Why do some missiles have to be erected before they can be launched?

The earliest truly modern missile, the German V-2, was launched from an erector. Many missiles, especially ballistic missiles, are still launched from an erector for the following three reasons.

First, when launching in this way, the thrust-to-weight ratio of the missile is low. The thrust-to-weight ratio is the ratio of the ground rated thrust of the rocket engine to the take-off weight of the missile. When launching vertically, as long as the thrust slightly exceeds the take-off weight, the missile can take off. As the propellant is continuously consumed, the weight of the missile gradually decreases, and the flight speed becomes higher and higher. Therefore, vertical launch is very beneficial for the acceleration of the missile and the full utilization of energy, allowing the missile to exert its maximum "strength". For example, the German V-2 missile has a thrust of 26 tons, a take-off weight of 13 tons, and a thrust-to-weight ratio of only 2, so it can only be launched vertically. Later, the "Sergeant" missile developed by the United States had a thrust-to-weight ratio of 5.05, so it chose to launch in an inclined manner.

▲ China's intercontinental ballistic missile takes off and is launched vertically from the launch silo.

The second is to reduce flight resistance. If a ballistic missile wants to have a long range, it needs to fly as far as possible outside the atmosphere or in the thin air at high altitudes. If the missile does not take off vertically, it will take more time and distance to pass through the atmosphere, and the air resistance will cause a greater loss in the flight speed of the missile. Therefore, most ballistic missiles will turn according to the program and fly to the target 4 to 10 seconds after vertical launch.

Third, it is easy to deploy in combat and survive. Most ballistic missiles are large in size, usually between 10 and 30 meters, and their diameters are between 0.8 and 2.5 meters. If a tilted launcher is designed for such a missile, it will not only be large in size and have a considerable structural weight, but also occupy a larger area and be more difficult to operate. It is also more difficult to stabilize, and the vibration and impact of the missile when it is ignited and launched will affect the accuracy of the hit. When launching at an angle, a wider tail flame corridor needs to be maintained behind, making such a launch position more difficult to conceal and maneuver. Vertical launch can not only avoid these problems, but also change the direction of fire within a 360° range, improving the flexibility, maneuverability, stability and concealment of missile combat deployment.

▲ Tactical ballistic missiles, erected and ready to launch at any time

Fourth, it helps to maintain a good state of readiness. In the ballistic missile flight control system, the inertial device is a very important part. Before the missile takes off, it needs to be accurately aligned with the shooting surface, and the missile also needs a basic shooting direction. With the vertical take-off posture, the missile can easily aim at the shooting direction by properly adjusting the horizontality of the launch platform through the aiming system before launching, and maintain this state for a long time without major changes. In this way, the missile can quickly enter a high state of readiness before being deployed for combat.

About the Author:

Li Wensheng

He holds a bachelor's degree in electronic engineering and a master's degree in military science. He was formerly a senior engineer in a department of the General Staff. He is engaged in research on military information and military strategy, as well as long-range combat issues. He has long participated in the writing of the "Annual International Arms Control and Disarmament Report" of the China Arms Control Society and the "Global Nuclear Posture Assessment (Annual) Report" of the China Institute of International Studies. He has published more than 400 academic and military popular science papers in more than ten journals inside and outside the military, and participated in the writing of many monographs such as "The Basic Situation of Russia's New Military" and "Future Combat Systems of the United States". He has presided over or participated in many national and military scientific research projects and won many military science and technology progress awards. He is an expert in nuclear strategy and nuclear weapons development and combat use, and has in-depth research in air defense and anti-missile, as well as conventional long-range combat.