The MK3A Rebel kit comes in a long, corrugated box. Inside the box are thirteen components of the kit, several printed sheet and the water-slide decal sheet.. The rocket uses standard "BT-60" size body tube and a 24mm tube for the motor mount. The kit also contains an 18" plastic parachute kit, 2 screw eyes and a Kevlar shock cord. This is where the similarity to old style low power rocket kits ends. The rest of the kit parts are all 3D printed pieces.
The fin can and motor mount assembly have five pieces plus a spacer for 70 mm or 95 mm long motors.
One of my favorite design elements is the faux nozzle that doubles as the motor retainer. This eliminates the steel engine hook and makes it easy to swap out a used motor to quickly fly again. The launch lug is printed into the fin can. This design is very robust and improves the appearance.
The conical nose cone is also 3D printed. The nose is much heavier that a typical plastic nose cone of similar size. This is on purpose. The nose was made to weigh around 1 oz (28 g) to allow for the use of larger motors with out the need for additional nose weight. There is a small starter hole on the base of the nose cone where a screw eye is inserted for the Kevlar shock cord to attach.
The last 3D printed piece is the tube coupler/baffle system. This piece contains a baffle system printed into it. This unique feature eliminates the need for protective materials that prevent the parachute from melting due to the hot ejection gasses. The baffle system contains several chambers which collect the hot ejection particles and allow the gasses to cool before they can melt any components of the recovery system. The coupler has the upper launch lug printed into the unit to improve the overall look of the rocket.
Finally, the kit contains a large exploded view of the component assembly, a large, full color finishing guide, assembly instructions, launching instructions and a sheet of water slide decals.
Overall there are many unique design features that the 3d printing process allows to be added to the kit. The appearance of the pieces is slightly layered with a somewhat rough texture. The surface imperfections can easily be filled with thinned wood filler or squadron putty.
In part 2 of this blog series, I will begin the assembly of the MK3A Rebel.Mark