I've stumbled across a solution to this one elsewhere in the forum, but for ease of reference, I thought it worth including here.
There is a line in the panel.cfg for this aircraft "render_3d_window=1".
Change this to "render_3d_window=0" and the F106 will work (the F105 & WT9 too). The cockpit scale is a little off (either that or the F106 has the largest, most spacious fighter cockpit ever) but it works.
The same trick works on the Republic F105 & the Aerospool WT9 also, but not on the Hawker Heroes.
Original thread can be found here:
viewtopic.php?f=10&t=3113