3D model description
This includes all the 3D printed parts to modify the Space Monkey V-2 1/24 scale model kit to make it launch on D or E engines.
You can see the model launching here on a D12-3 engine: https://www.youtube.com/watch?v=YxeI3T8m_L8
Adapting the model is quite easy and it flies great (I launch on D12-3 engines) and looks incredible (much more detail and scale accuracy than other models including the kit from Estes). The Space Monkey V-2 is currently selling on Ebay for around $30 for a pack of two shipped (yep, 2 complete rockets with shipping).
You will need to provide an 18" BT55 body tube as well as a shock chord and parachute (24" plastic chute works fine) as well as weight for nose cone. This requires around 1 ounce or 30 grams of weight in the nose (I used a fishing weight).
3D printing settings
You should print these in ABS or another materials that tolerates high temperatures (at least the engine retainers and E to D adapter). I printed w/ .4mm nozzle and .2mm layers.
For installation (this sounds much more complicated than it is):
Cut the shoulder off the nose cone and cut the bulb off the nozzle insert that comes with the Space Monkey kit (you also need to cut the bulbs off either end of the rocket body and build / attach fins per instructions from Space Monkey). I did not install antennae or other details since I was afraid they would be damaged in flight.
To attach the top / inside engine block / centering ring combo part inside the BT55 tube -- I press-fit the engine block / centering part on an E-size engine, slid rear engine mount around engine, press-fit engine retainer cap on bottom of engine, and locked rear mount and retainer together. This lets you insert the whole engine mount setup inside the body tube the correct distance. See the render picture included if you need a visual. I used a stick to put some wood glue around 3.5" inside and all around tube and then slid the mount w/ engine inside tube till rear mount fit inside the tube (you can also do the rear mount at the same time with some CA glue; I use wood glue for top block so that it creates a build-up above block to hold it in place against thrust but CA glue may provide a more reliable connection between cardboard and plastic). Try not to get glue on engine and wait for glue to dry before removing engine to be sure block stays in the correct place.
Sand the nozzle insert so that the 3D printed rear engine mount fits flush inside the nozzle insert. Glue 3D printed rear engine mount into nozzle insert and nozzle insert into Space Monkey rocket body. Pictures should make this clear.
Mount BT55 top adapter into top of V-2 body and around top of BT55 tube (may need to sand parts to be sure that everything fits but is not too tight - do not want to crush body tube). If you want to attach shock chord to engine mount you can run Kevlar chord through body before gluing interior tube in place.
Load weight into nose cone and glue 3D printed shock chord adapter into nose cone (lip of insert should be flush with cone and shoulder will stick out of nose cone so that it can insert into bod tube that has been installed in model).