What part of the Viggen folds for storage?

The part that folded was the vertical stabilizer: an actuator allowed it to be folded down so the aircraft could be stored in smaller hangars, hardened shelters, and underground hangars. The latter were used by the Swedish army to limit damage from pre-emptive strikes.

The landing gear followed an equally tight logic: the legs shortened during retraction. In climb rate, the Viggen went from 0 to 10,000 m (33,000 ft) in one minute and forty seconds.

Development of the Medway engine was cancelled because the de Havilland Trident, the aircraft meant to introduce it, was downsized during its development. Instead, Saab adopted a licensed production version of the American Pratt & Whitney JT8D, the Volvo RM8.

Saab built a total of 651 Drakens. By the mid-1980s, the Swedish air force's Drakens had largely been replaced by the more advanced JA 37 Viggen fighter.