With higher speeds other issues like temperature of the whole airframe arise.
If you are interested in more details, i recommend the book from Paul F Crickmore "Lockheed SR-71 Blackbird" published with Osprey Air Combat. The order Number is ISBN 0-85045-653-3.
I dont know if it is still available somewhere, but it is very entertaining.
franzl
Last edited by RetiredF4; 20th August 2010 at 14:40.