Ideas that you get when you're in the shower/in bed

[tutrakan4e]

Those are the ideas about life and the universe that you get when you're in the shower and you forget to shower because you're thinking about them. Mine are all about spaceflight. For example: Let's say you have an infinetly accurate fuel pump. You have a simple liquid fuel rocket with one capsule, a fuel tank and an engine (like those starter rockets in KSP carreer). The fuel tank is 100% full and you start the engine at 99.9(9)% thrust. When the fuel goes down to 99.9% you throttle down to 99.8(9) percent thrust. When the fuel gets to 50% you have throttled down to 49.9(9)% trust. So when the fuel gets to 0.0000001 you have throttled to 0.0000000(9) % thrust. Does that mean you can burn forever? But I recently realised that you'll get as far as you would get at 100% constant trust. But maybe if the capsule, engine and fuel tank had no mass, but the fuel did have mass, the rocket would go forever... ? What do you think? Would the rocket go forever if it had 0 mass? What are your bedtime/shower ideas?

(I'm sorry if there are other posts like this one)

[falofonos]

http://en.wikipedia.org/wiki/Zeno%27s_paradoxes#Achilles_and_the_tortoise

[Ralathon]

Those are the ideas about life and the universe that you get when you're in the shower and you forget to shower because you're thinking about them. Mine are all about spaceflight. For example: Let's say you have an infinetly accurate fuel pump. You have a simple liquid fuel rocket with one capsule, a fuel tank and an engine (like those starter rockets in KSP carreer). The fuel tank is 100% full and you start the engine at 99.9(9)% thrust. When the fuel goes down to 99.9% you throttle down to 99.8(9) percent thrust. When the fuel gets to 50% you have throttled down to 49.9(9)% trust. So when the fuel gets to 0.0000001 you have throttled to 0.0000000(9) % thrust. Does that mean you can burn forever? But I recently realised that you'll get as far as you would get at 100% constant trust. But maybe if the capsule, engine and fuel tank had no mass, but the fuel did have mass, the rocket would go forever... ? What do you think? Would the rocket go forever if it had 0 mass? What are your bedtime/shower ideas?

(I'm sorry if there are other posts like this one)

This is simply Zeno's paradox. If the fuel was infinitely divisible and you scaled your thrust correctly you could keep burning forever. But in real life fuel is made out of atoms, and you can't burn half an atom. So you'll flame out at some point. In either case your dV stays the exact same, so you can't use this to get anywhere that you otherwise couldn't.

If your capsule, fuel tank and engine where weightless you would indeed have infinite delta V. Look at the rocket equation:

dV = Isp * g * ln(m(full)/m(empty))

If your empty mass goes to zero the equation tends to infinite. This is why weight is so terribly important for spacecraft, saving a few kg of can give you a lot of dV margin.

[Doozler]

Does that mean you can burn forever? But I recently realised that you'll get as far as you would get at 100% constant trust.

Yup, Zeno.

You can keep burning for ever in the same sense that you can keep eating a cake for ever if you eat half, then 1/4, then 1/8.... but at the end of the day you only get to eat one cake (i.e. use one rocket's worth of dV)

[basbr]

hi,

i am a student electrical engineering and the other day i had a idea when i lay in bed.

as a hobby i work with 3D printers, reprap printers to be exact. what if you integrate a pick and place machine with the printer.

for the people that don't know, a pick and place machine assembles circuit board. if you make a 3D printer that could integrate electrical components and connect them using some sort of metal (soder) filament, it could make 3 dimensional circuit board or product with electronics in its casing.

wel thats my idea. dos any one know if i am the first?

-basbr

Edited April 17, 2014 by basbr

[Yoha]

hi,

i am a student electrical engineering and the other day i had a idea when i lay in bed.

as a hobby i work with 3D printers, reprap printers to be exact. what if you integrate a pick and place machine with the printer.

for the people that don't know, a pick and place machine assembles circuit board. if you make a 3D printer that could integrate electrical components and connect them using some sort of metal (soder) filament, it could make 3 dimensional circuit board or product with electronics in its casing.

wel thats my idea. dos any one know if i am the first?

-basbr

https://www.kickstarter.com/projects/cartesianco/the-ex1-rapid-3d-printing-of-circuit-boards

[Ralathon]

https://www.kickstarter.com/projects/cartesianco/the-ex1-rapid-3d-printing-of-circuit-boards

Not fully his idea though. This just makes the circuit board, you still have to manually add the actual components.

While it would be really cool if we managed to build something that also builds the components, I wonder how you'll ever get it versatile enough. The big appeal behind a 3D printer is that you can print practically everything. But for electrical components you're limited to the supplies of the machine. You can't make a transistor out of the same stuff as a DC motor after all.

[Yoha]

Not fully his idea though. This just makes the circuit board, you still have to manually add the actual components.

While it would be really cool if we managed to build something that also builds the components, I wonder how you'll ever get it versatile enough. The big appeal behind a 3D printer is that you can print practically everything. But for electrical components you're limited to the supplies of the machine. You can't make a transistor out of the same stuff as a DC motor after all.

Well, that's basically already, what we do. Only the components are no casing at all, burned into silicon and put into a casing for simpler handling. The ony problem though is that we need a perfectly clean process due to the size of the circuit. Maybe going mesoscopic, we could do home-made big integrated circuits.

[basbr]

most components cant be 3D printed because they are to complex. however you could use a metal with a given resistance, and by making the track wider or smaller you could alter the resistance. all other components have to be pre made.

[andrewas]

hi,

i am a student electrical engineering and the other day i had a idea when i lay in bed.

as a hobby i work with 3D printers, reprap printers to be exact. what if you integrate a pick and place machine with the printer.

for the people that don't know, a pick and place machine assembles circuit board. if you make a 3D printer that could integrate electrical components and connect them using some sort of metal (soder) filament, it could make 3 dimensional circuit board or product with electronics in its casing.

wel thats my idea. dos any one know if i am the first?

-basbr

Adrian Bowyer got there first. http://www.newscientist.com/article/dn7165-3d-printer-to-churn-out-copies-of-itself.html#.U1Ecx1d5fyA

[R0cketC0der]

Those are the ideas about life and the universe that you get when you're in the shower and you forget to shower because you're thinking about them. Mine are all about spaceflight. For example: Let's say you have an infinetly accurate fuel pump. You have a simple liquid fuel rocket with one capsule, a fuel tank and an engine (like those starter rockets in KSP carreer). The fuel tank is 100% full and you start the engine at 99.9(9)% thrust. When the fuel goes down to 99.9% you throttle down to 99.8(9) percent thrust. When the fuel gets to 50% you have throttled down to 49.9(9)% trust. So when the fuel gets to 0.0000001 you have throttled to 0.0000000(9) % thrust. Does that mean you can burn forever? But I recently realised that you'll get as far as you would get at 100% constant trust. But maybe if the capsule, engine and fuel tank had no mass, but the fuel did have mass, the rocket would go forever... ? What do you think? Would the rocket go forever if it had 0 mass? What are your bedtime/shower ideas?

(I'm sorry if there are other posts like this one)

If something is completely massless, it is already moving at the speed of light without any energy added to it. This is why photons are moving at the speed of light.

[X10Z]

Deploying military cargo such as tanks or planes from orbit.