Full variable-geometry wings — as on the American F-111 or the later MiG-23 — are heavy and complex, with pivots buried near the fuselage and elaborate structure to carry the loads. Sukhoi could not justify that cost simply to fix the Su-7’s field performance. So the design bureau placed the pivots partway out along the wing, leaving a large fixed inner glove and swinging only the outer sections. The moving panels are lighter and the fixed inner wing still carries the landing gear and pylons.

The trade-off is that a part-span swing wing gives less of a change in overall sweep and area than a full one, so the aerodynamic benefit is smaller. But it was cheap, robust and good enough: takeoff and landing distances fell sharply and payload and range improved, all on an airframe that shared much of its tooling with the Su-7. It is often cited as a textbook example of a pragmatic engineering compromise.

Unlike a fully automatic swing wing, the Fitter’s outer panels are set by the pilot to suit the phase of flight — broadly spread for takeoff, landing and low-speed manoeuvre, and swept for high-speed flight. Sources describe both selectable fixed positions and intermediate settings across the roughly 30°-to-63° range. Because only the outer panels move, the change in total wing area is modest compared with a full variable-geometry design, so the Fitter is best understood as a fast strike aircraft with much-improved field performance rather than an agile dogfighter.

The confusion of designations reflects Cold-War export policy. The Su-17 was the domestic Soviet version. The Su-20 was an early, somewhat downgraded export model. The Su-22 covered the main export families, some with the Tumansky R-29 engine and simplified avionics and others — like the Su-22M4 — close to the Soviet standard with the Lyulka AL-21F-3. NATO gave the whole family one reporting name, “Fitter,” with letter suffixes (Fitter-C, -G, -K and so on) for individual variants.

Like other Soviet combat aircraft, the Su-17/Su-22 was a state product supplied to allies and clients on political and barter terms rather than sold on an open dollar market, so no firm flyaway unit price exists in the public record. Export deals were bundled with training, spares and credit arrangements that make any single figure meaningless. No credible cost-per-flight-hour number exists in open sources either. Any precise dollar figure attached to a Fitter should be read as an estimate, not a sourced fact.