Building the motor mount for Mach 1 Amraam AIM120

[tOD]

I picked up this kit a while back and have decided to start building it. Since there aren't any instructions I'm going on past experience to assemble the motor mount. It's an 18mm mount in a BT50 body tube. Before I start gluing anything I thought I'd post a description of my Idea to see if anyone can spot any problems with my technique.
Using a B6-6 motor for size locate the notch for the engine hook allowing the motor to extend 1/4" past the end of the tube. The motor tube would be flush with the end of the body tube.
Place the aft centering ring at the rear end of the fin slots.
Locate the forward centering ring at the forward end of the fin slot to sandwich the fins between the slots. The ring is notched to attach the shock cord by gluing it to the sides of the motor tube in such a way as not to interfere with fin placement.
Place the engine block at the forward end of the motor mount above the tab on the engine hook, about 1/2" down from the end of the tube.

 

[mh9162013]

That sounds right, if I correctly understand what you wrote (and your picture).

If you haven't already, take a look at some pics in my Mach 1 Patriot build thread that might help (can't link it here, for some reason). Dave Thomas (Rocketry Education and Research) from YouTube has also build several of these Mach 1 BT-50 kits, so those videos might help.

You should be able to dry-fit the MMT and its components into the main body tube and insert a new or spent casing to see how it all fits.

 

[tOD]

Thanks for the tips. I watched Dave's video which pretty much confirmed my technique. I'll post a few more pictures as I begin the dry fitting. This should be a nice rocket when it's finished.

 

[tOD]

Ready to install in the body tube.

 

[tOD]

Fins attached, first set of fillets applied.
Anybody flying this rocket? Did you add any noise weight? The Rocksim file has 14 grams. It doesn't seem necessary.

 

[tOD]

Photo

 

[86mustang408w]

Fins attached, first set of fillets applied.
Anybody flying this rocket? Did you add any noise weight? The Rocksim file has 14 grams. It doesn't seem necessary.

It might not be, you could go old school with a string and find the CG, and swing it around your head about 6 feet out. See how it flies in a circle. Then you can add weight if need be. Good job on mocking things up first, I use thin CA to do the same. Keep up updated!

 

[tOD]

Well, I Went ahead and added a 1/4-20 hex nut, a loop of kevlar, and two part foam to the nose. I attached a string and swung it around. Flys backwards. Oops.