A brief history of aviation
-Balloons, dirigibles, gliders, failed attempts. Wright, Dumont (what a record means), Blériot, Curtiss. Records. Airliners. WW1. Bombers, fighters. Air races. Metal and cantilever. Seaplanes. WW2. Jets. The sound barrier. Swept wings. Stealth. Materials. Computer control. Spaceplanes.
Science behind design
The 4 forces: origins, basic physics/aerodynamics, components of each, how to maximize or minimize them:
-1) Weight (and density) – weight is bad for range, speed, altitude, efficiency…
-2) Lift – airfoils, camber & crest, pressure, air down = plane up, changes w speed & density, Euler-N & Bernoulli.
-3) Drag – parasite and pressure – most obvious – sonic and induced – less obvious. Pointy planes, swept wings, high aspect ratio, smooth surfaces, teardropping. Cruise speed.
-4) Thrust. Engines: in line, radial, rotary, (then back to in line), turbojet, turbofan, turboprop, ramjet, and miscellaneous (time allowing): rocket, pulsejet, electric, man-powered…
Control: Pitch, roll, yaw. Elevators, ailerons, rudders. Exceptions (V-tails, drag rudders, elevons, wing-warping, differential thrust, RCS, hang gliders, powered chutes, thrust vectoring, canards). Trimming (center of lift moves back. Fuel pumping in REAL sleek planes).
Stability: Pitch. Balance of moments. CG forward with respect to surfaces, so engines forward, wings back, tail way back (that means nose-down, so how do you get a nose-up to balance? Low engines, tail pushes down). Fly-by-wire, fighters, computers, the Shuttle (and why it probably crashed). Roll stability, dihedral.
The Envelope: Min t-off to max speed at sea level (low end). Slow end: less air, less viscosity and less loading mean higher alpha and easier stall. Fast end: less drag and same thrust till you climb till all air is used (Stoich.), then less thrust cuz less air, so less speed until you’re both stalling and maxing the engines. Compare envelopes. 747. Cessna. F-22. Osprey. HH-60.
Performance, ratios and angles
- Wing Aspect Ratio
- Wing Loading, biplanes
- Wing Sweep
- Thrust to Weight – Lift to Drag – Glide slope
- Lift distribution, Twist/washout (vortices & tip stall), Taper
- Noise (engine, turbulence)
- Features (winglets, flaps, slats, VGs, spoilers, variable geometry, thrust reversers, landing gear)
- Exceptions in controls, engines, and layout – exotic airplanes.
A More Technical History
Early days – bad engines – slow flight – LIGHT planes – little material, thin – LOW loadings and stresses or else they break. (Wright, Dumont, Bleriot, Fokker Triplane, Curtiss, Vickers Vimy).
30’s – much, much better engines and lighter, more precise metal work means A) Faster planes and B) More robust planes and in consequence C)heavier planes (a few times heavier, on average). So no need for wires and struts. Cantilever wings. Enclosed canopies for faster, higher flight. (Gee Bee, T-6, P-36, Me109, Ford Trimotor, Macchi/Supermarine racers, Boeing 314, Vega/NYP)
40’s – even better engines – even faster – possibly even heavier – even more robust – more agile, or more load / more range. (P-47, Spitfire, DC-3, B-29, Connie, Sea Fury)
50’s – Jets. Sound barrier. Swept wings. MUCH more robust planes. Much higher drag. Temperature becomes an issue. Stubby wings set back for agility, or swept high-aspect-ratio wings for range. (Me262, F-80, F-86, F-100, F-102, B-58, F-104, B-47, 707, SR-71).
All the stuff AFTER this in nowhere near that important, and has mostly military applications, except of course for the turbofan.
By 1960, jets were aerodynamically equivalent to modern jets. So the 60s experimented with spaceplanes and rockets, with insanely fast planes, and with cold war bombers and interceptors. (Lifting bodies, X-13, X-14, F-4, B-52, 747, MiGs)
70’s – Stealth, computer control, turbofans. (F-16, F-117, Shuttle, F/A-18, HiMAT).
80’s – Light materials for everyone (Rutan planes, ultralights, gliders)
90’s – computers for everyone (777, next-gen fighters, manufacturing)
Late 90’s / Early 00’s – Spaceplanes. Everyone wants satellites, no one wants to pay for an ICBM. Hypersonic ramjets. Also, cheaper general aviation. Kitplanes, ULs, etc. Anyone can become a pilot. (X-33, Roton, X-40, X-47, RVs, WAR replicas, ULs, powered parachutes (since 007 The World is not Enough), trikes…)
So now, planes are lighter, stronger, safer and cheaper than in the 60’s, but look the same and are not any faster. So all the advances since then allowed us to build the same planes, but better (compare fuel consumption of, say, 747 and F-104, or 777 and 707, or F-22 and a century-series jet, compare weights of 777 and 707…). Then, the NEXT generation: Thrust vectoring, F-22 and 777 engines (and structures), sonic cruiser, ramjet to space (or to Japan), UAV’s.
Notice how progress is always driven by the desire to make use of a more powerful (or efficient) engine or of lighter/stiffer materials. Engines and materials are what allow airplanes to become better. And aerodynamics, to a smaller extent, but mainly only during some periods of innovation.