This accessory pack contains all the component parts for mounting one or two 24 mm D and E engines in BT-55, 60 and 80 body tubes. Included are:

• 30052 – Large Diameter Laser Cut Centering Ring (qty. 1)
  This BT-80 body tube centering ring set is laser cut from heavy duty cardstock and allows the model rocket builder the option to insert a single 4 in., BT-50 motor tube into a much larger diameter body tube.
   
• 30132 – Small Diameter Laser Cut Centering Ring (qty. 1)
  This BT-60 body tube centering ring set is laser cut from heavy duty cardstock and allows the model rocket designer and option to insert a 4 in., BT-50 engine mounting tube in a BT-60 diameter main rocket body tube.
   
• 30166-2 – AR-5055 Green Adapter Ring (qty. 4)
  Two spiral wound green rings are glued at marked locations on the 4 in., 24 mm engine mount tube and allow for proper centering of a single 24 mm, C11, D12 or E12 Estes model rocket engine in a BT-55 size body tube.
   
• 30164-2 – AR-2050 Green Engine Block (qty. 3)
  This spiral wound green paper motor tube engine block is glued into one end of the 4 in., 24 mm engine mount tube. However please note on the detailed instructions included with this accessory pack, the distance from the end of the 4 in. engine motor tube that the engine block is glued is dependent on if the designer is going to use a 24 mm C11 or D12 engine or if 24 mm E12 engine are planned for. In either case, installation of the engine block creates a positive stop when glued in front of the engine hook, which keeps the engine from pushing up through the main rocket body at ignition and during the thrust phase of launch.
   
• 30368 – BT-50 Engine Mounting Tube (qty. 3)
  These BT-50 Engine Mounting Tubes are the key component to providing the necessary thrust to lift a single egg to 800 ft. in a TARC competitive model rocket. Each tube is cut to 4 in. in length and when assembled with an engine block, engine hook, engine hook retainer and the appropriate centering ring size, TARC teams can explore the potential lifting limits of their rocket design.
   
• 30480 – Black Engine Hook Retainer (qty. 2)
  This special, spiral wound black paper tube is glued to the outside of the BT-50 engine mounting tube to securely hold the pre-bent, metal E engine hook in place.
   
• 35005 – Spacer E to D (qty. 1)
  This orange colored spiral wound paper spacer is used when converting from a more powerful 24 mm, 3 ¾ in. length E12 series engine to a less powerful and shorter 24 mm, 2 3/4 in. length C11 or D12 engine.
   
• 35021- D Engine Hook (qty. 1)
  This engine hook is bent from a mild, but durable steel and is used with an engine hook retainer to hold 24 mm C11 and D12 size engines in a BT-50 spiral wound motor tube for the ignition and ejection phases of launch. The hook is not recommended nor will it work with our 24 mm, 3 3/4 in. long E12 size engines.
   
• 35022- E Engine Hook (qty. 1)
  Pre-bent from a mild, but durable steel, this engine hook and is used with an engine hook retainer to hold 24 mm E12 size engines in a BT-50 spiral wound motor tube at ignition and during the thrust phase of launch. This hook will also work with our 24 mm C11 and D12 engines by placing an orange colored D to E spacer in the engine mounting tube before inserting a shorter length Estes C11 or D12 engine.