|
Post by Flying Monkeys on Jul 15, 2019 20:51:11 GMT
Like in the game Asteroids, by thrusting and changing attitude at the same time. You don't need six thrusters in a coordinated sequence, although that would work; just a main thruster in continuous operation while the thrust line is being changed But how will it change the direction of its thrust line? A side engine will simply cause a bit of acceleration in the direction of that thrust; it does not cause the ship to turn. You need two have two side engines, pointing in opposite directions t each other, and both with their lines of thrust not passing through the centre of the ship, so they can cause a rotating motion. Which brings us to what I am saying - multiple engines, one on each face. Again, however, the main point in achieving the curve is, in my view, that the power is applied in a sine wave. That is absolutely due to gravity - without it, it would only be going in a straight line. The thing that is causing its line of thrust to change is gravity pulling one end of the rocket down.
|
|
|
Post by Harold of Whoa on Jul 15, 2019 22:48:52 GMT
Like in the game Asteroids, by thrusting and changing attitude at the same time. You don't need six thrusters in a coordinated sequence, although that would work; just a main thruster in continuous operation while the thrust line is being changed But how will it change the direction of its thrust line? A side engine will simply cause a bit of acceleration in the direction of that thrust; it does not cause the ship to turn. You need two have two side engines, pointing in opposite directions t each other, and both with their lines of thrust not passing through the centre of the ship, so they can cause a rotating motion. Which brings us to what I am saying - multiple engines, one on each face. Again, however, the main point in achieving the curve is, in my view, that the power is applied in a sine wave. That is absolutely due to gravity - without it, it would only be going in a straight line. The thing that is causing its line of thrust to change is gravity pulling one end of the rocket down. No, the tumbling rocket in the previous post is not tumbling due to gravity. And to your earlier question, any thrust vector that does not align with the center of mass will cause a rotational moment, not just "cause a bit of side acceleration"; the rotation will change the main thrust line. In addition to gimbaled thrust (as depicted), there are also attitude thrusters which are installed to apply small amounts of thrust well away from the center of mass to create rotation, and there are mass momentum control gyro systems that can physically rotate a spacecraft around its axes without expending propellant. In reality, the hard part is not changing the thrust line; the hard part is keeping the thrust line the same, i.e. keep the craft pointed in the right direction while accelerating. Being in deep space vs. orbit really has no bearing on this.
|
|
|
Post by Flying Monkeys on Jul 20, 2019 21:16:33 GMT
No, the tumbling rocket in the previous post is not tumbling due to gravity. Poor choice of words. Without gravity, it would not be tumbling (tumbling meaning rotating and heading back to Earth). No it won't if it is not in a gravitational field. What would cause one side of an object to be held back if a force was applied on the other side?
|
|
|
Post by Harold of Whoa on Jul 20, 2019 22:15:26 GMT
No it won't if it is not in a gravitational field. What would cause one side of an object to be held back if a force was applied on the other side? Inertia. Inertia (acting through the center of mass) results in a rotational moment when any force is applied that doesn't act through the center of mass. The diagram of the rocket above shows this; gravity is not a force depicted in that. [edit - they call it the "center of gravity" in that graphic, but that is a synonym for center of mass, and its behavior is not a function of gravity]
|
|
|
Post by Flying Monkeys on Jul 20, 2019 22:32:03 GMT
Does inertia happen outside of a gravity field? Why would it?
|
|
|
Post by Harold of Whoa on Jul 20, 2019 23:51:17 GMT
Does inertia happen outside of a gravity field? Why would it? Yes. As to why, a countryman of yours figured all this out, not me. Three laws or some shit like that. Maybe it's all rubbish. But seriously, inertia doesn't happen. It is a basic property of matter. Well, mass is a basic property of matter. Inertia is just mass in the presence of some force. The reason that mass and weight are two different terms is because only weight is dependent on the gravitational force; mass is just a property of matter, it doesn't change depending on the local gravitational field. If you go to about 6:20 of the video at this link, the instructor specifically cites your example saying "in deep space". Now, you may not believe him because this is the Khan Academy, so that sounds dodgy, but he's right. www.khanacademy.org/science/ap-physics-1/ap-linear-momentum/center-of-mass-ap/v/center-of-mass
|
|
|
Post by Flying Monkeys on Jul 20, 2019 23:59:34 GMT
I say no. There is no reason for any part of a body to experience resistance to a force when not influenced by any other force.
|
|
|
Post by Harold of Whoa on Jul 21, 2019 0:13:08 GMT
I say no. There is no reason for any part of a body to experience resistance to a force when not influenced by any other force. That's the spirit! You're all set, then. No longer any need for you to mess with those pesky seatbelts. This has been great fun, but I'll be moving along, now.
|
|