Turnbacks are not a good idea for the inexperienced or the faint hearted. Here's why:
I read a Boscombe Down report a few years (about 20) ago that implied that the minimum height loss in a glide occurs at between 55 and 60 degrees of bank. Now, with 60 degrees of bank, the load factor is 2, which means you're flying with 2 G on the aircraft. At 2 G the stall speed is increased by a factor of just over 1.4. So, if you're gliding at 1.3 VS, you'll stall, flick, spin, crash and burn before you've even started turning.
Trying to turn back at any other angle of bank will lead to too great a height loss, so again, it's a lost cause.
Turnbacks have been carried out successfully, I've even done one myself - I may even talk about it publicly one day, but not just yet! But, far better to plan the takeoff and climbout to use available fields in the forward sector in the event of engine failure. If there's no such field available, you shouldn't be operating single engine there in the first place.
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