There would have been plenty of room had shuttle not been hauling around three useless launch engines. The Buran orbiter didn't have launch engines. Buran was

There would have been plenty of room had shuttle not been hauling around three useless launch engines. The Buran orbiter didn't have launch engines. Buran was launched essentially as cargo by the Energia heavylift rocket. That meant Russia had a huge lifting rocket that could launch separately from Buran. The shuttle stack couldn't ever work without the orbiter. The Russian program would have been much more dynamic and flexible had the economy not pulled out the rug. https://en.wikipedia.org/wiki/Energia_(rocket) https://en.wikipedia.org/wiki/Energia_(rocket)