Did I get the math right for my space drive?

[Spacescifi]

 

So after considering that rockets can lift anything to orbit with enough thrust and scale, I still decided not to use them in my scifi work as it is space opera. Not necessarily war but definitely an adventure.

Rockets lack reusability, and reusuable propulsion drives are what make space opera work. A fleet of staging rockets is an alternative along with electroplasma jets for air travel, but I did'nt want to go that route either.

So I made up an almost tachyon rocket. I say almost because it is really photons, flying through a special gas medium that when ionized allows the light to travel at FTL speeds. The glass over the flashlight is specially made NOT to slow the light down to lightspeed as it passes through, but once the superluminal light passes through to the environment outside it instantly shifts back to lightspeed since the universe normally does not apparently permit FTL photons.

The end result is a reusuable spaceship drive that can run on batteries or even a nuclear reactor. Since photons already produce thrust, but if you increased their speed dramatically then their thrust I imagine would also increase. Allowing for getting to orbit.

Yet I did not want the drive to be capable of endless acceleration, so I figured a 60 minute charge that allows one to do 1g for an hour is sufficient. If one wanted to do 3g to help leave Earth for orbit that would give you a charge of 3g for 20 min, but it should'nt take that long (eight minutes about) .

And if you wanted dangerous level accelerations you could do that too, but the charge would not last as long. For example, 10g would make you exhaust your charge in only 6 min.

All these calculatons were based on the division of 60 based on the number of g's accelerated.

So what I want to know is, did I get the math right? It is important because I need to know how much charge the ship has at any given time so I know what the ship can and cannot do.

 

Thanks also for previous answers.

Edited May 17, 2019 by Spacescifi
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[Bill Phil]

I think the math is alright.

Mostly.

Thrust is a change in momentum over a change in time. Momentum, unlike velocity, has no upper limit, even for photons. However providing large amounts of thrust is difficult.

A photon drive for example needs about 300 megawatts per Newton, or about 3 gigawatts to apply 1g to 1 kilogram.

Yikes.

3 gigawatts is similar to a massive powerplant’s output and that only gets you 1 kg at 1g. The actual powerplant will easily be in the many thousands of kilograms.

That said injecting other things into the light beam might give an afterburner effect, increasing thrust at the expense of efficiency. Doing this to lift off planets and then lowering the amount of propellant injected can be a good strategy. Like shifting gears for cars.

[Spacescifi]

35 minutes ago, Bill Phil said:

I think the math is alright.

Mostly.

Thrust is a change in momentum over a change in time. Momentum, unlike velocity, has no upper limit, even for photons. However providing large amounts of thrust is difficult.

A photon drive for example needs about 300 megawatts per Newton, or about 3 gigawatts to apply 1g to 1 kilogram.

Yikes.

3 gigawatts is similar to a massive powerplant’s output and that only gets you 1 kg at 1g. The actual powerplant will easily be in the many thousands of kilograms.

That said injecting other things into the light beam might give an afterburner effect, increasing thrust at the expense of efficiency. Doing this to lift off planets and then lowering the amount of propellant injected can be a good strategy. Like shifting gears for cars.

 

Well... I assumed one would not require power plant amounts of power since the special (fictional) gas medium makes light go FTL so long it is ionized. The only power imput from the ship involves ionizing the gas itself.

Unless I arbitraily require vast amounts of energy to ionize this fictional gas, it should not require a lot of power to provide thrust.

About the only bonus for using massive power loads to ionize the gas is that now your drive emits visible white rays like the sun in when in atmosphere. Looks awesome although blinding.

Yet if lower power levels produce high thrust as I think they would, the flashlight drive simply has a white glow that obscures the reflector inside.

 

On the other hand, I do find your inject propellant idea intriguing. I would have to adjust the physics to allow FTL light beams outside the nozzle, but the visual and sound effects would be awe inspiring.

I would make the beam itself just look like an EPIC sun ray flashlight, blowing lots of air but not actually propelling the ship UNTIL, one injects propellant. Which could be accelerated at at sublight but still arbtrarily high velocities.

This a new limitation comes into plat with launching. If your ship is too massive, you WILL obliterate tour launch site. If you do not want that to happen, scale your ship size down.

 

For that matter, make massive vessels modular so can land them in pieces and launch them piece by piece as well like Ironman armour. Since orbital assembly would easy, especially with this drive.

Edited May 17, 2019 by Spacescifi
Pucture