Comments by "" (@fromagefrizzbizz9377) on "Искаженное восприятие"
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There's a couple ways of doing this. Here's a test firing of such a one (called an "autophage") documented in a research paper:
http://eprints.gla.ac.uk/155610/
This works by having a "rod" of solid propellant and a "rod" of solid oxidizer, and pushing them mechanically into separate vaporizing chambers, then in turn push the gases into a combustion chamber. You can imagine that this will lose a lot of efficiency over a regular solid booster and be an engineering challenge in large scale. But it would make some sense with small motors (eg: vernier manoeuvring motors).
It's probably theoretically possible that you could do it "single rod" (combined fuel and oxidizer), but *vaporizing*, say, SRB PBAN/AP fuel and expecting it to tamely flow as a gas without igniting makes me very very nervous. You can't do this with, say, AN/sugar motors - the stuff will ignite before you hit vaporization temperatures. This is why AN/sugar motors aren't more popular - if you go a few degrees above mixing (as liquid) temperatures, *boom*.
Another method is to vary the geometry of the nozzle and bell similar to some aircraft jet engine. This is probably the only way to "retrofit" variability onto a fairly fixed design like an SRB with an existing solid formulation. The problem with this is that it's simply not possible to turn it off and on, and the useful variability range would be quite limited.
There's also apparently a small company that's working (and has tested a prototype) that essentually fluidizes fine particles of fuel and oxidizer and simply pumps them into a separate combustion chamber. Depending on the fuel type, you might not need to keep the fuel and oxidizer separate, but if you choose wrong, you run the risk of the entire fuel system go blammo all at once. Pumping "solids" isn't that terribly unusual. There are systems where, for example, finely ground coal is pumped through pipe.
And finally, the fuel grain for some missiles are formulated in "layers", say, fast-burn, slow-burn, then very very fast burn. Problem is that flight profile is determined at point of manufacture, not at point of use.
[It makes sense for an air-to-air missile to boost fast to depart the launching aircraft quickly and get up to a decent cruise speed, throttle down the rocket a bit to increase dwell time and improve chances of target acquisition, then very fast approach to target to avoid countermeasures.]
It's usually a whole lot easier to do hybrids - solid fuel, liquid or gas oxidizer. You just have to throttle the oxidizer. Which in self-pressurizing hybrids is nothing more than a single electronically variable valve.
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+Tina Springer He was referring to the black powder in the igniter. Never the less, the Estes B motor he used near the end is black powder.
The Aerotech G77 is an AP solid. AP solids are made by mixing together Ammonium perchlorate and freshly made polyester resin (you can use bondo if you're not fussy). Then you pour the sludge into a long cardboard tube, and let the resin set. The AP is the oxidizer, and the resin is the fuel.
Once the resin is set, you cut the rod into segments with a saw. You then have to cut a slot or drill a hole down the centre to provide a "burning space" for the combustion to start off in ("core burners", unlike estes motors which are all "end burners"), and room to shove the igniter into.
Aerotech engine igniters (formally known as "copper heads", we call them "crappy heads") suck at the best of times, which explains why he had so many start failures. It's not at all unusual to have 2 or 3 start failures trying to start an Aerotech during an ordinary amateur rocket launch. Especially with the Aerotech G motors, because the nozzle throat is too small for a normal crappy head, and you have to have a special really tiny one.
If he had been using the igniters from Cesaroni motors, it would have started first time. They're not blackpowder based, they are more like AP with possibly a soupcon of flash powder for kick. These are used in commercial applications like professional fireworks where they just have to fire reliably every time. I've never had a start failure with one of them.
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+Johnny Lloddte Right. The primary mistake here is using a larger motor like an Aerotech G.
Peter Leane went the other way and used a very tiny home-made motor:
https://www.youtube.com/watch?v=uf6158lBjGo
Peter didn't want to talk too much about the motors themselves (thinking he could patent something about them), but I did get out of him that it was .07 grams of propellant (about 1/4 a match head), and I estimated the power by assuming it performed about as well as APCP rocket fuel. That was probably overly generous. If it was blackpowder, it'd have been weaker.
I estimated his motor to be a 1/16A. Which is over 1000 times smaller than that Aerotech G. The smallest Estes motor is a 1/4A, and a Micromaxx (smallest commercially made) is 1/8A. A 1/16A is in turn half a Micromaxx.
Peter's test shows the gauge on his vacuum chamber barely twitches.
[Ignore much of Peter's blather, he actually doesn't know much about rocketry, or rocketry theory, and I don't think he's even flown one of his motors. I've personally flown 1/4A thru J, and am certified to L. You need to be certified to fly above G. BTW: each letter is double the total impulse of the previous letter in the alphabet. And the nonsense about vacuum leaking into the motor is more than a bit silly. But his basic physics is solid.]
But getting back to the basic principle, trying to prove to a flattard that rockets work in vacuum cannot be proven to a flattard's satisfaction in a vacuum chamber. They'll always whine about the chamber filling up with gas, or some nonsense about friction, no matter how big the chamber is and how small the motor is.
Since their argument is always based on the idiotic notion that Newton's 3rd law is a fraud, or doesn't work in vacuum, the key then becomes proving Newton's 3rd law in a vacuum without using gas pressure as the force, or at least, not letting the gas out of the motor.
The first method would be to use something like a spring loaded marble shooter. Which obviously works in a vacuum chamber to demonstrate thrust. For the second, you could use expanding gas inside a captured piston pushing a marble. then simply point out that it's precisely the same principle as a rocket. You'll get a smaller cadre of flattards pulling things out of their asses like somehow the gas's mass is "spent", and no longer behaves like mass. Er what? Sent that moron packing.
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+Meto U "everything that space telescopes and satellites do can be done from Earth's surface...just need stronger receivers and transmitters.." Please explain how a stronger transmitter or receiver could duplicate Himawari-8, Elektro-L or DISCOVR/EPIC photos. Don't say they're faked, because it's impossible. You can't fake a picture and get it perfectly right, if you don't know what the picture is supposed to look like.
Please explain how GPS could work thousands of miles in the middle of the ocean, which it does. And don't say "radio bounce", because GPS signals can't bounce, and even if they could, the daily random wobbling of the stratosphere makes locating things down to a metre or less impossible. Don't say "balloons", because balloons *move*.
Please explain how satellite TV dishes work, when they only work when pointed at precisely the right spot in the sky (the angles of which use spherical math to calculate), that they can't bounce off the stratosphere, and even if they could, the random wobbling of the stratosphere would make a perfectly stationary dish useless. And don't say "balloons", because balloons *move*.
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+Show me the evidence: That the pressure of air declines from sea level pressure to almost zero in space is not a theory, it is not a hypothesis, it is not a guess or a prediction from a theory, it is an observed,measured and indisputable fact.
Yes. a fact.
It just is, now matter how how hard you stomp your feet. Denial of indisputable fact isn't going to get you very far.
How do we know this? Because we've measured it. What do you think old fashioned barometric altimeters work? I'll answer: the pressure declines as you rise an a way so predictable you can calibrate the barometric display in feet rather than PSI (or pascals or inches of mercury).
The pressure at 10000 feet is considerably less than at sea level, lower at Everest, even lower at 40,000', even lower at 100,000. Literally thousands (if not 10s of thousands) of sounding rockets and balloons have been flown to altitudes higher than 100,000' - in fact, some sounding rockets to 1500 miles. And every single one shows that the air pressure drop from sea level to so close to zero, it might as well be vacuum at such high altitudes.
Not a theoretical result. This is reality. Period.. You can't get any better than that. Don't need science or hocus pocus, or reading a book to know this, just go out and measure.
Since it is an indisputable fact, there's no need to try replicating it. But actually, we can replicate it, in gas centrifuges. But we don't need to.
You've been boonswoggled by scammers into believing that Scientists say there is some thin line in the sky where the pressure abruptly changes from high to low. If there was, it would need a barrier. But in reality, proven by straight forward measurement, there is not, and has never been an abrupt line. There is no place in the sky where high pressure is right up against low pressure without a divider. The pressure drop is very gradual. No barriers required.
Incidentally, the rule of thumb is the pressure declines by half every 18,000 feet. it isn't exactly that, and atmospheric conditions (called "weather" - I've sure you've heard of it) can make it change a little bit, but on average, useful for descriptions of average conditions, it's plenty good.
Which means, starting at 0 ASL, the pressure is 14.7 PSI. At 18,000 it's 7.35. At 36000 it's 3.67PSI (too low for humans to breathe). At 52,000' 1.83PSI, 70000 .91PSI and keeps getting lower and lower, until (at around 100 miles) might as well not be there at all.
No barriers required.
It's time to become awake and throw off the lies of scammers.
The only place where science-y things come into it is explaining why the pressure drops. Which it can. Easily and predictably. Understood 100s of years ago. But it includes a word that is banned in your religion, so best not to confuse you until you wake up.
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+Gilee Wrong. First you need to define what you mean by "next to". An inch? A mile? 100 miles? And second, you have to define which higher pressure and lower pressure you're referring to. Atmosphere? Where in the atmosphere? Ground level, or Mt Everest? Or at airliner cruising height? Maximum balloon height? Maximum sounding rocket height?
Science has NEVER said that space starts "abruptly", your interpretation of what they mean by "space starts at 100 miles" is wrong. Nor does it say that space is absolute pure vacuum. Nor does it say that space vacuum is immediately adjacent to sea level pressure. It has never said that. But you're imagining that, which is just plain wrong.
All Science really has to prove is that pressure declines monotonically (only goes down) from sea level as the altitude rises.
Which it has. It's been measuring air pressure at different altitudes for hundreds of years. It's how barometric altitude sensors work. It's why airliners have to have pressurized compartments to keep the passengers alive above 20,000-30,000 feet. It's why rapid depressurization at cruising height is so, er, unpleasant. It's why balloons expand when they rise.
To deny that atmospheric pressure doesn't decline as the altitude rising would not just deny the obvious, it would make many things we all rely on from day to day to simply not work. Indeed, if it didn't, then gas centrifuges wouldn't work, and nobody would be whining about Iran's nuclear processing centrifuges - which work to separate isotopes of uranium in gaseous form through exactly the same effect.
We even have a rule of thumb for how much it declines. Air pressure reduces by half every 18,000 feet. After 36,000 it's half. After 180,000 feet (36 miles) it's declined by a factor of 1024 - the air pressure at 180,000 feet is approximately .014 PSI. At 500,000 feet (100 miles is arbitrarily chosen to be the threshold of space), do the math: 18,000 feet goes into 500,000 feet 27 times. Halving 14.7 PSI 27 times is 14.7 * (.5)^ 27, => .0000001087 PSI.
That's a pretty good vacuum. It's not absolute zero pressure, but it was never claimed to be. It's not immediately adjacent, but it was never claimed to be.
Science can also demonstrate it in the small scale - gas centrifuges. Gas centrifuges work on the principle that under acceleration forces (centrifugal, instead of gravitational in this case) DO show a pressure gradient, and you can achieve VERY HIGH pressure differences over distances as small as you want, depending on how fast you can spin the centrifuges. This is the principle behind Iran's nuclear gas centrifuges.
Which are touchy beasts, because if you can trick them into spinning a little too fast, they stop working too well to separate, and possibly fly apart.
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+Nine Elevan "Gases push against themselves? How did it come to this that graduates are trained to think in circles? Gases need other gas to push against, like push against air. "
I can tell you've never taken chemistry or physics in high school or anywhere else for that matter. Gases aren't solid objects. Gases are gazillions of tiny particles called molecules that repel each other. The repulsion that these molecules is what we measure as pressure. When you heat up a gas, the repulsion, and hence pressure - the force behind the gas increases.
Further, since molecules have mass, gas has mass. Which means that accelerating gas requires force. Squirting gas out a nozzle requires force to push the mass out the nozzle. Heating up gas increases the pressure, which in turn increases the force available to push the mass out of the nozzle, resuliting in higher speeds.
Do I sound like I'm repeating myself? Yes, I am, because you're clearly too dim to get it.
A rocket works by producing massive forces to push mass out the nozzle. The force required to do it can be easily calculated by taking the mass of the gas, and the acceleration the gas goes through. But fancy this: by the 3rd law, the force required to accelerate the gas is, by Newton's 3rd law, ALSO pushing the rocket forward.
Rocket engines like the F1 or RD-170 burn and push through the nozzle some 10-15 tons of gas *per second*, and accelerate it to speeds near 1 mile per second. Imagine the force that that requires. And that force, through newton's 3rd law, as restated in the laws of the conservation of momentum, mean that the rocket will accelerate forwards with exactly the same force. The exhaust gas does not need to hit anything.
The whole notion of a rocket pushing "against air" providing the forward force is hilarious. Once you fire a gun at a wall, how could the bullet communicate "I hit something" back to the gun, let alone push the gun? Gas is, well, a gas. Gazillions of tiny bullets travelling really fast. How could they communicate back to the rocket "I hit something, move forward"? It's like extruding limp noodles and expecting them to push you only when the far end hits something.
3rd law not proven? It's to giggle uncontrollably. Proven repeatedly, undeniably and incontrovertibly every second of the day since time began, but only quantified around Newton's time. Newton didn't dream it up on his own, he consolidated earlier work by other scientists, figured out the math, and gave it a name (well, other people afterwards called it "Newton's" third law). But if you want an experiment that makes it undeniable, here's a trivial one:
Stand on a skateboard, throw a bowling ball sideways. You move. "Oh, you say, pushing against air!". Horseshit, try it again with a balloon the same diameter (and hence the same air resistance) and throw it the same speed. You don't move. So much for air pushing rockets.
Or,
Take a spring loaded "gun" that shoots marbles. Or ball bearings. Or bowling balls. Stick it on a wheeled cart inside a vacuum chamber. Fire the gun. What happens? The "bullet" goes one way, the gun and the cart goes the other. Period. Full stop. 3rd law is proven.
Or take a real gun, and extend the barrel out as far as you want. Depressurize the barrel in front the bullet, and fire the gun. When does the recoil happen? When the bullet is fired, or when it hits the other end? Careful timing will show that it's when it's fired, and in fact when the bullet hits the other end, and assuming it doesn't punch through, there will be an equal and opposite jerk the other way. Newton's 3rd law, twice in one experiment. Cool eh?
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+Thomas Gronek "So with that said, you are correct about me moving in the opposite direction,,,, let's reduce the weight of the truck,,, now I do not move as fast... let the truck weigh nothing..... now I don't move at all... "
So you agree with me, except that you're fooling around with the weight of the expelled mass. You don't get to play a game with magic mass disappearance if you expect to match reality.
A 10 ton truck weighs 10 tons, right? So you take a combined total of 10 tons of kerosene and liquid oxygen and burn it. What does it produce? 10 tons of CO2 and H2O. How can it weigh nothing? Where did the mass go? So what makes you think that the exhaust gas of a rocket weighs nothing?
Your point isn't counter-intuitive or difficult to grasp. It's quite simply as wrong as it can possibly be.
I spent the hour or so required to understand this long before I got my BSc and MSc in physics over 40 years ago. it's time you caught up. If it takes you weeks, you're clearly doing it wrong.
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+thomas gronek Your theory, so far, consists of having the gas being ejected out of the back end of the rocket at high velocity having NO mass. Where did the fuel mass go, if not out the nozzle?
Until you can explain where it goes, your theory can never be more than half-baked.
Remember you've already admitted that if you throw a 10 ton truck at 4000 feet per second, you'd experience one hell of a lot of thrust the other way, atmosphere or no atmosphere. So you seem to be accepting the law of conservation of momentum and its corollary, Newton's 3rd law works in vacuum.
if you accept them, then the ONLY way that a conventional gas powered rocket wouldn't have thrust in vacuum, is that the gas has no mass. So again, WHERE DID DID THE FUEL MASS GO IF NOT OUT THE NOZZLE?
Do stop trying to evade the question.
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+Thomas Gronek Still evading the question I see.
Oh I assure you, if that elephant threw 10 tons of ants at 4000 feet per second downhill, that elephant would be going up hill probably rather faster than that (most elephants don't quite make 10 tons). Atmosphere or no atmosphere.
Thomas, Thomas, sigh, Thoomasssss.... 10 tons of reaction mass is 10 tons of reaction mass, whether it's a 10 ton truck, 10 tons of exhaust gas, or 10 tons of ants. Tsiolkovski rulz rockets you know, and Tsiolkovski's equation doesn't even mention gas or pressure. Just mass ejection. Period.
I'd hate to think of the effects of 10 tons of ants impacting at 4000 feet per second - the splash of formic acid alone would have everybody itching for miles. 6000 feet or so per second straight up, means about that much coming straight down. Poor elephant....
Why are you still evading the question? Why does the exhaust gas have no mass? Where did the 10 tons of fuel and oxidizer go?
If you're going to try to claim that exhaust gas has no mass, and thus provides no reaction, you'd better have a good explanation of where the mass goes. So far, we got bupkis.
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@meh11235 Word salad will never get you anywhere. What we are taught, experiment with, and prove ourselves is what has been observed in reality. There is no absolute vacuum in reality. Period. If you think there is, prove it. Barometers work and proves that atmospheric pressure declines as you increase in altitude, and keeps declining as far as you wish to go. if you think they don't, prove it. Space is a purely arbitrarily chosen point based on, NOT when air disappears entirely, but when air pressure is close enough to zero it no longer matters for the purposes at hand. If you think you know otherwise, prove it.
Rockets are a lot more useful in vacuum, because there's no other way to move around.
Or are you another one of those idiots who doesn't understand Newton's 3rd law, the law of conservation of momentum, or Tsiolkovski's rocket equations either?
Rockets work *just fine*, in fact better, in vacuum than they do in air.
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@meh11235 "extreme efficiency at which the angular momentum of each molecule is ripped apart at the speed of disassociation at low pressure..."
Er what? You're slinging together scientific terms without any idea what they mean. Not the least being the absurdity that angular momentum has anything to do whatsoever with combustion or thrust or rocket motors in general. Indeed, combustion has nothing to do with thrust either. Read the Tsiolkovski equations. No combustion. No molecular disassociation. Combustion is merely a means (production of energy) to an end (ejecting gas). The "end" provides thrust, not the beginning.
"The efficiency increase of rockets in vacuum is precisely the Mechanism that kills their ability to work long term in vacuum. Thanks for making my point clear. "
That is a ridiculous conclusion. They work as long as they have something to eject, and a means by which they can eject it. More efficiently in vacuum than air.
"Your assertions seem to push the notion that as no actual vacuum exists, then there is a cap applying pressure to earth atmosphere."
An equally ridiculous conclusion. If, as observations prove, the atmospheric pressure declines as you increase in altitude, it's going to have to stop decreasing somewhere, right? Well, it doesn't actually, the pressure simply gets lower and lower to the point where it's not worth mentioning. Have you ever heard the term "asymptotic approach" - I don't expect you have because FE's can't math. Do look it up and prove me wrong.
As for the observed behaviour of space/not-space not matching theory. That just means you don't understand the theory. The people who study, work with, and use it every day do.
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@thomasgronek6469 Of course there's a mass of ejected gas.
One: mass is not the same thing as weight. Mass is a unit of "quantity" (how much "stuff" there is in something) whereas weight a unit of force applied to that mass by the pull of gravity. The distinction isn't obvious in that archaic units of measurement you use, because a pound of mass is used to define the "amount of stuff" by the force exerted by earth's gravity on that amount of stuff. In metric, the distinction is obvious: mass is in kilograms. Force is in newtons.
2: it doesn't matter in the slightest what happens to the gas once it leaves the rocket. It doesn't matter if it hits something, or not. The recoil of a gun is not affected by what the bullet hits/or doesn't.
The Saturn V "worked" by burning 10 tons of fuel and oxidizer per second, and throwing it out the back end at 4000' per second. That takes a tremendous amount of force to do, whether it's gas, marbles, bricks or firetrucks. It makes no difference whether the 10 tons of mass, whatever it is, hits something, blows up, "dissipates" or not, the force has been applied, and the recoil aka "every action has an equal and opposite reaction" happens.
Which is why, for example, the rocketry equation EVERYBODY USES to design rockets doesn't give a flying fuck what the expelled mass is, and has never done so since the 1800s.
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+Lance Lawson. Put on a space suit, sit on a wheeled chair inside a vacuum chamber, and throw the ball. Voila, thrust works in space. You don't have to be in space to prove what happens in a vacuum.
There's a building 15 minutes drive from here that has seven*, count 'em, *seven vacuum chambers. They're used for satellite shake-and-bake tests in vacuum. One of them is 25 feet in diameter, and 40 feet deep. Looks like a big pressure cooker, with the lid hoisted into place with an overhead crane. Yes, I've been there and seen it - an acquaintance of mine works there and uses the thing for his work. You could do this experiment in there easily. Easier still would be to use a spring loaded "ball shooter" - I doubt they'd allow people into that chamber while in operation for any reason *ever*. The insurance implications are ridiculous.
But would CSA allow this? "You want to do what to prove what? Do you know how much vacuum cycling that beast costs? You want to bounce bowling balls off the inside and possibly damage some of the instrumentation? It's fully booked for the next 5 years doing tests on equipment that we're paid to do. We're not going to spend thousands, risk a few million dollars worth of equipment, and screw up our paying schedule just so that we can re-prove centuries old basic high school physics to flattard morons".
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