Estes/Semroc Orbital Transport Help

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Aug 13, 2009
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I am building the Semroc Orbital Transport and have run into a problem with the "ram jet" motors and housing that goes on the bottom of the booster fins. I am building them per the instructions but the small tubes are too tall for the housing to fit on the wing. I had this same problem with the Estes re-issue of the OT many years ago. Back then I got frustrated and gave up. Am I doing something wrong? I guess I will have to make shims for the bottom of the housings so that they sit flush with the fins. Can anyone with OT experience give me any ideas?
Thanks!
 
I built the Estes reissue a few years ago, and don’t recall this problem. The fins were cut your own, so it’s possible I tweaked them, but I don’t recall having to do so. Looking at my built kit, they fit just right.
 
I am currently working on a build of the Orbital Transport. In fact, I cut out those very pieces last night. Doing the math, the width of the parts needs to be at least 9/16" to accommodate both the 1/2" diameter tubes plus the 1/16" bottom housing piece. I cut mine to 5/8" to make sure they were wide enough, and will sand them down to exact height before gluing to the wings.
In your case: yes, some shims would work, or you could just re-cut the parts out of some scrap stock.
Good luck with the rest of your build. The OT is such a cool bird!
 
Thanks! I am going to rebuild the housings with scrap balsa and add about a 16th of an inch to the height. I was just curious as to if I did something wrong or there was a "gotcha" I didn't know about.
 
One further tip that might save you some headaches later on: This concerns the small balsa piece that serves as the dowel stand-off for the glider. (Estes plans show it as #15 on the fin pattern sheet. Not sure what the Semroc designation would be.) I strongly recommend cutting this piece so that the wood grain runs across the narrow dimension as opposed to length-wise. This part will bear a lot of flight and landing stresses and will likely break off along the grain direction. I would even go as far as to make this piece out of basswood or plywood.
 
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