Zenit- 2 & Zenit-3

  Diameter: 3.90 m, Structure: Skin-stringer, Material: Aluminum
  Diameter: 4.10 m, Structure: Honeycomb sandwich, Material: Graphite-epoxy face sheets over aluminum honeycomb
  Diameter: 4.10 m, Structure: Monoque sandwich;  Material: Composite. Conical base (2.10 m) Aluminum ?
  Diameter: 4.10 m, Structure: Monoque sandwich;  Material: Composite. Conical base (2.40 m) Aluminum ?