John,
I hope you don't think I am trying to be smart for I don't intend to be. I thought Sid's response as to why recurves make string noise and how the recurve limb tip design will help to eliminate it was in part an answer to your question. He said, and I quote, "The newer XP30, HEX4, and HEX5 limbs have been designed to significantly reduce the pre and after string slap." It makes sense since most responses to your post have been bows that have radical recurve limb tips. Sovereign bows have static limb tips that bend radically, Horne bows have semi-static limb tips that bend rather radically, and Border XP30, HEX4, and HEX5 limbs bend radically at the tips. Now that I think of it I used to shoot a Chastain take down that was really quiet and they have radical recurve limb tips. If the string has to wrap it cannot slap. I would think that would be an answer to your design question would it not? I don't know if there is a recurve that is totally quiet with bare string. Longbow strings do not touch the limbs much, if at all, when braced and therefore do not have as significant string noise problem as do recurves.
Louis