Sophisticated Lady T-tail repairs

On RC Groups.com there has been a long running thread on “woodies”.  These, of course, are not what you think they are.  In the RC Soaring community “woodies” are models made from balsa, lite ply, and other woods in a more traditional model aviation fashion.  More and more models are only available as Almost Ready to Fly (ARF) models and are typically either some sort of foam or a carbon/fiberglass composite material.  Those of us that like wooden models are largely relegated to the back benches but we surely do love our woodies!

 

In this case I found a model that had been sitting in a box for 20 years or so.  On a whim I started building it and found that sailplanes are really, really relaxing to fly compared to everything else I’ve flown including aerobatic planes and helicopters.  While the Sophisticated Lady is a fairly pretty airplane it does have some weaknesses.  Primarily in the T-tail section where you have a large mass on top of a thin structure.  Mine cracked repeatedly which required repair after repair until I started strengthening it.  Keep in mind that any weight at the tail of any airplane, particularly in sailplanes, is Triple Bad Not Good(tm).  You need to be desperate to add weight to the tail for repairs and strengthening.  I got desperate.  The vertical stabilizer is built up in the plans, I sheeted it with 1/32″ balsa on both sides and added some fillets to the bottom of the fin to distribute some load.  Then I had to add some fiberglass to distribute some more of the torsional load along a greater area than just the joint at the bottom of the tail.  I also had to add some fillets to the top of the fin to stabilize the horizontal stabilizer when it kept cracking.  Now with these added bits of balsa and fiberglass the tail seems to be fairly strong.  At least strong enough to withstand my dumb thumbs!

Orange – 1/4″ triangle stock fillets

Yellow – 0.75 oz fiberglass strip, laminating epoxy

 

 

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