Map of the Verse discussion
POSTED BY: jewelstaitefan
UPDATED: Tuesday, April 30, 2024 08:33
VIEWED: 49136
PAGE 15 of 18
If I remember correctly, the Traveler RPG has these equations already simplified to a form that's easy to punch out on a calculator. Just plug in your starting numbers, and they'll spit out the result at the end.
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Quote:The closest Rocket to a glowing Firefly engine is this one:
Originally posted by ElectricLion:
As a kid, I was excited when I first learned this because that meant that every time I turned on a flashlight, I was igniting a rocket engine powered by light.
http://spaceflight.nasa.gov/shuttle/support/researching/aspl/vasimr.ht
ml
The company engineering that engine is here:
www.adastrarocket.com/aarc/VASIMR
http://en.wikipedia.org/wiki/Ad_Astra_Rocket_Company
Plasma Sensors Glowing Red Hot in Rocket Exhaust
The Joss Whedon script for Serenity, where Wash lives, is Serenity-190pages.pdf at www.mediafire.com/folder/1uwh75oa407q8/Firefly
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Quote:
Originally posted by ElectricLion:
If you want to get numbers happy on the subject, you can start with the Tsiolkovsky Rocket Equation:
Delta v = v(e) ln (m0/m1)
Delta v = change in velocity
v(e) = exhaust velocity
ln = natural logarithm function, or approx 2.718
m0 = starting mass of the ship (including fuel)
m1 = Mass of the ship after boosting (minus the fuel burned)
Simply stated, if you want to move forward at 5 miles/sec, you have to throw out a mass equal to the entire mass of your ship at 5 miles per second, or half your ship's mass at 10 miles/sec, or a quarter of your ship's mass at 20 miles/sec, and so on.
This formula defeats you claims of limited velocities. Your explanation states movement, or speed, but the formula defines acceleration, or change in velocity. So if you are at 10% Speed of Light, and you produce more thrust, not even as much as 10%, than you will continue to accelerate. Without checking to much, I can agree with this formula you provided, assuming it applies to the drive you specified. But your explanation is opposite of these facts, and there is no max acceleration other than approaching the limit of Speed of Light itself.
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Quote:
Originally posted by ElectricLion:
You do know that according to QMx, the fastest ships in the Verse are the great big Dortmunders, and they can go only 10% of light? Serenity's top speed is supposed to be somewhere around 7%. The arks from Earth made the 40 LY journey in 120 years because they were frakking hauling some gorram ass at an unheard-of 34% of light.
This sounds preposterous.
If Dortmunder is fastest at 10%, then the little speed racers or chase craft that come out of it to chase Serenity or others would immediately fall behind the mother craft, and never be able to catch back up until Dortmunder decelerated, and the little craft all would have run out of fuel and life support by the time that happened. All chase craft would be essentially discharged chaff or waste, and all pilots would be on suicide missions. Who can believe that is correct?
What canon reference do you have for this 7% and 10% data?
Firefly?
Serenity?
Official Companions (authored by Joss)?
The Verse in Numbers?
Where is the canon source?
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Your velocity isn't limited by your engine. It's limited by economics and fuel supply. IF you had an unlimited amount of time and an unlimited amount of fuel, you could accelerate up to within a small fraction of the speed of light. But you don't have either. Your engine is at its most efficient when your speed is 0. As your speed increases, the efficiency of your engine decreases. Remember Newton's law.
If your ship masses 1000 tons, and you want it to go 10 miles/second, you have to throw 1000 tons of propellant mass out the back at 10 miles/sec. Once you're at 10 miles/sec, however, your propellant mass has to be moving at greater than 10 miles/sec, or else, its more like just leaving mass in your wake. You get some speed boost but not much.. So your top speed is really limited by the speed of your propellant mass relative to your own.
I see what you're doing here. You're saying that if you have fuel, you should be accelerating. You aren't taking into consideration the mass of your propellant or the exhaust velocity. You know what? Go ahead. It's another one of those little things that if you go in too deep, you'll discover that it wouldn't work anyway.
I named my source in the very first sentence: "... according to QMx..." I never said anything about Joss, Tim, or any other document source. But those numbers are what the travel times in the "Atlas of the Verse, Vol. I" are based on.
There is a throw-away line in the Firefly pilot, "Serenity," that would seem to back this up. When Serenity runs from the Dortmunder in the beginning, and the commander is faced with catching Serenity or going to the distress signal... Remember his answer when the crew member asks if he should continue deploying the gunships: "They'd never catch us in time." This suggests that the bigger ships can really move if they need to. It also suggests that the gunships are very short range, about like a shuttle.
The gunships would only be left behind if the Dortmunder was under acceleration. If she was cruising, the gunships would start with the bigger ship's current velocity. Their smaller engines would enable them to maneuver as usual, but they wouldn't have enough power to shed the velocity imparted on them by the Dort. But, yes, if the Dort was under acceleration when she deployed her gunships, they would fall behind and not be able to catch up.
The real problem with that scene is another one of Joss' throwaway numbers that he didn't think about. The signal is supposed to be coming from a personnel carrier 13 klicks (or kilometers) ahead. But 13km in space is a naked-eye-object. The commander should have raised his head slightly, looked out the front window, and said, "Where? I don't see it."
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Quote:
Originally posted by ElectricLion:
Your velocity isn't limited by your engine. It's limited by economics and fuel supply. IF you had an unlimited amount of time and an unlimited amount of fuel, you could accelerate up to within a small fraction of the speed of light. But you don't have either. Your engine is at its most efficient when your speed is 0. As your speed increases, the efficiency of your engine decreases. Remember Newton's law.
If your ship masses 1000 tons, and you want it to go 10 miles/second, you have to throw 1000 tons of propellant mass out the back at 10 miles/sec. Once you're at 10 miles/sec, however, your propellant mass has to be moving at greater than 10 miles/sec, or else, its more like just leaving mass in your wake.
Does Newton define outside a gravity field, like Earth?
Anyway, this contradicts your previous formula. CHANGE IN VELOCITY is equal to multiplication of factors including velocity of ejecta. If you are at 10 miles/sec in a vacuum and you eject no more, are you saying you slow down? Does not ejecting at 5 miles/sec INCREASE your VELOCITY, or positively CHANGE your VELOCITY? Ejecting more propellant at 10 miles/sec should still CHANGE your VELOCITY at the same rate, otherwise the prior formula you quoted would have a starting velocity or current velocity included in the formula. It does not, from what I saw, correct?
Quote:
You get some speed boost but not much.. So your top speed is really limited by the speed of your propellant mass relative to your own.
I see what you're doing here. You're saying that if you have fuel, you should be accelerating. You aren't taking into consideration the mass of your propellant or the exhaust velocity. You know what? Go ahead. It's another one of those little things that if you go in too deep, you'll discover that it wouldn't work anyway.
I named my source in the very first sentence: "... according to QMx..." I never said anything about Joss, Tim, or any other document source. But those numbers are what the travel times in the "Atlas of the Verse, Vol. I" are based on.
There is a throw-away line in the Firefly pilot, "Serenity," that would seem to back this up. When Serenity runs from the Dortmunder in the beginning, and the commander is faced with catching Serenity or going to the distress signal... Remember his answer when the crew member asks if he should continue deploying the gunships: "They'd never catch us in time."
It's not really a throwaway line, it is critical to the plot direction. Serenity is going the opposite way, Dortmunder is going to the fake SOS signal, that's why the gunships can't go in the opposite direction at Serenity's velocity and have fuel to get back to the mothership - that was the entire point of the Crybaby. If your claim that the gunships were not as fast as the mothership, then this situation would be the case every single time, not just when an evading ship is heading away from the fake signal.
Quote:
This suggests that the bigger ships can really move if they need to. It also suggests that the gunships are very short range, about like a shuttle.
The gunships would only be left behind if the Dortmunder was under acceleration. If she was cruising, the gunships would start with the bigger ship's current velocity. Their smaller engines would enable them to maneuver as usual, but they wouldn't have enough power to shed the velocity imparted on them by the Dort. But, yes, if the Dort was under acceleration when she deployed her gunships, they would fall behind and not be able to catch up.
The real problem with that scene is another one of Joss' throwaway numbers that he didn't think about. The signal is supposed to be coming from a personnel carrier 13 klicks (or kilometers) ahead. But 13km in space is a naked-eye-object. The commander should have raised his head slightly, looked out the front window, and said, "Where? I don'tNOTIFY: Y | REPLY | REPLY WITH QUOTE | PERMALINK | TOP | HOME
I really enjoyed what you had to say, and more than that. Thank you
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JSF, if you're going to quote my emails, please quote the relevant part. Throwing my entire email up there is just wasting space.
I did not contradict my previous formula. All I said was that if you start with a big boost, you'll get a big acceleration. Any smaller boost will also increase your speed. It just won't be as much. The same rules apply whether your ship is in a gravity field, or at a speed of 0 in space. In fact, the explanations above are assuming a speed of 0 (starting) with no gravity field present. I'm just talking about the Tsiolkovsky Rocket Equation and Newton's laws, which are all very basic.
Anything you throw out the back will increase your speed. If you stand at an open rear-facing port and throw out a baseball (ala "Defying Gravity") you will get a positive change in speed. It will just be very small.
I said nothing about braking or slowing down.
The "Atlas of the Verse, Vol I" is a commercially available product:
http://store.qmxonline.com/Atlas-of-The-Verse_p_86.html
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Quote:
Originally posted by JEWELSTAITEFAN:
The claim of Serenity's top speed of 7% of Speed of Light (or 0.50Au/hr) is incompatible with canon of episode Safe.
In Safe, to get from Jaingyin to Greenleaf at top speed while Book bleeds to death, will take 10 hours.
Travel distance between these 2 planets, assuming not passing through the center of the Red Sun, is between 6.375Au and 7.312Au.
IF Serenity had instantaneous acceleration to top speed of 0.50Au/hr, then everybody here can clearly see that in 10 hours Serenity would cover 5.0 Au, which falls far short of 6.37Au - that would take at least 12.76 hours.
This claim is preposterous. Sorry.
Even if max velocity of Serenity was 10% of Speed of Light (0.72Au/hr), she would need near instantaneous acceleration to travel 6.375Au in 10 hours.
Unlikely.
Mal might be estimating about 10 hours. He could be rounding 12.76 hours down to 10. Only River would really be so exact as to call it 12.76 hours.
I don't really have anything we could use to quick-patch the Beaumonde thing though. Moving it to the other side of it's orbit is a start, but 10 hours is a pretty set in stone number. And at these speeds relativity isn't really going to shave off much time.
Could they have used a grav slingshot to increase their velocity instead of just engine acceleration? That might be a pittance compared to being able to manage multiple AU per hour just by the engines, but we really need something to bridge this gap.
Maybe the 10 hours Mal says to Beaumonde is really kinda a cruel comment/threat to Simon about kicking Simon off the ship before they get there? Sort of like in the pilot episode when he makes a similar threat that Simon "will be getting off a mite sooner" if he doesn't save Kaylee.
Or, he could just be underestimating the travel time by about half. Maybe if they had to make any stops on their way to Lilac after their meeting with Fanty and Mingo that set up the bank heist he doesn't know off hand the amount of time it'll take.
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Quote:
Originally posted by ElectricLion:
JSF, if you're going to quote my emails, please quote the relevant part. Throwing my entire email up there is just wasting space.
Sorry, I had planned to respond to more, ran out of time.
Quote:
I did not contradict my previous formula. All I said was that if you start with a big boost, you'll get a big acceleration. Any smaller boost will also increase your speed. It just won't be as much.
No, you said that the same boost would produce less acceleration, based upon your existing velocity, or that at the start of the acceleration period according to the formula you provided. The formula does not include coefficiant for starting or ending velocity.
Quote:
The same rules apply whether your ship is in a gravity field, or at a speed of 0 in space. In fact, the explanations above are assuming a speed of 0 (starting) with no gravity field present. I'm just talking about the Tsiolkovsky Rocket Equation and Newton's laws, which are all very basic.
The "Atlas of the Verse, Vol I" is a commercially available product:
http://store.qmxonline.com/Atlas-of-The-Verse_p_86.html
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