Madcow Super DX3 Build aka My License to Learn

[mrblack859]

Hello everyone,

I do apologize if this thread is a bit lackluster since it is my first post of any substance. To introduce myself, I am a new resident of Louisville, KY and recently finished my bachelor's degree. With that out of the way, I now have time to do something fun outside of work and my heart has landed on hobby rocketry. Up until a few years ago, I would launch various Estes rockets every now and then on land owned by the church I attended, but my hobby at the time never progressed much further than that. With renewed interest and determination, I purchased a Madcow Super DX3 to begin my foray into HPR and L1 certification. I also purchased an avionics bay since it sounded convenient, but I'm not yet sure what it's role will be in this build...Lots to figure out! Here are some goals/characteristics/requirements that I have, which may or may not be appropriate for this build (let me know your thoughts!) :

• Body
  • Bright orange for visibility
• Motor
  • Low and slow
• Recovery
  • Single deployment
• Avionics
  • Altimeter, accelerometers, data logging device, camera(?)...Ideally I would like to have the e-bay ready for dual deployment without actually doing it.

I feel that I should mention that I do have some experience with building balsa airplanes (wrapping up a SIG Four Star 20EP build right now), epoxy, and alignment jigs, though the fit and finish of my model airplanes has always been terrible since I'm always in a rush to get them flying lol. Any advice is appreciated! I will be perusing the technique forum for the next little while...

 

[mrblack859]

Motor mount tube has been sanded and top centering ring attached. While I was waiting for the epoxy to dry, I found Green Jello's Madcow Super DX3 build and am using that for guidance given my lack of experience. Since he used three centering rings and my kit came with two, I decided to pause progress on the motor tube while my motor retainer and Madcow centering ring shipped.

I began working on the altimeter bay and attempted to assemble it in the same fashion as Green Jello. I placed the 1" spacer ring in the middle of the 8" heavy duty coupler, traced the spacer ring with pencil, then moved the spacer ring out of the way and placed masking tape around the tracing opposite of the spacer. I applied would glue between the two lines and attempted pull the spacer ring into place. However, it was alrighty so tight when getting the spacer ring on the coupler that it wouldn't budge. I should have sanded inside of the spacer ring and outside of the coupler when I felt how hard it was to get them to slide over each other. So, I just glued the spacer ring in place about 1" off of the middle of the coupler. First mistake accomplished already!



I used wood glue to assemble the sled and threadlocked the the forward bulkhead nuts in place on the tray. Both holes for the ematch wire in the bulkhead and rivets in the coupler and forward body tube have been drilled.

 

[mrblack859]

The motor retainer and additional centering ring arrived in the mail yesterday. I slid the center and bottom centering rings in place on top of the motor retainer, then taped the fins in place. I glued the center CR in place with Titebond and waited for it to dry before placing an epoxy fillet on the top of the center CR.

I taped the fins as Green Jello did, placing a 3/8 inch edge on all the fins that will be sanded here in a few days.

 

[DMehalko]

Nice! Enjoy the build, you picked a good kit!

 

[mbeels]

Looking good! Following along.....

 

[mrblack859]

Thank you for the support!

I have finally begun sanding the fins to a bevel. I really want to get a belt sander now.......Anyway, here are the progress pics so far using the palm sander. In the second picture, you can see how the layers of plywood helped as guide to make fairly even bevels. I've also attached a picture of a mockup of what I'd like the color scheme to be all said and done. The CG/stability isn't accurate in the picture so don't panic just yet

 

[jbrracer]

Looks good. Have you downloaded open rocket or rocksim yet?

another good download is ThrustCurve.org
Or the app

those could all help you find the right motor. Confirm cg vs cp ect