# Constant Off-Center Propulsion (without gravity)

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• Gabriel Mota
In summary: Ok, so choose a coordinate system and define some variables.In Cartesian, with x, y as the coordinates of the mass centre, you need the angle the body makes to the x axis, and an offset distance from the mass centre to the line of action of the thrust. Take the offset as being in the +x direction when the angle is zero.If point application was center of mass (0,0):y = (1 / 2) * F * Time2AngularVelocity increases every frame by = ( Position Cross Product with Force ) / Moment Of InertiaIf point application was center of mass (0,0):But it isn't, and you need
Gabriel Mota
Hi,

How to calculate the position in time by applying a force, like a Thrust, not in the center of mass:

I only know about the linear and angular formulas: Pos/rotation = 1/2 * F * Time^2

I have struggled finding topics about this maybe because i don't know the correct nomenclatures and maths.

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First step is to be clear about what exactly is constant here. Is the direction and point of application of thrust constant relative to the rigid body, as would be the case for an engine within the body, or is the point of application fixed in the body but the direction fixed in the rest frame?

haruspex said:
First step is to be clear about what exactly is constant here. Is the direction and point of application of thrust constant relative to the rigid body, as would be the case for an engine within the body, or is the point of application fixed in the body but the direction fixed in the rest frame?

By constant i mean the same force is constantly being applied and as you mention, could be for example a spaceship with an engine.

Gabriel Mota said:

By constant i mean the same force is constantly being applied and as you mention, could be for example a spaceship with an engine.
You seem to have missed the crux of my question.
I understand that the force is to be of constant magnitude, but what about its direction? If it is from an engine rigidly fixed to the body then its direction changes as the body rotates; but if it is from an outside source then the direction may be constant in the inertial frame.

haruspex said:
You seem to have missed the crux of my question.
I understand that the force is to be of constant magnitude, but what about its direction? If it is from an engine rigidly fixed to the body then its direction changes as the body rotates; but if it is from an outside source then the direction may be constant in the inertial frame.

Yes, the engine would be fixed and rotates with the rigid body.

Gabriel Mota said:
Yes, the engine would be fixed and rotates with the rigid body.
Ok, so choose a coordinate system and define some variables.
In Cartesian, with x, y as the coordinates of the mass centre, you need the angle the body makes to the x axis, and an offset distance from the mass centre to the line of action of the thrust. Take the offset as being in the +x direction when the angle is zero.

If point application was center of mass (0,0):
y = (1 / 2) * F * Time2

AngularVelocity increases every frame by = ( Position Cross Product with Force ) / Moment Of Inertia

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Gabriel Mota said:
If point application was center of mass (0,0):
But it isn't, and you need to make the origin fixed in space, not fixed as the mass centre.
Gabriel Mota said:
y = (1 / 2) * F * Time2
You omitted mass.
Gabriel Mota said:
AngularVelocity increases every frame by = ( Position Cross Product with Force ) / Moment Of Inertia
That's the angular acceleration. To turn it into the increase in angular velocity in a time step you need to multiply by something.
From the reference to "every frame ", sounds like this is for a simulation.

## 1. What is constant off-center propulsion?

Constant off-center propulsion is a concept in physics where an object is propelled in a specific direction without the use of gravity. This means that the object is able to move continuously in a specific direction without any external forces acting upon it.

## 2. How does constant off-center propulsion work?

The mechanism behind constant off-center propulsion is still being studied and researched. However, some theories suggest that it involves manipulating the object's mass distribution or utilizing electromagnetic fields to create a continuous propulsion force.

## 3. Can constant off-center propulsion be used for space travel?

At this point, constant off-center propulsion is still a theoretical concept and has not been successfully demonstrated or used for space travel. However, some scientists believe that it has the potential to revolutionize space travel if it can be effectively harnessed.

## 4. What are the potential applications of constant off-center propulsion?

If constant off-center propulsion can be successfully developed and utilized, it could have a wide range of applications in various fields such as space travel, transportation, and energy production. It could also potentially lead to new technologies and advancements in physics.

## 5. Are there any challenges or limitations to constant off-center propulsion?

As with any new concept or technology, there are still many challenges and limitations that need to be addressed before constant off-center propulsion can become a practical and viable solution. These include finding a reliable and efficient way to generate and control the propulsion force, as well as addressing potential safety concerns.

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