Brian Abraham
The SAAB Viggen was the first to use the close coupled canard delta configuration
I'm not disputing that. I'm wondering when it was first
possible to produce such a design that would work.
the reason given for choosing this layout was,
The canard arrangement has notable advantages in achieving a good field performance and weight-lifting abilities without resort to complex highlift "flappery."
What kind of "high-lift flappery" could have provided the desired performance for a delta-winged fighter design? As I understand the Viggen had a fairly low AoA on takeoff and landing.
Lift/drag ratios are better by virtue of the fact that the foreplane, with drooped elevators to raise the nose on take-off, is providing positive lift, rather than lift being partially killed by the raised elevators or elevons of conventional wing-before-tailplane or tailless delta aircraft.
I always thought that would always result in an unstable design?
There are much reduced interference effects between the mainplane and the smaller surface with a canard than with a conventional configuration.
Unless you're talking about downwash off the tail, I'm not sure I understand.