The powered aeroplane
Add an engine and propellers to a controllable airframe, keep weight and balance inside limits, and fly only proven, inspected designs with trained pilots.
Everything for this step
- Field guide
- Flight → 8 sections
- Builds
- None yet.
- Reference sheets
- 2 sheets on this page ↓ · 5 sheets in Flight
- Sciences it rests on
- Physics · Engineering
- Track
- In the air, level 4 of 6 · next: Jets, helicopters and air traffic control
Why this matters
On 17 December 1903 the Wrights' powered machine flew 120 ft (37 m) in 12 seconds, and later that day 852 ft (260 m) in 59 seconds (National Park Service). It worked because wings and control were solved first; then they built an engine of about 12 hp when no light enough engine existed, and propellers from their own theory that came within 1 % of the thrust they calculated.
The shape of it
- Power against weight: an engine light enough for the power it gives.
- Propellers designed as rotating wings.
- Weight and balance inside the envelope on every flight.
- Controls tested and learned before power is added.
- Oxygen above 12,500 ft.
- Proven designs only, inspected; pilots trained.
Doing it, step by step
The summary above says what has to happen. This says how, with the numbers that decide whether it works.
1 — The 1903 machine
From the National Park Service's account (handbook):
- Span 40 ft 4 in (12.3 m), wing area 510 sq ft (47.4 m²), camber 1 in 20, length 21 ft 1 in (6.4 m), 605 lb (274 kg) without the pilot.
- The engine sat on the lower wing right of centre, and the pilot lay prone left of centre to balance it; the right wing was 4 in longer to carry the engine's extra 34 lb.
- Elevator in front; twin movable rudders behind, linked to the wing-warping.
- First flight: 120 ft in 12 s at an airspeed of about 30 mph (48 km/h) into a strong wind, darting up and down because the elevator was over-sensitive. Fourth flight: 852 ft in 59 s.
2 — Power against weight
The Wrights asked engine makers for 8–9 hp weighing no more than 180 lb — 20 lb per horsepower, about 12 kg per kW — and nobody could supply it. Their own engine gave 15.76 hp at 1,200 rpm in its first 15 seconds, settling to 11.81 hp at 1,090 rpm (National Park Service).
- Power needed = drag × speed. Measure the airframe's drag in the tunnel, add a margin for climbing, and choose the engine from that.
- The engine itself: the engine.
3 — Propellers are rotating wings
No theory of the air propeller existed, so the Wrights worked one out, treating each blade as a wing turning in air that is also moving forward (National Park Service).
- Their propellers turned 66 % of the engine's power into useful work, and gave within 1 % of the thrust they had calculated.
- Two pusher propellers about 10 ft apart turned in opposite directions — one chain crossed in a figure of eight — so their twisting forces cancelled.
- Each was three laminations of spruce, 1⅛ in thick, glued and shaped with a hatchet and drawknife.
4 — Weight and balance, every flight
Every aircraft's flight manual gives a maximum weight and a range of balance positions (FAA, Pilot's Handbook of Aeronautical Knowledge).
- Overweight: stall speed rises with the square root of weight, so 20 % heavier stalls about 10 % faster; take-off is longer and climb weaker.
- Balance aft of the limit: unstable in pitch, and it may not recover from a stall.
- Balance forward of the limit: the elevator may not raise the nose to land.
- Weigh fuel, people and baggage, work out the balance, and check it is inside the envelope before every flight.
5 — Height and the body
- The rule (US): the crew uses oxygen above 12,500 ft for any part of a flight longer than 30 minutes, and always above 14,000 ft; above 15,000 ft everyone aboard must be given it (14 CFR 91.211).
- Hypoxia gives no warning you can trust. Without oxygen the time of useful consciousness is about 3–5 minutes at 25,000 ft and 30–60 seconds at 35,000 ft (FAA).
6 — Proven designs, inspected; pilots trained
This site gives no construction procedure for an aeroplane that carries a person. The recognised route for a home-built aircraft is a proven design built from its designer's plans or kit, with more than half of the work done by the builders, every stage recorded and inspected (FAA AC 20-27G), followed by a period of test flying before anyone else is carried. Learn to fly at a school first.
Reference sheets
One drawn sheet covering the whole subject at once — the breadth a photograph cannot give, bought at the cost of accuracy. Read them for range and vocabulary, never as the thing you identify from.