Does Rocketry Work beyond Earth's atmosphere?

[SacredCowSlayer]

I do appreciate the thoughtful discussion on this topic. It seems to generate a lot of attention from time to time, and one gets the feeling that there are some members (perhaps, and from time to time) that wish to imply the following (in italics):

Since rocketry in the vacuum is feasible and possible (a conclusion I am NOT convinced of), NASA must be legitimate. Those words are never stated, but the implication lies just under the surface.

So, in an effort to keep things in perspective, I will simply note that if the NASA claims and their abundance of released imagery were authentic and convincing, then this thread would never have achieved liftoff in the first place.

Here (below) is a previous post of mine that can be found in the Elon Musk thread for a classic example of just how un-serious I consider these propaganda artists.

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?

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".

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


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.


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.

Note to Mods: Please feel free to reduce my previous post (quoted above) to a link if this is a poor use of bandwidth.

[Penelope]

Flabbergasted, if my purpose were to prove that rocketry is possible I would have to answer all challenges to it. My purpose is merely to show that CF misinterprets Newton's 3d as it applies to lift-off, flight in atmosphere, or vacuum. And therefore impairs its credibility.

[Penelope]

by starfish prime on March 29th, 2018, 11:15 am
An object dropped and one projected forward from the same height will land at the same moment. There is no orbital velocity that an object can reach allowing it to simply freefall around the Earth without constantly consuming fuel.

You know, starfish, I originally thought this was correct. But upon reflection I have doubts: Imagine we have two pickup trucks drop off over a cliff's edge at the same instant. But one is going 5 mph & the other 85 mph. Surely the one going 85 would make a considerable inertial path pretty close to horizontal before he began his gravity-pulled descent. His path would actually be longer than that of the slow truck. Also his time to hit bottom.

We've all seen this "temporary defiance of gravity" by skiiers and skateboarders. It's actually just that their paths are the result of the gravity force vector at right angles to the horizontal inertia of motion vector-- with the resultant path being an hypotenuse whose dimension is largely determined by their initial velocity.

As for a velocity which would allow an object to orbit, defying a reduced gravity long-term, I wouldn't know how to compute that. Wikipedia says
Near the surface of the Earth (sea level), gravity decreases with height such that linear extrapolation would give zero gravity at a height of one half of the earth's radius

So at 2,000 mi above Earth we'd have 0 gravity. We don't want that. Is there a distance where satellites would neither fly off at 0 gravity, nor fall to earth? Since we do have natural satellites, it appears so. And it's logical that speed of orbit would help to offset gravity, allowing a lower orbit.

Do we have the fuel-carrying and other technology to get there? I haven't a clue. Obviously they've told us a lot of lies about nonexistent programs. It's possible that the lies dovetail with the constant refreshing of the "alien visitation" hoax. Another major psy-op that could be pulled out of the hat if it suits some scenario.

[Kham]

Penelope,

Why don’t you do your own research and THEN present your findings here at Clues Forum instead of presenting half finished thoughts expecting members to resolve your issues. I think we would all appreciate that.

You are engaging in tactics that are sucking time from members over tired old issues. How things fall is a pretty basic idea, a straight drop or the parabolic motion of projectiles. Perhaps you can start your research there and then make an awesome post of your findings of which you will be proud.

Take care.

[patrix]

I agree Scacredcowslayer and Kham. And if this is deliberate "noise making", (which I have no way of knowing) it's about seeding doubt. To accept that there's no way for rockets and satellites to work "because physics" is a hell of a leap. At least it was for me. Cognitive dissonance kicks in and looks for the slightest reason to be able to dismiss it.

But as it turns out, much of science, including physics have been turned upside down during the entire 20th century. Einstein, the "rocket equation" and so much more is utter propaganda BS.

I encourage everyone interested in physics to go back about hundred years, to unlearn and relearn. Look at the works of Joule, Thomson, Michelson and Morley for example. And this is possible from your armchair because of the wonders of internet :-)

A suggested starting point:
https://archive.org/details/baltimorelecture00kelviala

Edit:
Penelope made a comment that was derailed and rightfully so. This is supposed to be a thread about Rocketry and I've slided away from that subject as well. But forgive me for commenting on it in an edit. I will also keep non rocketry issues elsewhere from now on.

Patrix, I guess Isaac Newton would be even safer then, since he lived in the 17th century.

Penelope, it's not about the age of the science, it's about if it follows the scientific method that stipulates that if you have an hypothesis, you should try to find observations and experiments that falsify your hypothesis. And if you and others fail to do this, then you have something more than a hypothesis - a theory and if it stands the test of time, a law. But this principle has eroded. It started as far as I know with Kepler who made elliptical orbits to seemingly make the Copernican model work. A hypothesis that's been falsified through observations as Simon shows in his book. Then we have Newton and his "laws" of gravity. Another hypothesis disproven by observations, if we are not willing to accept binary stars have absurdly high masses. Something I'm not willing to do because there are no evidence what so ever that could be the case.

So the entire field of science needs a renaissance, and hopefully this forum and its discussions is the first steps towards that. And at the bottom lies in my view a media that for a very long time has been about selling lies and hiding the truth. Einstein, Kepler and Newton has been raised to the skies by media, even though their hypotheses have been falsified. And the ones who have not like Joule-Thomson expansion, are ignored. So I'd definitely say this falls into the realm of media fakery.

[Altair]

Ok, here we go again... Sorry for the crude graphics, but it's much fasterthis way than fiddling with graphing applications.
To illustrate my, point, the one and only thing that can move a rocket (or any other thing) upwards is a FORCE exerted in the same direction as the desired movement. That's physics 101.

As we're dealing with gases, the one and only way a gas can exert a force upon a solid body is by means of PRESSURE. We're not absolutely concerned about action-reaction and such niceties, because we don't need to know how much and how fast the gas is ejected. That is just a nice-to-know datum, but what we want is just to have the maximum possible force applied to our dear rocket. Right?

So, as we see in the graphic, the most important thing is to build a huge pressure in the combustion chamber. Being it a closed recipient except for one end (where the gases exit), assuming a more or less homogeneous pressure, the horizontal components of the force neutralize themselves leaving only the vertical component, that would be dependent upon the throat's surface, as only in this part of the chamber pressure is zero or near zero.

The same would happen also for the nozzle, but forces there would be much less, as it is the pressure.

Now, the problem is whether it's possible to maintain such pressure in the combustion chamber in a vacuum, or the gases would be effectively 'sucked' out of it as soon as they're generated. And no pressure, no thrust! It's that simple.

I've looked at the purported parameters of a 'real' rocket engine as the Merlin 1C: https://en.wikipedia.org/wiki/Merlin_(r ... ine_family)#Merlin_1C



This thing is supposedly capable of generating 480 kN of thrust, roughly 48 tons of weight. To make an idea of it, that's enough to lift three 15 ton fully loaded articulated trucks. Yet, I cannot see any massive attachment fixtures capable of sustaining such a force and transmit it to the rocket's structure. Another issue is that most of the force is applied to the combustion chamber, which de facto would be 'pulling' from the inside.

Also, the purported pressure inside the combustion chamber is 6.7 MPa. So if we want to have a forward thrust of 480 kN, we need a 'zero pressure' area in the bottom of the chamber of 0.07 sq. meters, what tells us that the throat should have a radius of 0,011m, or 11 cm, which more or less could match the photo.

Now, all what rests is to find out whether such pressure in the chamber can be maintained in vacuum conditions. In fact, that would be a near-perfect implementation of the Joule-Thompson box experiment!

As a corollary, it's quite funny that all discussions verse about the 3rd law, the gas exit speed and so on, which are absolutely irrelevant points.