Howdy Rip,
Ok, here is a link for a flying cardmodel SR 71 that uses compressed air in the form of an internal bladder. It is a large model, but I dont know about 9 ft. You can find the plans at the bottom of the first posting at that link.
http://www.cardmodels.net/forum/show...ghlight=flying
To see a video showing the size of the model and its actual flight, try this link:
paper smash.wmv its a 3 minute video , but it shows the model actually flying.
I know of other SR 71's, but they are smaller scales.
hope this helps,
Greg aka GW