Flying Model Rocket: Eris 1.2

Introducing the second in a series of 3D-printed model rockets: the Eris 1.2!

The Eris 1.2 is a flying model rocket designed to launch using 18mm model rocket motors, classes B through D. It utilizes a 1/8th-inch (3mm) launch rod. It attains altitudes ranging from approximately 600 to 1600 feet (180 to 490 meters), depending on the motor used and wind conditions.

Needed Materials:

PETG filament: Approximately 86 grams
A ~10 parachute for recovery; can be assembled using a cut-out from a plastic bag and string or purchased from most model rocket manufacturers (recommended)
A shock cord to attach the nose cone, fuselage, and parachute (~20in of thin tubular nylon or paracord OR ~25in of Kevlar, at least 100lbs-strength for safety)

Recommended Motors: Estes B6-4, C5-3, C6-5; Quest/Aerotech C12-6, C18-6, D16-8, D20-8W

Assembly Guide:

After printing the pieces, tie the shock cord to the upper recovery mount and the fore section of the fuselage. It is recommended to use eye screws to do this, but it is also possible to tie the cord into the cross-structure on the fuselage and glue it to the upper recovery mount. Next, glue the upper recovery mount into the tip of the nose cone. Then, glue the motor retainer mount to the aft end of the fuselage. Lastly, Tie the parachute to the shock cord near its halfway point. Glue with super glue (medium CA) or epoxy of any strength.

When ready to launch (also see below), insert the motor into the aft end of the rocket. Then, line up the motor retainer channels with the teeth on the motor retainer mount and push the retainer in as far as it will go. Lastly, twist the retainer such that the teeth lock into the channels. It may be necessary to sand the inside of the launch lugs, the motor retainer channels/teeth, or the motor mount depending on the quality of your print. The same goes for the nosecone.

NOTICES
The recovery system, motor, and launch system are not included. Without each of these, the rocket will be unable and/or unsafe to fly.

I am not responsible for any damages to property, individuals, or otherwise caused by failures of this product. Model rocketry regulations exist to prevent such damages, but there is still a chance of a failure of the rocket on any flight, in any conditions, for any reason.

IF YOU ARE NOT PLANNING TO FLY AT A SANCTIONED MODEL ROCKET CLUB, CHECK ALL LOCAL, REGIONAL, AND NATIONAL REGULATIONS ON THE USE OF MODEL ROCKETS IN YOUR COUNTRY.

America's National Association of Rocketry, as well as numerous model rocketry websites, guides, and manufacturers, have information about how to set up, safely launch, and recover flying model rockets. Search for these if you do not have a more experienced model rocketeer/rocketry club to help you.

These models are for FDM printing using PETG. They have only been test-printed on a Prusa Mini printer, and are designed to fit within its 7in-x-7in-x-7in (177mm-x-177mm-x-177mm) volume. The following settings apply when using PrusaSlicer; however, this rocket is not very dependent on the relative masses of its components, so as long as the nose cone and recovery mount have higher infill amounts than the fuselage, then there should be no issues with stability. Nothing less than 15%, or more than 30% is recommended or necessary.

Fuselage Settings:
0.2mm layer height
Vertical Shells: 2 perimeters
Horizontal Shells: 6 top solid layers, 4 bottom solid layers
Minimum shell thickness: 0.7mm top, 0.5mm bottom
Infill: 15% Gyroid
Overhang Threshold: 50 degrees
Supports: unneeded
3mm outer brim
Raft unnecessary

Upper Recovery Mount Settings:
0.15mm layer height
Vertical Shells: 2 perimeters
Horizontal Shells: 8 top solid layers, 5 bottom solid layers
Minimum shell thickness: 0.7mm top, 0.5mm bottom
Infill: 40% Gyroid
Supports: unneeded
Brim: unneeded
Raft unnecessary

Motor Retainer Mount Settings:
Same as the Upper Recovery Mount, except with a 2mm outer brim

Motor Retainer Settings:
Same as the Motor Retainer Mount, except with Snug Supports (top and bottom contact Z distance 0.2mm; Rectilinear pattern)

Nose Cone Settings:
0.2mm layer height
Vertical Shells: 2 perimeters
Horizontal Shells: 6 top solid layers, 4 bottom solid layers
Minimum shell thickness: 0.7mm top, 0.5mm bottom
Infill: 25% Gyroid
Supports: Snug (top and bottom contact Z distance 0.2mm; Rectilinear pattern)
3mm outer brim
Raft unnecessary