Whatever BT-60 booster you choose, do a swing test on the completed stack. In the case of the Estes Titan IIIE kit, it was necessary to use larger fins to ensure stability (2" root, 1.5" tip, 3" semi-span clipped deltas are adequate). Use a live engine in the booster for the swing test. In the Titan IIIE, a D12-3 is called for; it gives plenty of lift at launch and is stable. With a lighter booster such as a Big Bertha, you may get away with a C5-3 or C6-3, but I haven't tried it (Simulate! Simulate! Simulate! then Test Swing! Test Swing! Test Swing!).
While the adapter may be recovered on its own separate streamer, I recommend tying the adapter to the booster's shock cord, as with a conventional nose cone. This way if the orbiter doesn't separate, it parachutes back with the rest of the model.
Finally, keep in mind that the orbiter is fairly small and glides about as well as any hypersonic vehicle trying to fly subsonically. Mine usually lands before the booster does. There isn't much time to re-acquire it if you loose sight even briefly, so have a helper along to watch the booster while you track your orbiter.
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