Volga inflatable airlock
볼가 팽창식 에어록
An inflatable airlock mounted on hatch No. 3 of Voskhod 2 that enabled extravehicular activity (EVA) without depressurizing the entire cabin. Designed and built in just nine months at Factory No. 918 in Tomilino near Moscow, it deployed from a folded 74 cm package into a 2.5-meter double-walled fabric tunnel pressurized by about 40 airbooms. After Alexei Leonov's historic first spacewalk, the airlock was jettisoned before reentry.
In depth
Design Rationale
Voskhod 2's avionics used vacuum tubes requiring constant air cooling, so the cabin could not simply be depressurized as on the American Gemini. Weight limits also precluded carrying enough nitrogen and oxygen to replenish the cabin atmosphere after an EVA. OKB-1 under Sergei Korolev therefore adopted the unprecedented solution of an external inflatable airlock.
Structure
The Volga airlock consisted of a 1.2 m metal ring fitted over Voskhod 2's inward-opening hatch No. 3, a double-walled fabric tunnel deploying to 2.5 m in length and 1 m in internal diameter, and an upper metal ring holding the 65 cm outer EVA hatch. The fabric tube was made rigid by about 40 airbooms (informally called "dutiki" in Russian), grouped into three independent sections, and any two sufficed for deployment. Full inflation took seven minutes. Four spherical tanks supplied oxygen for boom inflation and airlock pressurization. Two lights illuminated the interior, and three 16mm cameras (two inside, one boom-mounted outside) recorded the historic spacewalk.
Operation
Commander Pavel Belyayev controlled the airlock from inside Voskhod 2, while a backup control panel hung inside the airlock on bungee cords for Leonov. Once Leonov entered Volga, Belyayev sealed the inner hatch behind him and depressurized the airlock; Leonov then opened the outer hatch and pushed out to the end of his 5.35 m umbilicus. After the EVA, the airlock was cut loose with pyrotechnic bolts and discarded.
Test Flight
Three weeks before the crewed launch, the uncrewed Kosmos 57 was launched on 22 February 1965 and successfully tested the Volga airlock's opening, closing, and re-pressurization. However, two ground stations simultaneously transmitted commands that triggered the self-destruct system, destroying the spacecraft. With no backup test vehicle and a one-year lead time for a replacement, Voskhod 2 proceeded as scheduled.
Sources
- Wikipedia (EN) Voskhod 2 article detailing Volga airlock design specs, 40 airbooms, 9-month development, and operational sequence
- Wikipedia (EN) Kosmos 57 article confirming the Volga airlock test flight and its self-destruct
- Wikipedia (RU) Russian-language article with technical parameters: folded dimensions 70 cm diameter × 77 cm length, deployed 1.2 m diameter × 2.5 m length, mass 250 kg
- russianspaceweb.com Anatoly Zak's Russianspaceweb.com: detailed Volga airlock assembly at Factory No. 918, 40 dual-layer resin tubes in three independent groups, 7-minute inflation, backup controls on bungee cords
- airandspace.si.edu Smithsonian National Air and Space Museum article explaining the engineering rationale for the inflatable airlock: air-cooled avionics prevented cabin depressurization