Thank you very much B
That report explains the quoted approach speeds in the Wikepedia article.
Your NASSA report also says that the approaches were at 8 to 10.5 alpha for ground effect checks. Plus as is normal for ground effect landings a near as possible hands off touchdown was aimed for (I know how hard that is - on one occasion with a CN235 I was asked not to touch the controls for a minute before we hit!). It also explains some of the video of the NASA flights which has appeared from time to time accompanied by comments about ropey standards of touchdown and planting it etc. How people who do not have all the info let themselves down!
So the mystery re the high quoted speeds is solved. The 8 to 10.5 alpha is lowish for a conventional aircraft let alone a slender delta where one could expect 15 plus (hence the need for a droop nose)
From the airfield pic I would guess the distance to turn of was about 4200ft. Which would suggest 130 - 135 kt max?
Concorde in the same wind conditions was using the full length of 25 and a chute.
JF