3D printed Egg Capsule for Model Rocketry.

This Egg Capsule is for NRC (NAR) Egg lofting model rocket competition. Previously competition capsules were vacu-formed styrene capsules. Now these are harder to find. This approach offers an alternative that is very close in size with a manageable increase in weight.

GENERAL CONCEPT: The top and bottom 2 sections are hollow spheroids. Sized for a US grade A Large egg. A third optional smaller shoulder ring fits in between the two (2) top and bottom sections after the egg and foam. The bottom section has a small 18 mm extension attached to the end to hold in place a contest altimeter to report out the max altitude. 

PRINTING: Printed with PLA at 0.3 mm draft mode, suggest 5 - 15% infill to keep weight and printing time to a minimum. Bright filament color is suggested. These settings can be varied to suit your needs, preferences or experience level. Now I am trying out flexible TPU

PRINTER: I used a PRUSA MK3S+

BUILD NOTES: 

• Makers must ADD foam or bubble wrap to cushion the egg securely so that it does not rattle around in the capsule. 
• Two versions can be used for either an Egg Loft Duration or Egg Loft Altitude 
  • DURATION version:
• Print two (2) top sections and optional one (1) shoulder ring. One of the top sections will become the bottom of the Egg capsule. This needs two holes drilled to accept a piece of Kevlar cord. Foam, bubble wrap or equivalent is placed inside the capsules with the egg and shoulder ring. Lastly seal up with mylar tape or equivalent.
• Recovery use the largest parachute you can pack in the boost section rocket. Typically, these will have a length of shroud that allows a bigger chute
  • ALTITUDE version:
• Print the top section and the bottom section with the 18mm extension. This tube is open on both ends of the bottom or lower capsule. this allows your choice of many altimeters. I have connected so far, the FireFly,  FlightSketch, and MicroPeak altimeters with a short length of Kevlar and a longer length for the parachute. These are attached to a fiber or cardboard disk inside the lower capsule (Bot).
• IMPORTANT a minimum three barometric vent holes must be drilled in the cylinder extension tube for proper operation of the altimeter. Tie and secure your altimeter so that it can't fall out. 
• Lastly ADD by gluing a small length of 18mm coupler stock to connect to the lower 18 mm model rocket. The altimeter is inserted before the egg is sealed up. A layer of mylar tape over the halves is sufficient. 
• Recovery  a 15 in diameter min parachute is recommended. Connect the chute securely to the egg capsule with a kevlar\elastic shock cord. Some modelers use a length of elastic cord to reduce (absorb) the shock forces. You have the option of attaching the model rocket to the same egg capsule chute or using separate individual parachutes.

BOOSTER ROCKET: Important the Egg Capsule must be connected to a model rocket that has the Model Rocket engine (motor fins, launch lug etc. These items are not included. This capsule is designed to fit a variety of 18 mm kits or original rocket designs as typically designed and sold by Apogee, ASP, Custom Rockets, Estes, Quest, and other suppliers\vendors. 

RESOURCES: See www.nar.org for competition tips, competition rules, egg lofting categories, and information about altimeters for model rockets.

Finally have fun and be safe!