Lilienthal's glider (3D)
About this app
Normal soaring apparatus of 1894: fly centre of gravity, profile and glide ratio yourself, up to the 1896 crash.
With explain mode: an AI tutor walks you through the app, points out what matters in the scene and answers your questions.
Steering with the body
From 1891 Otto Lilienthal made at least 2,000 gliding flights. His Normal Soaring Apparatus, built in series from 1894 as the first production aircraft, was a hang glider with a 6.7 m span, about 13–14 m² of wing area and a mass of about 20 kg, made of willow and cotton fabric. It had no control surfaces: the pilot hung by his forearms in the frame and shifted his centre of gravity. Weight forward lowers the nose, and the glider gets faster and steeper. Weight back slows it down until the angle of attack becomes too large and the flow separates. Such a stall after a gust caused his fatal crash at the Gollenberg on 9 August 1896.
What the app shows
The app reconstructs the glider in 3D from its documented main dimensions and launches it from the 15 m Fliegeberg in Lichterfelde or from the Gollenberg. Simplified longitudinal dynamics compute position, speed and pitching from a model polar. Arrows show lift, drag and weight, and the flight path stays visible as a track. Live values show airspeed, angle of attack, glide ratio, glide angle and sink rate. The polar compares the cambered profile with a flat one, and a reconstruction re-enacts the 1896 accident in a factual way.
What you can try
Shift the centre of gravity with the slider, the arrow keys or by dragging the pilot, even in mid-flight. In neutral posture the model glider covers about 69 m at a glide ratio of about 1 : 4.6. Move the centre of gravity far back and the flow separates, so the glider falls although its nose is up. Fly a cambered and a flat wing side by side, add a headwind or switch to slow motion to follow the stall closely.
Frequently asked questions
- How did Otto Lilienthal steer his glider?
- Only by shifting his body’s centre of gravity. He hung by his forearms in the frame and swung his legs and hips forward or back. This moved the centre of gravity relative to the wing’s centre of pressure and changed the angle of attack, speed and glide angle. The tail surfaces were fixed.
- Why does a cambered wing lift more than a flat one?
- The camber deflects the air further downwards and tilts the air force forwards. For the same drag it produces clearly more lift. Lilienthal measured this on a whirling arm and published it in 1889 in “Der Vogelflug als Grundlage der Fliegekunst” (Bird Flight as the Basis of Aviation).
- What is a stall?
- If the angle of attack becomes too large, for cambered wings from about 14°, the flow separates from the upper surface. Lift collapses, drag rises, and the aircraft drops although its nose is up. Without enough height the flight can no longer be recovered.
- How accurate is the simulation in the app?
- The glider’s main dimensions are documented; the flight physics are simplified longitudinal dynamics with a model polar and an assumed pilot mass of 80 kg. Distances and speeds are model values, not historical flights. The Gollenberg terrain and the gust and centre-of-gravity position in the accident are marked as a schema.
Subject: Physics experiments (Deutsches Museum)
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