Shastas Rocket Site

Cosmic Explorer (2)

ESTES Model #2421


Search the cosmos with the Estes Cosmic Explorer! This unique sport rocket has styling and power that’s BIG on performance. The Cosmic Explorer is an easy to assemble, high tech marvel on the launch pad. Powered with standard Estes engines, this adventurer can easily top the 1,000 foot level, then returns safely on a large 18 inch preassembled parachute.

This easy to build, Skill Level 1 rocket is over 2 feet tall! It features quality body tubes, a super big balsa nose cone, laser cut wood fins and easy to apply waterslide decals. This action-packed rocket is great for beginners who are looking for awesome, high altitude performance in a remarkably streamlined rocket!

Additional Information

  • Length: 24.0″
  • Diameter: 1.33″
  • Weight: 2.7oz.
  • Fins: Balsa
  • Recovery: Parachute
  • Decal: Waterslide
  • Recommended Motors:
    • B4-4, B6-4, C6-5


Photo Gallery

Build History

  • 12/27/2013 – Purchased Estes #2421 Cosmic Explorer from Estes for $3.29 (Retail $21.99).
  • 03/28/2018 – Took pictures of package and parts. Scanned parts and instructions.
  • 03/31/2018 – Measured and recorded components on page 20 Book #4. Marked motor mount tube at 1/2″, 1-1/2″ and 2-1/2″ from aft end. Made 1/8″ slit at 2-1/2″. Inserted hook end of engine retainer clip into slit. Glued retainer ring over clip up to 1-1/2″. Glued and filleted centering rings at 1/2″ and 2-1/2″ on engine tube. Modified location of aft centering ring to fit fin tab. Glued black engine block into forward end of tube. Glued motor mount assembly into forward end of body tube.
  • 04/01/2018 – Filleted aft motor mount tube centering ring joint. Glued tube coupler into body tube and glued fins into fin slots located in aft end. Filleted two of the four fin joints.
  • 04/02/2018 – Filleted remaining fin joints. Glued shock cord to mount and then 2″ inside forward end of body tube. Glued top body tube to lower tube with tube coupler.
  • 09/24/2019 – Sanded fin surfaces of balsa sheet and removed them. Rounded leading edges and tapered trailing edges. Measured motor mount tube @ 1″ & 2-1/2″ from aft end. Glued centering rings at these points and filleted both sides.
  • 09/25/2019 – Glued fins onto motor mount tube through body tube slots and filleted them. Glued and screwed Eye Screw into base of nose cone. Glued tube coupler to lower body tube and then to upper body tube.
  • 09/26/2019 – Glued shock cord to mount and then into upper body tube approximately 2″ from forward edge. Glued launch lug 4″ fron aft end of body tube along reference line. Filleted both launch lug joints with yellow glue.
  • 09/29/2019 – Spray painted white primer and epoxied fins to tail section.