Launch Lug Standoffs

 

 On most of my recent LPR model builds I have adopted the practice of mounting the launch lugs on short standoffs rather than gluing them directly to the body tubes.

The primary reason for doing this is the added height makes for the formation of smoother and better looking lug/tube glue fillets. It eliminates those unsightly bumps and gaps in the joints that usually require multiple applications of glue to fill.

The standoff for a standard 1/8 lug are made from 1/8 inch wide strip of 1/16 balsa cut to lug length.  The ends can be rounded over if desired.

Sure, the added height may increase launch lug interference drag by a small amount, but this might be compensated for by the presence of a smoother fillet.

Anyway, these are after all, sport models, where optimizing for flight performance is not the primary concern.

Another small advantage of the standoff - the effects of the inherent slop in the fit between lug and launch rod causing the latter to contact the rocket airframe during liftoff are greatly minimized. I'm not sure how much this would effect the model's initial flight path in terms of rod tip-off and/or angle of attack.  Perhaps there has been some past investigation in this area that I haven't yet encountered.  Also, the effect wouldn't be as large with models using two widely spaced lugs versus a single longer lug.  Again, we're talking sport models. At the least this build technique might help to prevent the launch rod from marring the model's finish on the launch lug side during liftoff.