Wednesday, June 13, 2018

Shock Cord and Glue TIP

An email TIP from Bruce Levison,

"I prefer to use white glue to fasten shock cord mounts into my rockets, that way if they get stuck in a tree they come down after a few rains."

 "I also use white glue to fasten engine mounts since this adhesive has less of a tenancy to grab than many others. The old rocketeers rule of thumb: white glue inside yellow glue outside." 

Thanks Again,
Bruce Levison  NAR # 69055 L2

The first tip makes great sense. 
Yellow glues are waterproof when dry, white glues remain water soluble after they dry.


  1. Not knocking this tip, but I can think of a couple of cons to go with the pros: if the inside of the tube (and the shock cord mount) has become sufficiently wet to release from the rains, wouldn't that mean the outside of the tube, as well as the fins and nose cone, have become drenched repeatedly? Might the tube be swollen and mushy, and the fins possibly warped?
    As far as the quick grab feature of yellow glues, I look at it as a plus 99% of the time. When I became a BAR the first rockets I assembled were with Elmer's white glue, the only adhesive I had handy. Some of the motor mounts and thrust rings had slipped down during the glue drying, leaving the engine sticking out a bit too much. I didn't want to lay them down horizontally to dry, as gravity would have pooled the glue to one side of the rings, so I let them dry vertically. Also I'm the impatient type, so I despise gluing a tri-fold shock cord mount and holding it down to conform to the tube for longer than necessary. Yellow glue sets up and holds the contour much more quickly than white glue. The only issues I've had with the quick grab feature is with couplers or coupler/centering ring motor mounts. I've learned to dry fit and sand if needed to get a snug but not tight fit, use a dowel to place the glue just in front of it's final position, and line up the coupler/ mount with any marks before shoving it in. After many screw-ups. Live and learn.

    1. Hi BAR,
      I can only speak from my experience. I had the Always Saturn IV sit up in a tree for a month. It finally fell down. The tubes were wet and squishy. I let them dry out and they were strong and stiff again! Not really round and straight, but strong enough to be flown again. The fins were finished (sealed) so they had no warps.
      Yep, you do have to sand those Estes red couplers. With Elmer's glue now a thinner formula they can seize up in the wrong place.