I came across this article today it is saying it is 5-10 times more fuel efficient than wan't they are using now.One of the main problems with getting up into space other than cost problem is fuel!! Getting in space 90% to 95% of the rocket is just fuel to get that small 5% payload up there, current rockets are multi-stage clamber to reach orbit. The fuel packs just enough of a punch to make the trip at all!! It uses fuel like drunken sailor!! This new fuel they found Paraffin Based Fuel is 5-10 times more fuel efficient!!Read here.http://www.space.com/16378-hybrid-rocket-motor-test-spg.htmlWhat are you thoughts on this? Would Monatomic Hydrogen + Fluorine be better option?
LOX/paraffin has a lower specific impulse than LOX/RP-1 even under ideal conditions. Additionally, the dry mass is higher because the fuel "tank" is also the combustion chamber and must have thick walls capable of withstanding high pressures. Finally, it is difficult to control or optimize the mixture ratio because the oxidizer burns the surface of the fuel casting (and affects its structural integrity) in an uncontrollable and relatively inconsistent manner, usually resulting in a substantial amount of unburned fuel in the exhaust.
Why not researching to find alternative fuel source that is more fuel efficient.
Because fuel efficiency isn't the most important thing. If it was, you'd see nothing but LH2 and LOX vehicles. Cost is generally more important.
Quote from: nec207 on 04/25/2014 07:32 pm Why not researching to find alternative fuel source that is more fuel efficient.Because of physics, there isn't any more efficient chemicals.
And in the article it says, "...using the motor's hybrid technology have the potential to be five to 10 times cheaper than existing rockets."Five to ten times cheaper would be beneficial even for only a 200 ISP motor.
Quote from: NovaSilisko on 04/25/2014 07:34 pmBecause fuel efficiency isn't the most important thing. If it was, you'd see nothing but LH2 and LOX vehicles. Cost is generally more important.And in the article it says, "...using the motor's hybrid technology have the potential to be five to 10 times cheaper than existing rockets."Five to ten times cheaper would be beneficial even for only a 200 ISP motor.
Quote from: ClaytonBirchenough on 04/25/2014 07:49 pmAnd in the article it says, "...using the motor's hybrid technology have the potential to be five to 10 times cheaper than existing rockets."Five to ten times cheaper would be beneficial even for only a 200 ISP motor.Yep. Not sure where you're getting the "more fuel efficient" angle at all, nec207.
But propellant cost are minor for launch vehicles.
Quote from: Jim on 04/25/2014 07:57 pmBut propellant cost are minor for launch vehicles.But it says "... have the potential to be five to 10 times cheaper than existing rockets. Rockets, not fuel.
The cost of propellant for a Falcon9 launch is 200k USD according to Elon Musk. The current cost for a F9 launch is 60 million (or so). So the propellant cost is pretty much irrelevant. So I don't get what this article is aiming at.
Quote from: Jim on 04/25/2014 07:48 pmQuote from: nec207 on 04/25/2014 07:32 pm Why not researching to find alternative fuel source that is more fuel efficient.Because of physics, there isn't any more efficient chemicals. Well, there's solid metallic hydrogen. But no one knows how to make it, store it, or do pretty much anything else with it other than study it.
The highest specific impulse chemistry ever test-fired in a rocket engine was lithium and fluorine, with hydrogen added to improve the exhaust thermodynamics (all propellants had to be kept in their own tanks, making this a tripropellant). The combination delivered 542 s specific impulse in a vacuum, equivalent to an exhaust velocity of 5320 m/s. The impracticality of this chemistry highlights why exotic propellants are not actually used: to make all three components liquids, the hydrogen must be kept below -252°C (just 21 K) and the lithium must be kept above 180°C (453 K). Lithium and fluorine are both extremely corrosive, lithium ignites on contact with air, fluorine ignites on contact with most fuels, including hydrogen. Fluorine and the hydrogen fluoride (HF) in the exhaust are very toxic, which makes working around the launch pad difficult, damages the environment, and makes getting a launch license that much more difficult. The rocket exhaust is also ionized, which would interfere with radio communication with the rocket. Finally, both lithium and fluorine are expensive and rare, enough to actually matter. This combination has therefore never flown.
Quote from: Jim on 04/25/2014 07:48 pmQuote from: nec207 on 04/25/2014 07:32 pm Why not researching to find alternative fuel source that is more fuel efficient.Because of physics, there isn't any more efficient chemicals. They've been researching more efficient fuels since the 1950's if they were going to discover unobtanium they would have by now. There is only so much energy you can get out of a fuel before it becomes an explosive. ADN and Ionic liquids offer some increased in energy but they burn really hot so you need better structural materials to make them work. Better structural materials makes your rocket engine more expensive. Similarly Ozone of Flourine as an oxidizer is more efficient as well but our highly corrosive and toxic. Even if you could make a rocket with those fuel mixtures at most you would only see about a 20% increase in efficiency so it's not really worth the cost for a launch rocket. On the other hand ionic fuels would be useful for bimodal propulsion systems for in-space maneuver engines like the Shuttle's OMS.
Quote from: Elmar Moelzer on 04/25/2014 11:34 pmThe cost of propellant for a Falcon9 launch is 200k USD according to Elon Musk. The current cost for a F9 launch is 60 million (or so). So the propellant cost is pretty much irrelevant. So I don't get what this article is aiming at. No, the price for launching an F9 is $60 million or so. The cost is less.
I thought the more densely packed molecules more energy output and more fual efficient.Where less densely packed molecules less energy output and less fual efficient?
Quote from: nec207 on 04/26/2014 02:59 amI thought the more densely packed molecules more energy output and more fual efficient.Where less densely packed molecules less energy output and less fual efficient?Think of it this way -- for chemical reactions, you can only pack so much potential energy into fuel(s). I call this the energy density of the fuel(s). Just having heavier atoms doesn't give you a better fuel, as heavier elements tend to be less chemically reactive. For example, if you want to get a hotter campfire, do you add more wood (mostly carbon) or do you throw some tire irons into the fire (mostly iron)? Iron is a much denser atom, but carbon is much, much more reactive. The amount of energy you can liberate via combustion in a carbon-based fuel is much greater than in an iron-based fuel. Even though the iron is heavier.Now, energy density goes up by orders of magnitude when you access the forces within the nucleus of the atom. But this requires either fission or fusion, and that energy is released so quickly that you can't easily use it directly. You have to interfere with a fission reaction and make it run really slowly to use it for power, and even then you usually just use the heat from the fission to make steam and use the steam to run generators. In rocketry, you use the heat from a slow fission reaction to heat up an insert propellant and send it out the nozzle. Again, you're a big step away from the actual energy inherent in the atomic forces, as you have to use the secondary effect of heat generated by slow moderated fission as you would use heat from burning fossil fuels. (You could make a steam rocket engine using coal and water that would have the same thrust as a nuclear rocket, but it would be inferior in performance because the water and coal are a lot heavier than the fission pile and the propellant.-Doug (with my shield, not yet upon it)
I read alternative to Chemical rockets would be to use a reactor to heat a gas and blast it out the back. They say it is more fual efficient.Can some one elaborate on that as I'm confused.
Quote from: ClaytonBirchenough on 04/25/2014 09:17 pmQuote from: Jim on 04/25/2014 07:57 pmBut propellant cost are minor for launch vehicles.But it says "... have the potential to be five to 10 times cheaper than existing rockets. Rockets, not fuel.I'd call that a mistake of the article author then. Jim's right, propellant costs are minor compared to everything else.
Quote from: nec207 on 04/26/2014 02:59 amI thought the more densely packed molecules more energy output and more fual efficient.Where less densely packed molecules less energy output and less fual efficient?Think of it this way -- for chemical reactions, you can only pack so much potential energy into fuel(s). I call this the energy density of the fuel(s). Just having heavier atoms doesn't give you a better fuel, as heavier elements tend to be less chemically reactive. For example, if you want to get a hotter campfire, do you add more wood (mostly carbon) or do you through some tire irons into the fire (mostly iron)? Iron is a much denser atom, but carbon is much, much more reactive. The amount of energy you can liberate via combustion in a carbon-based fuel is much greater than in an iron-based fuel. Even though the iron is heavier.
Quote from: the_other_Doug on 04/26/2014 03:33 amQuote from: nec207 on 04/26/2014 02:59 amI thought the more densely packed molecules more energy output and more fual efficient.Where less densely packed molecules less energy output and less fual efficient?Think of it this way -- for chemical reactions, you can only pack so much potential energy into fuel(s). I call this the energy density of the fuel(s). Just having heavier atoms doesn't give you a better fuel, as heavier elements tend to be less chemically reactive. For example, if you want to get a hotter campfire, do you add more wood (mostly carbon) or do you through some tire irons into the fire (mostly iron)? Iron is a much denser atom, but carbon is much, much more reactive. The amount of energy you can liberate via combustion in a carbon-based fuel is much greater than in an iron-based fuel. Even though the iron is heavier.That back track a bit on some basic chemistry before we can have a discussion about this.The higher the energy density the more fuel efficient.The holy grail is to find higher energy density fuels that cheap at least for cars ,power stations and airplanes.There are many different matters in universal it just at this time fossil fuels is cheapest and has the higher energy density than any other fuel.You can't just burned something because you want it to.It has to chemically burn.This is why cars don't run of sand, clay,water ,milk or stones so on. It has to chemically burn and bonded with oxygen.If there was no oxygen than cars and airplanes would have to carry a oxygen tank like rockets do.The reason we use fossil fuels is it is the cheapest and has higher energy density than any other fuels.There is some research going into methane ,ethanol ,biofuels like corn , vegetable oil and animal fats so on.But they have less energy density than fossil fuels so not as fual efficient.But reading the replies here ( if I undestand ) rockets use hydrogen fuel as they have higher energy density than fossil fuels or biofuels.And say there are other fuel sources that have higher energy density , but the rockets get very hot and is unstabled and so the rockets needs strong materials because burning the fuel gets too hot and become unstabled.So I guess this is fundamental limitations imposed by the laws of chemistry on rockets.So really rockets cannot get any more fuel efficient because switching to fuel source with higher energy density the rocket would become unstabled and way too hot with out new strong materials.
Quote from: Nomadd on 04/26/2014 12:38 amQuote from: Elmar Moelzer on 04/25/2014 11:34 pmThe cost of propellant for a Falcon9 launch is 200k USD according to Elon Musk. The current cost for a F9 launch is 60 million (or so). So the propellant cost is pretty much irrelevant. So I don't get what this article is aiming at. No, the price for launching an F9 is $60 million or so. The cost is less.No, the price for launching an F9 is $60M or so. The cost is more.
So SpaceX loses money on every launch? That doesn't sound right.