Tune in for SpaceX's return to flight and first landing success

Or you can look into the fact ariane are developing a reusable launcher. Ariane 5 launch cost is in the area of 200 million  falcon 9 is in the 60 million mark. Now ariane 5 can launch twice the weight of falcon 9 but that is only an advantage to very large payloads. The current market trend is for smaller cheeper sats. So this is not a long term advantage. Now obviously there will ways be a need for some very large craft to be put in orbit and space x are building the Falcon heavy to corner this market to.

You sound like a SpaceX sales person = copy/paste the Elon nonsense. Topic is the SpeceX fake return/recovery show and not Arianespace.

And you might want to think about selling you shares in a company that's 10 years behind the curve.

Quote from: markjo on January 01, 2016, 10:21:12 PM

Quote from: Gaia_Redonda on January 01, 2016, 03:10:45 PM

Quote from: markjo on January 01, 2016, 02:08:48 PM

Quote from: Gaia_Redonda on December 31, 2015, 11:20:26 AM

At the moment a gas molecule is exposed to the vast nothingness of space it turns solid.

How can you tell if a single molecule is solid, liquid or gas? 

I've not used the word "single".

You most certainly said "a gas molecule", which is in the singular form.  How else was I supposed to interpret your statement?

Needless nitpicking.

Aren't you supposed to be a teacher or a scientist or something like that?  If so. then it seems to me that precision in your words should be very necessary nit picking.

There will be no "propellant gas molecules" anyway, so the whole thought experiment becomes rather silly.

Oh?  Why not?  Do Newton's laws of motion stop working in a vacuum?

Quote

Quote from: Gaia_Redonda on January 01, 2016, 03:10:45 PM

And that's evading the point; the conditions of space do not allow for gas to exist. That's not me saying that, that's physical-chemical laws. Any phase diagram of near-zero Pressures and Temperatures will show you that.

As Papa Legba is fond of pointing out, gasses (freely) expand in a vacuum.  Expanding a gas is not a very efficient way of turning it into a solid.

"Efficient way"? Nature's ways are not about human labels like "efficiency". Nature behaves like it does; according to physical laws, no matter how "efficient" mere humans will label that.

And the below ad hominem is hilarious. You give no science-based answer, so it's not me who doesn't understand basic chemo-physics. A phase diagram really is not hard to grasp.

Since the important reactions occur within the high pressure, high temperature environment within the rocket's combustion chamber, I hardly think that your low pressure, low temperature turns gasses solid argument is even relevant.

Since the important reactions occur within the high pressure, high temperature environment within the rocket's combustion chamber

LOL!!!

You just won't give up on your 'high pressures & combustion are possible in an infinite vacuum' schtick, will you, Humpty Dumpty?

But that is your nature, after all.

Frankly, you'd get better brainwashing results by employing a Hypnotoad...

Because if you did, thALL GLORY TO THE HYPNOTOAD!

Quote from: markjo on January 02, 2016, 07:04:54 AM

Since the important reactions occur within the high pressure, high temperature environment within the rocket's combustion chamber

LOL!!!

You just won't give up on your 'high pressures & combustion are possible in an infinite vacuum' schtick, will you, Humpty Dumpty?

But that is your nature, after all.

Frankly, you'd get better brainwashing results by employing a Hypnotoad...

Because if you did, thALL GLORY TO THE HYPNOTOAD!

According to the flawed "physics" presented by markjo you can just seal the end of a cannon, fire the thing and it moves backward (backfire).

Obviously the work is only done by the exiting gases of a rocket pushing against atmosphere and not inside the chamber of combustion itself.

Repeating NASA lies has nil to do with proper physics.

Preaching to the Choir, Gaia...

That's why I say these guys really need a Hypnotoad.

It's the only way thALL GLORY TO THE HYPONOTOAD!

Quote from: Papa Legba on January 02, 2016, 11:31:17 PM

Quote from: markjo on January 02, 2016, 07:04:54 AM

Since the important reactions occur within the high pressure, high temperature environment within the rocket's combustion chamber

LOL!!!

You just won't give up on your 'high pressures & combustion are possible in an infinite vacuum' schtick, will you, Humpty Dumpty?

But that is your nature, after all.

Frankly, you'd get better brainwashing results by employing a Hypnotoad...

Because if you did, thALL GLORY TO THE HYPNOTOAD!

According to the flawed "physics" presented by markjo you can just seal the end of a cannon, fire the thing and it moves backward (backfire).

Obviously the work is only done by the exiting gases of a rocket pushing against atmosphere and not inside the chamber of combustion itself.

Repeating NASA lies has nil to do with proper physics.

rockets and jet engines in general rely on conservation of momentum, they do not work pushing against air.

LOL!!!

'In general'?

No, troll-thing, in fact thALL GLORY TO THE HYPNOTOAD!!!

jet engines as a whole, both air breathing jet engines and rocket engines

According to the flawed "physics" presented by markjo you can just seal the end of a cannon, fire the thing and it moves backward (backfire).

Obviously the work is only done by the exiting gases of a rocket pushing against atmosphere and not inside the chamber of combustion itself.

Repeating NASA lies has nil to do with proper physics.

The canon would start moving backwards, until the canon ball hits seal, causing the Canon to move back to its original position.
No one believes that the force comes from the gases hitting the chamber, its the gas leaving the rocket, since the gas has momentum, the rocket must gain moment in the opposite direction.
Or is conservation of momentum not "proper physics"

since the gas has momentum, the rocket must gain moment in the opposite direction.

LOL!!!

So, no need for Newton's tALL GLORY TO THE HYPNOTOAD!!!

To return to topic it was the rocket engines that pushed the Falcon 9 rocket up and away into the sky and space, i.e. the engines pushed the rocket (and not air or vacuum). Works in air or vacuum and even water (my favourite medium). To push the rocket the engine produced thrust burning fuel.

The topic is if it was possible to do the same thing when Elon's rocket started to drop down to Earth again by gravity, i.e. at the right moment fire the engines again to provide thrust to stop the drop ... and land vertically.

Elon suggests that his expensive rocket came dropping down at say 1 500 m/s speed and after a quick Landing burn the rocket landed hole in one on a little cement platform in Florida a minute later in clouds of smoke ... as seen on a TV screen.

It was a simple magician's trick. The rocket was on the cement platform all the time.

Again you provide no reason or evidence as to why it's not possible.  Just your opinion.

Quote from: markjo on January 02, 2016, 07:04:54 AM

Since the important reactions occur within the high pressure, high temperature environment within the rocket's combustion chamber

LOL!!!

You just won't give up on your 'high pressures & combustion are possible in an infinite vacuum' schtick, will you, Humpty Dumpty?

And you just won't give up your tired old straw man.   I'm claiming that high pressure and combustion are possible in a finite combustion chamber.  If you can't tell the difference between a finite combustion chamber and infinite space, then you really shouldn't be discussing anything even remotely scientific.

According to the flawed "physics" presented by markjo you can just seal the end of a cannon, fire the thing and it moves backward (backfire).

No, that would be your flawed interpretation of the physics that I presented.

Obviously the work is only done by the exiting gases of a rocket pushing against atmosphere and not inside the chamber of combustion itself.

How does the atmosphere push back against the rocket?  Remember, that Newton said that every action has an equal and opposite reaction. 

Tell me Gaia, are you one of those people who think that the exhaust is still a part of the rocket?

Repeating NASA lies has nil to do with proper physics.

That's right, proper physics has to do with proper physics.  Unfortunately, it doesn't seem like you have a grasp on proper physics just yet.

And you just won't give up your tired old straw man.

LOL!!!

'Help me to understand' why you are so morally & intellectually bankrupt.

Preferably without saying 'NO U!' please.

Or, just fALL GLORY TO THE HYPNOTOAD!!!

Again you provide no reason or evidence as to why it's not possible.  Just your opinion.

OK, it was the first time in history of a rocket return flight, recovery and landing. It was night time and dark. Any viewers of the landing were far away unless they were in some control center watching it on TV.

At a certain time T+00:08:02 the rocket, mass say 76 tons (with fuel) was passing altitude 50 000 m at 1 600 m/s speed vertically down and should in principle crash after 32 seconds but an Entry burn was fired and the rocket slowed down one way or another by a 77 tons thrust. Maybe 16 tons of fuel was used. It takes 62 seconds to burn that much fuel so in my opinion Elon should have crashed now.

But no.

At time T+00;08;40, i.e. 38 seconds later - the Entry burn was still on? - the rocket was at a hefty 10 000 m altitude at  speed say 504 m/s. It had thus travelled 40 000 m in 38 seconds = average speed 1 052 m/s. If the initial speed was 1 600 m/s, the speed at 10 000 altitude may then have been 504 m/s.

With that supersonic speed flying backwards you hit ground after 20 seconds.

But Elon fired a Landing burn providing 77 tons thrust so that the rocket - mass 50 tons - touched down at 2 m/s speed less than a minute later. 8 tons of fuel was used. It takes 31 seconds to burn that fuel, so again Elon should have crashed for the second time.

Don't you agree? Or do you think that Elon had speed 20 m/s at 300 m altitude, etc? Steering with his hypersonic grid fins?

But no. On a TV screen something looking like a rocket lands - producing plenty smoke, etc, etc.

A normal passenger jet takes 30 minutes to descend from 10 000 m to land horizontally at say <100 m/s speed.

You are comparing this to a normal airplane landing?

No, he's comparing it to a tacky, ridiculous CGI & sfx Fraud.

We all arALL GLORY TO THE HYPNOTOAD!!!

You are comparing this to a normal airplane landing?

Normal airplanes land horizontally and slow down a lot. Don't you know that?

Elon says his rocket landed - all automatic, auto pilot, comuters - vertically at hypersonic speed less than a minute before vertical touch down or it travelled 10 000 m down at average 252 m/s, which would take 40 seconds leaving ample time for adjusting the final touch down. But I doubt he had enough fuel to stop the descent at 1 600 m/s speed at T+00:08:02 . I explain more at my web site. 

Wouldn't it have been much nicer to stop higher up an slowly descend in full view in day light? But it would require much more fuel. So it had to go fast! But still there was no place for any fuel to do it.

You literally answered your own question. Yes hebhad to go fast because it uses the least fuel

How does the atmosphere push back against the rocket?

Pressure-gradient forces.

If you were right, then all the weather on earth would stop working...

But it hasn't, because you're not.

As usual.

Now; what about thALL GLORY TO THE HYPNOTOAD!!

but if the nozzle is adpated the pressure at the exit of the nozzle is the same of the atmosphere around it...
so there is no pressure gradient

but if the nozzle is adpated the pressure at the exit of the nozzle is the same of the atmosphere around it...
so there is no pressure gradient

That is pure Comedy Gold...

Just perfect Clown Derf self-mockery; thank you!

Anyhoo; tALL GLORY TO THE HYPNOPOODLE!!!

You literally answered your own question. Yes he had to go fast because it uses the least fuel

Correct. But he still does not have sufficient fuel/energy to stop. Try to park a car backwards in a garage while braking from full speed using the engine also to brake. I cannot understand how anyone takes Elon serious. But it is fun. It cannot go on.

Quote from: Pythagoras on January 03, 2016, 11:10:44 AM

You literally answered your own question. Yes he had to go fast because it uses the least fuel

Correct. But he still does not have sufficient fuel/energy to stop. Try to park a car backwards in a garage while braking from full speed using the engine also to brake. I cannot understand how anyone takes Elon serious. But it is fun. It cannot go on.

Well, people are taught you can just go light speed and enter the new Death Star without problems. Science fiction has taken over from real science and the line between film and reality has been blurred by NASA and Elons space dinky toys, so you really cannot blame the brainwashed sheeple.

That is different for the brainless proponents of shpayze shit here in the topic. They deliberately propagandize the shockingly shabby Scheisse of the clawy clowns.

but if the nozzle is adpated the pressure at the exit of the nozzle is the same of the atmosphere around it...
so there is no pressure gradient

Note to Papa Legba:  Don't read past this point, as it is way above your pay grade!

One tiny correction, it is only for the "optimal nozzle" that "the pressure at the exit of the nozzle is the same of the atmosphere around it..."
This is a problem for rockets that are launched from ground and have to reach high altitude (100 km for Space-X stage 1 at separation). 
The nozzle is then designed for an intermediate altitude.  At launch the nozzle is over-expanded and at maximum altitude it is under-expanded, leading in both cases to a little lost efficiency.
A nozzle that is too much over-expanded can lead to instability of the exit stream.  This is more serious for high-altitude jet planes (like the SR-71A) which must spend most of their flight time at extreme altitudes, yet be able to take off from sea level.  In this case, some form of variable nozzle becomes necessary.

Notwithstanding all this, the rocket nozzle works perfectly well even when not optimised.  And, of course, under vacuum conditions it is completely impractical to "optimise" the nozzle - it would need an "infinite" area!  So, an optimised nozzle very often is not the best nozzle for a particular application.

An important point to note is that, even for the non-optimal nozzle, the thrust of a rocket always increases as the external pressure falls, right down to a vacuum, as in:
Here: T=static thrust, m.dot=rate of change of momentum (it's the rocket's mass that is changing), A_e=exhaust area, p_e=exhaust pressure and p_o=outside or ambient pressure.
The first term is the major one and is simply the time derivative momentum, the second smaller term shows
Just watch this trigger a memory dump from the AI we all know as Papa Legba - wait for it.........................!
(I hope you will forgive me for hijacking your post a bit to get up you know who's nose a bit.)

Quote from: markjo on January 03, 2016, 10:14:22 AM

How does the atmosphere push back against the rocket?

Pressure-gradient forces.

Would you care to elaborate?

We should all realize that this stuff is something someone is actually trying to do. It is because the founder of Amazon doesn't pay his workers squat and has wayyyyyy to much money to play with. I think it is possible to do but at the same time I think it is stupid and unnecessary. It increases the cost way too much for the benefit and makes everything have to work twice as hard to lift the extra fuel. It's a neat idea I guess but there is no real practical application.

Note to Papa Legba:  Don't read past this point

Why not?

And, of course, under vacuum conditions it is completely impractical to "optimise" the nozzle - it would need an "infinite" area!

Oh, here's why: not-Geoff/Rayzor/Soulblood drunkenly omitted to edit some Truth out of his copy/pasta spam!

What a loser.

Would you care to elaborate?

Would you care to remember that I already have?

Oh, you can't, cos of your crippling alzheimers.

What a cuALL GLORY TO THE HYPNOTOAD!!!

We should all realize that this stuff is something someone is actually trying to do.

We should all realise it is Fraud.

And, by promoting it, you & your cronys are aiding & abetting in a Conspiracy to Defraud.

Which makes you all Criminals.

You'll never get busted for it, mind...

But that doesn't mean we shouldn't despise you all the same.

Toodle-pip, Criminal Clowns!

Quote from: rabinoz on January 03, 2016, 05:35:28 PM

Note to Papa Legba:  Don't read past this point

Why not?

I was just worried about your blood pressure!

Would you care to elaborate?

You, never really elaborate anything - just spew out another memory dump!

Toodle-pip, Criminal Clowns!

I have just realised that way back in another place, after you claimed that I didn't understand it,  I asked you to explain the mass flow ~ pressure difference relationship for the "choked de Laval nozzle" ie when the throat velocity becomes sonic!  You have not yet done that, just fumed and blustered.
If you carefully explain this I might just see why these nozzles fail under some ill-defined conditions - like very low pressure.