Hi Folks,
I've never used "deflappers" on my awning, and probably never will. If the wind is so strong that I can't stand the flapping noise it's time to roll up the awning. I do use an awning strap on occasion but NEVER in the classic way: stretched across the top of the awning and anchored in the ground at either end.
IMHO the purpose of an awning strap is to prevent the awning material from excessive movement. When attached in the classic way that will help ONLY when the wind blows the awning upward, away from the RV. Unfortunately the wind is not that regulated and it can blow the awning down just about as easily as up. When blown down (or towards the RV) the awning strap is of no help. Secondly, with the awning strap anchored to the ground that could have an adverse effect on the awning and its hardware should the RV ever move for any reason. And thirdly, I'm not a fan of using springs or bungees, et al, between the awning strap and its anchor points. The awning strap is installed to prevent excessive movement of the awning. A spring or bungee will allow the awning to push the strap even further away and that may not be good for the awning.
I solve the problems by using the awning strap to make a "sandwich" with the awning material in the middle. I fold the strap in half, then pass the folded end over the top of one awning arm (between the arm and the awning material). Using a D-ring at the fold I anchor that end to the base of the awning rail (where it attaches to the side of my MH) using a web strap and tensioning device. Then I take the two bitter ends of the strap and pass one over the top of the awning and the other over the bottom of the awning. Join them together at the opposite end of the awning and pass both over the top of the other awning rail. Then I use a large S-hook to connect the bitter ends to another web strap and secure it to the base of the other awining rail. Now the awning strap is anchored to the motorhome and if necessary I could drive it away if I had to. Additionally, the awning is now better protected from movement in either direction -- up or down.
Next time I set it up I'll take some photos and post them here.