Tuesday, June 10, 2008

Rail guides

I was all hot to prime the sustainer and finish this beast but I'm glad I lagged because I almost forgot the rail guides!  These standoffs will compensate for the nose cone bulge near its bottom and prevent scraping during liftoff.  I designed this airfoil-shaped standoff to be cut from 1/2" plywood:

The top shape is the top view and the bottom is the cross section showing the curvature to match the 7.67" diameter tube.  I traced the top design on plywood and did a rough cut using my bandsaw.  I then finished the top-down shape using my disc/belt sander.  I then used the curved end of the belt sander to form the curvature of the bottom shape.  
    I center punched the hole in the top and drilled a 1/8" hole through it.  I then marked the sustainer tube both 4" and 29.25" from its bottom (into the centering ring plywood) using a 90˚ strip of extruded aluminum and center punched markers there.  I drilled a hole in each 1.1" deep and sanded the area around these holes.  I applied epoxy to the bottom of the standoff, mashed it down on top of these holes, and screwed 1-3/4" machine screws through the rail guide/standoff and into the 1.1" holes.  Since these assemblies will need to support 40+ pounds of weight they had to be solid and I'm confident I achieved that goal:

No comments: