 Lavochkin's proposed missile, the G-300 utilized a guidance system based on vacuum tubes and was so heavy (about 1,000 kg (2,200 lb)) that no fighter in the Soviet arsenal could carry it.Instead, a Tupolev Tu-4 bomber (Soviet version of the Boeing B-29 Superfortress) was modified to carry four G-300s under the wings, with the whole system receiving designation G-310.For all this trouble, G-300 was expected to have a range of only and a ceiling of .