|
|
|
bigbrain
BANNED
409 Posts |
 Posted - 08/10/2005 : 14:06:50 [Permalink]
|
quote:
Originally posted by Valiant Dancer
quote:
Originally posted by bigbrain
"The probe does not go faster than that"
Than that????? How much?
Than the figures linked to by STS60 and referenced by Dave W.
Stop being deliberately obtuse.
A probe could go at any velocity  |
"Obsequium amicos, veritas odium parit" (Flattery gets friends, truth hatred)
Publius Terentius Afer, "Terence", Roman dramatist
|
 |
|
|
sts60
Skeptic Friend
141 Posts |
Posted - 08/10/2005 : 14:09:41 [Permalink]
|
Oh, what the heck. I said I wouldn't. But I'm feeling playful.
Since yoy can't refute my statement, you then offend me: "I've seen mental patients with a better grasp of reality"
No, you haven't grasped why I made that characterization.
It wasn't because I can't refute your statements - I have, with supporting details.
It wasn't because I'm looking for ways to offend you - though the word you're looking for is "insult", and I wasn't really trying to do that either.
The reason I said that was simply because I really have seen mental patients with a better grasp of reality than you.
Since I'm European you offend me again: " 3-year-olds with better conversational skills"
I don't care where you're from: Europe, China, Chile, or Springfield, Illinois as you falsely claimed over on the space.com forum. It's immaterial to me.
The reason I said that was because I know a 3-year old boy who has better conversational skills than you do, even allowing that English is not your native language.
Since you speak like a professor, you think to be superior "and U.S. Congressmen with less ignorance of simple physics. I am not exaggerating"
Your syntax is mangled, but more importantly both your premise and conclusion are wrong. I don't speak like a professor; I use plain English as much as possible. Nor do I think I'm "superior" except that I know something about this, and you do not.
I also know that despite the generally (and sometimes spectacularly) poor understanding of basic physics among elected officials, there are Congressmen out there who are much less ignorant than you. That's why I said that part.
Dear professor (who knows, does; who doesn't know, teaches)
I'm not a professor. I am a practicing engineer, with actual space flight program experience. I get paid for what I know and for what I do.
Sometimes I try to teach, informally in fora like this. But "teaching" presumes someone else with the ability and willingness to learn. You have demonstrated neither.
This is a biggest stupidity because to go to Saturn you must travel to the OUTER solar system.
Not if you need to get there faster than your launch vehicle can do by itself. The entire point of going inwards is to gain velocity relative to the Sun by "slingshot" maneuvers around Venus (twice) and Earth (once). Everybody else seems to grasp this concept.
Only an idiot could decrease velocity of the probe.
No, thrusting against your velocity vector will do it quite nicely. It's really quite simple. Anybody who has ever been a passenger on a jet aircraft has seen and felt this when the thrust reversers come on.
Or perhaps you meant "would decrease..." In that case, you have it backwards: only an idiot would not decrease the heliocentric speed to take advantage of the gravity assist option.
sts60, you can only do involved reasonings to confuse people.
No. I've taken care to be as straightforward as possible. However, you can only simplify a problem so far before you get it all wrong - which you continue to do. Things simply don't move in a straight line around the Sun. Period. Planets, asteroids, comets, coasting spacecraft - all move in elliptical orbits. Kepler worked this out centuries ago, and today billions of dollars of communication and sensing satellite business is done every year based on these principles.
Your probe runs at 101,000 miles per hour
Wrong, but the number isn't so important as your basic misunderstandings.
and you decrease its velocity and then you pass near Venus for 2 times
And Earth once.
to increase velocity.
Correct - relative to the Sun.
You reason like NASA engineers. Do you work for NASA?
I'll take that as a compliment. No, I don't work for NASA. |
|
|
|
bigbrain
BANNED
409 Posts |
Posted - 08/10/2005 : 14:13:08 [Permalink]
|
quote:
Originally posted by pleco
quote:
Originally posted by bigbrain
"Cassini experienced a force of about 33 Newtons towards the Sun while still in the vicinity of Earth".
Do you know how many kilograms are 33 Newtons?
approx 3.366 kg
33 x 98 grams = 3234 grams = 3.234 kilograms
What can 3 kilograms cause to a probe going at 59,250 or 80,000 or 101,000 miles per hour? |
"Obsequium amicos, veritas odium parit" (Flattery gets friends, truth hatred)
Publius Terentius Afer, "Terence", Roman dramatist
|
|
|
|
sts60
Skeptic Friend
141 Posts |
Posted - 08/10/2005 : 14:17:17 [Permalink]
|
quote:
Originally posted by bigbrain
quote:
Originally posted by sts60
quote:
Nasa engineers don't consider Earth's velocity in their calculations
From the Cassini Alternate Mission and Power Study (JPL 1994), section A.1, Trajectory and Propulsion Background Information:
The spacecraft's velocity with respect to the Sun, if found by vector addition: the Earth's velocity with respect to the Sun is added to the spacecraft's asymptotic, hyperbolic departure velocity with respect to the Earth. For transfers to the outer solar system, the net effect of the Earth departure hyperbola is to increase the spacecraft's velocity with respect to the Sun above the value corresponding to the Earth's velocity. This requires that [the hyperbolic excess velocity] be pointed in the same general direction as the Earth's velocity vector. For transfers to the inner solar system, however, the spacecraft's velocity must be decreased, requiring [the hyperbolic excess velocity] to be opposed to the Earth's velocity.
<snip>
How many of you have understood anything?
It's really quite simple. You claimed NASA engineers don't take Earth's velocity into account. I provided explicit examples of NASA (and contractor) engineers taking Earth's velocity into account in mission planning, in particular for the Cassini mission. It can't get any more plain than that.
quote:
sts60 speaks like a professor and like many professors doesn't teach.
As a full-time engineer, it is true that I don't spend much time teaching. |
| Edited by - sts60 on 08/10/2005 14:24:12 |
|
|
|
sts60
Skeptic Friend
141 Posts |
Posted - 08/10/2005 : 14:22:46 [Permalink]
|
Do you know how many kilograms are 33 Newtons?
Kilograms are units of mass. Newtons are units of force. Your question, as any grade-school physics student could tell you, makes no sense. |
|
|
|
bigbrain
BANNED
409 Posts |
Posted - 08/10/2005 : 14:25:23 [Permalink]
|
Dear friend sts60
What can 3 kilograms cause to a probe going at 59,250 or 80,000 or 101,000 miles per hour? |
"Obsequium amicos, veritas odium parit" (Flattery gets friends, truth hatred)
Publius Terentius Afer, "Terence", Roman dramatist
|
|
|
|
bigbrain
BANNED
409 Posts |
Posted - 08/10/2005 : 14:31:46 [Permalink]
|
"Do you know how many kilograms are 33 Newtons?
Kilograms are units of mass. Newtons are units of force. Your question, as any grade-school physics student could tell you, makes no sense".
It makes practical sense: it would be as if the probe had 3 kilograms of weight (sun's gravity force) in direction of the sun (nothing practically)
|
"Obsequium amicos, veritas odium parit" (Flattery gets friends, truth hatred)
Publius Terentius Afer, "Terence", Roman dramatist
|
| Edited by - bigbrain on 08/10/2005 14:35:14 |
|
|
|
GeeMack
SFN Regular
USA
1093 Posts |
Posted - 08/10/2005 : 14:38:03 [Permalink]
|
quote:
Originally posted by bigbrain...
Do you know how many kilograms are 33 Newtons?
2 Newtons = 57 grams...
57 grams / 2 = 28.5 grams per Newton...
28.5 grams * 33 = 940.5 grams or 0.9405 kilograms...
So, 33 Newtons = 0.9405 kilograms, and pass the milk, please.
|
|
|
|
bigbrain
BANNED
409 Posts |
Posted - 08/10/2005 : 14:44:24 [Permalink]
|
sts60 wrote:
"... It's really quite simple. You claimed NASA engineers don't take Earth's velocity into account. I provided explicit examples of NASA (and contractor) engineers taking Earth's velocity into account in mission planning, in particular for the Cassini mission ..."
It's not quite simple.
NASA engineers don't take Earth's velocity into account.
NASA engineers are only buffoons who write, write and write but do only craps, craps and craps.
|
"Obsequium amicos, veritas odium parit" (Flattery gets friends, truth hatred)
Publius Terentius Afer, "Terence", Roman dramatist
|
|
|
|
bigbrain
BANNED
409 Posts |
Posted - 08/10/2005 : 14:48:11 [Permalink]
|
Dear GeeMack
children must sleep at this time.
1 Newton = about 98 grams
Excuse me, I didn't click on "2 Newtons = 57 grams"
I like humour |
"Obsequium amicos, veritas odium parit" (Flattery gets friends, truth hatred)
Publius Terentius Afer, "Terence", Roman dramatist
|
| Edited by - bigbrain on 08/10/2005 14:53:52 |
|
|
|
Siberia
SFN Addict
Brazil
2322 Posts |
Posted - 08/10/2005 : 15:32:30 [Permalink]
|
quote:
Originally posted by bigbrain
NASA engineers are only buffoons who write, write and write but do only craps, craps and craps.
But they do that better than you, no doubt, as they can get probes to Saturn, Mars and men on the Moon much better than you can. |
"Why are you afraid of something you're not even sure exists?"
- The Kovenant, Via Negativa
"People who don't like their beliefs being laughed at shouldn't have such funny beliefs."
-- unknown
|
|
|
|
Dave W.
Info Junkie
USA
26022 Posts |
Posted - 08/10/2005 : 16:19:14 [Permalink]
|
quote:
Originally posted by bigbrain
Do you know how many kilograms are 33 Newtons?
Doesn't matter. The important thing is that you take the 33 Newton force, divide by the 5,655-kg mass of Cassini, and find that Cassini, at the start of its trip, got pulled toward the Sun at 0.006 m/s2. A large acceleration? Of course not. But as the craft passed a million miles, after just 10 hours, you'll find that it's sunward velocity is already over 200 m/s. The craft curves away from your straight-line tragectory. After I finish plugging the numbers into my simulator, I suspect it'll curve right into the Sun, never getting close enough to Saturn to be captured by its gravity.
Speaking of which... Any math geeks want to help me solve for d in the equation c=d2/(1-d)2? I seem to have forgotten how to do so. Of course, 10th grade was so very long ago... |
- Dave W. (Private Msg, EMail)
Evidently, I rock!
Why not question something for a change?
Visit Dave's Psoriasis Info, too. |
|
|
|
ktesibios
SFN Regular
USA
505 Posts |
Posted - 08/10/2005 : 16:19:41 [Permalink]
|
quote:
Originally posted by filthy
It is what I love about these folks; they bring forth some really excellent info. And some rather silly shit, as well..... A little earlier, I successfully balanced a full can of beer (Coke is not allowed in my house) on the tip of my finger just to see if it could be done. Whaddya know; it can.
Yeah, but how'd it work after you drank the beer?
Actually, the balancing a beer can, or a funnel or a yardstick on your finger- or any of bigbrain's analogies is irrelevant to the stability of the LM or any other rocket.
When you balance the beer can, it and your finger are in two different reference frames which can move independently of each other. This is not the case for a rocket- the engine and the rest of the craft are in a single frame of reference. The rocket can't topple off its thrust like a dictator's statue from its pedestal.
If the direction of the engine's thrust lies on the line joining the engine's center of thrust with the spacecraft's center of mass, firing the engine will produce motion only in translation. If the thrust vector is cockeyed- say, because the engine nozzle isn't aligned just right, it will produce some motion in rotation- the craft will start to rotate around its center of mass at a rate which increases as long as the engine is firing.
If you plow through this Apollohoax thread you'll find better explanations of how this works and how the LM engine location, mass distribution and RCS thruster location were arranged to minimize unwanted roll rates and maximize the control systems' ability to cancel them than I can give. There's also one of JayUtah's troll-buster example problems to try your understanding on. The answers are given on a later page, like your old school math textbooks, so you can have some fun working out the problem and then check your answer and your work. It's all so lucidly presented that I was able to grasp it all using only the math and physics knowledge that you expect a competetent electronics technician to have.
As far as the Newtons/kilograms thing goes, the only way bigbrain's question makes any sense is if we read it "what is the mass on which Earth-normal gravity will exert a force of 3 Newtons?".
Okay, one Newton is the force which acting on a mass of 1 kg will accelerate it at a rate of 1 m/s^2. The acceleration of Earth-normal gravity is approximately 9.8 m/s^2, so I get 3 kg*m/s^2 / 9.8 m/s^2 = 0.306 kg.
306 grams.
Of course, as sts60 pointed out, units of mass and units of force are not the same thing. There's a guy called Interdimensional Warrior who hangs out at the GLP forum who a few months ago put on a pages-long performance of insisting on not getting the distinction and basing lots of comically wrong "calculations" on that very mistake.
That sort of willful confusion seems to be kind of endemic in the antiscience crank population.  |
"The Republican agenda is to turn the United States into a third-world shithole." -P.Z.Myers |
|
|
|
Dry_vby
Skeptic Friend
Australia
249 Posts |
Posted - 08/10/2005 : 16:55:13 [Permalink]
|
I don't think Brainbox is anti-science so much as anti-NASA.
He's got a bug up his patootie about something (perhaps people not thinking that he is intelligent) and he's decided to make NASA the target of his vitriol.
From this base of churning resentment he dredges up ridiculous pseudo-bigbrain bargain bin science in order to find one person who might agree with whatever the hell he's shrieking about.
Alas, he and he alone, has been able to put all the peices together and now he is here to save us from ourselves.
But, before we go into any further detail, could you explain why? |
"I'll go along with the charade
Until I can think my way out.
I know it was all a big joke
Whatever it was about."
Bob Dylan
|
|
|
|
Stargirl
Skeptic Friend
USA
94 Posts |
Posted - 08/10/2005 : 17:04:05 [Permalink]
|
I don't have much to add other than bigbrains opening post reminded me of and old 1950's sci-fi movie, (sorry I don't remember the title).
In the movie a spaceship is launched and the crew looses all radio communications and when they land they find they're in the future. It's a bleak future where I think aliens or robots or something are taking over the earth. Naturally it's imperative that the crew return to the present, (1950's) to warn the people of earth about the impending peril. The question is how do they get back? One of the few remaining humans in the future is a brilliant scientist, (isn't there always a surviving scientific genius) and figures out that the crew can get back the same way they traveled to the future. All you have to do is travel faster than light and you can travel through time. Of course anyone who has ever watched Star Trek knows that. But how does the scientist figure out a way for the 1950's pre-warp drive technology spaceship to travel faster than light? It's simple you use bigbrains technique of adding the velocity of earths rotation on its axis and the earths orbital velocity around the Sun, and the Suns orbital velocity around the galaxy and the galaxies velocity through space, etc., etc. As it turns out in the movie the spaceship only has to reach a ridiculously low relative velocity once it escapes earth's atmosphere and voila they're moving faster than light and traveling through time.
It's a pity space flight isn't as simple as bigbrain and the movie would like to make it appear because it would give us an easy way to explore not just the solar system but the entire universe.
|
If God did not exist, it would be necessary to invent him - Voltaire |
|
|
 |
|
|
|
Topic Locked
