Rocket Construction

In the construction of a rocket a player has mainly 7 things to consider. They are explained in this article.

Fuel capacity

Depending on where the player wants to get and what maneuvers they plan on doing in space, they will need enough fuel. It's recommended to bring a little bit more fuel than required to cover unexpected situations, and so they don't fly in fear.

The fuel capacity is also affected by which engine is used as different engines have different fuel efficiency. Some engines may take more fuel to finish one job than the other. This is explained more thoroughly in the Thrust section.

Mass

Side separator

It's recommended to make rockets as lightweight as possible. It can be done by removing unnecessary parts (such as empty stages) by separators.

Docking Ports can also be utilized as separators — the plus point is that new parts can be added to the rocket if needed; the downside is that they do not provide a large separation force to ensure that the rocket and the discarded part will not collide.

Thrust and TWR

In the first stage, the engines must produce more thrust than the rocket weighs to lift off. Look at the "Thrust / Weight" number. That is the TWR. TWR stands for Thrust to Weight Ratio. It is measured by dividing thrust (in tons) at max power on the first stage by mass (in tons) of the whole rocket. If it is below 1, the rocket will not lift off. If is above 1, the rocket will lift off. A good TWR is between 1.05 and 1.99.

In the second stage, TWR should be around 0.6 to 1. Not much is needed because the rocket is already at an angle, and thus, not directly fighting against gravity. Additionally, it is already traveling at high speed. If your rocket has a lander that will return to Earth, the optimal TWR with the amount of fuel remaining is 2 to 4.

Also note that as fuel burns, your rocket will weigh less, thus increasing TWR. Most landers return to Earth with 20% to 50% fuel, so to check the TWR of the lander, remove all stages except the lander, set the fuel to 20%–50%, then check the TWR.

In addition, some engines are more efficient than others. For example, a Frontier Engine produces a 100 tons of thrust; a Hawk Engine produces 120 tons of thrust. Although they provide almost similar amounts of thrust, the specific impulse (I_sp) and the fuel consumption rates are different. They may cause difference in actual gameplay.

Aerodynamics

Aerodynamic Fuselage

Nose Cone

The planets Venus, Earth, Mars, and Jupiter have atmospheres that slow down spacecraft. If the aerodynamics are not done properly, there may not be enough fuel to complete a mission.

It's recommended to consider using Aerodynamic Nose Cones, Aerodynamic Fuselage and/or a combination of Fairings to improve the aerodynamics and to make all parts of the rocket exposed to airflow "A"-shaped. Using flat surfaces produces too much drag that efficiency lowers significantly.

For extra protection against reentry heat, use heat shields on parts that will land on the planets said above. They are meant to slow your rocket down safely.

Control

A probe.

There are 2 types of control craft controller, each with different weight and torque (essentially rotation force). The Capsule is for manned missions, and the Probe is designed for unmanned ones. There are absolutely no consequences for using which in the current version 1.5.9.5

Others

1. Landing legs can be employed for not destroying the rocket since engines cannot take as much impact force as landing legs. A landing leg can withstand an impact speed of around 12.5 m/s and rover wheels can withstand around 60 m/s.
2. Parachutes are extremely useful also if player wants to save fuel when landing on planets with atmospheres. They are also recommended to be used when going back to the Earth.
3. Heat shields are used to protect a rocket from the heats of reentry.

Additional links

• Rocket Showcases
• Building Orbital Rockets
• Building Moon Rockets
• Building Mars Rockets
• Building Jupiter Rockets
• Equations