Water verses O2 and H2

I did some calculations based on atomic weight to figure out what would be smaller several years ago, one cubic foot of water @78 degrees/sea level or the same mass stored as O2 and H2.


The answer I came up with was water could be stored in a smaller space. I got this result from taking the mass of one cubic foot of H2 and one cubic foot of O2 calculating how much of each I would need to make H2O and ran out of hydrogen before I filled the water tank.


If anyone has a different answer please let me know and thank you.

If you could beam power, you could do direct thermolysis on a fine atomized mist, entering a rocket cone, and explode it, while mixing in incoming air to expand...

that would be nice....

I always liked the idea of a "power beam" so that you could have far less weight.

Makes perfect sense to me. The volume of a gas obviously depends on the pressure as well as the amount, so let's assume that the H2 and O2 are stored in liquid form. Liquid H2 has a density of about 0.07 g/cm3, liquid O2 1.141 g/cm3, and water 1 g/cm3. Invert those and you'll find that you need 14 cm3/g for liquid H2, 0.88 cm3/g for liquid O2, and 1 cm3/g for liquid water.

So, if you don't want the H2, then storing liquid O2 takes less volume than an equivalent mass of water (and you would need to store more grams of water than O2 to have the same amount of O2). However, if you do want the H2, then binding it chemically to something is a very good idea, since it takes a lot of volume to store in its pure form.

There are different options for that, water is one of them. Binding hydrogen to oxygen essentially means burning it, which yields energy. To separate them again, you have to put in energy, for example through electrolysis. But an extra solar panel on your spacecraft may well be cheaper and is definitely safer than a pressure vessel or cryogenic storage for H2 and O2.

Great! I was wondering because I had an idea to boost rocket performance but depending on the volume ratios it wouldn't work.

We all know that thrust depends on only two things, the mass being ejected and the speed of ejection. If we burn our fuel and inject water in a cyclone pattern we could ...,

1. Create a barrier between the hot gasses and the walls of our burn chamber and exhaust nozzle and possibly use lighter composite materials for our engine parts.

2. Use the steam or extra mass ejected to boost our thrust and possibly give us a cheap and easy way to store a thrust enhancing agent that is also environmentally friendly.

This would, if it worked, reduce cost of flight dramatically and seems to be something that could be tested by almost anyone with some mechanical aptitude and a little money.

Have you seen water as a shape charge?

Could you make a "pulse" engine?

Incoming Linear H.e.r.f or another scheme is used to broadcast power, to a antenna array, that has a ultralight capacitor, that turns the steady incoming energy in into snaps of energy great enough to detonate some water, while somehow using some of the water as a "shape charge"

So

Water tank
antennas/some other scheme
"detonator"

Can it work?

WWII fighter planes had water injection to give an emergency boost. The water cooled down the engine so it could run at higher compression without knocking for a while. Wasn't very good for the engines though. Actually, looking it up on Wikipedia it seems that it's used with military jet engines as well. While it cools the turbine, it also cools the flame, and the hotter your rocket the better. In the end you may be better off just using a denser fuel, i.e. RP-1/LOX instead of LH2/LOX for the lower stages where the thrust is needed the most. Or, e.g. for a single stage to orbit vehicle, a tripropellant rocket.

I am interested in the tri-propellant rocket too. I thought I was the first with that idea , kind of.

The Wikipedia site also has good information on the advantages of different fuels. I was thinking of the exhaust mass gain and low cost and simplicity as the main selling point. Although we would be reducing heat between the exhaust and the engine the core of the exhaust would still be hot. I also believe the change from liquid water to steam would be a boost to ISP. Other fuels might give as much (maybe more) ISP but again I was thinking that the cheapness and easy access to water might out way the other advantages.

If a smaller storage space is what you wanted your proportions of one cubic foot of H2 and one cubic foot of O2 would have given Hydrogen Peroxide which is almost 1&1/2 times as dense as pure water. I am not sure if anybody has worked out the ISP of rocket grade H2O2 and H2 and whether it would have advantages over cryogenic O2 as you would not need as much kit and you could still cool the engines with H2.

I did a quick search for H2O2 and found it is used as an oxidizer in rocket engines. So depending on the fuel the exhaust might be water what ever you get from burning kerosene. But yeah that does seem like you would get more mass and no I haven't found the ISP yet.

Some of the nuclear (radiothermal) rocket/jet propulsion schemes from the 50s and 60s were going to use water as a reaction mass.

I have been thinking about the laser "rocket" that uses ground based laser to heat on board water to generate thrust.

Do we have the laser technology to achieve this? I mean lasers that can sustain high power output over minutes, yet not requiring major maintenance or complete rebuild after every launch. Also what's the distance in the atmosphere we can shoot a laser without much losses to scattering.

They seem to be proposing stations of possibly multitudes of lasers along the ascent path so as the rocket travels along, the lasers delivering the energy come from different locations.

Best locations probably would be deserts or mountain ranges with the installations above a significant portion of the atmosphere. Though both would be expensive to build facilities in.

Anyway, anyone has seen any recent development or work on this?

I have seen it being advocated a lot on the net by various famous scientists etc... but there isn't much in the media about any research making significant steps towards this.

Of course the US military can now shoot down rockets with lasers, but I am talking about civilian or commercial laser technologies that are being developed or are already available.

http://www.lockheedmartin.com/us/news/press-releases/2013/may/0507-ss-adam.html

So could we buy and then adapt this system for our use?

Also here is something else I found on wikipedia:
http://www.niac.usra.edu/files/library/meetings/fellows/mar04/897Kare.pdf

Why isn't somebody throwing a 100 million at this concept?

The keyword is laser motive. I ranted about this in the other topic. How on earth would you stumble upon this key word unless you actually spend a whole heap of time reading and following links.

Though it's still pretty fast. I spent the past hour or so reading stuff like their pdf and now I am on this companie's website that is actually working on this.

Go Internet!