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Aviation History
1965
1965 - 0172.PDF
104 ••tan.; i '965 Slanting rays of the northern winter sun and the reflections from the photographic Lansen's canopy accentuate the bizarre silhouette of the Draken's double-delta wing SAAB DRAKEN in the Air . . . Pilot and attendant groundcrew illustrate the Draken's compactness. The man at left is detaching the refuelling hose from the socket in the star- board wheel-well. Main undercarriage legs are splayed outwards sharply swept double delta plan-form with elevon control surfaces is a major feature, particularly in an aircraft used for training relatively inexperienced pilots. The potential handling problems are considerable, and appear even more so when one first hears about the potentialities of "back of the drag curve" flying, super stall and a completely linear control-gearing and spring-feel system. The three-axis autostabilization loops of the Lear autopilot are used all the time, although the aircraft can be flown "raw." Instructors joke of the pitch oscillations induced by pilots unaccus- tomed to the type, and it is not unknown for such oscillations to become sufficiently severe to slightly injure the pilots, but this can easily be avoided by letting go of the stick and allowing the auto- stabilizer to damp the aircraft. All J35As and subsequent versions now have a non-linear feel spring which increases stick force near the centre point, leaving a relatively low force at the larger deflections used in supersonic flight. Draken controls are in any case optimized for supersonic flight, and the aircraft is not unnecessarily difficult for pilots accustomed to modern intercepters. Although the Draken has ample stall warning in the form of high- frequency buffet at high speeds and a tell-tale lateral wobble at low speeds it is possible, if either symptom is ignored, to enter a super stall condition during which the aircraft may perform any evolution from a stable nose-up descent to compound pitching and rolling at up to 2|g. The super stall has been investigated in all flight conditions by Saab test pilots and the recovery technique is to apply full forward stick as the nose pitches down, to rock the aircraft into a steep dive. Although well understood, the super stall will not be demonstrated during training until the new explosively ejected tail parachute is fitted to the Sk35C. At present, an average of four or five pilots in each Wing have experienced and recovered from the condition. During my two sessions in the simulator, without the physical sensations of actual flight, I inadvertently entered four or five super stalls in various attitudes, but I found that the actual aircraft with its perfectly distinct g and buffet background was altogether less Sensitive. Continued on page 105
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