Rosetta's Philae probe makes historic landing on comet

Quote from: Lemmiwinks on December 12, 2014, 10:18:23 AM

Pencil, paper and calculator Heiwa. Thats the only way to do it so you can then go back over it and verify you didnt make any errors.

No wonder you come up with such wildly inaccurate numbers.

Paper and pen? Calculator?? Inaccurate numbers??? What's wrong with a fresh brain and using it for simple calculations? Anyway, plenty of people above think they know the answer and are therefore invited to present the calculations to reach it. It is simple astrophysics:
A. Calculate the kinetic energy of the total mass 1000 kg spacecraft at 7000 m/s velocity relative Earth in space (mv²/2).
B. Calculate the kinetic energy of the fuel mass 500 kg after it has been ejected from the spacecraft as hot gas at velocity 4500 m/s relative the spacecraft polluting the space at 2500 m/s velocity relative Earth and having slowed down the space craft to unknown speed.
A-B is then the kinetic energy of the 500 kg spacecraft after braking (ejection of 500 kg fuel as hot gas), speed of which is easy to find (sqr((2(A-B)/500))).

Edit : Just Kidding

Quote from: Lemmiwinks on December 12, 2014, 10:18:23 AM

Pencil, paper and calculator Heiwa. Thats the only way to do it so you can then go back over it and verify you didnt make any errors.

No wonder you come up with such wildly inaccurate numbers.

Paper and pen? Calculator?? Inaccurate numbers??? What's wrong with a fresh brain and using it for simple calculations?

You claim to work in a responsible engineering position and ask this?  Wow!

You claim to work in a responsible engineering position and ask this?  Wow!

In Anders' case, "claim" is the appropriate verb.  A claim is nothing more than a declaration, made without any support or reason.

Poor old Anders' whole life has been one filled with claims LOL.  And "reason" is a word obviously missing from his vocabulary.  From what he posts here, it's obvious that he couldn't reason his way out of a damp paper bag.

   

Quote from: Heiwa on December 12, 2014, 10:48:18 AM

Quote from: Lemmiwinks on December 12, 2014, 10:18:23 AM

Pencil, paper and calculator Heiwa. Thats the only way to do it so you can then go back over it and verify you didnt make any errors.

No wonder you come up with such wildly inaccurate numbers.

Paper and pen? Calculator?? Inaccurate numbers??? What's wrong with a fresh brain and using it for simple calculations?

You claim to work in a responsible engineering position and ask this?  Wow!

You are just jealous I assume. Question is how to brake a 1000 kg spacecraft incl. 500 kg fuel. The initial speed of the spacecraft is 7000 m/s. However, the velocity of the fuel exhaust is not 4500 m/s, but a more realistic 2800 m/s. So what is the speed of the 500 kg spacecraft, when all 500 kg fuel has been burnt and ejected as exhaust?

You are just jealous I assume. Question is how to brake a 1000 kg spacecraft incl. 500 kg fuel. The initial speed of the spacecraft is 7000 m/s. However, the velocity of the fuel exhaust is not 4500 m/s, but a more realistic 2800 m/s. So what is the speed of the 500 kg spacecraft, when all 500 kg fuel has been burnt and ejected as exhaust?

"Jealous".....?  Oh puhleeze!   

The size of this guy's ego never ceases to amaze me.  He quotes nonsensical astrophysical and jet propulsion figures as though he really knows what he's talking about.  I took the time to check up on his academic credentials...

I can confirm that a Mr Anders Björkman was awarded the degree of Master of Science at the School of Naval Architecture and Marine Engineering
(Civilingenjörsexamen i Skeppsbyggnad) at Chalmers University of Technology in Gothenburg, Sweden. His degree diploma was issued on 15 October 1969.

So... what does a forty-year-old degree in naval architecture and/or marine engineering have to do with aerospace and/or astronautics you may ask.  Absolutely nothing.  End of story.

Björkman simply fills all his posts with absurd "facts" and meaningless figures, and hopes that nobody on these forums can see that they warrant no merit at all.  To put it even more bluntly, Björkman is an inveterate bullshitter.

He's also made it to the "List of Internet Kooks" which you can check out HERE.

As well, I've taken the liberty of posting a link to another site HERE wherein a qualified mechanical engineer debunks most of Björkman's "theories" about the 9/11 disaster and his nonsensical claims about the towers' structural collapse.

Still, I need a good laugh some days.  Thanks Anders.   

Quote from: Heiwa on December 12, 2014, 10:23:13 PM

You are just jealous I assume. Question is how to brake a 1000 kg spacecraft incl. 500 kg fuel. The initial speed of the spacecraft is 7000 m/s. However, the velocity of the fuel exhaust is not 4500 m/s, but a more realistic 2800 m/s. So what is the speed of the 500 kg spacecraft, when all 500 kg fuel has been burnt and ejected as exhaust?

"Jealous".....?  Oh puhleeze!   

The size of this guy's ego never ceases to amaze me.  He quotes nonsensical astrophysical and jet propulsion figures as though he really knows what he's talking about.  I took the time to check up on his academic credentials...

I can confirm that a Mr Anders Björkman was awarded the degree of Master of Science at the School of Naval Architecture and Marine Engineering
(Civilingenjörsexamen i Skeppsbyggnad) at Chalmers University of Technology in Gothenburg, Sweden. His degree diploma was issued on 15 October 1969.

So... what does a forty-year-old degree in naval architecture and/or marine engineering have to do with aerospace and/or astronautics you may ask.  Absolutely nothing.  End of story.

Björkman simply fills all his posts with absurd "facts" and meaningless figures, and hopes that nobody on these forums can see that they warrant no merit at all.  To put it even more bluntly, Björkman is an inveterate bullshitter.

He's also made it to the "List of Internet Kooks" which you can check out HERE.

As well, I've taken the liberty of posting a link to another site HERE wherein a qualified mechanical engineer debunks most of Björkman's "theories" about the 9/11 disaster and his nonsensical claims about the towers' structural collapse.

Still, I need a good laugh some days.  Thanks Anders.   

The question remains: So what is the speed of the 500 kg spacecraft, when all 500 kg fuel has been burnt and ejected as exhaust?
With your IQ and multiple PhDs it should be simple to answer. Pls show that you are clever.

Quote from: ausGeoff on December 13, 2014, 12:10:00 AM

Quote from: Heiwa on December 12, 2014, 10:23:13 PM

You are just jealous I assume. Question is how to brake a 1000 kg spacecraft incl. 500 kg fuel. The initial speed of the spacecraft is 7000 m/s. However, the velocity of the fuel exhaust is not 4500 m/s, but a more realistic 2800 m/s. So what is the speed of the 500 kg spacecraft, when all 500 kg fuel has been burnt and ejected as exhaust?

"Jealous".....?  Oh puhleeze!   

The size of this guy's ego never ceases to amaze me.  He quotes nonsensical astrophysical and jet propulsion figures as though he really knows what he's talking about.  I took the time to check up on his academic credentials...

I can confirm that a Mr Anders Björkman was awarded the degree of Master of Science at the School of Naval Architecture and Marine Engineering
(Civilingenjörsexamen i Skeppsbyggnad) at Chalmers University of Technology in Gothenburg, Sweden. His degree diploma was issued on 15 October 1969.

So... what does a forty-year-old degree in naval architecture and/or marine engineering have to do with aerospace and/or astronautics you may ask.  Absolutely nothing.  End of story.

Björkman simply fills all his posts with absurd "facts" and meaningless figures, and hopes that nobody on these forums can see that they warrant no merit at all.  To put it even more bluntly, Björkman is an inveterate bullshitter.

He's also made it to the "List of Internet Kooks" which you can check out HERE.

As well, I've taken the liberty of posting a link to another site HERE wherein a qualified mechanical engineer debunks most of Björkman's "theories" about the 9/11 disaster and his nonsensical claims about the towers' structural collapse.

Still, I need a good laugh some days.  Thanks Anders.   

The question remains: So what is the speed of the 500 kg spacecraft, when all 500 kg fuel has been burnt and ejected as exhaust?
With your IQ and multiple PhDs it should be simple to answer. Pls show that you are clever.

You do realise you are dealing with a total paid shill don't you?

You do realise you are dealing with a total paid shill don't you?

I wish I was getting paid as a "shill".  Beats the pension LOL.

ITT:  Re'ers are shown the "maths" that they have been asking for, verfied the qualifications of the presenter. Yet, they sit back and laugh. Anders has them bamboozled. Good work heiwa.

You do realise you are dealing with a total paid shill don't you?

Of course. ausGeoff is probably also mentally ill of sorts. But the forum is open for them, too.

Quote from: sceptimatic on December 13, 2014, 12:58:00 AM

You do realise you are dealing with a total paid shill don't you?

Of course. ausGeoff is probably also mentally ill of sorts. But the forum is open for them, too.

I'm more than a little pleased I seem to be getting under Anders' skin;  he can't seem to resist responding to my comments LOL.

Must've struck a raw nerve?   

Quote from: ausGeoff on December 13, 2014, 12:10:00 AM

Quote from: Heiwa on December 12, 2014, 10:23:13 PM

You are just jealous I assume. Question is how to brake a 1000 kg spacecraft incl. 500 kg fuel. The initial speed of the spacecraft is 7000 m/s. However, the velocity of the fuel exhaust is not 4500 m/s, but a more realistic 2800 m/s. So what is the speed of the 500 kg spacecraft, when all 500 kg fuel has been burnt and ejected as exhaust?

"Jealous".....?  Oh puhleeze!   

The size of this guy's ego never ceases to amaze me.  He quotes nonsensical astrophysical and jet propulsion figures as though he really knows what he's talking about.  I took the time to check up on his academic credentials...

I can confirm that a Mr Anders Björkman was awarded the degree of Master of Science at the School of Naval Architecture and Marine Engineering
(Civilingenjörsexamen i Skeppsbyggnad) at Chalmers University of Technology in Gothenburg, Sweden. His degree diploma was issued on 15 October 1969.

So... what does a forty-year-old degree in naval architecture and/or marine engineering have to do with aerospace and/or astronautics you may ask.  Absolutely nothing.  End of story.

Björkman simply fills all his posts with absurd "facts" and meaningless figures, and hopes that nobody on these forums can see that they warrant no merit at all.  To put it even more bluntly, Björkman is an inveterate bullshitter.

He's also made it to the "List of Internet Kooks" which you can check out HERE.

As well, I've taken the liberty of posting a link to another site HERE wherein a qualified mechanical engineer debunks most of Björkman's "theories" about the 9/11 disaster and his nonsensical claims about the towers' structural collapse.

Still, I need a good laugh some days.  Thanks Anders.   

The question remains: So what is the speed of the 500 kg spacecraft, when all 500 kg fuel has been burnt and ejected as exhaust?
With your IQ and multiple PhDs it should be simple to answer. Pls show that you are clever.

I was clever enough to go to ApolloHoax.net and see you get slapped around by a group of aerospace engineers there a couple of years back.  It was very illuminating to see that you had no idea of how to apply the rocket equation there or even that it was instrumental in calculating the fuel usage on a variable mass rocket.

You are just jealous I assume. Question is how to brake a 1000 kg spacecraft incl. 500 kg fuel.

Which do you think would be more efficient: braking a heavy spacecraft or changing the orbit so that it intersects with the atmosphere and let atmospheric drag do the vast majority of the braking?

The vehicle began re-entry by firing the Orbital maneuvering system engines, while flying upside down, backside first, in the opposite direction to orbital motion for approximately three minutes, which reduced the Shuttle's velocity by about 200 mph (322 km/h). The resultant slowing of the Shuttle lowered its orbital perigee down into the upper atmosphere.

Quote from: Heiwa on December 12, 2014, 10:23:13 PM

You are just jealous I assume. Question is how to brake a 1000 kg spacecraft incl. 500 kg fuel.

Which do you think would be more efficient: braking a heavy spacecraft or changing the orbit so that it intersects with the atmosphere and let atmospheric drag do the vast majority of the braking?

Quote from: http://en.wikipedia.org/wiki/Space_Shuttle#Re-entry_and_landing

The vehicle began re-entry by firing the Orbital maneuvering system engines, while flying upside down, backside first, in the opposite direction to orbital motion for approximately three minutes, which reduced the Shuttle's velocity by about 200 mph (322 km/h). The resultant slowing of the Shuttle lowered its orbital perigee down into the upper atmosphere.

That's some funny s**t, markjo!

Shuttle: Houston, we're coming home.
Houston: Roger, shuttle. Remember to flip and spin that bird upside down!
Shuttle: [chuckling]
Houston: We are live to the world, shuttle.
Shuttle: [chuckling stops, coughing follows]. Roger, orbital resequence initializing.

Quote from: markjo on December 13, 2014, 11:21:12 AM

Quote from: Heiwa on December 12, 2014, 10:23:13 PM

You are just jealous I assume. Question is how to brake a 1000 kg spacecraft incl. 500 kg fuel.

Which do you think would be more efficient: braking a heavy spacecraft or changing the orbit so that it intersects with the atmosphere and let atmospheric drag do the vast majority of the braking?

Quote from: http://en.wikipedia.org/wiki/Space_Shuttle#Re-entry_and_landing

The vehicle began re-entry by firing the Orbital maneuvering system engines, while flying upside down, backside first, in the opposite direction to orbital motion for approximately three minutes, which reduced the Shuttle's velocity by about 200 mph (322 km/h). The resultant slowing of the Shuttle lowered its orbital perigee down into the upper atmosphere.

That's some funny s**t, markjo!

Shuttle: Houston, we're coming home.
Houston: Roger, shuttle. Remember to flip and spin that bird upside down!
Shuttle: [chuckling]
Houston: We are live to the world, shuttle.
Shuttle: [chuckling stops, coughing follows]. Roger, orbital resequence initializing.

What's this supposed to be?

I was clever enough to go to ApolloHoax.net and see you get slapped around by a group of aerospace engineers there a couple of years back.  It was very illuminating to see that you had no idea of how to apply the rocket equation there or even that it was instrumental in calculating the fuel usage on a variable mass rocket.

But it seems you are not clever enough to compute the speed of a spacecraft after braking. Before braking the spacecraft has mass 1000 kg (incl. 500 kg fuel) and speed 7000 m/s. Then 500 kg fuel is ejected as hot gases at a velocity of 2500 m/s in the opposite direction of flying to slow down the space craft to slow it down, which takes a certain time and pollutes the space. Question is what velocity has then the 500 kg spacecraft?

You can evidently apply the brake force perpendicular to direction of flying. You will then not slow down at all - just change direction at increased speed. Do you know what speed you have then ... and what is the new direction?

Please demonstrate that you are clever and know how to brake a spacecraft. Pls ask your Apollo.Hoax.net clowns for assistance if necessary. Last time I visited ApolloHoax the people there thought that braking an Apollo module was pushing down the pedal in the middle while looking out the window in the side.

Remember that Rosetta had to brake a lot to finally fly parallell with the PR67 comet at identical speed and then rotated around the comet for inspection, i.e. a force was applied in another direction. It was all ESA fantasies of course as the Rosetta does not even fly in space but it is great fun to ask the ESA astrophycists about it. They don't have a clue!

Here was Rosetta's path.
#ws" class="bbc_link" target="_blank" rel="noopener noreferrer">Rosetta's orbit around the comet

Quote from: Alpha2Omega on December 12, 2014, 05:56:52 PM

Quote from: Heiwa on December 12, 2014, 10:48:18 AM

Quote from: Lemmiwinks on December 12, 2014, 10:18:23 AM

Pencil, paper and calculator Heiwa. Thats the only way to do it so you can then go back over it and verify you didnt make any errors.

No wonder you come up with such wildly inaccurate numbers.

Paper and pen? Calculator?? Inaccurate numbers??? What's wrong with a fresh brain and using it for simple calculations?

You claim to work in a responsible engineering position and ask this?  Wow!

You are just jealous I assume.

You assume wrong.

Question is how to brake a 1000 kg spacecraft incl. 500 kg fuel. The initial speed of the spacecraft is 7000 m/s. However, the velocity of the fuel exhaust is not 4500 m/s, but a more realistic 2800 m/s. So what is the speed of the 500 kg spacecraft, when all 500 kg fuel has been burnt and ejected as exhaust?

Although this isn't my area of expertise, this sure seems like a routine application of the Tsiolkovsky rocket equation[nb]It's been ages since I've done this stuff. I admit I had to look it up again to be sure of the details.[/nb]



Delta-v is your change in velocity, v_e is your exhaust velocity, m₀ and m₁ are the starting and ending masses, respectively (m₀ - m₁ is the mass of the spent fuel), and ln is the natural logarithm function (use the ln, and not log, function on your scientific calculator or Excel).

Since we're calculating change in velocity, and v_e is relative to the rocket, the starting velocity is irrelevant. Using a typical 4500 m/sec for v_e as originally specified by Heiwa the change in velocity is:

Dv = 4500 m/s * ln(1000 kg / 500 kg)
 = 4500 m/s * ln(2)
 = 4500 m/s * (0.6931)
 = 3119 m/s.

If it's a braking maneuver, then the final velocity v₁ is the initial velocity v₀ minus the change in velocity Dv.

v₁ = v₀ - Dv
 = 7000 m/s - 3119 m/s
 = 3881 m/s

I'm not sure how the 2500 or 2800 m/s he mentions apply. It seems like Heiwa's subtracting v_e 4500 m/s from v₀ 7000 m/s to get 2500 m/s, for some reason. If he wanted the velocity of the exhaust relative to the frame of reference v₀ is measured against, for whatever reason, and since it's a braking maneuver, he should add those quantities and get

7000 m/s + 4500 m/s = 9500 m/s 11,500 m/s, shouldn't he?

Also, using the kinetic energy of the exhaust seems like it's unnecessarily complicated (if it is workable at all - I'm not sure it is). Using momentum might be easier, but even then... Compounding this by "doing it all in his head" so his different result can't be examined does not lend much confidence in his work.

[Edit] Crap! This is what happens if I try to do math in my head without writing it down. Removed added. Also, fixed typo.
 
 

Quote from: Rama Set on December 13, 2014, 10:23:36 AM

I was clever enough to go to ApolloHoax.net and see you get slapped around by a group of aerospace engineers there a couple of years back.  It was very illuminating to see that you had no idea of how to apply the rocket equation there or even that it was instrumental in calculating the fuel usage on a variable mass rocket.

But it seems you are not clever enough to compute the speed of a spacecraft after braking. Before braking the spacecraft has mass 1000 kg (incl. 500 kg fuel) and speed 7000 m/s. Then 500 kg fuel is ejected as hot gases at a velocity of 2500 m/s in the opposite direction of flying to slow down the space craft to slow it down, which takes a certain time and pollutes the space. Question is what velocity has then the 500 kg spacecraft?

You can evidently apply the brake force perpendicular to direction of flying. You will then not slow down at all - just change direction at increased speed. Do you know what speed you have then ... and what is the new direction?

Please demonstrate that you are clever and know how to brake a spacecraft. Pls ask your Apollo.Hoax.net clowns for assistance if necessary. Last time I visited ApolloHoax the people there thought that braking an Apollo module was pushing down the pedal in the middle while looking out the window in the side.

Remember that Rosetta had to brake a lot to finally fly parallell with the PR67 comet at identical speed and then rotated around the comet for inspection, i.e. a force was applied in another direction. It was all ESA fantasies of course as the Rosetta does not even fly in space but it is great fun to ask the ESA astrophycists about it. They don't have a clue!

Evidently you had the blinders on at apollohoax.net and so decided to come somewhere that has a smaller proportion of people with specific expertise in aerospace engineering and aeronautics. Probably smart since those people you so haughtily referred to as clowns provided calculations and sources to destroy your claim that spacecraft cannot make trans-lunar journeys due to fuel constraints. Not only that, but they provided information you insisted was classified, further disintegrating you cobspiracy assertions.

I highly recommend reading the thread to others because there is quite a bit of interesting conversation regarding manned space flight:

http://www.apollohoax.net/forum/index.php?PHPSESSID=3b4c7c5f4cb62807383919f4bbce606c&topic=269.0

It also demonstrates that the argument Heiwa is currently trying make is a derivative of a badly formed argument he tried two years ago.
 

Quote from: Heiwa on December 13, 2014, 02:06:28 PM

Quote from: Rama Set on December 13, 2014, 10:23:36 AM

I was clever enough to go to ApolloHoax.net and see you get slapped around by a group of aerospace engineers there a couple of years back.  It was very illuminating to see that you had no idea of how to apply the rocket equation there or even that it was instrumental in calculating the fuel usage on a variable mass rocket.

But it seems you are not clever enough to compute the speed of a spacecraft after braking. Before braking the spacecraft has mass 1000 kg (incl. 500 kg fuel) and speed 7000 m/s. Then 500 kg fuel is ejected as hot gases at a velocity of 2500 m/s in the opposite direction of flying to slow down the space craft to slow it down, which takes a certain time and pollutes the space. Question is what velocity has then the 500 kg spacecraft?

You can evidently apply the brake force perpendicular to direction of flying. You will then not slow down at all - just change direction at increased speed. Do you know what speed you have then ... and what is the new direction?

Please demonstrate that you are clever and know how to brake a spacecraft. Pls ask your Apollo.Hoax.net clowns for assistance if necessary. Last time I visited ApolloHoax the people there thought that braking an Apollo module was pushing down the pedal in the middle while looking out the window in the side.

Remember that Rosetta had to brake a lot to finally fly parallell with the PR67 comet at identical speed and then rotated around the comet for inspection, i.e. a force was applied in another direction. It was all ESA fantasies of course as the Rosetta does not even fly in space but it is great fun to ask the ESA astrophycists about it. They don't have a clue!

Evidently you had the blinders on at apollohoax.net and so decided to come somewhere that has a smaller proportion of people with specific expertise in aerospace engineering and aeronautics. Probably smart since those people you so haughtily referred to as clowns provided calculations and sources to destroy your claim that spacecraft cannot make trans-lunar journeys due to fuel constraints. Not only that, but they provided information you insisted was classified, further disintegrating you cobspiracy assertions.

I highly recommend reading the thread to others because there is quite a bit of interesting conversation regarding manned space flight:

http://www.apollohoax.net/forum/index.php?PHPSESSID=3b4c7c5f4cb62807383919f4bbce606c&topic=269.0

It also demonstrates that the argument Heiwa is currently trying make is a derivative of a badly formed argument he tried two years ago.

I'd forgotten that thread. He also had his ass handed to him - on the same topic - on cosmoquest.org.

Quote from: Heiwa on December 12, 2014, 10:23:13 PM

Quote from: Alpha2Omega on December 12, 2014, 05:56:52 PM

Quote from: Heiwa on December 12, 2014, 10:48:18 AM

Quote from: Lemmiwinks on December 12, 2014, 10:18:23 AM

Pencil, paper and calculator Heiwa. Thats the only way to do it so you can then go back over it and verify you didnt make any errors.

No wonder you come up with such wildly inaccurate numbers.

Paper and pen? Calculator?? Inaccurate numbers??? What's wrong with a fresh brain and using it for simple calculations?

You claim to work in a responsible engineering position and ask this?  Wow!

You are just jealous I assume.

You assume wrong.

Quote

Question is how to brake a 1000 kg spacecraft incl. 500 kg fuel. The initial speed of the spacecraft is 7000 m/s. However, the velocity of the fuel exhaust is not 4500 m/s, but a more realistic 2800 m/s. So what is the speed of the 500 kg spacecraft, when all 500 kg fuel has been burnt and ejected as exhaust?

Although this isn't my area of expertise, this sure seems like a routine application of the Tsiolkovsky rocket equation[nb]It's been ages since I've done this stuff. I admit I had to look it up again to be sure of the details.[/nb]



Delta-v is your change in velocity, v_e is your exhaust velocity, m₀ and m₁ are the starting and ending masses, respectively (m₀ - m₁ is the mass of the spent fuel), and ln is the natural logarithm function (use the ln, and not log, function on your scientific calculator or Excel).

Since we're calculating change in velocity, and v_e is relative to the rocket, the starting velocity is irrelevant. Using a typical 4500 m/sec for v_e as originally specified by Heiwa the change in velocity is:

Dv = 4500 m/s * ln(1000 kg / 500 kg)
 = 4500 m/s * ln(2)
 = 4500 m/s * (0.6931)
 = 3119 m/s.

If it's a braking maneuver, then the final velocity v₁ is the initial velocity v₀ minus the change in velocity Dv.

v₁ = v₀ - Dv
 = 7000 m/s - 3119 m/s
 = 3880 m/s

I'm not sure how the 2500 or 2800 m/s he mentions apply. It seems like Heiwa's subtracting v_e from v₀ to get 2500 m/s for some reason. If he wanted the velocity of the exhaust relative to the frame of reference v₀ is measured against, for whatever reason, and since it's a braking maneuver, he should add those quantities and get 9500 m/s, shouldn't he?

Also, using the kinetic energy of the exhaust seems like its unnecessarily complicated (if it is workable at all - I'm not sure it is). Using momentum might be easier, but even then... Compounding this by "doing it all in his head" so his different result can't be examined does not lend much confidence in his work.

The Tsiolkovsky rocket equation is, as we all know (I mention it on my web site), used to see how a rocket or spacecraft accelerates, while getting lighter with a constant force (exhaust gasses escaping at 2400 m/s) applied to it. If it can be used for deceleration is another matter. The force is then applied in the opposite direction or the rocket/spacecraft flies backwards, i.e. has been flipped around 180° in the direction of flight. The force must be applied in the right direction. If not you accelerate/decelerate into empty space. If you brake to get into, e.g. Moon orbit, you must also consider the grafity force of the Moon that accelerates your spacecraft.
And it was the topic at ApolloHoax.net. I showed that it was impossible for Apollo to brake flying backwards to get into Moon orbit, while it, at the same time, was accelerating due to Moon gravity. The Apollo crew had no means to brake/apply the force in the right direction (which changes) to get into Moon orbit. Bye, bye Apollo. Luckily it was just a Hollywood show 1969-1972.
Likewise the Shuttle re-entries during 20+ years leaving the International Fake Station at 400000 meter altitude is impossible. The  78 000 kg Shuttle at 7000 m/s must fly backwards and activate its jet/rocket engines to slow down and there is too little fuel aboard for it. When dropping down to 100000 meter altitude entering the atmosphere, the speed has increased and the Shuttle must flip 180° with nose forward and dip into the atmosphere. It is then, e.g. the front windows break apart and the Shuttle disintegrates. Luckily it was just another Hollywood show. Like the Rosetta/Philae = TOPIC! Too little fuel aboard for manoeuvering! And too far away from Earth! But a nice Babelsberg show! Berlin is much more fun than Los Angeles. But very boring as it is all magic tricks by  tired illusionists just making children happy. And stupid grown ups, of course, still believing in Father Christmas. 

Quote from: markjo on December 13, 2014, 11:21:12 AM

Quote from: Heiwa on December 12, 2014, 10:23:13 PM

You are just jealous I assume. Question is how to brake a 1000 kg spacecraft incl. 500 kg fuel.

Which do you think would be more efficient: braking a heavy spacecraft or changing the orbit so that it intersects with the atmosphere and let atmospheric drag do the vast majority of the braking?

Quote from: http://en.wikipedia.org/wiki/Space_Shuttle#Re-entry_and_landing

The vehicle began re-entry by firing the Orbital maneuvering system engines, while flying upside down, backside first, in the opposite direction to orbital motion for approximately three minutes, which reduced the Shuttle's velocity by about 200 mph (322 km/h). The resultant slowing of the Shuttle lowered its orbital perigee down into the upper atmosphere.

That's some funny s**t, markjo!

Shuttle: Houston, we're coming home.
Houston: Roger, shuttle. Remember to flip and spin that bird upside down!
Shuttle: [chuckling]
Houston: We are live to the world, shuttle.
Shuttle: [chuckling stops, coughing follows]. Roger, orbital resequence initializing.

  What's so funny?  Which way would you suggest pointing the rocket engines if you want to slow the shuttle?

Wow heiwa. You are literally using the exact same arguments as on the other sites.  And we're proven incorrect  by an order or magnitude. Is that what you are on this site? In the hope that the posters are less knowledgeable in the subjects as to be able to hoodwink them? I urge everyone to go read the two links provided.

I think we can conclude that poor old Heiwa's "theories" have been totally debunked on just about every forum on the interwebs LOL.

And yes; I agree with a couple of other guys here who've said the only reason he started infesting this forum was because he (mistakenly) thought that we'd all be ignorant of the sciences, and wouldn't be capable of shooting him down as we have.

This is a pattern that Heiwa has set over the years:  Infest a forum, crap on endlessly about stuff he knows nothing about, claim he has relevant academic qualifications in aerospace (which he hasn't), tell endless, blatant lies, get caught out by people who do have the appropriate aerospace credentials, and then finally disappear with his tail between his legs.

Maybe if we just ignore him he'll go away?  Or is that just wishful thinking?

   

This is a pattern that Heiwa has set over the years:  Infest a forum, crap on endlessly about stuff he knows nothing

Hm, you have made >4490 sick posts of little value at this forum and I have only made 117 incl. this one - all very intelligent and clear. And you cannot even explain how a spacecraft like Rosetta going backwards slows down by firing its rocket engine(s) in the exact, opposite direction of flight so it gets engulfed in its own exhaust, running out of fuel, etc, etc. The only evidences so far of Rosetta arriving anywhere are a video showing a track of something orbiting a comet and photos of a comet looking like a submerged island in the Nile or below water in the Assuan dam. What a stupid joke. I am not sorry if it destroys your illusions and beliefs. What is your objective? Proving Father X-mas is also flying around in 10 days?

Quote from: Alpha2Omega on December 13, 2014, 03:15:36 PM

Quote from: Heiwa on December 12, 2014, 10:23:13 PM

Quote from: Alpha2Omega on December 12, 2014, 05:56:52 PM

Quote from: Heiwa on December 12, 2014, 10:48:18 AM

Quote from: Lemmiwinks on December 12, 2014, 10:18:23 AM

Pencil, paper and calculator Heiwa. Thats the only way to do it so you can then go back over it and verify you didnt make any errors.

No wonder you come up with such wildly inaccurate numbers.

Paper and pen? Calculator?? Inaccurate numbers??? What's wrong with a fresh brain and using it for simple calculations?

You claim to work in a responsible engineering position and ask this?  Wow!

You are just jealous I assume.

You assume wrong.

Quote

Question is how to brake a 1000 kg spacecraft incl. 500 kg fuel. The initial speed of the spacecraft is 7000 m/s. However, the velocity of the fuel exhaust is not 4500 m/s, but a more realistic 2800 m/s. So what is the speed of the 500 kg spacecraft, when all 500 kg fuel has been burnt and ejected as exhaust?

Although this isn't my area of expertise, this sure seems like a routine application of the Tsiolkovsky rocket equation[nb]It's been ages since I've done this stuff. I admit I had to look it up again to be sure of the details.[/nb]



Delta-v is your change in velocity, v_e is your exhaust velocity, m₀ and m₁ are the starting and ending masses, respectively (m₀ - m₁ is the mass of the spent fuel), and ln is the natural logarithm function (use the ln, and not log, function on your scientific calculator or Excel).

Since we're calculating change in velocity, and v_e is relative to the rocket, the starting velocity is irrelevant. Using a typical 4500 m/sec for v_e as originally specified by Heiwa the change in velocity is:

Dv = 4500 m/s * ln(1000 kg / 500 kg)
 = 4500 m/s * ln(2)
 = 4500 m/s * (0.6931)
 = 3119 m/s.

If it's a braking maneuver, then the final velocity v₁ is the initial velocity v₀ minus the change in velocity Dv.

v₁ = v₀ - Dv
 = 7000 m/s - 3119 m/s
 = 3880 m/s

I'm not sure how the 2500 or 2800 m/s he mentions apply. It seems like Heiwa's subtracting v_e from v₀ to get 2500 m/s for some reason. If he wanted the velocity of the exhaust relative to the frame of reference v₀ is measured against, for whatever reason, and since it's a braking maneuver, he should add those quantities and get 9500 m/s, shouldn't he?

Also, using the kinetic energy of the exhaust seems like its unnecessarily complicated (if it is workable at all - I'm not sure it is). Using momentum might be easier, but even then... Compounding this by "doing it all in his head" so his different result can't be examined does not lend much confidence in his work.

The Tsiolkovsky rocket equation is, as we all know (I mention it on my web site), used to see how a rocket or spacecraft accelerates, while getting lighter with a constant force

This is correct. No quibble with the calculations or result above?

(exhaust gasses escaping at 2400 m/s) applied to it.

Why did you change v_e yet again? If the numbers change, the answer changes, but the principle doesn't. Fortunately v_e is determined by the design of the engine and chemistry of the fuel, and not by fiat. It can be tested and measured, so meaningful calculations can be made.

If it can be used for deceleration is another matter.

Acceleration is rate of change of velocity and says nothing about whether the magnitude of the velocity is increasing or decreasing. This is an acceleration, which you agreed is what the rocket equation is used for.

You claim to be an accomplished engineer. Why is it necessary to say this? This is about as basic as you can get.

The force is then applied in the opposite direction or the rocket/spacecraft flies backwards, i.e. has been flipped around 180° in the direction of flight. The force must be applied in the right direction. If not you accelerate/decelerate into empty space.

If you want to change your velocity in a particular way, you'd better apply force in the proper direction or you aren't going to get the desired result. This applies not only to rockets; it applies to any vehicle that can accelerate. No news here.

If you brake to get into, e.g. Moon orbit, you must also consider the grafity force of the Moon that accelerates your spacecraft.

The rocket equation accounts only for velocity change due to ejecting exhaust mass. Outside forces must be accounted for elsewhere in the larger solution. You can use it to solve for the fuel needed to provide the net delta-v necessary to accomplish what you want to do. The calculations, equipment, and supplies are not trivial, but are a scientific and engineering problem that can be solved.

And it was the topic at ApolloHoax.net. I showed that it was impossible for Apollo to brake flying backwards to get into Moon orbit, while it, at the same time, was accelerating due to Moon gravity.

No, you didn't. You refused to acknowledge where you were repeatedly shown to be wrong, in detail, before you unceremoniously disappeared. The link is posted; everyone is invited to read for themselves. AFAIK, you're still not banned there;you did fail to make your point before you vanished without admitting you were wrong.

The Apollo crew had no means to brake/apply the force in the right direction (which changes) to get into Moon orbit.

Citation needed. A lot of of evidence suggests otherwise.

Bye, bye Apollo. Luckily it was just a Hollywood show 1969-1972.
Likewise the Shuttle re-entries during 20+ years leaving the International Fake Station at 400000 meter altitude is impossible. The  78 000 kg Shuttle at 7000 m/s must fly backwards and activate its jet/rocket engines to slow down and there is too little fuel aboard for it.

Please show why you think this maneuver was impossible, how much fuel was needed, and how much was available. Please provide details of your calculations and evidence for the amount of fuel available.

When dropping down to 100000 meter altitude entering the atmosphere, the speed has increased and the Shuttle must flip 180° with nose forward and dip into the atmosphere. It is then, e.g. the front windows break apart and the Shuttle disintegrates.

Please show details why you believe the required maneuver was not possible. Citation needed on the window thing.

Luckily it was just another Hollywood show. Like the Rosetta/Philae = TOPIC! Too little fuel aboard for manoeuvering!

Citation needed.

And too far away from Earth!

For what?

But a nice Babelsberg show! Berlin is much more fun than Los Angeles.

OK

But very boring as it is all magic tricks by  tired illusionists just making children happy. And stupid grown ups, of course, still believing in Father Christmas.

Can you at least try to stay on topic?

[Edit] Nested quotes.

Please show why you think this maneuver was impossible, how much fuel was needed, and how much was available. Please provide details of your calculations and evidence for the amount of fuel available.

Please refer to Section #1.5 of my paper/web page linked to on page 3 of this thread. Note that I write simple and popular based on the NASA reports of the alleged space trip (all mentioned in my paper).
As it is clear from the beginning that all space trips (apart from unmanned satellites orbiting Earth) are stupid hoaxes, detailed calculations are not required. Input data provided by NASA differs all the time, etc, so no detailed results can be computed and this fact is used to show that criticism is not valid, bla, bla.

Hm, you have made >4490 posts at this forum and I have only made 117 incl. this one - all very intelligent and clear.

LOL... Nice to see I'm still getting under Heiwa's skin.  It looks as though he now wants to get into a pissing competition.  How old is this guy in reality?  Fourteen?  My dad's truck is bigger than yours?

And you cannot even explain how a spacecraft like Rosetta going backwards slows down by firing its rocket engine(s) in the exact, opposite direction of flight so it gets engulfed in its own exhaust, running out of fuel, etc, etc.

Of course I can't.  I don't pretend to be an expert on aerospace or aeronautics.  I leave it to the engineers and scientists.

You, on the other hand, like to pretend you know what you're talking about with this stuff, when in fact your only, totally irrelevant "qualification" is a 40-year-old marine engineering degree LOL.

It's obvious that you don't know any more about aeronautics than any Joe Blow in the street.  And maybe less?   

Quote from: Alpha2Omega on December 13, 2014, 11:04:23 PM

Please show why you think this maneuver was impossible, how much fuel was needed, and how much was available. Please provide details of your calculations and evidence for the amount of fuel available.

Please refer to Section #1.5 of my paper/web page linked to on page 3 of this thread. Note that I write simple and popular based on the NASA reports of the alleged space trip (all mentioned in my paper).

If you already have the calculations, can you please post them here for everyone's convenience. I attempted to visit your website a while back and was warned that it was on the suspicious web page blacklist, so I declined.

As it is clear from the beginning that all space trips (apart from unmanned satellites orbiting Earth) are stupid hoaxes, detailed calculations are not required. Input data provided by NASA differs all the time, etc, so no detailed results can be computed and this fact is used to show that criticism is not valid, bla, bla.

So you you haven't done the calculations? I'm glad I didn't risk visiting your web page.

Hm, you have made >4490 sick posts of little value at this forum and I have only made 117 incl. this one - all very intelligent and clear.

It looks like some of us have a different idea of what makes for an "intelligent and clear" post than you seem to.

And you cannot even explain how a spacecraft like Rosetta going backwards slows down by firing its rocket engine(s) in the exact, opposite direction of flight so it gets engulfed in its own exhaust, running out of fuel, etc, etc.

Umm...  Do you understand how things work in a microgravity, nearly perfect vacuum environment?  If I fire my thrusters in the direction that I'm traveling, then the exhaust are accelerated away from me while I'm being decelerated.  How can I be engulfed in those exhaust gasses if those exhaust gasses are traveling faster than I am and being dissipated into the vacuum of space?

As for running out of fuel...  Let's just say that a lot of the maneuvers are a lot more subtle than you would think.