You don't seem to understand how important a 20-40X difference in specific impulse is. It's game-changing.
It may be, but it specific impulse is not a rate, so it has nothing to do with acceleration. You are confusing different factors in the parameters of engine design - efficiency to weight, weight to power, and power to efficiency. The same reasons we don't build turbine powered cars or diesel airplanes. Ion engines are efficient BECAUSE of a process that puts out small amounts of thrust over long periods.
No, I'm not confused at all. Specific impulse is "is a measure of how effectively a rocket uses propellant" (Wikipedia), and it dominates rocket design. A 20-40X change implies a completely different architecture. I have neither the time nor the inclination to explain to you the details; you'd preferably already have mastered freshman-level college physics before anyone even tries to. But the Internet is out there, "go go google search!" -- Inspector Gadget
"Effectively uses propellent" is not a rate, it is a change per mass of fuel without reference to time. You are basically saying that a car that gets 50 miles per gallon is has more thrust than one that gets 25 miles per gallon. But the 50 mpg car is the one with more specific impulse (and likely less horsepower).
I'm saying no such thing; that you think I am just shows you don't know what I'm talking about. Now stop making us BS and claiming it came from me. That's dishonest, and defamatory.
Why do YOU think specific impulse means "more acceleration", as you have used increases in specific impulse to support your idea that a high specific impulse engine could deliver high enough thrust to simulate gravity?
Seriously, I don't have time to give you the knowledge nearly a decade of higher education and three decades as an R&D engineer have imparted upon me. And that's not what these forums are for anyway. Go look it up. Read the Wiki article on Specific Impulse. Google some more and find out how it dominates and limits chemical rocket design. Then think about it, and maybe, if you have what it takes to be an engineer or scientist, all that new learning will make you realize that, yes, you might have been wrong.
I read this well before wading into a debate with you: https://en.wikipedia.org/wiki/Specific_impulse#Layman's_definition And it continues to confirm my point that specific impulse is not a rate, and can't be substituted for acceleration thrust, so a claim that a larger specific impulse is equivalent to a larger thrust is erroneous. That doesn't mean a high specific impulse engine can't be high thrust, but just that it doesn't demonstrate that newer ion engines changed their basic quality in being defined as low thrust engines. Maybe they have change, but I haven't found any reference to an ion engine putting out a significant fraction of G.
This just shows how little you understand even the basics of physics: no rocket engine "puts out" Gs. They put out thrust, and that thrust divided by the mass it acts on produces acceleration which can be measured in Gs. This is high-school physics: Newton's laws, F=MA -> A=M/F. If you don't understand it, you have no business talking about what various advance propulsion technologies can and cannot do.
No, I was merely stating that I have heard of no application of an ion engine that produces high acceleration in the complete vehicle. No need to try and play gotcha. All of this comes down to whether there is an ion engine with a very high fuel flow rate to turn a high specific impulse engine into a high thrust engine. Do you know of one?
What part of "no reason to have only one ion engine, or even only one hundred" did you not understand? You do understand that when you're running multiple rocket engines, the thrust adds up, right? I only ask because you seem to have no knowledge of physics at all.
You did read the previous comments about how adding engines adds weight, which moderates the change in thrust to mass ratio by adding mass, right? Satire: I only ask because you seem to have trouble reading.
Then why does the Falcon 9 use nine engines, and the Falcon Heavy 27? Seriously, you just don't get it. It's like you think the engine mass is a significant portion of the mass of a typical rocket. Come on man, even a person who can't read could look at the pictures and see it isn't.
I would assume the Falcon heavy uses more engines because it masses more. Are you suggesting it uses more engines to achieve greater acceleration than the Falcon 9? Engine mass isn't the that significant, unless you're counting the fuel per engine toward that mass, which has already been addressed. We are discussing engine plus fuel.
I concur. They have an inherent top speed but it’s way above chemical. I didn’t mention it because I assumed we were talking about relatively short flights to the planets. I’d expect by the time we work our way out to the stars, the whole conversation would be mute and we’d use some more advanced technology.
You really ought to take this down a notch. No one is being as rude as you are, and you really aren't addressing the comments made. So I formally withdraw "assume" because I'm certain that the Falcon Heavy is, in fact, designed to lift a much greater payload than the 9.
Eh, I'm done here. My WIP is hard SF, and I've got the science and engineering chops to pull it off. If other people want to embarrass themselves by making basic physics mistakes in their manuscripts, that's fine. Why should I correct their mistakes? I don't need more competition in my genre. Besides, this is a writing forum. People with physics questions should try www.physicsforums.com.
If you can't explain yourself in a dialogue, what makes you think you can do it when no one is asking for clarification? I'm well educated and have worked in aerospace for 12 years.
Same, but in computers. We use QM on a regular basis. I’m also a long time member at that physics forum you mentioned, they don’t allow rhetoric like that there either.
Does even a research thread need to be closed nowadays? Everyone, keep it down. Now, I know nothing about Physics, nor do I care enough about this to look it up - what I do know is I don't want a flame war on my turf. People, please speak politely to each other. If you feel you cannot do it, it is ok to be quiet and move on. I'll leave the thread open for now but if this continues, I will come back and close it!
There is already a thread on Artificial Gravity that may or may not have some information you're looking for.
