Der Drei Max (a canted cluster version on the MDRM)

This rocket has already been built and flown, but there has been a lot of interest in the build.

First off the Motor mount was designed by William F. Cook of MD, CNC Upscale did the fine work of cutting the Motor mount and Fins. I just hopped on the bandwagon and gave it my own twist.

Started off with a 48 inch length of 4 inch Blue tube and marked up all of my cuts, Fin locations, centering ring placements and where the AV bay ends.

A couple of days later the Canted motor mount and fins arrived and I had to do some dry fitting to see how it looked.

Next to arrive is the nose cone and tailcone. Dry fit of those in the original planned length.

Cut the fin slots and test fit the mount and fins


More to come in the next post.

Next is to cut out the 15 degree cant motor tube penetration holes. I started with cutting a piece of 1 inch PVC pipe at 15 degrees to create a template. Tracing around the template with a sharpie gave me the extra 5 mm of space to cut out. I wrapped piece of 220 sandpaper around a 6 grain 29mm case to smooth things up.


Test fit of the 29mm blue tube motor mounts and the centering rings with the fins. I put the Estes Motor retainers on the motor tubes to check for clearance. I used Aeropack retainers in the end, much less drag.

The AV bay arrived and got assembled, so I had to dry fit everything together

Next is using the 5 minute epoxy to install the motor tubes, fins and upper centering ring. Lower installed after everything is epoxied inside and out.




More in the next post.

Next is running epoxy around the upper edge of the motor tubes and you can see the eyebolt for the shock cord.

Dry fitting with the short payload bay and again with the long payload bay. no tail cone on either.


Added the tail cone and start using JB Weld to fill in the gaps and fillet the fins.


Next is building out the electronics for the AV bay. I use 2 nerf darts to create shock absorbers.


Nose cone comes next. I drilled a 6mm hole through the tip of the nose cone and insert a 6mm carbon fiber rod, in the process I drop a loop of Kevlar in and catch it with the carbon fiber rod to create my nose cone retention, I don't trust those plastic loops. Having the rod across the nose gives the epoxy and nose weight extra support and keeps it in the right place. 2 ounces of BBs and 2 ounces of epoxy.


Bondo, sand, bondo, sand, prime, sand, prime, sand and paint

Got everything ready and started packing the drogue and main chutes and found that the payload bay was not big enough. Lucky for me I had a 24 inch section of blue tube left. That left me with plenty of room.


I had to wait until I got to the launch field to install the Aeropack retainers, because I forgot to buy them and had to get them from Ken of Performance Hobbies (our wonderful onsite vendor). Also picked up 3 Aerotech single use H135 motors. Tom Binford was kind enough to give my Electronics the once over since this was my first dual deploy.

This was what I called my parting shot incase something failed in flight.


The rocket gods smiled on me and all the motors lit at the same time and the Apogee deploy on the main pay load bay popped out the Main in Burrito and an 18 inch drogue, about 3 seconds later the motor eject popped out a back up 12 inch drogue, at 600 ft the cable cutter fired and the 60 inch main deployed like a champ. It drifted down and settled gently in a drainage ditch full of water, Rocket gods smiled yet again and the AV bay stayed dry. I did have to drill a hole in the tail cone to let the water drain out. 2 days of drying and a little sanding and everything went back together again.


Launch video: It isn't great but it is what I got. I think Tom may have better quality video.
https://youtu.be/nsbEpnEqPQ0

Once the motors burned out, I lost it in the viewfinder. The new camera has poor contrast in the viewfinder.

We did have a little difficulty finding a support then wouldn't wedge against the tailcone

Great flight