We likely could strap 30 engines on the shuttle if we assembled it orbit.
Actaully in reality I think their would be no concrete limit to the number of engines you could put on a ship. Although what would happen, and I think this is what Fyron and SJ were trying to say, is that putting an engine on a ship by itself increases the mass of the ship. In SEIV terms there is a limit to the number of engines for a specific hull size becasue once you reach a certain number of engines you have in effect changed the hull to the next size up.
Geoschmo
[ June 16, 2003, 20:10: Message edited by: geoschmo ]