Mechanics of a missile liftoff

In summary, the conversation discusses the challenges of designing and launching a missile, particularly in regards to maintaining stability and preventing tilting or falling over in the first few seconds after launch. The high center of gravity and small base of a missile make it susceptible to disruptions, and early NASA launches had a high rate of catastrophic tilting. The speaker also raises the question of whether single or multi-engine missiles are more prone to tilting and how differential control of thrust can compensate for this. They also mention the role of upward linear momentum in stabilizing the missile's flight path. The conversation concludes with the speaker asking for help in understanding the mechanics of a successful launch and being directed to search for information on rocket stability.
  • #1
Jozsef
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From a "design" viewpoint, a missile (see: Saturn V) has a very high center of gravity and a very small base.
It can therefore be expected that the least disruption of the location of the center of gravity relative to the base, will result in the missile to tilt and fall over, especially in the very first seconds after launch.
Indeed, in the early days of the NASA program, almost 50% of the test launches resulted in a catastrophic tilt.
I can find no better comparison for my lack of insight than keeping a broom stick upright and in balance on your palm. This is not easy.
In my mind, this problem is more pronounced for single engine missiles than for multi engine missiles because it can be expected that differential control of the thrust from the multi engines could compensate for a beginning tilt. But then, I presume that the corrective directional forces must be tremendous, given the height and the mass of the missile.
I think to understand that after launch, when the missile has already build up a high vertical speed, its massive upward linear momentum will further help in stabilizing its flight path, with less corrections needed. My problem to understand "mechanically" a successful launch, is indeed in the very first seconds after liftoff.
Can someone help me for a better understanding? Many thanks, respectfully, Jozsef
 
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  • #2
Jozsef said:
its massive upward linear momentum will further help in stabilizing its flight path
What do you mean here? Angular acceleration due to an unbalanced torque, doesn't depend on linear momentum.
 
  • #3
Use a well-known search engine to look for "rocket stability". The first link probably takes you to the NASA site which has all the information you want.
 
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1. What is the purpose of the first stage of a missile liftoff?

The first stage of a missile liftoff is responsible for providing the initial thrust and acceleration necessary to overcome the force of gravity and lift the missile off the ground. It typically uses powerful engines and fuel to generate this thrust and propel the missile into the atmosphere.

2. How does the guidance system of a missile work during liftoff?

The guidance system of a missile uses sensors, such as gyroscopes and accelerometers, to measure the missile's position, velocity, and orientation. This data is then used to make adjustments to the missile's trajectory and keep it on its intended flight path.

3. What are the main components of a missile's propulsion system?

A missile's propulsion system consists of an engine, fuel tanks, and a nozzle. The engine converts the chemical energy of the fuel into thrust, while the fuel tanks store the fuel until it is needed. The nozzle directs the flow of exhaust gases to generate thrust and control the direction of the missile.

4. How does a missile's payload affect its liftoff?

The payload of a missile, which includes any weapons or instruments it carries, affects its liftoff by adding to the overall weight of the missile. This requires the first stage to generate more thrust to overcome the increased weight and achieve liftoff. The size and shape of the payload can also impact the aerodynamics of the missile and its flight path.

5. What are the main forces acting on a missile during liftoff?

The main forces acting on a missile during liftoff are thrust, weight, and drag. Thrust is generated by the propulsion system and propels the missile upwards. Weight is the force of gravity pulling the missile down towards the ground. Drag is the resistance caused by the air as the missile moves through the atmosphere and can slow the missile's acceleration if not properly accounted for.

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