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This should also be a rather minor fix, but it annoys me since I picked up the game. Many scalars lack the proper unit for no reason.

Some examples (I probably missed some)

  • Fuel: It has a mass tag, but no unit.  The rocket does have units. Suggested unit: t
  • Isp: Suggested unit: s
  • Reaction Wheel: Torque? Is it kNm? Nm? Who knows.
  • Electric Charge: Is it 50J? Or 50Wh? kJ?
  • Antenna Rating: Is it dBi?
  • RCSFX / Thrust Power: Is it kN? It should be kN.
  • Lifting surface: Is it m2? It could also be unitless because it says "relative wingarea" but some have a relative wing area much greather than 1.
  • Legs/Wheels: Stress Tolerance? Is it Pa? kPa? Something different?
  • (Inconsistency: On Wheels the degree symbol is used, on control surfaces it is both spelled out (degree) and abbreviated (deg). Some consistency would be nice.)
  • Separators: Ejection Force. Is it kNs? It should be kNs.
  • Deployable panels: Tracking speed. Is it deg/s?
  • Parachute Diameter: m, probably.

It should be applauded that some components already use proper units (e.g. Engine Thrust, Heat components, etc.).

Adding a unit would have only advantages. Most prominently: 1. The user could properly assess the effect the parts would have for a given craft. 2. Without effort people would learn what units go with those dimensions. 3. It would be physically correct.

 

Units! Please! :)

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For the purposes of playing, units don't really matter too much, because they're standard in the game. 1 unit of LOX is always 1 unit of LOX, and likewise for fuel. Doesn't matter what its called, could be gooblydooks. We also always know that 1 unit of LOX is always some mass. I'd be willing to make the argument an average player doesn't really care what units its in as long as he knows what to do with it (what it represents, and how changing it will do something). I know I personally am not going to bother to calculate the exact wheel pressure, or how fast my solar panels need to track, or exactly how much parachute I need because its too much work to calculate for something fixable by basically adding more or less, or changing the relative sizes (which you want to assign units to).

I will say, for certain suggestions (RCS power,  tracking speed, ejection force), it would be a nice quality of life thing. But I don't think its necessary for the devs to invest time into fixing that instead of fixing bugs.

Also, ISP I believe is also already listed as s.

1 hour ago, bitzoid said:

Most prominently: 1. The user could properly assess the effect the parts would have for a given craft. 2. Without effort people would learn what units go with those dimensions. 3. It would be physically correct.

1 - The current unit system already allows us to do that, because its a standard. Doesn't have to be standard to reality, just to itself.

2 -  Eh? For example, like wheel stress, I don't know what sort of unit you'd put there because its heavily dependent on many things, not just simple pressure (like, what if i'm going sideways for instance)

3 - Again, doesn't have to be. The usage of standard SI in some places of the game is because it makes the calculations easier and the math and tools already exist to work in those units. And if we were to "make something physically correct" units is an odd place to pick on first.  You could pick on the super dense planets. Pick on the terrible realworld engine mass ratios. Units seem like a minor thing.

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I absolutely agree! It's hard to do the math when you don't know what the values mean.

Going by the power output of the Dawn, I think one unit of electrical charge is close to 1.21 megaJoules.  For a non-chemical engine, Thrust = 2 × Power / Ve. The Dawn produces 1,000 N of thrust with an exhaust velocity of 3690s × 9.80665 m/s², so its power is 18.09 MJ/s. It uses 14.999 electrical charge / second, so one Ec = 18.09 MJ/s ÷ 14.999 Ec/s = 1.206 MJ.  (the Nerv by the same calculation produces 235 megawatts of power, which is one order of magnitude smaller than the real-life NERVA designs from the space race.) (That would mean the stock radioisotope generator puts out close to a megawatt of power, which is about three orders of magnitude too much. I think the Dawn is 1,000× overpowered, but nobody would want to use an engine with 1 N of thrust.)

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I wholehearteldy agree that fixing bugs should be priority one. Then nothing for a long while. Then again some nothing. Then after some more nothing, features (which I believe this subforum is for).

And this is a very low hanging fruit as it probably just requires to edit some strings in config files (localisation shouldn't be too hard, too). Perhaps some research. 

 

Maybe it is just me, but I cannot stand a lack of units for things that should have units. For one, currently, there is no way to compare the thrust of an RCS block with, say, an Ant engine. Sure, you can just rig an experimental rig, but then the value it gives for the block is pretty much useless. Secondly, it is a missed opportunity to sneakily get some subtle knowledge into the head of the player.

 

Note also, that it is well known that fixing low hanging fruit issues or implementing easy features from time to time can significantly increase the morale of devs. So that is also a thing to consider.

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3 minutes ago, MrSystems said:

1.21 megaJoules

Doc Brown should like to have a word with you...

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4 hours ago, MrSystems said:

I absolutely agree! It's hard to do the math when you don't know what the values mean.

Going by the power output of the Dawn, I think one unit of electrical charge is close to 1.21 megaJoules.  For a non-chemical engine, Thrust = 2 × Power / Ve. The Dawn produces 1,000 N of thrust with an exhaust velocity of 3690s × 9.80665 m/s², so its power is 18.09 MJ/s. It uses 14.999 electrical charge / second, so one Ec = 18.09 MJ/s ÷ 14.999 Ec/s = 1.206 MJ.  (the Nerv by the same calculation produces 235 megawatts of power, which is one order of magnitude smaller than the real-life NERVA designs from the space race.) (That would mean the stock radioisotope generator puts out close to a megawatt of power, which is about three orders of magnitude too much. I think the Dawn is 1,000× overpowered, but nobody would want to use an engine with 1 N of thrust.)

I'm not sure you did the math correctly... that, or you're using a mod that changes the Dawn thruster (which IIRC, Near Future Propulsion does).

The Dawn has an Isp of 4200 sec, and a thrust of 2 kN. That works out to a xenon flow of 0.0486 kg/sec. Since the propellant is exiting at (4200s*9.8063 m/sec^2), you get a kinetic energy per second of about 41 MJ. Assuming the wiki-listed value of 8.74 E/sec is correct, that means about 4.7 MJ/EC... assuming the ion engine is 100% efficient, anyways.

This conflicts horribly with several other calculations (including one of my own) that would suggest about 1-2 kJ/EC, but it's widely known that the ion engine is amazingly overpowered so that people actually use the thing.

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10 minutes ago, Starman4308 said:

I'm not sure you did the math correctly... that, or you're using a mod that changes the Dawn thruster (which IIRC, Near Future Propulsion does).

The Dawn has an Isp of 4200 sec, and a thrust of 2 kN. That works out to a xenon flow of 0.0486 kg/sec. Since the propellant is exiting at (4200s*9.8063 m/sec^2), you get a kinetic energy per second of about 41 MJ. Assuming the wiki-listed value of 8.74 E/sec is correct, that means about 4.7 MJ/EC... assuming the ion engine is 100% efficient, anyways.

This conflicts horribly with several other calculations (including one of my own) that would suggest about 1-2 kJ/EC, but it's widely known that the ion engine is amazingly overpowered so that people actually use the thing.

First I did the math the way you did. Then, in the Wikipedia entry for Nuclear thermal rockets I saw the formula I ended up using in my post. I assumed it was more likely to be right than my initial calculations, but perhaps I was mistaken on that point.

The .cfg file for the Dawn agrees with your stats regarding the engine. I must have a mod installed (maybe Near Future Propulsion?) that re-configures it to the numbers I cited.

In both cases, thank you for the corrections.

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When you start making or messing with mods and you have the mind of an engineer or a practitioner in any logic-intensive field, you're going to want things to be physically accurate and measurable at every turn. These little things don't mean much to the simple player, but for the core fan-base, people who know the various maths and sciences, these things matter a lot. The unit for ElectricCharge is the biggest thing that has been argued over as far as I can tell. And just what is the unit of a relative wing area? The square wing board with the value of "1" is 2m long per side. And I've seen wheels that can take 5 million stress in unknown units. :/ 

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Consistently displaying units, where they are established, would help a lot.  That would show players which numbers in the in-game part-descriptions can be combined with other quantities, and which are just a relative measure in some nonconvertible scale.

Showing Isp with the units of seconds helps KSP players, that fraction who might know or be learning rocket science, know which version of the rocket equation to use.

Reaction wheel torque is consistently in kN-m; showing the units would reveal just how strong they are.

It would be simpler to measure fuel in tonnes; capacity in tonnes is already shown in-game for the fuel-tanks. The fuel tanks look big enough to hold about 4-litres per 'unit' of their labelled capacity. (Maybe the units are old-Kerbin imperial gallons, but it wouldn't matter if fuels were figured in tonnes.)

Wing area looks like 4 m² per 'relative wing area', and the numbers in the aerodynamics debug menu are close to consistent with that conversion.  If we used m² the advice to new space-plane builders could be simply "start with 1m²/tonne and experiment from there".

Electric charge, though,  cannot be converted consistently. Electric charge (which really should be called electrical stored energy) seems to be about ~1kJ/EC based on the solar-panel sizes and electronics demands, ~10 kJ/EC if you look at mass of batteries, ~100kJ/EC if you look at powered wheels,  and ~1000 kJ/EC if you do the math for electric engines.  Here, using a nonsense unit like EC would warn players not to convert to any other physical quantity.

Edited by OHara
grammar

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1 hour ago, JadeOfMaar said:

And I've seen wheels that can take 5 million stress in unknown units.

This absolutely made my day :D :D:D

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This is a pandora's box of issues as much as it's a nice solution on paper.

KSP works as a physics simulator and as a result it attempts to best emulate physics using calculations and factors but as anyone who's worked with real rockets or hell, even just booted up RSS/RO for a spin will know, KSP is still in a reality of it's own. So providing realistic units is akin to trying to put values to ethereal concepts as hope and happiness. Even if KSP did, then Squad would have the problem of having engines with vastly unrealistic thrust values, generated torque, energy density for batteries, unrealistic fuel density for fuel tanks, so on and so forth.

Some may say "it's a game, it isn't supposed to be 100% realistic" but if you're adding this, you're intent is to push towards realism.

I'd be preferable to compromising and adding units to all values that current exist as arbitrary numbers, but use original units like keters (meters), bliters/blitres (liters/litres) and so on and so forth so that those who want units of measure, can have one and all units actually have a universal unit to compare to but the values still exist in the fictional word of KSP and can be exempt from the "that isn't realistic" tag.

This is just an idea from someone who's been up for 22 hours straight.

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Totally agree with @ZooNamedGames, apart from the keters thing. That sounds like hanging a label on something for the sake of it having a label more than anything else but reasonable people may reasonably differ on that one.

However, in my opinion, adding real-world units to KSP parts sounds like an absolutely fabulous way to create a never-ending flow of pointless forum threads arguing over the realism and/or balance of parts. To which the answers (after many, many pages of descending grumpiness) will almost inevitably boil down to one of 'it's for gameplay balance' or 'there's a mod for that if you really care.'

Or maybe I've just been around here too long.

Edit:

Ahh yes, elitism. I forgot about elitism

"When you start making or messing with mods and you have the mind of an engineer or a practitioner in any logic-intensive field, you're going to want things to be physically accurate and measurable at every turn. These little things don't mean much to the simple player, but for the core fan-base, people who know the various maths and sciences, these things matter a lot."

Speaking as a filthy casual - my apologies, 'simple player' - I can only give thanks to the kindly folks who wrote Real Solar System and other scaling mods. Why, think of the pain caused to our metrology-minded, logical overlords every time they fire up stock KSP and gaze befuddled on those implausibly dense planets. 

Edited by KSK

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If this was done from the beginning, (which it could be argued should have) it would be an easier proposition.  The undertaking now is probably bigger than appears on the surface.  If I had developed KSP, I would have kept the numbers generic, but, behind the scenes, known exactly how they relate generally to their real life counter parts.  EC particularly pops out as a problem area.  The way electricity is treated in general.

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16 hours ago, bitzoid said:

This should also be a rather minor fix, but it annoys me since I picked up the game. Many scalars lack the proper unit for no reason. (...)

As @5thHorseman points out, the reason is that it will open up the can of worms about the values being wrong. Or “unrealistic.” Or about the choice of units. We have units where we need them; I’m fine with things the way they are.

no additional units, please!

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But aren't the existing values already unrealistic? Engines have a kN thrust value from this and the mass of fuel (which we know because the mass of a rocket is measured in metric tonnes), we can compute that the Isp is, in fact, in seconds.

I have zero problem with parts being unrealistic. It is a game and game balance is a proper "excuse". If you want different numbers before your units use one of the mods that make things more realistic, no problem.

 

P.S.: That "unrealistic" argument is a daft one anyway, because it assumes that kerbkind and humankind have discovered similar technologies with similar efficiency. But perhaps Kerbin has some extremely advanced technology in some areas while lacking in others, compare to Earth. And if anything breaks conservation of energy you must enable the suspension-of-disbelief button in your brain, which we do regularly.

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I often belive these are for metric units. like the lfo tanks hold liters and not units. although the monoprop tanks are actually kind of ridiculous when you add this liters. how do a tiny monoprop tank hold 50 liters of monoprop?!? is truly confusing. I dont bother calculating so I just assume with metric units for everything.

Just now, bamslamkabam said:

I often belive these are for metric units. like the lfo tanks hold liters and not units. although the monoprop tanks are actually kind of ridiculous when you add this liters. how do a tiny monoprop tank hold 50 liters of monoprop?!? is truly confusing. I dont bother calculating so I just assume with metric units for everything.

sorry the tiny mono tank holds 20 liters. I somehow still remember it being 50.

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I've never understood why this wasn't done from the beginning. You need to use units in the game anyway, why not use real ones? 

@klgraham1013 has the right idea though: At this point the effort:reward ratio is likely way too high for this to be worthwhile. Maybe if there's a KSP2? 

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Because: Kerbals don't use SI units, and we haven't yet figured out what the conversions are for all of them.

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I support this. Why use unnamed "units" if there's a real world unit that everyone already knows the dimensions of? And if there's a problem with using the real world names, then why are they used for some things but not others? The worst of these is EC, there's no way (without experience in KSP) to tell whether that has the same dimension as Joules, watts, or some other concept related to power.

This would make it easier whether you want to plan missions by hand with math, or if you're just a casual player and want to get an idea of how powerful the decouplers are relative to an engine. On the other hand, as others have pointed out, it may not be worth it this late in development, especially since the way some resources work could use an overhaul anyway. Specifically electricity, heat, and intake air.

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On 1/26/2019 at 3:15 PM, qzgy said:

For the purposes of playing, units don't really matter too much, because they're standard in the game. 1 unit of LOX is always 1 unit of LOX, and likewise for fuel. Doesn't matter what its called, could be gooblydooks. We also always know that 1 unit of LOX is always some mass. I'd be willing to make the argument an average player doesn't really care what units its in as long as he knows what to do with it (what it represents, and how changing it will do something). I know I personally am not going to bother to calculate the exact wheel pressure, or how fast my solar panels need to track, or exactly how much parachute I need because its too much work to calculate for something fixable by basically adding more or less, or changing the relative sizes (which you want to assign units to).

I will say, for certain suggestions (RCS power,  tracking speed, ejection force), it would be a nice quality of life thing. But I don't think its necessary for the devs to invest time into fixing that instead of fixing bugs.

Also, ISP I believe is also already listed as s.

1 - The current unit system already allows us to do that, because its a standard. Doesn't have to be standard to reality, just to itself.

2 -  Eh? For example, like wheel stress, I don't know what sort of unit you'd put there because its heavily dependent on many things, not just simple pressure (like, what if i'm going sideways for instance)

3 - Again, doesn't have to be. The usage of standard SI in some places of the game is because it makes the calculations easier and the math and tools already exist to work in those units. And if we were to "make something physically correct" units is an odd place to pick on first.  You could pick on the super dense planets. Pick on the terrible realworld engine mass ratios. Units seem like a minor thing.

When people playing don't care what the units mean, having that little unit on the end doesn't matter. It is only a bonus for when people want to design craft ahead of time, to know right away what the numbers mean so they can start applying math and/or converting to different units. Knowing my thrust in kN means I can figure out my TWR, but when I look at RCS (which can be used as main engines...), I see "thruster power"; I wouldn't know what "thruster power" is and it doesn't help me understand my TWR...but knowing that it is just kN does help me. This is one area where the game has, quite simply, slightly hurt my ability to design craft, and there is no justification for "thruster power", someone who is doing something else with RCS thrusters won't care whether it's called that or kN, but in fact, seeing kN helps them understand how powerful their translation/rotation is compared to using normal engines. It only helps to have units, provided the units aren't blatantly wrong.

On 1/26/2019 at 9:59 PM, OHara said:

Consistently displaying units, where they are established, would help a lot.  That would show players which numbers in the in-game part-descriptions can be combined with other quantities, and which are just a relative measure in some nonconvertible scale.

Showing Isp with the units of seconds helps KSP players, that fraction who might know or be learning rocket science, know which version of the rocket equation to use.

Reaction wheel torque is consistently in kN-m; showing the units would reveal just how strong they are.

It would be simpler to measure fuel in tonnes; capacity in tonnes is already shown in-game for the fuel-tanks. The fuel tanks look big enough to hold about 4-litres per 'unit' of their labelled capacity. (Maybe the units are old-Kerbin imperial gallons, but it wouldn't matter if fuels were figured in tonnes.)

Wing area looks like 4 m² per 'relative wing area', and the numbers in the aerodynamics debug menu are close to consistent with that conversion.  If we used m² the advice to new space-plane builders could be simply "start with 1m²/tonne and experiment from there".

Electric charge, though,  cannot be converted consistently. Electric charge (which really should be called electrical stored energy) seems to be about ~1kJ/EC based on the solar-panel sizes and electronics demands, ~10 kJ/EC if you look at mass of batteries, ~100kJ/EC if you look at powered wheels,  and ~1000 kJ/EC if you do the math for electric engines.  Here, using a nonsense unit like EC would warn players not to convert to any other physical quantity.

I actually would rather they fix things to be a bit more realistic with at least wheels, cause the current battery usage of wheels is downright ludicrous, making rover design a serious headache on power. As for the ion engines, they are most definitely unrealistic on purpose to make them somewhat usable, and I wouldn't worry about players trying to do the math on how much energy it takes to shoot out Xenon, as anyone going that far would surely know that KSP's ions are intentionally more like LFO engines for gameplay reasons.

On 1/26/2019 at 11:20 PM, ZooNamedGames said:

This is a pandora's box of issues as much as it's a nice solution on paper.

KSP works as a physics simulator and as a result it attempts to best emulate physics using calculations and factors but as anyone who's worked with real rockets or hell, even just booted up RSS/RO for a spin will know, KSP is still in a reality of it's own. So providing realistic units is akin to trying to put values to ethereal concepts as hope and happiness. Even if KSP did, then Squad would have the problem of having engines with vastly unrealistic thrust values, generated torque, energy density for batteries, unrealistic fuel density for fuel tanks, so on and so forth.

Some may say "it's a game, it isn't supposed to be 100% realistic" but if you're adding this, you're intent is to push towards realism.

I'd be preferable to compromising and adding units to all values that current exist as arbitrary numbers, but use original units like keters (meters), bliters/blitres (liters/litres) and so on and so forth so that those who want units of measure, can have one and all units actually have a universal unit to compare to but the values still exist in the fictional word of KSP and can be exempt from the "that isn't realistic" tag.

This is just an idea from someone who's been up for 22 hours straight.

Lots of things like fuel tanks and the planets themselves are unrealistic, sure...but that's not the point of units. Nobody comes in expecting the units to match up with real life perfectly, but units allow us to do proper math on things and compare things. Because the fuel tanks are in metric tons, and the thrust in kN, I know that I can just multiply my vehicles listed mass number by Kerbin's gravity (9.81m/s) and divide by my total thrust and I get my TWR. That's a little less important in the current version, which calculates TWR for me, but still, it's really nice to know how to compare things. A big one that KSP messes up is RCS thrust; it states "thruster power" when it means "kN". Knowing that an RCS thruster's thrust is some amount of kN while an engine's thrust is so many more kN gives me an idea of relative scale. Similarly, knowing that KSP's reaction wheels are using kN*m would go towards comparing a given reaction wheel setup with a given RCS alternative. Having to check what KSP's numbers actually mean first is just an extra step the game is throwing in my way to reason about things, and that's bad.

It is most sane to always display units from the same system so that we can compare across things. As to which system to use, it's best to just stick to the real life one because learning an additional one is a lot of work. It doesn't matter that the data points of what KSP has in that system are a little different than real life, what matters is that KSP should tell us straightup how it's numbers relate.

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On 1/26/2019 at 11:15 PM, qzgy said:

For the purposes of playing, units don't really matter too much, because they're standard in the game. 1 unit of LOX is always 1 unit of LOX, and likewise for fuel. Doesn't matter what its called, could be gooblydooks. We also always know that 1 unit of LOX is always some mass.

Yea, 1 unit of fuel is always 0.05 tons, for LF or oxidizer (what we care about mostly). It would be nice if it was standard though.

 

Wee math coming:

On 1/26/2019 at 11:38 PM, MrSystems said:

I absolutely agree! It's hard to do the math when you don't know what the values mean.

Going by the power output of the Dawn, I think one unit of electrical charge is close to 1.21 megaJoules.  For a non-chemical engine, Thrust = 2 × Power / Ve. The Dawn produces 1,000 N of thrust with an exhaust velocity of 3690s × 9.80665 m/s², so its power is 18.09 MJ/s. It uses 14.999 electrical charge / second, so one Ec = 18.09 MJ/s ÷ 14.999 Ec/s = 1.206 MJ.

On 1/27/2019 at 4:43 AM, Starman4308 said:

I'm not sure you did the math correctly... that, or you're using a mod that changes the Dawn thruster (which IIRC, Near Future Propulsion does).

The Dawn has an Isp of 4200 sec, and a thrust of 2 kN. That works out to a xenon flow of 0.0486 kg/sec. Since the propellant is exiting at (4200s*9.8063 m/sec^2), you get a kinetic energy per second of about 41 MJ. Assuming the wiki-listed value of 8.74 E/sec is correct, that means about 4.7 MJ/EC... assuming the ion engine is 100% efficient, anyways.

This conflicts horribly with several other calculations (including one of my own) that would suggest about 1-2 kJ/EC, but it's widely known that the ion engine is amazingly overpowered so that people actually use the thing.

EC has always been wonky... just like the ion engines are wonky with thrust in the kN instead of mN. Somehow running those consumes less energy than transmitting data.... *rolls eyes*

Also I think the config file somewhere defines solar irradiance... its the same values we have, about 1 kw per m^2 at earth's surface on a clear day IIRC. We can figure dimensions for the panels and how much they would produce at 100% efficiency... but the results will not agree with the engine calculations....

Anyway, the exhaust velocity of the ion engine is known: 4200*9.81 m/s= 41,202 m/s. 1 kN of force will accelerate 1 ton of material at 1 m/s. M_1 * V_1 = M_2 * V_2. 1 tons at 1 meter per second requires 1/41202 tons shot the other way at 41202 m/s. Since its 2 kN, its expelling 2/41202 tons per second

So the kinetic energy of the exhaust is equal to 1/2 m*v^2. We need 1/2 *2/41202 * (41202)^2 KiloJoules = 1/41202*(41202*41202) = 41202 KiloJoules = 41.2 MJ

Note that the mass required per second is Thrust * 1/V_e, and the energy required per second (power) is 1/2 mass * V_e*V_e, which essentially gives us Power = 1/2 V_e * T.. ie Power = T*V_e/2

The wikipedia article he quoted said: " P=T⋅Ve/2{\displaystyle P=T\cdot V_{e}/2}{\displaystyle P=T\cdot V_{e}/2} "... we're in agreement

On 1/27/2019 at 5:00 AM, MrSystems said:

First I did the math the way you did. Then, in the Wikipedia entry for Nuclear thermal rockets I saw the formula I ended up using in my post. I assumed it was more likely to be right than my initial calculations, but perhaps I was mistaken on that point.

The Wikipedia calculations, and @Starman4308's calculations are equivalent. You just used the "wrong" stats

Note, @MrSystems said "Thrust = 2 × Power / Ve"

Algebra tells us that 2 *P = T*V , and then T= 2P/V... he's right so far... But you said "The Dawn produces 1,000 N of thrust".. Nope, it produces 2KN, not 1 Kn of thrust

"with an exhaust velocity of 3690s × 9.80665 m/s" Nope, you quoted its Isp as 3690, its 4200... so 3690/4200 * 1/2 * 41.2 = .... 18.1...

Both of you did the math right, and it seems near future changes the stats

If we use the engine calculations for what one EC equals in terms of energy, and then look at what solar panels produce... kerbin should be vaporized....

 

EC is wonky for gameplay purposes

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