alpha curve.
- High-lift devices (flaps, slats, Krueger flaps, slotted flaps, flaperons), slots, vortex generators, VG strakes, vortilons
2: Drag
- The four types of drag and the various airplane design practices and features used to minimize them:
- Viscous drag and boundary layers; Laminar Flow Control,
- Pressure drag and separation; VGs, golf-ball dimples, teardropping as function of Reynolds Number
- Induced drag and wingtip vortices; Aspect ratio, elliptical lift distribution, winglets and raked wingtips
- Wave drag and the “sound barrier”; thin swept wings, supercritical airfoils, gradual changes in cross section
- Will we have supersonic transports again someday?
3: Thrust (Engines)
- The different kinds of aero engines and their components
- Optimizing engines for efficiency
- Jet engines: Inlet, compressor, combustor, turbine, nozzle (Brayton cycle)
- Higher compression means higher efficiency but also higher temperatures, heavier engines, and slower max speeds. Where is the "sweet spot"?
- Turbofans (wider engine ➯ higher efficiency), thrust reversers
- Pros & cons of electric and solar airplanes, hydrogen fuel cells
4: Weight (Structures)
- Airplane loads: Pressurization, bending from lift & weight
- Materials technologies and selection: steel, aluminum, titanium, carbon fiber, honeycomb
- How to select the optimal material to resist tension with the lightest weight. Other criteria: costs, temperatures, corrosion...
- Selecting the optimal shape to resist bending with the least material: The key for stiffness is "height" (depth, thickness).
- A tour of modern airplane structures: Frames, longerons, stringers, ribs, spars, skins, bulkheads... and the building block of airplane structure, the stiffened panel
- The future of composites/laminates
- How structural fatigue & damage tolerance determines maintenance and when each airplane should be retired
- How flutter (aeroelasticity and resonant frequencies) determines the max safe speed
5: Balance & Stability
- Balance: Relationships between the forces from the wing and tail fins relative to the location of the Center of Gravity
- Pitch stability, decalage rule: Why the horizontal tail fins must be at lower angle of incidence than the wings
- How the above factors determine the size of the tail fins
- Advantages & disadvantages of canards and of flying wings / blended wing bodies / tail-less designs
- How the vertical tail fins provide yaw stability
- How wing dihedral causes roll stability
6: Controls & Turns
- What all the control surfaces are and what they do: Ailerons, elevator, rudder, spoilers, flaperons, elevons...
- How the total lift force during a coordinated banked turn is split between a vertical component (1G) and a horizontal component (centripetal acceleration)
7: Performance: Takeoff & Landing, Climb, Engine-Out
- How required engine thrust is determined by the required capabilities for takeoff & climb in case of an engine failure
- How to determine the required runway length that will prevent an over-run even in case of an engine failure
- How the rudder size is determined by the need to overcome thrust asymmetry at slow speeds in case of an engine failure
- Landing gear design, sizing, and location
8: Performance: Cruise Speed, Altitude, Top Speed, Gs
- The Power Curve: The lowest-drag speed will be the best-glide and fastest-climb and longest-endurance speed, the speed closest to the lower right corner of the curve gives the best range (most miles per gallon)
- How cruise altitude is selected, why it goes up during a flight
- The causes of the limitations around the speed-altitude flight envelope: VNE/MMO, stall, max power
- How high can a given airplane fly? How fast?
- The limitations around the V-G (V-N) diagram: stall, VNE / MMO, structural failure. How tight can a given airplane turn?
9: Design & Sizing: Payload, Range, the Market, Cost
- How the useful load can be made up of various combinations of payload and fuel
- Payload-range diagrams, developing derivatives based on market needs, how to compare competing airplane models
- How to design an airplane that sells. How to balance fuel efficiency with development & manufacturing costs to minimize the overall lifetime cost of an airplane
10: Activity: Build and Test-Fly a Glider!
- Design and build wings that maximize lift and minimize drag
- Design and build tail fins, adjusting their size and angle so as to provide balanced, stable flight
- Quantify the “efficiency” (Lift to Drag ratio) of your glider by launching it and measuring its “range”
- Improve the efficiency by modifying draggy features
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The following additional topics are only covered in the 16-hour version of the course, not in the 8-hour version.
History
- Key aeronautical technologies: When, where, why, and by whom each technology was introduced
Lift
- Drooped wingtips as a STOL feature
Drag
- Diverters and splitter plates prevent fighter engines from ingesting boundary-layer air
- How to minimize wave drag for supersonic flight
- The pros and cons of forward-swept wings
- The pros and cons of variable-geometry swing-wings
- Spiroid winglets, minix wingtips, and wing grids
Engines
- Piston engines, the four-stroke cycle (Otto cycle)
- In-line, radial, rotary, and horizontally-opposed (boxer) engines
- Carburetors, turbochargers, fuel octane level, two-stroke engines
- Jet engine nozzles are shaped so that exhaust exits at atmospheric pressure.
- Supersonic airplanes with variable-geometry / converging-diverging nozzles
- Afterburners, thrust vectoring, ramjets, pulsejets
- Rockets-powered aircraft, human-powered aircraft
Structures
- Biplane wings and external struts - non-cantilever structure
- Wood-and-fabric truss structure and the transition to metal monocoque
- Fiberglass foam sandwiches as primary structure
Balance and Stability
- The dynamics of airplanes with high-mounted engines such as seaplanes; Power reduction causes the nose to rise, decreasing speed quickly!
- The unstable ground dynamics of taildraggers (airplanes with a tailwheel instead of a nosewheel), ground loops, why bushplanes are typically taildraggers
Safety
- Commercial air travel is incredibly safe, and getting even safer:
- Hull loss rate has fallen from one in ~50,000 flights (1960s) to literally one in a million
- Hull loss accidents are increasingly survivable
- This is due to industry and regulatory response to each accident: Understand the cause, and change airplane design and maintenance to ensure this problem does not happen again
- How the causes of accidents in small airplanes differ from those in jetliners
Latest Developments
- Appreciate that many exciting new aeronautical technologies are currently being developed:
- New fighter jets with unprecedented performance
- New airliners with extremely high fuel efficiency
- Rotorcraft with unprecedented speed and range
- Smart UAVs that can fly themselves and make decisions
- X planes testing high-efficiency and high-speed technologies
- New "spaceplanes"
- Safer small airplanes making it cheaper to learn to fly
Stealth Airplane Design
- Low visibility: Camouflage, and shade of grey to blend against sky as function of altitude (high-flyers are darker)
- Super-low-noise airplanes
- Evading infra-red sensors: Flattened exhausts, emissive paint
- Radar absorption: RAM and carbon ferrite
- Radar cancellation: "Dirty Bird" U-2s, re-entrant triangles, active cancellation
- Radar reflection, the real key to stealth: Flattened fuselages, aligned edges, no right angles, non-constant radii, flat facets, serpentine intakes.
Vertical Take-Off & Landing (VTOL) technologies
- Tail sitters
- Tilt-rotors (and tilt-wings and tilt-engines)
- Thrust vectoring
- Ducted fans
- Dedicated lift engines
- Hybrid rotorcraft and latest developments
Record-breaking airplanes
- The biggest and smallest airplanes
- The fastest airplanes
- The highest-flying airplanes
- The longest flights ever
- The most efficient airplanes
Aerobatics
- Doing a roll, step-by-step: What is required? How do we know if a given airplane could do it?
- Doing a loop, step-by-step: What is required? How do we know if a given airplane could do it?
- Related maneuvers: Split-Ss, Immelmans, Vertical 8s, Cuban 8s
- Sustained inverted flight, slow rolls, outside loops
- Spins, tailslides, torque rolls, tumbles/lomcevaks
- What could an airliner do? How do we know?
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