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Sir T
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Reply #840 on: June 30, 2017, 10:39:14 PM

This has inspired me... to make a moon rocket in Minecraft!  why so serious?



(Ok, its the Galacticraft mod but hey, roll on me dying because I forgot an oxygen tank!)

"I think its pretty troubling when a backyard decoration comes out swinging harder against Nazis than the President of the United States." Stephen Colbert
calapine
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Reply #841 on: July 01, 2017, 05:05:13 PM

Let's get a bit nostaglic. What could have been:


Hermes, ESA's answer to the shuttle, designed to fly on Ariane5, carry crew of 3 and 3000 kg payload. After many design changes and after $2 bn invested it was canceled in 1992.







I can write a little essay if someone really is interested, but the short version: You might notice the it looks pretty similar to the Dreamchaser, but the difference is the concept is from 1985, over 30 years ago. The design constantly got iterated and was never frozen, and basically: the tech wasn't there yet. Neither was it really for the Space Shuttle, as we saw by it's high cost and lack of safety, but ESA didn't have the funds to just smother the problems with money. The desired payload performance was never reached and development dragged on, so after 7 years the involved countries decided to pull the plug.

« Last Edit: July 01, 2017, 05:07:00 PM by calapine »

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calapine
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Reply #842 on: July 08, 2017, 03:02:07 PM

I recently posted some about BepiColombo, ESA & JAXA's probe to Mercury. (See here)


Now the vibration test of the full stack was done. Recommended watching with headphones and sound on full.

I really like how the sounds changes when the shaking frequency goes up...



It also already wins the prize as the fluffiest space probe alive. (Click image for full size)




The probe from bottom to top, as it will separate:
  • the Mercury Transfer Module, the thingy sitting on top of the cone-shaped adapter and with one folded solar array visible to the right)
  • the Mercury Planetary Orbiter, the boxy thingy with the folded solar array seen towards the left and satellite TV-dish to the right.
  • the Mercury Magnetospheric Orbiter (MMO), the round thingy.
« Last Edit: July 08, 2017, 03:09:55 PM by calapine »

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calapine
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Reply #843 on: July 08, 2017, 03:53:59 PM

Oh, and here is the gimballing of the 4 ion thruster engines. 80x times faster than actually happening in RL. They will fire for 2 out of the 7.5 years journey.





How they look when active:



Specs:
T6 Kaufman-type ion thruster produced by QinetiQ, United Kingdom

Thrust 145 mN (or 0.015 Kilogram Force)
Specific Impulse 4300 s
Power draw 4600 W

Basically the concept of ion thrusters is that you have less thrust than with a chemical engine, but much higher exhaust speeds as the propellant is first ionised and then accelerated using electrical energy generated by the solar panels.
The higher velocity means less propellant is required, and are thus a lighter propulsion system, allowing more payload weight. The engines need to fire longer of course, but as there is not friction in space it doesn't really matter.
« Last Edit: July 08, 2017, 04:01:05 PM by calapine »

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Abagadro
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Reply #844 on: July 09, 2017, 12:25:05 AM

Very cool. I totally didn't get the scale of that thing until I noticed the person standing there.

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Jeff Kelly
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Reply #845 on: July 09, 2017, 08:51:01 PM

Very low thrust, very high specific Impulse. The most efficient drive possible.
calapine
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Reply #846 on: July 09, 2017, 09:02:58 PM

Very cool. I totally didn't get the scale of that thing until I noticed the person standing there.

Yes. I learned some more about it today, the entire mission is quite a technical challenge. 60% of the compontens used to developed specifically for it. That includes things like the paint on the high-gain antenna dish. And the antenna itself, the reflecter dish is titanium with a ceramic thermal coating, qualfied to operate at up 450 C. The motor and gear assemble to move the solar panels is rated up to 200, etc...)

And more complex parts as the solar cells. High temperature (300 C) resistant cells were available, but during the design phase it turned out they could not withstand the extreme UV radiation so close to the sun. Which required the development of a new type, operating "only" to 215 C but able to withstand UV better.

The fluffy white covering (thermal coating) you see in the earlier post is another one-of-kind development for Bepi.


A rare picture you wont find on Google (well, now you will). The insides of the transfer module, ion thrusters clearly visible:


« Last Edit: July 09, 2017, 09:06:17 PM by calapine »

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Goumindong
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Reply #847 on: July 10, 2017, 11:14:33 AM

Very low thrust, very high specific Impulse. The most efficient drive possible.

Well... no? Not by any metric that makes sense really. But then again efficiency doesn't make sense as a standard here. Claiming an ion drive is most efficient is like claiming a point on a line is most line.

To be more specific; in general you can achieve the same amount of thrust in two ways. Throw something heavy out the back slow. Or throw something light out the back fast. As such there are only two perfectly efficient drives possible and everything else is a trade off. The first drive pushes against the entirety of the universe and the second drive is a flashlight.

Both of these have obvious problems and they're similar to the problems exhibited by drives that we can actually use and are derived from the same concept. That is energy is equal to 1/2*mv^2. In order to generate trust by pushing against the universe you're now relative to the universe and so you require an increasing amount of thrust as you push faster. Since we do not know* the uhh current relative velocity of the earth to the universe we don't have any clue how much V were at and so how much energy it would take to speed up or slow down.

The opposite end of the line from "pushing literally everything" is pushing literally nothing and so putting a flashlight on your ship. Same as a light sail this will impart thrust despite light having no mass and so not needing to be carried. The downside here is that light is moving very fast and so despite having no real mass still requires a massive amount of energy per impulse.

All drives fall somewhere in this spectrum. Ion drives aren't at the end, just much closer to the "literal flashlight" side of the line than chemical rockets are which while closer to the "universal flinstone" side are still pretty close to the flashlight side all things considered.

*but could measure if we had this sort of drive... as an aside this might also explain some of the EM drives weirdness if it were such a drive. Such a drive would produce optimal travel velocities which would not relative to the velocity of the earth. Traveling away from earth in one direction at high speeds could be less energy intensive than traveling away at the same speed in the other. And this could change relative to how the earths velocity was changing relative to the universe.

To visualize this think of is the solar system were the entire universe and it was sitting on a table. The earth a marble rotating around the sun at 30km/s. If one were to "flinstone stop" on the table the earth would appear to be rocketing away at 30km/s. So in order to do this you would have to exert enough energy to go from 30km/s to zero.  But then the earth comes back around propelled by the force of gravity around the sun...and our flinstone drive is at zero velocity to the solar system. We exert zero energy except to resist gravity and everything comes back to us changing massively in relative velocity.

 What if we want to go the opposite direction away from earth... now instead of going from 30 to 0 we have to go from 30 to 60. Which requires many many times more energy if you were looking at these two drives from the frame of the earth one would expend far more energy to do the exact same thing.


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Reply #848 on: July 10, 2017, 05:54:34 PM

Um.. you are forgetting that where you are going to is ALSO moving. Movement of everything is relative to everything else. So if you were expending enough energy to come to a stop in an absolute sense, it would still seem to you that you were hurtling at your destination at your 30v, so it would be unnecessary to do the 60v you are suggesting it would take to go the opposite direction. Everything in this part of the galaxy is moving in roughly the same direction, so there would be no need for the double acceleration and double energy you are talking about. You are not going against the rotation of the earth here.

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Goumindong
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Reply #849 on: July 10, 2017, 07:38:10 PM

Um.. you are forgetting that where you are going to is ALSO moving. Movement of everything is relative to everything else. So if you were expending enough energy to come to a stop in an absolute sense, it would still seem to you that you were hurtling at your destination at your 30v, so it would be unnecessary to do the 60v you are suggesting it would take to go the opposite direction. Everything in this part of the galaxy is moving in roughly the same direction, so there would be no need for the double acceleration and double energy you are talking about. You are not going against the rotation of the earth here.

You're misunderstanding what you're pushing on with the hypothetical flinstone drive. Maybe this will work. Suppose that you're in the ISS on an orbit around the earth. If I am on the ISS I can get out and continue just like normal because energy has not changed much. I continue besides the ISS as it goes around the earth. If I engage a rocket booster in direction 1 I will accelerate away from the ISS at whatever the acceleration of the rocket booster is. If I accelerate away from the ISS in the opposite direction then I will also accelerate away from the ISS at whatever the acceleration is. The total energy of this system will look proper because it's simple two body problem. If you added the earth everything works because the start point KE is much higher and so the chemical engines energy transfer cancels out no matter your frame of reference.

Now suppose I extend invisible super stilts and literally attach myself to the earth. In order to stop relative to the earth I need to go from 4.76 miles/second to 0. Relative to the ISS I am now traveling away from it at 4.76 miles per second. If I wanted to travel in the other direction away from the ISS I would need to change speeds relative to the earth from 4.76miles/s to 9.52 miles/second in order to appear to be moving 4.76 away from the ISS in the other direction.

If you cannot see the stilts (and/or do not realize that it's pushing off the earth rather than nothing) then the total energy required (and force produced) in order to travel in different directions away from the ISS will be be look different from the ISS in a way that is bonkers with our understanding of physics;  you will be looking at a 2 body with excess energy when the proper answer is that a third body is absorbing that excess. The energy required to travel at the same acceleration in different directions will actually look different (so will the force produced be different) when just looking at the two body problem and the drive will appear reactionless.

Such a drive is pretty far fetched... after all only being an example of the exact opposite type of drive as a flashlight. But it's not so far fetched. Gravity is, after all, a force in which all matter effects all other matter at the speed of light.
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Reply #850 on: July 10, 2017, 08:51:51 PM

The ion drive has the highest specific impulse (Isp) in vacuum, meaning that it provides the highest energy output per unit of propellant. Which is pretty much all that counts given that the total mass of both the vehicle and the propellant goes into the rocket equation.

The theoretical limit would be a drive that always provides an exhaust velocity that is equal to the actual speed of the vehicle but in the eopposite direction. In case of that variable exhaust speed dive propellant use would be 100% efficient since the propellant would use 100% of its kinetic energy (minus thermal losses) to provide forward momentum.

Also of course there is a meaningful measure of efficiency. It's energy provided per unit of reaction mass. Because

Delta v = Isp * g * ln (m0/mf)

m0 = total mass including propellant
mF = dry mass of the vehicle.
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Reply #851 on: July 10, 2017, 11:36:19 PM

A flashlight provides more as it needs no propellant yet still produces thrust. The ion drive is only the most efficient currently viable production engine(that also produces enough thrust to propel a spacecraft to sufficient velocity in reasonable time). It not the most efficient drive possible; which was claimed. You can always throw less(or the same) mass out faster which will always have a higher specific impulse... until you're throwing out only energy in the form of photons*

*Or maybe gravity? I don't know enough to say because that would be super weird.
Jeff Kelly
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Reply #852 on: July 11, 2017, 06:50:14 AM

Without reaction mass there is no acceleration of a center of mass (e.g. a spaceship) in space. This is a direct result of Newton's laws of motion or more specifically the conservation laws (in this case conservation of linear momentum). The Tsiolkovski rocket equation is basically an extension of Newton's second law to variable mass systems (Newton's second law requires the mass of the system to be constant)

The reason is that acceleration is a change in linear momentum that is proportional to the force applied and due to the conservation of linear momentum that force has an equal but opposite force. Also since F = dP/dt = d(mv)/dt and P = mv there is no change in linear momentum without a "mass" that can "carry" momentum.

Propellant in that context is any source of reaction mass that is able to affect a change of linear momentum. This leaves you with only two Options. One: expel more mass (F = d(mv)/dt) or Two: increase the velocity of the expelled mass (F = d(mv)/dt)

In case of a chemical rocket the velocity of the reaction mass comes from the energy of an exotheric chemical reaction
In case of an ion drive the velocity of the reaction mass comes from an electric field gradient that accelerates charged particles. This can be further differentiated by the power source used to generate the ions and the electric field (thermal, solar, nuclear etc.)
There are other types of drives which create reaction mass in a different manner (e.g. ablation via laser or plasma arcs) or use other types of Forces (gravitational potential energy, radiation pressure).

All types of drives have upper limits, either due to the amount of mass you can carry with you (which gets more and more inefficient the more mass you carry) or the amount of energy you can create (reactor size and mass).

Ion drives usually have low thrust because they are reaction mass efficient (high specific impulse) but not energy efficient (they require a high amount of energy to acellerate the ions) and thus the energy Budget is usually limited by the payload size.

By the way a flashlight does not need propellant, the force generated is due to radiation pressure by emission of photons (Boltzmann's law). It needs an energy source though (battery, electric or thermoelectric Generator etc) to be able to generate and emit the photons and so similar upper limits (size and amount of energy that can be output) apply.

Lastly there is a hard upper limit on v and therefore a hard upper limit on specific Impulse or thrust and that is the speed of light. As the exhaust velocity approaches c the amount of energy required approaches infinity.
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Reply #853 on: July 11, 2017, 08:33:28 AM

Wrong. Space sails work ergo reaction mass is not necessary. We have experimentally verified force by bouncing photons off a mirror. Photons don't have mass ergo force with no reaction mass. Ergo acceleration with no reaction mass.

It's... it's that simple. The thing you're claiming does not exist does indeed actually exist. This does not violate conservation of energy.

I don't understand the point of he rest of your post unless you're trying to rewrite my post above explaining that for a fixed F = d(mv)/dt | m ~ 1/dv.. There can be no local maximization or minimization solutions on such a continuum without another relationship between the values (which does not exist as theoretical limitations as far as I can tell) except the corner solutions.

Edit: this is true on the plane created as well if you let F float
« Last Edit: July 11, 2017, 01:18:47 PM by Goumindong »
Jeff Kelly
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Reply #854 on: July 12, 2017, 06:19:21 AM

Wrong. Space sails work ergo reaction mass is not necessary. We have experimentally verified force by bouncing photons off a mirror. Photons don't have mass ergo force with no reaction mass. Ergo acceleration with no reaction mass.

Reaction as in actio = reactio. You need something to "push against" or something that pushes against you.

We were talking about vessels with internal drives that don't have to rely on external forces for propulsion. You're now talking about methods of propulsion that use external forces. A solar sail works because of radiation pressure due to reflection, absorption or emission. In that case you don't need to carry your own reaction mass because your space craft is externally powered and used as reaction mass by something else (photons in that case) which also means that the energy source is external (in that case the sun's fusion process)

Bouncing photons of a mirror imparts a net force due to radiation pressure. The photon either changes direction due to reflection or it gets absorbed. This exerts a net force on the reflector due to the change of direction of the momentum vector of the photon with the photon losing energy in the process (redshifting). (see Newton's second law). Absorption and reemission work because of Boltzmann's law.

"The two largest issues (...) are to find a way for a vehicle to induce external net forces on itself, and secondly, to satisfy conservation of momentum in the process."

"A key aspect of conservation of momentum is the reaction mass. When an automobile accelerates, its wheels push against the road using the Earth as the reaction mass. Helicopters
and aircraft use the air as their reaction mass. In space, where there are no roads or air, a rocket must bring along propellant to thrust against." (Assessing Potential Propulsion Breakthroughs https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20060000022.pdf)

"The net external force requirement is closely related to conservation of momentum. Conservation of momentum requires that the momentum imparted to the vehicle must be equal and opposite to the momentum imparted to a reaction mass." (The Challenge To Create The Space Drive. https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19990023236.pdf)

Quote
It's... it's that simple. The thing you're claiming does not exist does indeed actually exist. This does not violate conservation of energy.

Conservation of linear momentum not conservation of energy. Reaction mass as in actio = reactio (Newton's third law) not as in "chemical reaction". In case of a solar sail the photon from the sun uses the ship as its "reaction mass" as it "pushes against" the sail to change direction.

For movement you need a source of kinetic energy either because of a "reaction mass" or because you found a way to convert some form of potential energy into kinetic energy.

Quote
I don't understand the point of he rest of your post unless you're trying to rewrite my post above explaining that for a fixed F = d(mv)/dt | m ~ 1/dv.. There can be no local maximization or minimization solutions on such a continuum without another relationship between the values (which does not exist as theoretical limitations as far as I can tell) except the corner solutions.

If you expel mass you're either limited by the exhaust velocity (v) since v must be smaller than c (in reality v must be << than c because of relativistic effects) or by the amount of reaction mass you can carry with you. The obvious limit being that you can't carry an infinite amount of mass and the less obvious being the fact that additional mass means that you increase the wet mass of your ship which creates additional mass you need to accelerate/decelerate which requires additional mass as propellant etc. If you increase DeltaV by a factor of 3 your total mass increases by a factor of 20, given that the dry mass stays the same for example.

For other types of hypothetical drives that rely on other types of force interactons you're still limited by your energy source and the upper limit on conversion efficiency of the physical process/cycle used to generate energy. You're also running into the same problem that you need to carry fuel with you that runs your generator and that adds additional mass to your vehicle which requires additional energy output for acceleration/deceleration.

This places a real upper physical bound on efficiency of your propulsion system if you need to be self reliant (independent of external sources of energy, like the sun for example or a laser pointed at you from earth)

As for your "torch drive". Photons have no rest mass. They carry momentum because E = pc but very very little since p = E/c and therefore the force (dp/dt) is very very small, meaning that you'd need a lot of photons and therefore a lot of energy to propel something forward. 1 gigawatt would give you about 3.3 Newtons of force

There are ideas to use thermic photons (waste heat or thermal energy) for Propulsion that is emitted via blackbody radiation (see for example https://en.wikipedia.org/wiki/Nuclear_photonic_rocket) but emitting photons yields you less force than just emitting the reaction products of the energy source directly.
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Reply #855 on: July 16, 2017, 12:55:42 AM

now I'm wondering if it would be possible for an ion drive craft to collect reaction mass from the solar wind so it wouldn't be limited to what it was launched with? I guess the collection would impart thrust as well, in a fixed direction, same as a solar sail. but if it could then re-emit those particles as thrust in whatever direction it wanted ... hmm. extremely small amounts of mass, even on ion drive scales. but those small amounts do add up over years.

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satael
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Reply #856 on: July 16, 2017, 01:34:06 AM

now I'm wondering if it would be possible for an ion drive craft to collect reaction mass from the solar wind so it wouldn't be limited to what it was launched with? I guess the collection would impart thrust as well, in a fixed direction, same as a solar sail. but if it could then re-emit those particles as thrust in whatever direction it wanted ... hmm. extremely small amounts of mass, even on ion drive scales. but those small amounts do add up over years.


You mean a Bussard ramjet?
MahrinSkel
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Reply #857 on: July 16, 2017, 06:54:36 PM

Bussard Ramjet would be a different thing. Problem with trying to collect your reaction mass from the solar wind is that the ion engine is pretty fussy about what it will use, and hydrogen, helium, plus whatever else got scooped up would probably not fit the bill. And any mass used to collect and filter it could simply be used to add more reaction mass in the first place.

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Count Nerfedalot
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Reply #858 on: July 16, 2017, 09:27:31 PM

not ramjet, no.  Trying to remember but I thought solar wind particles were already mostly ions. ion drives use the charge differential to emit the ions, right? just curious, but too lazy to look it up right now.  why so serious?

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MahrinSkel
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Reply #859 on: July 16, 2017, 09:50:20 PM

not ramjet, no.  Trying to remember but I thought solar wind particles were already mostly ions. ion drives use the charge differential to emit the ions, right? just curious, but too lazy to look it up right now.  why so serious?
This page will tell you more than you want to know, according to it the only type that uses hydrogen as a propellant is the magnetoplasmadynamic thruster (MPDT), which the Russians are working on. It has particularly high energy requirements, and still more theoretical than practical.

Having it already be ions might make it easier to capture and handle,  but you would need some awfully strong and subtle magnetic systems to do it, which again begs the question of why you don't just use that payload to carry more propellant.

--Dave

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Reply #860 on: July 16, 2017, 11:10:13 PM

I really don't understand what you're trying to say Kelly. I understand the physics of it so telling me what I described again doesn't change anything. If you're trying to redefine terms into meaninglessness then I don't know why.

Ion drives simply are not the most efficient drive possible as you claimed. 
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Reply #861 on: July 17, 2017, 02:58:46 AM

Then tell me what would be the most efficient drive in your opinion. Also what you define as most efficient.

I have tried to show you why - barring some sort of revolutionary breakthrough in propulsion - ion drives are the most efficient drives when it comes to the most important benchmark reaction mass efficiency (going farthest with the least amount of wet mass)

Chemical drives are less efficient because their maximum V(exhaust) is limited.
Photon drives have such high energy requirements (because each photon carries very little impulse) that it's more efficient to use the exhaust products directly.
Solar sails and laser drives or similar drive concepts require external energy input and line of sight, either to earth or to the sun and the amount of energy that can be transferred shrinks with 1/r^3 so they are not really suited for interplanetary or interstellar travel

Evertging else is in the realm of theory which may or may not work and may or may not be technically viable.
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Reply #862 on: July 17, 2017, 07:27:08 AM

I know better than going between Goumindong and Jeff, but wonder if the more "normal" F13 posters can even follow this debate.

Does everyone know what ISP is, how an Ion drive works, etc?

If not I could make a Rocket Engines - the Basics for Dummies post in the next days (when havingaccess to a PC)

Just so we all are on the same page

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Reply #863 on: July 17, 2017, 10:48:04 AM

There is no "most efficient engine" because such a concept is meaningless.

And Jesus Christ I know. I already said " The ion drive is only the most efficient currently viable production engine(that also produces enough thrust to propel a spacecraft to sufficient velocity in reasonable time). It not the most efficient drive possible; which was claimed"
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Reply #864 on: July 17, 2017, 04:22:07 PM

So if he goes back and adds "currently" to his post you'll shut the fuck up?
MahrinSkel
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Reply #865 on: July 17, 2017, 04:32:38 PM

I know better than going between Goumindong and Jeff, but wonder if the more "normal" F13 posters can even follow this debate.

Does everyone know what ISP is, how an Ion drive works, etc?

If not I could make a Rocket Engines - the Basics for Dummies post in the next days (when havingaccess to a PC)

Just so we all are on the same page
I am not sure how close any of us come to "normal", but other than a vague sense that they use electromagnetic fields to accelerate ions, I don't actually know much about how ion drives work. ISP relates to the efficiency of the propellant use, in essence the faster your reaction mass goes out the rear end, the less of it you have to use, and the more total vector change you can get for a given mass of propellant.

--Dave

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Reply #866 on: July 17, 2017, 10:57:27 PM

I know better than going between Goumindong and Jeff, but wonder if the more "normal" F13 posters can even follow this debate.

Does everyone know what ISP is, how an Ion drive works, etc?

If not I could make a Rocket Engines - the Basics for Dummies post in the next days (when havingaccess to a PC)

Just so we all are on the same page

 Basics: All engines work in roughly the same way. You push on something and it pushes you back in the opposite direction. This can be like a car (you push on the world) or a rocket (you push on rocket fuel) or a sail (you push on the wind).

The heavier the thing the faster you go. If you sit on a dolly and throw a baseball behind you at a fixed velocity you wont go very far or go very fast. But if you throw a medicine ball the same speed then you will go faster and further.

The faster you throw the thing the faster you go as well. In the dolly example throwing a baseball 10 mph will make you go less far than throwing it 100 mph. As you know, throwing a ball 100 mph takes much more energy than throwing one 10 MPH.

For a rocket then there are naturally two constraints

1) how much mass your rocket can carry. if I put 100 baseballs on my dolly and throw a baseball out the back I have to push me +99 baseballs. Then when I throw the second me +98. This is generally the most important constraint in a rocket. If we were throwing baseballs out the back and wanted to do this for a very long time you would have to eventually add so many baseballs that an additional baseball would not push you any faster; the increased mass we needed to push would negate all the value of the increased ability to push.

2) how much energy you can expend to push the material out the back. If you're an MLB pitcher you can throw harder and longer. But if you're me then you're shit out of luck.

Because of the first constraint very long range rockets tend to focus on trying to take as little fuel mass as possible. The less you throw out the back the less you have to take with you and so the less you have to push yourself in order to move. This allows longer trips in more reasonable amounts of time because you can burn for a longer portion of the trip. Going to mars with an ion drive you could burn half the way there (and then turn around to decelerate) but with a chemical rocket you would only be able to burn for a few minutes.

The end point of the first constraint is not a drive that uses mass at all. You can literally create light out of the void and so, given enough energy, could create enough light to push a ship. The problem here is more the ability to create enough energy (and then of course the ability to somehow not murder everything behind you for million of miles) which we absolutely definitely do not have.

The most commonly known rocket is a chemical rocket. Energy is stored in a chemical reaction and when the reaction goes off the expansion of the gasses in a controlled manner push the rocket forward. This releases energy very fast but contains relatively little energy per mass and so cannot push to very high velocities even though they will achieve those velocities very fast.

The current best we can do* is an ion drive which is, more or less, smaller/modified version of a particle accelerator. (Like the large hadron). Rather than accelerating a small number of particles to super high speeds it accelerates relatively loads more particles to much lower speeds. Because "relatively loads more" than a normal particle accelerator is still "a fuck ton less than a chemical rocket" these drives can go further into space in reasonable time frames than chemical rockets.

*besides the enminently buildable, but impossible to reasonably test on earth, nuclear bomb sails.
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Reply #867 on: July 28, 2017, 11:04:35 AM

Just happening:

A new crew flying to the ISS.

A Russian, Sergey Ryazansky (2nd spaceflight for him), an European, Paolo Nespoli (3rd spaceflight) and an American, Randy Bresnik (2nd flight).

Here are they together:



Guess who is who!



Liftoff:



1 minute 58 seconds later... Booster seperation


Note the 4 small dots, the side boosters falling away. The famous Korolev Cross.

GIF from an earlier Arianespace mission showing how it looks closeup:




And here an inside picture of the crew and the most important equipment: The Stick of Control



The Soyuz (rocket) did it's job, now there is a free fly phase of the Soyuz (capsule). Docking at the ISS will be i a few hours.
« Last Edit: July 28, 2017, 11:14:56 AM by calapine »

Restoration is a perfectly valid school of magic!
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Reply #868 on: July 28, 2017, 12:09:36 PM

And here is a "On This Day" in 2005:




Survey operations (checking the integrity of the heat shield) on Space Shuttle Discovery.

The image was shot over Switzerland (altough I cant find the exact location) from inside the ISS.

Edit: As much as the Shuttle was the wrong choice from a development point of view, it's just looks so very cool.  Heart  Capsules can't compare to that.
« Last Edit: July 28, 2017, 12:14:50 PM by calapine »

Restoration is a perfectly valid school of magic!
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Reply #869 on: July 31, 2017, 05:14:18 AM

Soyuz trip was safe and uneventful. Here just seconds before docking:


Restoration is a perfectly valid school of magic!
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Reply #870 on: August 01, 2017, 03:12:47 PM

Super Typhoon Neru, photographed by Randy. The same Randy from your local NASA space agency that we shot into the air few days ago with Soyuz.








Restoration is a perfectly valid school of magic!
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Reply #871 on: August 03, 2017, 06:36:35 AM

Another image from the new crew, this time shot by the Russian member:






Think it's an awesome image. That it was photographed in portrait ratio changes a familiar view. Good reminder there is no up and down in space.
« Last Edit: August 03, 2017, 06:42:46 AM by calapine »

Restoration is a perfectly valid school of magic!
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Reply #872 on: August 04, 2017, 03:13:03 AM

Space guessing game.

Which comet is this?




Restoration is a perfectly valid school of magic!
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http://tinyurl.com/d89qk7g


Reply #873 on: August 04, 2017, 04:00:42 AM

Great stuff, keep it coming!

"My great-grandfather did not travel across four thousand miles of the Atlantic Ocean to see this nation overrun by immigrants.  He did it because he killed a man back in Ireland. That's the rumor."
-Stephen Colbert
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Further proof that Italians have suspect taste in games.


Reply #874 on: August 31, 2017, 08:22:31 PM

Let's give this 6+ billions-years old alien civilization a warm welcome once they get here!!!  DRILLING AND MANLINESS why so serious?

http://news.berkeley.edu/2017/08/30/distant-galaxy-sends-out-15-high-energy-radio-bursts/


But seriously, this is extremely cool.

" He's so impatient, it's like watching a teenager fuck a glorious older woman." - Ironwood on J.J. Abrams
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