So, who wants to win 1 million Euro?

[Andromeda]

So in Earth orbit the CSM was disconnected from the last stage of the Saturn rocket, rotated 180° and then connected to the Lunar Module?

Yes.

No! Except for Apollo 9 transposition and docking took place after TLI.

Apologies, I woke up early and I'm sleepy this morning - I missed that he said "in Earth orbit".

[DataCable]

Of course - evidently the Apollo 11 space ship - its mass - slowed down going to the Moon due to Earth (and Sun) gravity force and then, at the end (after 90% of distance travelled), accelerated again due to Moon gravity force being stronger than Earth gravity acting on the Apollo 11 mass.

Essentially correct, though the Sun's gravity has little to do with it, since the Earth/Moon system is in perpetual freefall about the Sun.

Problem is to change the actual velocity/direction when this happens during space travel applying another force (by your rocket engine!)

Of course.  You made an absolute blanket statement: "Every change in speed or direction during Moon travel requires energy."  Your implication being that the spacecraft would always travel in a straight line at a constant speed unless it fired its engine.  I corrected this assertion.  I did not, however, claim that gravity was the only relevant force.

[Heiwa]

The kinetic energy of a mass m = 43000 kg at velcocity v=2400 m/s is evidently 43 000*2400²/2= 123.84 GJ
At v=1500 m/s the kinetic energy is 48.375 GJ.
The difference in kinetic energy of a mass of 43000 kg at 2400 and 1500 m/s is therefore 123.84-48.375=75.465 GJ.
In order to reduce the velocity from 2400 to 1500 m/s, which takes a certain time t (seconds) you must apply a force F (Newton), while the space ship displaces a distance d (meter).
Say that the time t is 600 seconds? What is the force F? And the distance d? Show me that you can calculate.

The force would be 1.5 m/s².
The distance would be the average velocity (assuming constant acceleration, which would not be the case) = 1,170,000 m.
The kinetic energy in joules would be 43,000 kg · 1,170,000 m · 1.5 m/s² = 75.465 GJ.

Doing the same calculations with different velocities that differ by 900 m/s, say from 10,000 m/s to 9100 m/s, we get:
The force would be the same: 900 m/s ÷ 600 s = 1.5 m/s².
The distance 5,730,000 m.
Kinetic energy = 43,000 kg · 5,730,000 m · 1.5 m/s² = 369.585 GJ.
Using your equation kinetic energy is 43,000 kg · (10,000² - 9100²) ÷ 2 = 369.585 GJ, the exact same value.

But notice the force remains the same, 1.5 m/s², regardless of the initial velocity. It is force that accelerates a spacecraft, not energy. Force = mass · acceleration which means acceleration = force ÷ mass. Nowhere in this acceleration equation is there a place for energy.

Unit of force is Newton (N). Unit of mass is kilogram (kg), unit of distance is meter (m), unit of time is seconds (s).  FYI 1 N = 1 kg m / s² . It is very easy; Pls, try to get the basics right.

Unit of energy is Joule (J). 1 J = 1 N m .

Acceleration is change in velocity over time, etc, etc.

Applying a force 1 N to a mass of 1 kg will accelerate that mass at 1 m/s² ... and no energy is required for that acceleration.

But you need energy to produce the force.

[nomuse]

Hrm.  I was about to make some comment about water vessels pointing in the direction of travel -- the old "banking in space" error -- but then I recalled the last water craft I was on were ferries crossing the Rhine.  And they didn't care WHICH way they pointed (pivoting props front and rear; and even the brisk current was no match for those engines).

Point is, after a gaff like "direction and velocity" you have to ask if the person actually understands that spacecraft aren't constrained to fly nose-first.

[Andromeda]

Pls, try to get the basics right.

That is rich from someone who talked about "direction and velocity".

[Heiwa]

The ship moving over waves does so passively. It has engines that can move it forward, backwards, left and right. Wave motion is not something it drives itself upwards or downwards to compensate for.

It is correct that waves will move a ship in 3D and that the ship is then subject to forces. FYI, ships normally use a rudder to move starboard and port. Actually forces acting on the rudder move the ship sideways or transversly. And the force produced by the rotating propeller moves the ship longitudinally. Changes in motion velocities (i.e. accelerations in all 3-D directions) apply inertia forces on the ship. Quite complex, actually. Much more complicated than simple space travel. That's why I am qualified to judge the Apollo 11 space trip that could not happen due to lack of fuel. Basic. But prove me wrong and earn € 1 million. Details are in the link of my paper (post #1).

[nomuse]

I still want to know what the whole point of bringing up the reconfiguration is.

I mean; why not ask how the suit umbilicals were switched from cabin system to PLSS, at that point.  Or ask how food got out of the packages and into the astronauts!

I am really scratching my head trying to understand why this would strike anyone as an important (or, for that matter, unanswered) question.

[nomuse]

The ship moving over waves does so passively. It has engines that can move it forward, backwards, left and right. Wave motion is not something it drives itself upwards or downwards to compensate for.

It is correct that waves will move a ship in 3D and that the ship is then subject to forces. FYI, ships normally use a rudder to move starboard and port. Actually forces acting on the rudder moves the ship sideways. And the force produced by the rotating propeller moves the ship longitudinally. Changes in motion velocities (i.e. accelerations in all 3-D directions) apply inertia forces on the ship. Quite complex, actually. Much more complicated than simple space travel.

Wait, what?  The rudder moves you sideways?  I was coming in to the pier all wrong when I used to sail my dear little El Toro around the Marina, back when I was a boy!

Yes, yes...it is a combination of forces, not simple, and inertia figures as well.  But even in sailing you are dealing largely with motions that can be best described as the resultant of vector addition.  Thinking of things only in regards to which way the bow is pointed is a really great way to ram the side of the slip!

[Jason Thompson]

Changes in motion velocities (i.e. accelerations in all 3-D directions) apply inertia forces on the ship.

'Motion veocities' and 'inertia forces'? You don't even sound like an engineer.

Yes, there are forces applied on the ship in all three dimensions, but the design of the ship's propulsion systems, and its navigational systems, consider the motion in two dimensions. It has no need to correct for up and down forces produced by waves because they are self-cancelling. After it has ridden up a large wave or swell it must go down again, and it will always, no matter what sea conditions are, arrive at its destination on the same level as the port. It only has to correct for lateral deflections in order to arrive at its destination, and any retardation or acceleration of its forward motion will simply make it early or late.

Space travel not only has forces acting in all three dimensions but they do not cancel out and the navigation of the vessel must consider its motion in all three dimensions or else it will miss its target entirely. Any deviation in any direction must be corrected or it will not arrive where it intends to be at all.

So the forces applied to a seafaring vessel may be more complex than those on a spacecraft, but the navigation concerns of any vessel travelling over the surface of the Earth are considerably simpler.

[Andromeda]

That's why I am qualified to judge the Apollo 11 space trip that could not happen due to lack of fuel. Basic.

To all appearances, you are not qualified to judge anything.

I note you have focused on Apollo 11.  What about Apollos 8, 9, 10, 12, 13, 14, 15, 16 and 17.  Have you heard of them.

But prove me wrong and earn € 1 million.

I think that even if you do have the money, you have demonstrated that you will not accept or admit that you have been proven wrong.

[Daggerstab]

I still want to know what the whole point of bringing up the reconfiguration is.

I mean; why not ask how the suit umbilicals were switched from cabin system to PLSS, at that point.  Or ask how food got out of the packages and into the astronauts!

I am really scratching my head trying to understand why this would strike anyone as an important (or, for that matter, unanswered) question.

Read Heiwa's page or my post on the second page of this thread that has excerpts from it. He apparently is not aware of spacecraft's reaction control systems - he was also mystified by the CSM and the LM undocking and re-docking in lunar orbit. Talk about ignorant...

[Jason Thompson]

FYI, ships normally use a rudder to move starboard and port. Actually forces acting on the rudder move the ship sideways or transversly.

FYI, I am aware of how a rudder works. The water moving over the rudder causes the ship to turn, not move sideways. I have watched many ships move sideways, however, while visiting the harbour near my house when i was a boy. Judging by the huge roaring noise and spray that was no rudder doing that....

[Daggerstab]

Changes in motion velocities (i.e. accelerations in all 3-D directions) apply inertia forces on the ship.

'Motion veocities' and 'inertia forces'? You don't even sound like an engineer.

To be fair, English is not hist first language. Earlier in the thread I asked him if he's using machine translation, because of some recurring peculiarities. He didn't answer. I suspect that he reads only the last page of the thread, not all the posts since his last one.

[Glom]

I missed all the action while I was asleep.

When talking about "direction and velocity" are you talking about the direction of the velocity or the attitude of the spacecraft? Because if the former, your phrase is redundant because velocity includes direction since it's a vector quantity, if the latter, then direction is irrelevant for coasting in space.

Also, do you acknowledge the explanations of transposition, docking and extraction now and also that many of the details of you said were unknown, such as the density of propellant and the delta-m of burns, are actually readily available?

[Chew]

The kinetic energy of a mass m = 43000 kg at velcocity v=2400 m/s is evidently 43 000*2400²/2= 123.84 GJ
At v=1500 m/s the kinetic energy is 48.375 GJ.
The difference in kinetic energy of a mass of 43000 kg at 2400 and 1500 m/s is therefore 123.84-48.375=75.465 GJ.
In order to reduce the velocity from 2400 to 1500 m/s, which takes a certain time t (seconds) you must apply a force F (Newton), while the space ship displaces a distance d (meter).
Say that the time t is 600 seconds? What is the force F? And the distance d? Show me that you can calculate.

The force acceleration would be 1.5 m/s² so the force would be 64,500 N.
The distance would be the average velocity (assuming constant acceleration, which would not be the case) = 1,170,000 m.
The kinetic energy in joules would be 43,000 kg · 1,170,000 m · 1.5 m/s² = 75.465 GJ.

Doing the same calculations with different velocities that differ by 900 m/s, say from 10,000 m/s to 9100 m/s, we get:
The force acceleration would be the same: 900 m/s ÷ 600 s = 1.5 m/s².
The distance 5,730,000 m.
Kinetic energy = 43,000 kg · 5,730,000 m · 1.5 m/s² = 369.585 GJ.
Using your equation kinetic energy is 43,000 kg · (10,000² - 9100²) ÷ 2 = 369.585 GJ, the exact same value.

But notice the force acceleration remains the same, 1.5 m/s², regardless of the initial velocity. It is force that accelerates a spacecraft, not energy. Force = mass · acceleration which means acceleration = force ÷ mass. Nowhere in this acceleration equation is there a place for energy.

Unit of force is Newton (N). Unit of mass is kilogram (kg), unit of distance is meter (m), unit of time is seconds (s).  FYI 1 N = 1 kg m / s² . It is very easy; Pls, try to get the basics right.

Unit of energy is Joule (J). 1 J = 1 N m .

Acceleration is change in velocity over time, etc, etc.

Applying a force 1 N to a mass of 1 kg will accelerate that mass at 1 m/s² ... and no energy is required for that acceleration.

But you need energy to produce the force.

You have not explained why the accelerations were the same for both examples I gave yet the kinetic energies were vastly different. You are also ignoring the rocket equation.


(I mistyped force when I meant acceleration. I fixed my that post and I striked out my errors and fixed them in this post.)