Ultimate Travel scope, I emailed Pete Smitka, the maker of the Portaball, wanting to find out if the Portaball 8"F5 can be made Airline carry-on. Here is his reply:
Ramon -
Actually, it (as well as the 10" and even the 12.5") already is a "carry on" scope. The only difference between your thought and actuality, is that you don't carry on the entire
telescope - but only the mirror in it's cell in a wood box like we ship it, and perhaps the pole tube (though in the 8" f/5 that wood easily fit in a suitcase) and the rest goes as
luggage. In the configuration it is shipped in, there is even room for a sleeping bag and some clothes in the spheres container.
Call me for additional details.
Peter Smitka
So if you are willing to do a little more work, you have The ultimate travel scope. Wide field of about 2.5 degees, Zambuto optics limited only by the atmosphere, curved spider for no diffraction spikes,and the smoothest altaz mount on the planet, I think I found my ultimate travel scope!

Ramon