The Irbitis I-1 "Spriditis", powered by a 25-h.p. three-cylinder Anzani engine

The I-2 "Ikars" two-seater, powered by a 45-h.p. Anzani;

The I-9 was based on the experience gained with the I-5.

Te Irbitis I-4.

The I-5 was developed from the I-2, but was powered by a 77-h.p. Siemens & Halske Sh.5 engine;

The I-18 developed from the I-8.

The I-6 had folding wings with considerable sweep-back;

The I-8 was stressed for aerobatics and was powered by an Armstrong Siddeley "Genet" engine.