MY prototype, a water bottle rocket, When it is filled with water, and pressurized air is filled inside it, it launches at a great speed with a huge amount of thrust. A good example at a small level to show the power of the combined effort of air, water and pressure. This model can be used to understand that how much useful these simple methods can be when doing something big such as launching a space shuttle. The fuel cost can be reduced drastically, which would lower the overall cost of the project plus, it is environment friendly also.
So, I think this would help us in building more efficient launching methods of space shuttles.