To reach space without giant fuel tanks, the idea is to use a massive airship to slowly accelerate with electric/chemical hybrid rocket engines over days until reaching orbital velocity. The airship would need to be over a mile long and exceptionally light, creating a three-stage approach due to complications like flying at the edge of space. This unique concept challenges traditional rocket launches and offers a potentially more efficient and sustainable way to access space.
https://www.jpaerospace.com/ATO/ATO.html