Half a croissant, on a plate, with a sign in front of it saying '50c'
h a l f b a k e r y
Extruded? Are you sure?

idea: add, search, annotate, link, view, overview, recent, by name, random

meta: news, help, about, links, report a problem

account: browse anonymously, or get an account and write.

user:
pass:
register,


                                                                                                               

Please log in.
Before you can vote, you need to register. Please log in or create an account.

heavier rocketing

two ways to increase fuel heft.
  (-2)
(-2)
  [vote for,
against]

This is probably hokum but there are no stupid questions when search for that elusive percentage increase. More mass means more thrust

A) Add heavy nuclei or molecules into the liquid fuel. I was thinking of that sands on a vibrating plate patterning, Chladni mixing. If liquid fuel was oscillated, heavy atoms or molecules could be patterned throughout the fuel to increase thrust mass. Pre combustion of course.

B) I don't know how to pull this one off. but spin up each individual fuel molecule and oxidiser molecule becfore ignition. Energy is mass, right ? so having molecules with tons of molecular rotational energy is going to add to the sort after, moving cheaply against gravity, reaction. Pressure is not the only energy that ould be put into the system.

Let the spikely rain commence. At my age, no cartilage please.

wjt, Sep 16 2019

Specific Impulse https://en.wikipedi...ki/Specific_impulse
Specific impulse - important for getting rockets into space [Frankx, Sep 16 2019]

Blue Streak https://en.wikipedi...ue_Streak_(missile)
Britain’s rocketry system [Frankx, Sep 17 2019]

Possible combustion chamber texture https://www.deviant...9-0609-1n-812135106
An intermediate step till reactive volume environments are fully designed. [wjt, Sep 21 2019]

Kingston Daily Gleaner - Thursday, October 06, 1881 - Page 2 https://newspaperar...er-oct-06-1881-p-2/
Mentioned in my anno. Find in page within the OCRed text [notexactly, Oct 01 2019]

The Chi Phi Quarterly - July 1885 - Literary Department: A Conversation Extraordinary https://books.googl...ron%20sheep&f=false
Mentioned in my anno [notexactly, Oct 02 2019]

Project Orion https://en.wikipedi...nuclear_propulsion)
Efficient propulsion of people sitting atop nuclear bombs [lurch, Oct 09 2019]

[link]






       //This is probably hokum// Bang on.   

       //Add heavy nuclei or molecules into the liquid fuel// You're ultimately limited by the energy in the fuel+oxidant and, as I understand it, the most energy-dense combination is hydrogen/oxygen. If you were using an ion thruster (where your energy comes from elsewhere), then you'd want heavy ions, but you're not.   

       //having molecules with tons of molecular rotational energy is going to add // Three problems. (a) molecular rotational energy will, I think, become heat in a microsecond or so. So you could just heat the fuel up. (b) the amount of extra energy you'd get would be negligible compared to the chemical energy (c) ah, something else will occur to me.
MaxwellBuchanan, Sep 16 2019
  

       // More mass means more thrust //   

       No, more momentum means more thrust. A denser fuel does have benefits but you need energy to give your delta-vee. As [MB] points out, that's the attraction of nuclear propulsion; the energy comes from elsewhere. Just tip water, a cheap, convenient, safe and reasonably-no-reactive fluid (therefore in many ways an ideal propellant) onto a hot* nuclear reactor, then vent the resultant steam through a venturi.   

       Or you could use a linear motor to accelerate iron oxide (another cheap, plentiful and fairly inert material) as your reaction mass.   

       But binary ergols like UDMH/RFNA have gone about as far as they can. If there was something better it would be in use; rocket scientists have been chasing that particular Holy Grail for decades.   

       *A specially designed reactor is required. Just borrowing one from a disused Soviet sub, while a good option for those doing non-chemical rocketry on a limited budget, is not likely to have any good outcomes.   

       But interesting to watch ... from a distance.
8th of 7, Sep 16 2019
  

       //the most energy-dense combination is hydrogen/oxygen.//   

       I don't think that's true. My understanding is that both are relatively cheap, neither is /ridiculously/ hard to handle, and the reaction isn't too fierce.   

       The most energy-dense combination might well involve chlorine trifluoride, which can burn water, sand ... and asbestos.
Loris, Sep 16 2019
  

       // I don't think that's true.//   

       ... and you are correct.   

       Your other points about cost, availability and (relative) safety are cogent.   

       CTF is an extremely entertaining compound, but not for the faint-of-heart.
8th of 7, Sep 16 2019
  

       // I don't think that's true.// I had the same inkling when I posted it.
MaxwellBuchanan, Sep 16 2019
  

       Wikipedia about specific impulse [link]   

       If you’re getting upward thrustiness by burning stuff and squirting it downwardly, then density is important, but velocity more so.   

       Velocity is related to chemical energy (per unit mass) - so more energetic fuels are good. Most of your mass at lift-off is fuel and oxidiser, and you have to lug that mass with you as you go, so the measure of “specific impulse” becomes a useful one to compare fuel/oxidiser combinations, or entire launch architectures.   

       Cost and ease/safety of handling also become very important!
Frankx, Sep 16 2019
  

       //ease/safety of handling// pshaw.
MaxwellBuchanan, Sep 16 2019
  

       Depends on your application.   

       Civilian applications prioritize safety and cost.   

       Military applications prioritize efficiency and shelf life; safety is trailing behind and cost is not really an issue.   

       The military want kit that can sit at cold standby for years and then go to full launch readiness in a short time. RFNA isn't ideal for that, it has to be stored externally and pumped on board just prior to launch. Hence the preference for solid fuels - lower specific impulse, but definite turn-key-and-fire capability.
8th of 7, Sep 16 2019
  

       //launch readiness//   

       Very true. It was partly that that led to the British rocket/ICBM Blue Streak [link] being canned. Shame, had we persevered, we might have had our own home-grown space programme by now.
Frankx, Sep 17 2019
  

       //Energy is mass, right ?// No.   

       They do sit there in the same equation, but there's this big freakin' unignorable conversion factor which, practically speaking, only converts when your everything else is fully converted to damage.   

       Besides, in most cases you have to run cryogenic coolants through the nozzle walls to keep them from melting / vaporizing. If you use LOX and cryofuels, you get a free turn of coolant going through the bell. If you carry them pre-heated, then you lose density, lose cooling, and have to carry some other method of keeping your combustion chamber and nozzle from changing phase and leaving.
lurch, Sep 17 2019
  

       //so more energetic fuels are good.//   

       Could have had a significant boost on the Saturn V 1st stage if they'd gone for zip fuel.
bs0u0155, Sep 17 2019
  

       They'd have done even better if they'd gone with the General Dynamics proposal - true SSTO - but there were ... issues ... for a manned vehicle ...
8th of 7, Sep 17 2019
  

       A) If there molecular space for packing, in the liquid and it doesn't dampen combustion it's all the more mass to Newton's reaction mill.   

       B) So, molecules don't have a higher energy stable rotational states?   

       If it is about impulse then isn't the goal a short lived reaction. As soon as the action/reaction splits, the rocket has no more advantage. Why have the particles stream off with heaps of energy, qomma, just have them lose momentum as soon as possible as close to the rocket as possible.   

       Of all the strange stuff quantum mechanics throws up, it is a wonder that the quantum collapse due to scalling doesn't allow through shaddow quirks of nature. Engineering that uniqueness with the right energy patterns in the right environment may give us the tiny momentum changes over the incredible tiny periods and distances we need.   

       More experimental stuff is need to highlight quirks. oooh, now I am imagining an Oobleck rocket fuel additive that has pressure patterning in the combustion chamber.
wjt, Sep 18 2019
  

       A) Liquids are not compressible.
B) "Higher energy rotation states" is exactly what happens in a microwave. It's called "heat".
lurch, Sep 18 2019
  

       // Liquids are not compressible //   

       Do you wish to to modify that bold assertion in any way ... ?   

       <Brings whiteboard duster to launch readiness/>
8th of 7, Sep 18 2019
  

       [wjt]: it’s not a bad idea, but some bits won’t work.   

       For conventional rockets, increasing fuel density only helps if you increase chemical energy too   

       Relativistic/quantum scale effects on bulk chemical fuel are unlikely to have any benefit   

       If you add relativistic mass to your fuel before lift- off (spin etc), at best it imparts (probably catastrophic) heat energy. If you were planning to add the energy after lift-off, you’d be carrying the mass-energy with you anyway, so no benefit gained.   

       Chemical energy really is very convenient, compact and dense. Best bet is to find a very energetic reaction between “light” elements.   

       That’s why Carbon, Hydrogen, Oxygen and Nitrogen compounds come up so often.
Frankx, Sep 18 2019
  

       Oh, I forgot, there’s the whole nuclear rocket thing too. You’re still carrying all the mass with you, but converting a tiny part of that via nuclear reactions.
Frankx, Sep 18 2019
  

       I will modify that bold assertion with an invitation - if you wish to apply the pressure necessary to cause an appreciable decrease in both your fuel and oxidizer volume, while they are stored adjacently in a flight-weight containment vessel, I would that you might do it with the real thing and lots of cameras.   

       I mean, I typically am willing to do such a thing on a whiteboard, but in this case, the result of the math very clearly screams for a physical demo.
lurch, Sep 18 2019
  

       You're right of course, the pleading and begging is the best part.   

       <Lowers whiteboard duster/>   

       But liquids are compressible. Not much; the corresponding changes in volume and density are small, but non-zero. Building a flight-capable pressure vessel, even using carbon-fibre composites, is extremely difficult.   

       Not just cameras; microphones as well, and a couple of seismographs for good measure.
8th of 7, Sep 18 2019
  

       While the word relativistic is being mentioned... what happens with reaction mass if it starts getting some serious velocity? Obviously rockets aren't in the right league, but there's plenty of space drive designs that are essentially particle accelerators, firing ions out the back. If you fire ions out the back at relativistic speeds the apparent mass increases, so, does your ship accelerate in reaction to the original or relativistic mass>
bs0u0155, Sep 18 2019
  

       That depends if the observer is on the ship being accelerated, or in an independent frame of reference and observing both the ship and the propellant.
8th of 7, Sep 19 2019
  

       I'd tend to say relativistic... mostly because it makes physicists turn amusing colours (that term having been deprecated), but also because it makes sense.
FlyingToaster, Sep 19 2019
  

       When I thought Oobleck, my thought lines were along the lines of the blast wave calculations and shape design for the ignition of a nuclear ordnance. In other words is the combustion chamber only using internal surface area or is it volume shape controlling like the lotto machine. Passive not dynamic. Although a design could be dynamic via external environment pressure mechanism.
wjt, Sep 20 2019
  

       // If you’re getting upward thrustiness by burning stuff and squirting it downwardly, then density is important, but velocity more so. //   

       Most important, though, is that the thrust-to-weight ratio has to be greater than 1. Otherwise, you will not go to space today.   

       In rocketry, there's usually a tradeoff between thrust (generally gained by throwing more stuff out the back) and specific impulse (generally gained by throwing stuff out the back faster). Specific impulse, and more specifically exhaust velocity, is directly related to propulsive efficiency, so you want it as high as possible so you can minimize your propellant load for a given mission (with the rocket equation's positive feedback amplifying that reduction in mass). But if you need a certain amount of acceleration at any point in the flight, such as >10 m/s^2 to climb off of Earth, then that dictates a minimum amount of thrust. This is one of the reasons multiple stages are used, including not just the launch vehicle's multiple stages but also the final spacecraft's own main engine, if equipped. The thrust vs. specific impulse tradeoff is most apparent in e.g. the VASIMR concept (which is named for its ability to vary its specific impulse and thrust), but that just shifts the decision from design time to flight time, and still isn't quite capable of accessing the higher thrust/lower specific impulse area where chemical rockets usually operate.   

       // colours (that term having been deprecated) //   

       Britain has adopted the American spelling?
notexactly, Sep 26 2019
  

       I speeled "deprecated" wrongly ?
FlyingToaster, Sep 27 2019
  

       I interpreted it as you saying "colours" had been deprecated, presumably in favo(u)r of "colors".
notexactly, Sep 28 2019
  

       Has humanity done everything possible to get the most from fuel combustion? If there was a magical crane, wouldn't mgh give the lowest amount of energy to change height. A rocket is nowhere near that but if the fictional rockets are anything to strive for then finding ways to be more energy smart should be the goal. An axe is better that a sledge when bringing down a tree.   

       The right experiment will be the end of the world as we know it.
wjt, Sep 28 2019
  

       // Has humanity done everything possible to get the most from fuel combustion? //   

       Yes. All possible unitary and binary fuel systems, including the insanely dangerous monergols, have been very thoroughly investigated. There's nowhere to go with chemistry to get a more energetic fuel system; you have to start looking to physics, like nuclear isomers, for higher energy densities - or a deuteron ram.
8th of 7, Sep 28 2019
  

       Hey, that stereotype of violence is largely due to Genghis Khan and a few others. Most Mongols are normal people.
notexactly, Sep 28 2019
  

       It's just that, there is so much chemical energy there. Is it not possible to set the fire on fire? Undo a fraction of the atoms in the plasma for the impulsive benefit.
wjt, Sep 28 2019
  

       Dissociation takes energy to do. Where does that energy come from?
notexactly, Sep 30 2019
  

       I's the pattern of energy though, like with any work do it wrong way and the cost goes up. In the public knowledge the right way hasn't been found.   

       I believe there should be enough energy in the combustion chamber. Not many environments come close to that one.
wjt, Oct 01 2019
  

       Huh? You're making as little sense as usual.   

       Also, [8th], are you aware that the term 'deuteron ram' appears in an Earth newspaper from 1881? [link]
notexactly, Oct 01 2019
  

       //are you aware that the term 'deuteron ram' appears in an Earth newspaper from 1881?//   

       >> # Od. Deuteron Ram per gal.. 2s 4d Trinidad Cocoa, per ewe. £8 18#   

       I think that might be a breed of sheep. Possibly a very energetic and dense one.
Loris, Oct 01 2019
  

       A cursory Google search didn't confirm that hypothesis, but it did turn up a mention of someone named "Neighbor Liberal Deuteron" owning a flock of sheep: [link]
notexactly, Oct 02 2019
  

       // I believe //   

       Bad, naughty [wjt], you shall get a smack. Believe nothing, trust no-one. Demand evidence and proof. That is the scientific method. Refuse all substitutes.   

       // there should be enough energy in the combustion chamber //   

       There's a lot of energy, but it's doing work.   

       Consider:   

       An object is in uniform motion in free-fall. A mass is pushed away from the object with velocity v; so both objects will have momentum mv and kinetic energy 0.5 * m * v^2.   

       If the reaction process is efficient then the energy put into the process corresponds very closely to the kinetic energy of the masses after separation.   

       Now, consider your combustion chamber. Crunching the numbers for the mass of the fuels and the acceleration (increase of momentum & kinetic energy of your craft) that is produced gives the propulsive efficiency (percentage of energy converted to motion).   

       Now, you can calculate how much "spare" energy you might theoretically have available.
8th of 7, Oct 02 2019
  

       [8th] Your right, with random interactions, there will be little energy left over.   

       But, this is a question of getting to the unsprung energy inside the fuel species as well and 'how' to do it with the artificial environment of energy, reactions and containment present.   

       Exponentially more blindfolded sledge hammer swingers is going to be needed to cut the same number of trees as a few sighted ones with sharp axes.   

       My hope for humanity, is the atom is more like a hitch knot, random energy tightens it, ultimately to breaking point or the right jiggle loosens it to undone. If life teaches us anything there's usually a way and another better way that we wished we had been using all along.
wjt, Oct 04 2019
  

       //If life teaches us anything there's usually a way and another better way that we wished we had been using all along.// Tell me about it. I'm still trying to get pieces of okapi out of my DVD player.
MaxwellBuchanan, Oct 04 2019
  

       relativistic
FlyingToaster, Oct 04 2019
  

       What is that "unsprung energy", then? Nuclear energy? Nuclear rockets exist.
notexactly, Oct 05 2019
  

       [MB]... why are there pieces of okapi in your DVD player?
Frankx, Oct 05 2019
  

       What a stupid question. Of course the whole okapi won't fit.
lurch, Oct 05 2019
  

       Dang! I confused Okapi with Opepe.
Frankx, Oct 05 2019
  

       [Maxwell] Your not trying to create an [8th] fascimile, are you?   

       [notexactly] Yes, a chemical rocket with fringe benefits.
wjt, Oct 05 2019
  

       Yes, but from where?
notexactly, Oct 07 2019
  

       Well, "fringe" is usually understood to be a synonym for "edge" or "periphery", so that would be where to start looking.
8th of 7, Oct 07 2019
  

       What is the total number of atoms and electrons in a rocket combustion chamber ? What is the total number of patterns of vectored movement of those species?   

       Is it not possible that a certain pattern undoes an atom releasing some of it's nuclear energy. If one can be done, the chamber/ environment can be redesigned to give a larger percentage.
wjt, Oct 08 2019
  

       // Is it not possible that a certain pattern undoes an atom releasing some of it's nuclear energy. //   

       No.   

       The reaction is purely chemical. The temperature is many orders of magnitude below that needed for fusion; and for elements below iron, because of their position on the stability curve, fission absorbs rather than releases energy.   

       Statistically, fusion can occur in materials at "low" temperatures but requires two nucleii to coincidentally acquire high velocity and then be on converging paths. This happens so very rarely as to be insignificant. It's less likely than proton decay.
8th of 7, Oct 08 2019
  

       Nature has unseen quirks (Xrays from sticky tape) and the mathematical envelope will only show stuff about the included variables. To pick up on anomalies, the subtle variables causing them have to be in the envelope with the right scale.   

       [8th of 7] At your scale, No will always be the correct answer. Anomalies are just too small to be seen.
wjt, Oct 11 2019
  
      
[annotate]
  


 

back: main index

business  computer  culture  fashion  food  halfbakery  home  other  product  public  science  sport  vehicle