Madcow 8-inch DX3 Rocket

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As explained in another post, this rocket will be used to promote the Friends4Michael Foundation. It is a big rocket and should create a nice show for the people in attendance. The Madcow 8-inch DX3 rocket ( Toolkit Link ) is a beautiful kit that is well-made. It is a 98mm diameter motor mount. When I finalize the OpenRocket data, I will run simulations to determine the best motor for the task.

AirFrame - Madcow 8-inch DX3 Build
Assembled Airframe

Updated: 23 June 2019

Madcow 8-inch DX3 Rocket Kit Contents

I received the kit in two boxes right before Christmas. The parts are hefty and here is the kit after all the parts got a good wash with soap and water.

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Kit Contents - Madcow 8-inch DX3 Rocket
Kit Parts


OpenRocket Wire Diagram

Motor Mount / Fin Can

The fins of the 8-inch DX3 have an interrupted fin root. This was probably to save weight.

Fin Design - Madcow 8-inch DX3 Rocket
Fin Design (1 of 3)

It was an opportunity for me to use this irregular design to strengthen the fin can. I ordered an additional centering ring from Madcow and used four to complete the motor mount. The bottom centering ring is flush with the end of the motor mount tube and is drilled and tapped for an Aeropack motor retainer.

The fin can came together just fine. All the fins fit properly and I injected internal fillets and applied the external fillets with West epoxy and carbon fiber shavings.


The rocket will have redundant altimeter systems.

The TeleMetrum will provide real-time tracking and performance data. The StratologgerCF will be the backup with the apogee and altitude ejection charges being fired 2 seconds after the TeleMetrum.

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The rocket will also have a Communication Specialist radio tracker on board. This will provide a backup to the GPS if something were to happen.

The electronics bay on this rocket is huge. So, there will be no issues with space for the electronics. I am planning on mounting a camera in base of the nose cone. That makes putting this bay together a little easier.


The motor to be used for the first flight at LDRS 98 for the Friends4Michael charity launch is the Cesaroni 15227 N2501-P 98mm. It will burn for six seconds and get the rocket over 10,000 feet. The motor case is the Cesaroni 98mm – 6 Grain.


Rick Waters, the Prefect for Tripoli Tampa, is helping me finish the rocket. He has professional paint guns and we are using high-end, polyurethane paints. Mark Hayes at StickerShock23, provided the vinyl graphics for the project.


Here are some photos of the finishing work.

Wet Sanding the Primer
Starting the Color Coats

OpenRocket File

I will update my OpenRocket file for this project as I decide on parts, receive them, and weigh them. Here is the RockSim file from Madcow converted to OpenRocket: Original File

Here is the OpenRocket build file of this rocket: Build File


First launch is planned at LDRS 38 near Argonia, Kansas on Labor Day weekend 2019.

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