Some rather funny power prod. calcs for a Galaxy-class

CmdrWilkens · Post by **CmdrWilkens** » 2003-11-12 10:30pm

Sea Skimmer wrote:
Ender wrote:I know the engine limits for those kind of plants, so lets just say I disagree.
The Navy says Enterprise can make 33.6 knots. I'm not seeing much reason for them to lie about a forty year old ship when there was nothing compelling them to reveal the information in the first place.

Lets just say this is the same government that is only now declassifying documents from 50 years ago.

Iceberg · Post by **Iceberg** » 2003-11-12 10:33pm

Where does the Navy state the Enterprise's top speed? Because here they just say that her top speed is "30+" knots.

Post by **Sea Skimmer** » 2003-11-12 11:04pm

It was in a press release in June of 1999. I'll see if anyone has a copy about. They also gave the speeds of other nuclear carriers.

Enterprise 33.6 knots after last refit
Nimitz 31.5 knots
Theodore Roosevelt 31.3 knots
Harry S Truman 30.9 knots

I don't know why there own website doesn't, but just looking around it looks like they just put 30+ knots for every major warship. It may be it simply wasn't updated, the site was put up well before the speeds where released.

Ender · Post by **Ender** » 2003-11-12 11:21pm

Sea Skimmer wrote:
Ender wrote:So you question me... only to say I am correct.
Nope.

Ender:It's underpowered
Sea Skimmer: It's not underpowered, it just can't produce sufficient steam to provide sufficient electricity

Yeah, looks the same to me.

That would not happen.
The piping and engines being destroyed by being over worked or propellers cavitating from spinning too fast? The former has happened before, and the latter is inevitable with any propeller design, and at 280,000hp every shaft is already at the limit of current propeller designs.

The Former; I've read the incident reports and know about the changes made as a result. It should no longer be an issue.

[quote\I know the engine limits for those kind of plants, so lets just say I disagree.

The Navy says Enterprise can make 33.6 knots. I'm not seeing much reason for them to lie about a forty year old ship when there was nothing compelling them to reveal the information in the first place.[/quote]The tech manuals I've trained off for the past 2 years say differently.

Rightous Fist Of Heaven · Post by **Rightous Fist Of Heaven** » 2003-11-13 09:00am

Darth Wong wrote:I like the way idiots of his ilk think that all mathematically correct "calcs" have pretty much the same validity, regardless of how one came up with the numbers to plug into those calcs.

Exactly. Virus-X uses the same principle, even tough he can make mathematically correct calculations, the premise for those calculations is allways horrendously fucked up.

Post by **NecronLord** » 2003-11-13 10:07am

Isolder74 wrote:On that note since a star destroyer can slag a planet(BDZ) it has to have similer power generation capability. Remember V'Ger as big as it was, its weapons could only carterize the surface of planet Earth. V'Ger could not do the death Star Thing. If we want to play semantics games then we can say that V'ger is only as powerfull as Star Destroyer and as such a Star Destroyer can produce power level equal to V'Ger!

Vejur was using anti-'carbon unit' weapons there, it wouldn't want to destroy its creator after all. The novel has it totally 'patterning' a planet, make of which what you will.

Just out of curiosity, are there any errors in calculation of the rotational energy itself? (Other than our friend assuming that it would happen instantaneously, instead of over hours or days, which I'd say would be more likely.)

The Dude · Post by **The Dude** » 2003-11-13 10:55am

NecronLord wrote:Just out of curiosity, are there any errors in calculation of the rotational energy itself? (Other than our friend assuming that it would happen instantaneously, instead of over hours or days, which I'd say would be more likely.)

You mean, other than the fact that he took a negative energy change (a rotating body has MORE energy than a still one) and used that as an energy requirement?

That's roughly analagous to saying that burning a litre of gasoline requires 36MJ of energy because the net change in potential energy is -36MJ.

Aside from that, his equations are wrong: the rotational kinetic energy of a sphere is E = 0.5 * I * w^2, where I is the moment of inertia and w is the angular velocity. Any competent analyst would immediately recognize his energy equation is fucked; the units it produces are wrong (J =/= kgm^2/s!!!). Furthermore, the moment of inertia of a sphere about a central axis is 0.4*m*R^2, not mR^2.

So the real answer is:

I = 0.4 * (1.99e30kg) * (6.95e8m)^2 = 3.83e47 kg.m^2

The sun rotates about once every 28 days, so w = 2.60e-6 rad/s

Therefore, E = 1.29e36J.

In other words, the fucktard got the answer wrong by over FIVE orders of magnitude (in the wrong units), and then quoted his answer to NINE significant figures.

In summary:
1) he got at least two equations wrong
2) his answer is a 300,000X overestimate, in the wrong units
3) decreasing the rotational energy of the sun will release energy, not require it.

The Dude · Post by **The Dude** » 2003-11-13 10:58am

PS Feel free to quote this verbatim at the other board, if you wish.

Isolder74 · Post by **Isolder74** » 2003-11-13 11:12am

I noticed that myself. Bravo to you for actually taking the time to do the calculations. And for those who don't know significant digits is how accutate you data is and as such how accurate your answer has to be in order to be correct. AKa you can't magically get better information than you started with

Rightous Fist Of Heaven · Post by **Rightous Fist Of Heaven** » 2003-11-13 11:49am

The Dude wrote:PS Feel free to quote this verbatim at the other board, if you wish.

I was just thinking of doing that. Not only is his basis information for the calculation fucked up, but so is the actual calculation, ahh this will be good.

Thanks.

The Dude · Post by **The Dude** » 2003-11-13 12:13pm

Keep in mind that summary point #3 is the most important. No matter how large a value one calculates, it still represents a negative change in potential energy.

Post by **NecronLord** » 2003-11-13 12:26pm

The Dude wrote: 3) decreasing the rotational energy of the sun will release energy, not require it.

Humm. Given the context of the quote from TMP, I imagine the idea to be stopping it rotating by applying an opposite force rather than just removing KE from the star itself...

Darth Servo · Post by **Darth Servo** » 2003-11-13 12:36pm

NecronLord wrote:Humm. Given the context of the quote from TMP, I imagine the idea to be stopping it rotating by applying an opposite force rather than just removing KE from the star itself...

Of course applying a force doesn't necessarily require any energy.

Considering that in another thread over there, Tulkas says he thinks a three way between Leia and 7 of 9 is "Ga-ROSS" he can't have hit puberty yet.

The Dude · Post by **The Dude** » 2003-11-13 12:37pm

NecronLord wrote:Humm. Given the context of the quote from TMP, I imagine the idea to be stopping it rotating by applying an opposite force rather than just removing KE from the star itself...

Applying a force in the direction opposite to motion produces a negative work term. In other words, applying an opposite force is equivalent to removing KE from the star.

ClaysGhost · Post by **ClaysGhost** » 2003-11-13 12:43pm

The Dude wrote: Furthermore, the moment of inertia of a sphere about a central axis is 0.4*m*R^2, not mR^2.

0.6*m*R^2, surely (I think 0.4 is for a bar or rod). Not that it would matter, since the Sun is not a rigid body of uniform density anyway.

The Dude · Post by **The Dude** » 2003-11-13 01:04pm

ClaysGhost wrote:0.6*m*R^2, surely (I think 0.4 is for a bar or rod). Not that it would matter, since the Sun is not a rigid body of uniform density anyway.

Cylinders are 0.5; spheres are 0.4. The value is determined by integrating r^2 dm.

You're right that this would not apply precisely to the sun, but since its density will vary inversely with radius, the coefficient will be even lower than 0.4.

Post by **NecronLord** » 2003-11-13 01:15pm

The Dude wrote:Applying a force in the direction opposite to motion produces a negative work term. In other words, applying an opposite force is equivalent to removing KE from the star.

Indeed, but Vejur would still have to provide KE equivalent to the KE the star has in order to decellerate it to a stop, and thus be capable of generating that amount, correct?

Post by **NecronLord** » 2003-11-13 01:18pm

Darth Servo wrote:Of course applying a force doesn't necessarily require any energy.

I imagine that it probably does in this sense, given that it's referring to the power of an energy field having sufficient energy to do so.

The Dude · Post by **The Dude** » 2003-11-13 01:35pm

NecronLord wrote:Indeed, but Vejur would still have to provide KE equivalent to the KE the star has, and thus be capable of generating that amount correct?

Nope. The initial KE of the system is itself a source of energy. For example, stopping a moving car requires force, not energy. The initial KE of the vehicle is manifested in heating and deformation of the brake pads. Its momentum is transferred to the Earth via the friction force between the tires and road.

The V'ger example tells us that its force field can probably project immense forces, but tells us nothing about its power generation capabilities, since the act of stopping a star's rotation requires no energy (quite the opposite - it requires some mechanism for dissipating all of that excess energy).

Post by **NecronLord** » 2003-11-13 01:43pm

Ah, hang on, I've thought of an (insane) mechanism where the energy of a shield (which is what is being talked about) could be used to do that without applying a counterforce to the star.

Transfer the momentum into the ship via a gigantic tractor beam type affair, and then engage the warp drive and technobabble it away...

(Not an entirely serious suggestion... but still.)

Sothis · Post by **Sothis** » 2003-11-13 03:36pm

Tulkas... urgh, he's an idiot. I've only read a few of his posts and already I feel ashamed to be a Trekkie.

Rightous Fist Of Heaven · Post by **Rightous Fist Of Heaven** » 2003-11-13 04:18pm

Not to mention his friend Kayedog1, he is also quite funny.

darthdavid · Post by **darthdavid** » 2003-11-13 05:12pm

tsk tsk tsk. Sooooo much stupid in one place.

Master of Ossus · Post by **Master of Ossus** » 2003-11-13 05:20pm

Gah! What's up with this latest guy who can't even spell? Jesus. I have to be able to read your "arguments" before I can even begin to figure out whether or not they make sense. Even with generally poor spellers I can usually at least discern what the heck they're TRYING to say, but this guy.... ugh.

Rightous Fist Of Heaven · Post by **Rightous Fist Of Heaven** » 2003-11-13 05:37pm

Master of Ossus wrote:Gah! What's up with this latest guy who can't even spell? Jesus. I have to be able to read your "arguments" before I can even begin to figure out whether or not they make sense. Even with generally poor spellers I can usually at least discern what the heck they're TRYING to say, but this guy.... ugh.

You mean warsie killer? Yep, over half the time i read his stuff i cant make out heads or tails what he is trying to say.