Shastas Rocket Site
Polecat Rocketry

4″ Goblin

Description

The Goblin 4″is a small but versatile high power rocket. Capable of flying well on F and G hobby motors, it makes a great entry level rocket. The Goblin 4″ can be used for L1 and L2 certifications. It has a 54mm motor mount and will support motors up to 4 grain K reloads. The Goblin is a very tough and fun rocket designed with both the beginner and expert in mind.

Additional Information

  • Through the wall fins
  • Fiberglass molded nose cone
  • Pre-fiberglassed and pre-slotted body tube
  • Baltic Birch fins and centering rings
  • 54mm motor mount
  • Tubular nylo shock cords
  • Shock cord mounting hardware
  • This kit is designed to fly on motors ranging from F through K impulse. A 24″ to 36″ parachute is needed depending on motor selection and landing conditions.

Instructions

Photo Gallery

Build History

  • 03/30/2008 – Purchased Polecat Rocketry 4″ Goblin from Nocturnal Knight Rocketry for $80.00 (Retail – $89.95)
  • 06/08/2008 – Cut motor mount tube to 7″ so the U bolt would extend beyond the end when the centering rings wer positioned to the length of the forward end. Epoxied forward centering ring with 30 minute epoxy and positioned the U-bold forward. Filleted the forward centering ring joint. Mounted aft centering ring to motor mount tube without epoxy. Epoxied motor mount assembly into body tube. Epoxied 2 of 4 fins to motor mount tube with 5 minute epoxy.
  • 06/09/2008 – Removed aft centering ring and epoxied fins to motor mount. Filleted 2 fins at joints.
  • 06/10/2008 – Filleted remaining fin joints with 30 minute epoxy/
  • 06/19/2008 – Epoxied aft centering ring in place with 30 minute epoxy. JB Welded 54mm retainer on aft end of motor mount.
  • 06/20/2008 – Filleted aft ring to body tube with 30 minute epoxy.
  • 06/21/2008 – Filleted all external fin joints with 5 minute epoxy.
  • 06/06/2009 – Painted fins and body tube John Deere Yellow and nose cone Black. Masked all but on fin and painted it Gloss Black and later removed masking tape.
  • 07/22/2009 – Applied upscaled Goblin water slide decals to the fins and applied a piece of black electrical tape to body tube. This completes construction of 4″ Goblin.

Flights

  1. 03/07/2010
    1. Location – Sim’s Farm (TRA1)
      1. Motor – I117FJ
        1. Maiden flight. Great flight for about 100 feet then a beautiful loop de loop several times and landing on the ground before the ejection charge went off. Later in the day realized I had used the wrong (lighter) nose cone.
  2. 12/11/2010
    1. Location – Sim’s Farm (BS46)
      1. Motor – I229
        1. Ejection did not ignite and whistling rocket was buried up to the fins. Model material for the bone yard.
  3. 11/09/2013
    1. Location – Sod Farm (BS73)
      1. Motor – E9-6
        1. CATO. Propellant blew through the body tube pushing out the recovery device and leaving the rocket undamaged.
      2. Motor – E9-6
        1. Great flight. Went too high even with a streamer recovery. Lost it and my good yellow streamer in the corn field.
  4. 05/02/2015
    1. Location – Sod Farm (BS93)
      1. Motor – F29
  5. 09/13/2015
    1. Location – Sod Farm (BS97)
      1. Motor – F16-8
        1. Under-powered. Flew Horizontal about 50′ above ground level.
      2. Motor – F36 BS
        1. Long walk to recovery. ~15″ short of landing in Bean Field East of Launch site.
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