Why dont we use rockets to send rockets?

Shit. lol your right. Thanks for not being a dick though

This is called a multi-stage rocket, OP.

You are half a century too late with your brilliant idea.

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He still managed to figure out multi-staged space rockets without anyone helping him

Proves OP is actually a pretty smart guy imo

unfortunately even with a constant force applied to a completely solid rocket without any influence from gravitational waves run into special relativistic problems. As you get closer to the speed of light, your mass goes to infinity and the constant force eventually becomes much much less than your mass and your acceleration decreases to a very small amount so much so that it doesn't appear that you gain anymore acceleration at all.

Thanks bro
So, mass goes to infinite when aproaching the speed of light? Shit dude I didnt know that. Well that would mean that if were able to make two atoms circle eatchother at near the speed of light the gravity generated from the mass + speed could propel the atoms into light speed, or a black hole right?

>So literally any craft can achieve any acceleration as long as it can stay out of gravitational fields
It can reach any speed, yes (not any acceleration). But to do so it needs fuel. The more fuel you bring, the longer you can accelerate and the higher speeds to reach.

Unfortunately, fuel is heavy. Which means that the more fuel you bring with you, the less efficient your acceleration becomes, as you are accelerating a larger amount of material. It works out to the effect that you need more and more and more fuel to get smaller and smaller and smaller further speed boosts, and reaching speeds beyond a certain limit requires truly ridiculous amounts of fuel.

Google "the tyranny of the rocket equation" for more background on this fundamental problem.

Right. Gravity dictates weight which is how we account for propellant needed. But in space you can have all the fuel one could possibly need on one vessel withought any tangible weight. Leading me to believe that if we first put the required fuel in space, then attached it to a rocket that would then spend the fuel. That rocket now has 100%fuel and 0 weight becouse its in space. Giving the rocket the conditions to use that fuel at peak efficiency achieving any speed the rocket itself can handle. No?

omg there is alot of dump people on Veeky Forums

Not to mention the millions of kg that you have to accelerate to .9c, .8c etc.
Thatd the problem here, you have to carry the upper stages and fuel of the rocket with you from rear until the point they are used, inefficient!

ta-daa
youtube.com/watch?v=0qo78R_yYFA

But staging is different than what OP is talking about no? As far as I know staging aims to reduce the mass to reduce the energy consumption and increase max speed
What OP wants is sort of like building another catapult on a catapults projectile to double the speed
The effect would be similar because both are losing weight, but what OP wants is a rocket inside another rocket to double the propulsion

Stages are *exactly* what OP is proposing.

Multistage rocket.

Are you being sarcastic?

Because OP isn't proposing a system that gets rid of excess mass, he wants to combine two propulsions to achieve more speed, also clear with his following posts

youtube crackpot pop"scientist"

It only takes 1g for one year to accelerate any mass to relativistic speed. Please review your physics and units.

Weight (mass*gravity), which only matters on the surface of a planet or moon, has nothing to do with this. The deal is mass, and the more mass you have the more force it takes to accelerate it. Meaning you need more fuel, and more fuel means more force, and so on.

So what happens is that each amount of extra fuel you add is less efficient. Eventually you get to a point where large amount of fuel mass only gets you a tiny bit of extra speed.

>Why is this not a thing?
special relativity..

physlink.com/education/askexperts/ae169.cfm

acceleration is the result of a force, not the other way around. meaning to say knowing the acceleration required is useless if you dont relate it to a force and energy required to attain that acceleration for such a long period of time. and special relativity dictates that the energy required would be infinite. thus no object with mass can travel at the speed of light.

otherwise you are literally describing the basic principle of rockets. shoot some ignited atoms out the back and get to a high speed, then let out some more combining the first original speed with more propulsion. repeat until you're are at mars.

Then why don't they carve a rocket out of a single block of metal so it's just one piece?

Science btfo

You're kidding, right?

It's pretty obvious that he is, by that last line.

hmmm, i suppose it is. I might have been lurking too much on /b/ (too much being more than once). The line between sarcasm and frankness can get pretty blurred on these places.

You'd still need FUCKHUEG mass ratio to get anywhere near C, and that's assuming an exhaust velocity arbitrarily close to the speed of light.

Actually it's just about 0.25G, assuming constant acceleration as measured by an external observer (which technically isn't meaningful when you get close to C, but I don't feel like doing the relativity equations and it's close enough for up to 50-75% C which is already well above what we're capable of).

Real problem is that you'd need to carry a ridiculous amount of reaction mass to run the engine for that long, even at just 0.25G thrust.

So how is that diffeerent than just a rocket with multiple engines in a single stage?

Once you are moving fast enough, a simple ram scoop and cold fusion technology would supply enough energy through space dust collection to move a reasonably sized vehicle. It isn't the physics that limit FTL travel, it is tech.

Sorry, didn't mean ftl, just relativistic (0.5c+)

ah yes, "simple" cold fusion technology

was boutta say lol

The main issue with relativistic speeds is the random tiny space objects colliding with the spacecraft, also we don't really know how mass dilation and length contraction would affect humans