Does Rocketry Work in the Vacuum?

If NASA faked the moon landings, does the agency have any credibility at all? Was the Space Shuttle program also a hoax? Is the International Space Station another one? Do not dismiss these hypotheses offhand. Check out our wider NASA research and make up your own mind about it all.

Re: Does Rocketry Work in the Vacuum?

Postby simonshack on August 4th, 2016, 10:35 am

Hi MagicFlame007 and welcome. That was an interesting thought experiment. I take it that your conclusion is similar to mine, i.e. that NASA has been taking us for a ride all along - and that none of their rockets have escaped our atmosphere let alone re-entered and landed / returned back on Earth?

ps: Kindly introduce yourself to our readers as required - in our dedicated "welcome thread" for new members:
viewtopic.php?f=32&t=838
simonshack
Administrator
 
Posts: 6362
Joined: October 18th, 2009, 9:09 pm
Location: italy

Re: Does Rocketry Work in the Vacuum?

Postby MagicFlame007 on August 4th, 2016, 11:03 am

Hi Simon,

I thought I had posted my intro, but saw that I did not submit or whatever. My introduction is there now however.

My position is that it is impossible to send anything into outer space, slow it down enough to land anywhere using existing rocket technology and even more impossible to take off if you miraculously managed to slow the craft enough to land it. If you had a dense atmosphere at your destination, you might well be able to take off again, but keep in mind that you would have to fight gravity again and hence need copious amounts of fuel to do so. The catch 22 here is that the more fuel you have, the more you need to fight gravity.

Sending a craft to the moon would require you to turn your craft "ass end" to the moon as soon as you escape the earth's gravity and braking for all your worth! Remember, that craft is not going to coast to standstill, it will continue forever at the speed you escaped at.

I believe in fact that it might well be possible to "shoot stuff" out into the void of space, but anything more than a flyby of your destination is wishful thinking. In outer space, your rockets would produce very little "thrust" and really only be good for minor course corrections (slowly).

My opinion further is that the way NASA and most other space exploration companies launch space vehicles is ridiculous as mentioned in my wistful story. I think they do it that way because showing the brute force of a "millions of horsepower" Saturn V launching vertically, is just another form of "shock and awe" technique, calculated to impress.
Last edited by MagicFlame007 on August 4th, 2016, 12:59 pm, edited 1 time in total.
MagicFlame007
Member
 
Posts: 14
Joined: August 4th, 2016, 8:20 am

Re: Does Rocketry Work in the Vacuum?

Postby Flabbergasted on August 4th, 2016, 11:28 am

MagicFlame007 » August 4th, 2016, 7:03 am wrote:My opinion further is that the way NASA and most other space exploration companies launch space vehicles is ridiculous as mentioned in my wistful story. I think they do it that way because showing the brute force of a "millions of horsepower" Saturn V launching vertically, is just another form of "shock and awe" technique, calculated to impress.

Welcome aboard, MagicFlame007.

Are you saying that launching rockets vertically is a bad idea? Why is the launch mode shown in NASA videos ridiculous? Could you elaborate on that?
Flabbergasted
Member
 
Posts: 630
Joined: November 12th, 2012, 1:19 am

Re: Does Rocketry Work in the Vacuum?

Postby MagicFlame007 on August 4th, 2016, 12:56 pm

Hi Flabbergasted,

Thank you for the welcome.

My contention is that it takes a fraction of the energy to push (horizontally) a vehicle than to lift (vertically) it. Would it not make a lot more sense to push your vehicle and use wings (with it's known aerodynamic properties) to do the "heavy vertical lifting" way up into the stratosphere? That way you can dispense with at least the first stage rockets altogether.

Imagine a huge air frame type vehicle (not unlike the green machine in the Thunderbirds of old) with powerful jet engines and big wings. This monstrosity might cost as much or more than a Saturn V to develop and build, but it would be re-usable, since only the payload and final stage engine needs to be launched into outer space. This final stage would then already be traveling at perhaps one quarter of the velocity needed to escape earth's gravity and will have traversed much of the distance (height actually) by the time it separates from the air frame.

Have you noticed how a space rocket is not simply launched straight up into the air? Soon after launch they are gradually oriented to an attitude that is more perpendicular to the surface of earth (or so it would seem from watching footage). Surely the purpose of this would be to firstly "give you enough room" to reach escape velocity and secondly to not have to fight gravity every step of the way up.
MagicFlame007
Member
 
Posts: 14
Joined: August 4th, 2016, 8:20 am

Re: Does Rocketry Work in the Vacuum?

Postby SacredCowSlayer on August 5th, 2016, 4:31 am

MagicFlame007 » August 4th, 2016, 6:56 am wrote:Hi Flabbergasted,

Thank you for the welcome.

My contention is that it takes a fraction of the energy to push (horizontally) a vehicle than to lift (vertically) it. Would it not make a lot more sense to push your vehicle and use wings (with it's known aerodynamic properties) to do the "heavy vertical lifting" way up into the stratosphere? That way you can dispense with at least the first stage rockets altogether.

Imagine a huge air frame type vehicle (not unlike the green machine in the Thunderbirds of old) with powerful jet engines and big wings. This monstrosity might cost as much or more than a Saturn V to develop and build, but it would be re-usable, since only the payload and final stage engine needs to be launched into outer space. This final stage would then already be traveling at perhaps one quarter of the velocity needed to escape earth's gravity and will have traversed much of the distance (height actually) by the time it separates from the air frame.

Have you noticed how a space rocket is not simply launched straight up into the air? Soon after launch they are gradually oriented to an attitude that is more perpendicular to the surface of earth (or so it would seem from watching footage). Surely the purpose of this would be to firstly "give you enough room" to reach escape velocity and secondly to not have to fight gravity every step of the way up.


Welcome to the forum! I found your thought exercise to be very enjoyable and logical reading. Of course the launch straight up from a pad is just silly (and highly inefficient), but it looks good on TV, so what else matters. . . right? Plus, why not create maximum G forces and danger (i.e. drama) if you can afford to?

Of course this very idea is being made fun of in this short clip I took from the stupid movie Deep Impact from 1998.


full link: http://www.youtube.com/watch?v=RBPguDSKer0

And since we are talking about vertical launches I will quote myself from the Elon Musk, SpaceX, and PayPal thread:

SacredCowSlayer » July 2nd, 2016, 8:50 pm wrote:Here is the laughable and oddly named Mercury blastoff that has been posted above. But I have to wonder, which one of the released "videos" is the real one? :rolleyes:

I count at least three different versions so far, all collected from a variety of NASA documentaries depicting this glorious moment in history.

Moreover, I'd like to add that the first living thing put in space by the U.S. was a chimp named Ham. You really can't spell sham without "ham". :lol:

The following clip can be seen in the NASA documentary at https://youtu.be/v5ZFT7TpYqM at the 23:33 mark.
Image

And this one with the wooden shack (prop) flipping backwards (unlike the previous one above) can be seen here https://youtu.be/KkG1WMzoikY at roughly the 8:14 mark.
Image

Then of course there is this little bit of magic. Just one minor problem that should be readily observed. Yes, the entire scene is mirrored. :wacko:
Image
SacredCowSlayer
Member
 
Posts: 239
Joined: September 5th, 2015, 10:44 pm

Re: Does Rocketry Work in the Vacuum?

Postby MagicFlame007 on August 5th, 2016, 5:39 am

Thank you SacredCowSlayer.

Imagine you had to get produce to the market.
You live down in the valley and the market is on top of a hill. Do you hoist it up the sheer cliff face on the one side, or load it on a cart (thus adding the weight of the cart to your burden) and pull it up the winding road on the other side?
Why?
Hint: wheels.

Vertical launches have the following going for them:

1. Fantastic Spectacle.
Who would doubt what NASA says once they saw the awesome power of a Saturn V launch? Even NASA employees woulde be all like: holy hell! Looks like we really are going to the moon then! Looks fantastic on TV too, as you said!

2.To pre-empt difficult questions.
You don't want to have to explain how its possible to launch vertcally from the moon, when you are using a runway, atmosphere and wings to launch from earth.

p.s. love the little tumbling shack!
MagicFlame007
Member
 
Posts: 14
Joined: August 4th, 2016, 8:20 am

Re: Does Rocketry Work in the Vacuum?

Postby MagicFlame007 on August 5th, 2016, 7:00 am

To all reading this thread i just want to mention for clarity that I am not necessarily "married" to this idea of a horizontal vs. a vertical launch. Also I did not want to hijack this thread that after all seeks to discuss rocketry in a vacuum. For that reason, I will not be arguing this point too vehemently. Perhaps if it had a thread of its own someone more knowledgeable than me could explain why it makes sense.

However, the reason I even brought it up at all is that it was the one thing that initially set off my "B.S.-o-meter" long before I ever even heard of the whole Apollo-hoax theory. I've turned many a gathering "weird" by even uttering a word about it! -_-
MagicFlame007
Member
 
Posts: 14
Joined: August 4th, 2016, 8:20 am

Re: Does Rocketry Work in the Vacuum?

Postby SacredCowSlayer on August 5th, 2016, 8:11 am

MagicFlame007 » August 5th, 2016, 1:00 am wrote:To all reading this thread i just want to mention for clarity that I am not necessarily "married" to this idea of a horizontal vs. a vertical launch. Also I did not want to hijack this thread that after all seeks to discuss rocketry in a vacuum. For that reason, I will not be arguing this point too vehemently. Perhaps if it had a thread of its own someone more knowledgeable than me could explain why it makes sense.

However, the reason I even brought it up at all is that it was the one thing that initially set off my "B.S.-o-meter" long before I ever even heard of the whole Apollo-hoax theory. I've turned many a gathering "weird" by even uttering a word about it! -_-


Well I'm of course no moderator around here, but I don't sense that this particular point derails or "hijacks" the topic in any way. After all, one cannot thoroughly discuss maneuvering through the vacuum without considering how one gets there to begin with. And since NASA brought the topic to us, it's clearly fair and on point to discuss the logic (or lack thereof) of a vertical launch.

I can't think of a legitimate reason to create such intense force and danger that a vertical launch would involve. Unless of course trying to look cool, and like something . . . well, out of this world counts as legitimate.

P.S. Yes the little shack is quite the funny spectacle to be sure. Simon has it posted somewhere which led me to looking for any clip shown by NASA of their oddly named Mercury launches. After a couple of hours I had those three. Time permitting, I just may hunt down any others that could be out there. But I think 3 distinctly different ones make a good enough point.
Last edited by SacredCowSlayer on August 5th, 2016, 8:26 am, edited 1 time in total.
SacredCowSlayer
Member
 
Posts: 239
Joined: September 5th, 2015, 10:44 pm

Re: Does Rocketry Work in the Vacuum?

Postby MagicFlame007 on August 5th, 2016, 8:26 am

SacredCowSlayer » August 5th, 2016, 9:11 am wrote:
MagicFlame007 » August 5th, 2016, 1:00 am wrote:To all reading this thread i just want to mention for clarity that I am not necessarily "married" to this idea of a horizontal vs. a vertical launch. Also I did not want to hijack this thread that after all seeks to discuss rocketry in a vacuum. For that reason, I will not be arguing this point too vehemently. Perhaps if it had a thread of its own someone more knowledgeable than me could explain why it makes sense.

However, the reason I even brought it up at all is that it was the one thing that initially set off my "B.S.-o-meter" long before I ever even heard of the whole Apollo-hoax theory. I've turned many a gathering "weird" by even uttering a word about it! -_-


Well I'm of course no moderator around here, but I don't feel at all like this is a derail or "hijack" in any way. After all, one cannot thoroughly discuss maneuvering through the vacuum without considering how one gets there to begin with. And since NASA brought the topic to us, it's clearly fair and on point to discuss the logic (or lack thereof) of a vertical launch.


You're probably correct there.

I'll just add that in my opinion it makes little sense to launch a very massive load (note that to my knowledge - correct me if I'm wrong, the majority of the total mass is made up by the first stage and it's fuel), from it's point of maximum inertia (when its at rest) against the angle at which gravity has the best "leverage" (tangential to earth).
MagicFlame007
Member
 
Posts: 14
Joined: August 4th, 2016, 8:20 am

Re: Does Rocketry Work in the Vacuum?

Postby MagicFlame007 on August 5th, 2016, 8:50 am

As I understand it NASA states that rockets work in space because of Newton's third law of motion. It is the action of ejecting particles of fuel from the nozzle of the thrusters that makes the craft want to move in the opposite direction. The fuel is always moving with the craft and is thus always "at rest" in relation to the craft. Whenever a particle is ejected, it imparts an opposing force to the craft. This at least is my understanding of the forces at work.
It must be understood that the ignition of the fuel and the resulting rapid expansion of gasses has nothing to do with how it creates "thrust", other than rapidly accelerating the individual particles in the nozzle. The way a rocket works in an atmosphere is quite different from how it is purported to work in a vacuum! In fact there is no reason it has to be a rocket at all. It might be a pump ejecting water particles (or maybe some heavier liquid like perhaps mercury or something - less volume for the same force).
If that's the case I want to propose a possible design for a space rocket engine: Steam Power!
Huh?
Using steam power in space means you could use a less volatile mix of rocket fuel (or a small reactor) to create steam and then eject the high pressure water particles to create thrust. Since you are bombarded by an un-shielded by atmosphere sun all the way anyway, you might even use a radiator of some description to make more steam and travel for free!
MagicFlame007
Member
 
Posts: 14
Joined: August 4th, 2016, 8:20 am

Re: Does Rocketry Work in the Vacuum?

Postby MagicFlame007 on August 5th, 2016, 11:06 am

Actually in retrospect I would appreciate a little input on what I suspect might be a bit of flawed logic in my little story.

In the story I mused that if a rocket did work in space, the "speed limit" would be equal to the velocity at which I could "throw" particles away from my desired direction of travel. Surely if all particles of fuel traveling with me are at rest in relation to the craft (until they are forcibly ejected), I should continue to accelerate as long as I run my engine, regardless of my velocity? In other words, there should theoretically be no limit to my maximum speed (except for amount of fuel left in tank). I am always pushing against the inertia of the fuel particles while the engine is running. The only remaining "speed limits" then must be other laws of physics such as what happens as you approach light speed, which for obvious reasons are hard to fathom.

The rate of acceleration in a vacuum is affected by:
1.the mass of each particle of fuel.
2.the number of particles ejected.
3.the rate of acceleration of each particle as its being ejected.

The nanosecond that particle leaves the engine, it ceases to have any effect on the craft altogether and then, depending on the velocity of the craft and the power of the engine either follows along at an ever increasing distance forever, stays put, or speed off in the opposite direction forever.

To conclude then; if NASA's rockets are so effective in a vacuum (according to them even better than in the atmosphere!) even Juno's 25 miles per second seems a tad slow and don't even get me started on the whole "slingshot" malarkey.
MagicFlame007
Member
 
Posts: 14
Joined: August 4th, 2016, 8:20 am

Re: Does Rocketry Work in the Vacuum?

Postby MagicFlame007 on August 5th, 2016, 1:15 pm

feblogger » June 5th, 2016, 12:22 am wrote:I've read all the 39 pages of this thread, and, someone please correct me if I'm wrong, I didn't find the escape velocity as an argument.

We all learnt that a rocket has to gain the First Escape Velocity in order to leave the Earth's gravitation. But we don't speak of a truck having to have an "escape" velocity required to climb a hill, or an elevator's "escape" velocity to climb to the 68. floor. The truck and the elevator simply pull/push their way up to the destination. If there was a road, one could rich the Moon by a bike, right?

What is the point of talking about the escape velocity, if not because the pioneers of the rocket science, were aware that the rocket cannot push/pull in the vacuum, so they then concentrated into the rocket gaining the necessary velocity while in the atmosphere, in order to, just by the inertia alone, escape the Earth


Sorry Feblogger, I was meaning to respond to your post sooner as I have also not seen the issue of "escape velocity" mentioned in this thread until you did.
For me this is a glaring red herring too. There can be no such thing, since the earth's gravity does not suddenly cease at a certain distance or velocity, it gradually diminishes as you get further away. I must therefore wholeheartedly agree with you that "escape velocity" can be nothing but the minimum speed (momentum) you must attain while your thrusters still have some "oomph" (inside the atmosphere) to let you coast until you reach your destination, or until you run out of steam and start falling back to earth.
This decisively bolsters my feeling that rocket thrusters must be rather feeble in a vacuum.
MagicFlame007
Member
 
Posts: 14
Joined: August 4th, 2016, 8:20 am

Re: Does Rocketry Work in the Vacuum?

Postby Maarten Rossaart on August 5th, 2016, 5:42 pm

MagicFlame007 used the analogy of a rocket launch being like bringing goods to a hilltop market from out of a valley. This image helped clarify a question I have been tossing around in my head.

Any other market you might want to visit (i.e., any other body in this solar system) is up an even higher and steeper hill: namely, the gravity well of the Sun.

According to the Wikipedia article on Escape Velocity, the required speed for breaking free from Earth's gravity is 11.2 km/s. But once one has come free of the gravity of the Earth and the Moon, one is at a place in the solar system (93 million miles from the Sun) where solar escape velocity is still 42.1 km/s. In fact, according to the chart in the Wikipedia article, solar escape velocity does not drop lower than Earth's escape velocity until one is past the orbit of Saturn. If your rocket cannot get you up to escape velocity, you have a long, hot ride to meet old Sol.

https://en.m.wikipedia.org/wiki/Escape_velocity#List_of_escape_velocities

Perhaps I am wrong, but these numbers tell me that the most powerful stage of a rocket cannot be the first stage. It must be a stage after that, one with the power to accelerate the spaceship to solar escape velocity, which is to say, up a hill with a grade four times steeper than your first hill. Meanwhile, stage one still has the task of getting the whole hot mess out of Earth's gravity well.

Am I wrong, or does this smell like a paradox? My apologies if someone has made this point previously.
MR
Maarten Rossaart
Newbie
 
Posts: 3
Joined: August 2nd, 2016, 4:30 pm

Re: Does Rocketry Work in the Vacuum?

Postby MagicFlame007 on August 6th, 2016, 6:21 am

Morning Maarten,
Thanks for letting the proverbial cat among the pigeons! I must be honest; I had not even considered the sun's gravity at all! I slept little trying to wrap my head around the implications.
Do you think then one would be travelling "gravitationally" downhill if you planned your trip so that the moon for example was inetween earth and the moon on the way there and the opposite for your return journey?
Is your mass on earth reduced in sunlight as opposed to nighttime? :blink:
MagicFlame007
Member
 
Posts: 14
Joined: August 4th, 2016, 8:20 am

Re: Does Rocketry Work in the Vacuum?

Postby Maarten Rossaart on August 6th, 2016, 2:57 pm

Good morning to you, MagicFlame007,

I am no expert in astrophysics. I only know what I read from the experts.

Your first question is not clear to me. You seem to ask if there could be a gravity-assist from the Moon in plotting a course toward an outer planet. I couldn't say. If I understand what I read, it is ultimately not the Moon or the Earth per se whose gravity the rocket must escape, but rather the barycenter of the Earth-Moon system. If so, the Moon is more hindrance than help in the long run.

Your second question is very interesting. I have read physicists online who say that, yes, the Sun does affect one's weight, depending on position in the sky (i.e. is it night or day?). The effect is very small, almost negligible, and other factors (the Moon, air pressure) have a greater (but still slight) effect on one's weight. They also speak of solar tides: the Sun's gravity has a pulling effect on the oceans just like the Moon's, but it is a lesser force.

I cannot reconcile all of this, though, with the claim that the Earth is in orbit around the Sun: that is, we are in constant free fall. As such, with respect to the Sun, we should not experience any weight effect. The only weight we (and anything else on Earth or linked to Earth's gravity and orbit) should experience is due to the gravity of the Earth and the Moon. Think of that airplane, the Vomit Comet, on which Zero-G scenes for movies are filmed. When in free fall on the Vomit Comet, the passengers experience weightlessness with respect to Earth's gravity. In regard to the Sun, the planet Earth should act as our Vomit Comet, and the Sun's gravity should not have a bearing on our weight. How can the oceans (which are likewise with the rest of the planet in free fall around the Sun) experience any tidal effect from the Sun?

I wonder, too, about those Hollywood movies depicting interplanetary travel. The ship spins slowly on its long axis to generate centrifugal force that mimics gravity. But if one is traveling away from the Sun, there is already plenty of gravity pulling you toward the sun-facing side of the ship. You would not need to generate gravity, would you? If anything, you would need some way to counteract the crushing gravitational force of the Sun at the range of Earth orbit. Even at an alleged distance of 93 million miles, the Sun's gravity is strong enough to keep in its firm grasp a massive object moving at the velocity of 110,000 km/hour (namely, the Earth). Once a spaceship has managed to free itself from Earth's gravity well and the blessings of Earth's free fall in orbit, that tiny little ship is on its own to struggle against the Sun's gravity. It would be like swimming out to sea against the tide, only to reach open water and face a tsunami.

Or so it seems to me. No physicist am I.
MR
Maarten Rossaart
Newbie
 
Posts: 3
Joined: August 2nd, 2016, 4:30 pm

PreviousNext

Return to Apollo, and more space hoaxes

Who is online

Users browsing this forum: No registered users and 8 guests