Other designations or related variants include — I-3: I-3P, I-3U, I-380, I-400; I-7: I-7D, I-7K, I-7P, I-7U, I-410; I-75: I-75F.
Production/Prototype Quantities—All aircraft were testbeds and were built in quantities of one each or were modified from earlier airframes.
Cockpit—All I-3, I-7, and I-75 series aircraft were single-place designs w/ejection seat. Controls were conventional stick and rudder. Cockpit instrumentation was conventional w/analogue round dials. Canopies primarily were of organic glass w/aluminum support frames. All three variants utilized bubble-type canopies (I-75 utilized faired-bubble) hinged at their forward end and opened pneumatically.
Fuselage—All I-3, I-7, and I-75 series aircraft utilized conventional aluminum, stressed-skin construction. Essentially circular cross-section. All aircraft utilized circular, nose-type inlet. Each had a large intake spike for airflow and shockwave modulation. Spike was hydraulically actuated and adjustable per mass flow requirements and shock position. It is assumed that the forward half of each intake spike was dielectric, thus permitting installation of radar. Empennage area served as mounting point for slab-type horizontal stabilators and conventional swept vertical tail and rudder.
Lifting and Control Surfaces— I-1 wing sweep angle 55°; I-3U wing sweep angle 60°; I-7U wing sweep angle 55°; I-75F wing sweep angle 55°. Slab-type horizontal stabilator provided pitch moment only. All control surfaces were hydraulically actuated. Flaps were two-position Fowler designs. All three basic variants had one wing fence per wing.
Landing Gear—All three variants equipped w/hydraulically retractable tricycle gear. Main gear retracted inward toward aircraft centerline. Nose gear retracted forward into well built into space between bifurcated intake tunnel. I-3U and I-7U appear to have utilized early version of MiG-21-style articulated main gear wherein the main wheel and tire assemblies remained perpendicular during the retraction process and were stored in their respective wheel wells, accordingly. I-75 main gear retraction process was influenced by lever-type design.
Miscellaneous Equipment—Radar and related guidance and control equipment all optimized to operate w/in the Uragon ground control intercept (GCI) environment. Radar thought to be of Izumrud family.
Powerplant/Fuel-I-1: one 11,464 lb. (5,200 kg.) th. VK-7F; I-3U: one 18.519 lb. (8,400 kg.) th. VK-3; I-7U: one (8,400 kg.) th. AL-7F; 1-75F: one 18.519 lb. (8,400 kg.) th. AL-7F-1.
Armament—I-1: one 37 mm. machine gun and two 23 mm. machine guns; I-3U: two 30 mm. machine guns and four rocket launchers; I-7U: two 30 mm. machine guns and four rocket launchers; I-75F: two air-to-air missiles.
Length-I-3U: 53 ft. 8 in. (16.73 m.); I-75F; 54 ft. 5 in. (16.96 m.).
Wlngspan-I-3U: 29 ft. 9 in. (9.3 m.); I-75F: 31 ft. 11 in. (9.97 m.).
Wing area—I-3U: 279.83 ft. 2 (26 m.2); I-75F: 335.8 ft.2 (31.2 m.2).
Gross welght -I-1:14,991 lb. (6.800 kg.); I-3U: 20.327 lb. (9.220 kg.); I-7U: 17.527 lb. (7.950 kg.); I-75F: 25.091 lb. (11.380 kg.).
Max. speed @ s.l.—unknown.
Max. speed—I-1: 808 mph (1,300 km/h); I-3U: 1,218 mph (1,960 km/h); I-7U: 882 mph (1,420 km/h); I-75F: 1,429 mph (2,300 km/h).
Rate of climb—I-3U: 2 min. 24 sec. to 48,125 ft. (15,000 m.); I-75F: 2 min. 0 sec. to 32,083 ft. (10.000 m.).
Service celling—I-1: 54,541 ft. (17,000 m.); I-3U: 57,749 ft. (18.000 m.); I-7U: 61.279 ft. (19,100 m.); I-75F: 67,374 ft. (21,000 m.).
Max. range—I-1; 1,553 mi. (2,500 km.); I-3U: 1,118 mi. (1,800 km.); I-75F: 1.243 mi. (2,000 km.).