I did not know about this derivative:

[youtube]https://youtu.be/rSyaAMAW8Ng[/youtube]

Really? I remember reading about it and seeing models of it. Way cool plane. I wish it would have won.

Yup, I remember reading about the “cranked arrow” in my youth. Thanks for bringing that memory back to me!

Delta wings can turn really fast.......once. Then you lose all your energy for the fight.

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I remember it getting about a quarter of a page in Popular Science, c1984. Barely read about it since then and I always (distantly) wondered what the point of it was.

What is it about the wing design that makes the XL version so much faster?

I worked on the XL program so can say that the wing planform reduced the drag rise and supersonic drag. Not to take anything away from an F-16. The 70 deg sweep reduced the supersonic bluntness drag of the inboard panel. The cranked outer panel reduces the aft shift in aero center from sub to supersonic and provides a higher aspect ratio than a 70-deg pure delta. The XL also had more internal fuel than the F-16. To the earlier post point regarding maneuver, a fixed camber delta will be worse than a scheduled-flap wing+tail. In the XL some camber was added into the design over the supersonic-cruise camber baseline to obtain some improvement in sustained lift/drag. The definitive history of the XL program was written by Albert Piccirillo.

Is that what they call "mach tuck"?

Mach tuck is the nose down effect of the wing recompression moving aft as the aircraft enters transonic flow, if the aircraft has insufficient elevator control. The aft movement of the center of pressure causes a nose-down pitching moment that has to be trimmed out. In the cases where Mach tuck was severe (P-38, P-47) the wing shock from the thick wing caused a flow separation that reduced the elevator control power and the pilot could not exit the resulting dive. The elevator itself can also exhibit a separated wake at the hinge line, reducing the control power. The F-86 horizontal tail was redesigned with a stabilator to reduce this problem.

As a Swede it is my duty to point out that SAAB did that wing 30 years earlier.

I always liked the look of the Draken.

My first boss at Edwards was a female flight test engineer on the XL. She rode in the back seat during some of the high-alpha testing.

Later she was working on the F-16 test program with me, and had to brief a two-star general on a dangerous deep-stall test she was planning to run. She was also about 8 months pregnant.

The general didn't like her plan and said, "Little lady, have you ever been out of control in a high-performance fighter?"

She said, "Actually, yes...."