Liquid rockets

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A 1 HUNDRED dollar book that will make a wallet cry especially mine

If you are serious, get used to it!

Ok then I guess I will do my back up using my b4s and c11 looking for different altitudes for my science fair idea is thier any other protects I could do.
There you go!

Alex
 
I think I can check that book out at my library now I guess I will save the liquids rocket for my industrial class and my robotics class how bout some ideas for science fair using b4 and c11 I was planning on seeing thier different hieghts with my very small rocket called hi jinks from Estes mybe a d-11 on it would be cool to see and as hurting the wallet that is true
 
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I think I can check that book out at my library now I guess I will save the liquids rocket for my industrial class and do sticks class how bout some ideas for science fair using b4 and c11 I was planning on seeing thier different night with my very small rocket called hi jinks from Estes mybe a d-11 on it would be cool to see

Don't bother with that book until college, you have plenty of time 'til then.

But for us teasing you some on liquid motors I thought I'd make it up by finding you something that may help with your science fair project, good luck.

https://www.apogeerockets.com/Tech/Science_Fair_Projects
 
What a shocker my idea for a liquid rocket was destroyed within 2 hours on this forum probably the biggest one. Ever did
 
Well I think that's the end of this forum thanks for all your guys help if you have any more tips just typed them in I will look at them
 
I think I will make a new form for this but what about a good rocket I prefer c11 best possibly b4s
 
You guys are ridiculing someone for what Estes did back in about 1972-73 or so. They had a complete line of liquid fuel rockets. The engines used freon (can' get away with that now!) rather than liquid nitrogen, but the principle is the same. I think I may even have one of the engines in my box of ancient rocket parts...
 
Hi everybody I now liquid rockets are unstable but here is my plan and wondering if anyone could help with this I decided I wanted to build a rocket like nasa witch uses liquid propulsion so I am going to put a container carry I am hoping liquid nitrogen witch will then be connect to a tube with servos that open witch then pour the liquid nitrogen into another smaller container the liquid nitrogen will travel through a pipe going through the second tank holding some hot water or plain water allowing the nitrogen to expand witch will travel through the tank into a larger tube that will decrease in size as it reaches the end of the rocket increasing the velocity and decreasing the pressure and temp witch will then either be ignited or just pumped out so if you were able to follow this please help me and if you know where supply's are help any people with experience in liqua de rockets help and anybody with tips please join in

Thanks

Okay... first, pay attention in English class... learn what a run-on sentence is and then learn how to avoid it. Communicate clearly and correctly.

First off, your plan has some MAJOR flaws and is SO overcomplicated that it's not even funny. Basically what you're describing is called a cold propellant motor, and they've been done, decades ago. They're no longer produced because they used R-12 refrigerant (Freon 12) for propellant, and it is illegal to release Freon 12 into the atmosphere. Some folks are still flying cold propellant motors as a novelty or for nostalgic purposes, using "canned air" or airbrush propellant for the liquid propellant.

NASA liquid propulsion uses any of a number of different propellant combinations injected into a combustion chamber and actually combusted or burned to produce exceedingly hot, high pressure gas which is then expanded and exhausted out a nozzle to produce thrust. There are any number of excellent articles on various rocket engine cycles and diagrams and propellant combinations (which produce varying amounts of power per unit of propellant (called Specific Impulse) depending on the engine design or combustion cycle type... Google is your friend). Some vehicles have used "cold gas jets" (like the Mercury capsules IIRC, and various satellites) as small manuevering and control rockets (SpaceShipOne used compressed air jets from SCUBA tanks for thrusters). The available power is VERY small because they are so inefficient (not a good energy storage medium) and therefore they're practically useless for anything other than attitude control.

Liquid nitrogen is EXTREMELY cold to remain a liquid at room temperature and pressure (-346 degrees F). It will freeze living tissue on contact. It boils vigorously when exposed to the latent heat of a container. It is a deep cryogenic fluid and requires special handling and safety precautions to prevent the pressure vessel holding it from rupturing (exploding, essentially). This would ruin your day... https://en.wikipedia.org/wiki/Liquid_nitrogen

By the way, it's "which", not "witch"...

So, you plan to put this LN2 into a tank with a servo-controlled valve, which will then send the LN2 (liquid nitrogen) to a second tank containing hot water (so presumably to provide latent heat to vaporize the LN2 and then eject this gas through a tapering down tube (which would RAISE the pressure of the gas upstream all the way to the second chamber, NOT lower it, due to the restriction of the flow through the smaller orifice at the outlet end of the tube.) This is not how a De Laval nozzle works (again, Google is your friend). The orifice (convergent section) of the nozzle creates a "choke point" past which the gases then expand, along the DIVERGENT section of the nozzle, which creates thrust. Pressure is higher on the "upstream" side of the convergent section of the nozzle (nozzle throat) than it is downstream of the nozzle throat, allowing the gases to expand in the nozzle.

Just what type of "tanks" do you intend to have?? Any system containing LN2 at room temperature without insulation will rapidly experience boil-off of the liquid into nitrogen gas, thus pressurizing the container... all the way up to 1600 PSI. Where do you intend to get a pressure vessel capable of containing LN2 at 1600 PSI?? Especially one light enough for flight?? The other alternative would be to have a pressure relief valve, to vent the excess nitrogen gas as it boils off, to keep the pressure vessel safely below its burst point. However, this adds weight and complexity. https://en.allexperts.com/q/Physics-1358/Pressure-Liquid-Nitrogen.htm

Now, the only "energy" stored in the system is the latent heat of the 'hot water' you plan to use to boil your nitrogen into gas for propulsion... which will RAPIDLY be cooled and lost due to the refrigeration effect of the nitrogen boiling off into gas. Once everything is cooled down, the nitrogen will boil off slower and slower and finally just be "wheezing" out of the iced-up rocket motor.

Then, finally, and the most glaring error of the entire concept is the idea that you could IGNITE the nitrogen gas for some sort of secondary propulsion. Sorry, no, nitrogen gas is not flammable. In fact, NASA pumped nitrogen gas into the rear engine compartment of the space shuttle and into the interstages of the Saturn V rocket to prevent any possible leaks of propellant gases (liquid oxygen and liquid hydrogen, primarily) from creating a potential to ignite accidentally... (especially liquid hydrogen, which is a liquid at -423 degrees F and leaks through the tiniest of gaps due to the incredibly small molecular size) Displacing the air (with its 21% oxygen content, most of the remainder of which is nitrogen at 78%) with pure nitrogen gas (GN2) deprives any leaking LH2 of oxygen with which to combust, until the engine valves open and the rocket ignites that is. In fact, two technicians died after entering the aft propulsion section of the shuttle on the launch pad after a test firing, IIRC, when the nitrogen gas had not been purged from the compartment yet and replaced with regular air. With no oxygen to breathe, they collapsed and died from asphyxia. While nitrogen will "burn" to form oxides of nitrogen, it takes incredibly high temperatures sustained from other sources (such as nuclear weapons explosions in the atmosphere or the high combustion temperatures in a car engine) to produce these oxides of nitrogen... you cannot simply "ignite" nitrogen gas, otherwise the Earth's entire atmosphere would be one huge BOMB! (Nuclear fireballs in the atmosphere will react with nitrogen in the surrounding atmosphere to make oxides of nitrogen, which then forms a ruddy brown "shroud", "veil", or "haze" on the surface of the atomic fireball-- this is readily visible in many of the old atomic bomb test videos... air burning in the engine of a car produces oxides of nitrogen when any uncombusted oxygen combines with nitrogen in the high heat of the combustion in the car engine-- or in the high heat of old-style catalytic converters that injected air into the converter to consume unburned hydrocarbons... these oxides of nitrogen are pollutants, which is why modern "dual stage" catalytic converters have a second catalyst to break down the oxides of nitrogen and release the nitrogen gas from the bonds with oxygen to reduce pollution. Also why most vehicles have at least two catalytic converters).

So, you can see that your "nitrogen engine" is a non-starter on many levels. The weight and complexity would be too much for the poor levels of thrust you might be able to coax out of it, IOW, it'd weigh more than what the motor could possibly lift. (Thrust to weight ratio must be greater than 1 for any rocket to lift off, NASA or otherwise. In model rocketry, using passive stability systems as we do, a T/W ratio (thrust/weight) should be at least 5 or more to ensure rapid enough acceleration for fins to be capable of stabilizing the vehicle aerodynamically. NASA vehicles typically have liftoff T/W's in the 1.1-1.2 range, or thereabouts... but then again, they use ACTIVE stabilization systems that either gimbal the rocket motors via inputs from a guidance platform, or inject a liquid "steering fluid" (hydrazine) into the exhaust stream to divert the exhaust flow from the nozzle, again steering the thrust of the engine to keep the rocket stable. (again, Google is your friend... look up "liquid thrust vector control systems".)

Now, basically what you're describing, as previously mentioned, is a "cold propellant" rocket motor. These worked on the principle of using latent heat contained in a pressurized liquid (basically, for lack of a better term, a "low cryogen", usually R-12 or such refrigerants, or butane or liquid petroleum gases (LP gas, which is a liquid if kept pressurized at room temperature but boils off into a gas if the pressure is removed), but other non-harmful non-polluting alternatives exist, such as "canned air" used to blow off keyboards and electronics, and airbrush propellant-- which is basically spray paint can propellant. These cold propellant motors were designed to use R-12, but the other fluids can be substituted (of course you don't want to use propane or butane, since they're flammable and could therefore ignite and burn... unlike refrigerants which are specifically designed NOT to burn and are thus non-flammable. Hydrocarbon gases like butane, when released into the atmosphere, are polluting, so aside from the safety concerns, it's not a good idea to use them. This is the main reason that butane was prohibited from being used as an aerosol can propellant decades ago.) The cold propellant motors were designed basically like a small aerosol can, almost like a lighter fluid can (butane lighter refill tank). The main tank was constructed of a thin aluminum pressure vessel capable of holding the liquid propellant under pressure (about 70 PSI, FAR below the pressure of boiling LN2) at room temperature. The main tank was equipped with a fill valve, usually either on the side of the tank (much like a basketball inflating valve, which is to say, a tiny one-way check valve opened by a fill needle inserted through it, much like how a basketball is aired up). The head end (top end) of the tank had a threaded adapter to which the parachute timing device was installed (which itself consisted of a series of small paper disks stacked atop each other, which allowed the pressurized gas to slowly leak through them at a predetermined rate-- adding more disks slowed the leakage and therefore meant a longer "parachute delay" and removing disks speeded up leakage, meaning "less delay". The other end of the tank had a nozzle at the bottom, equipped with a plug to contain the liquid propellant, held in place for quick release either by a pull pin (pulled by a string or lanyard from a safe distance) or a burn wire (a nichrome wire slid through the nozzle and plug to hold it in place, which was then hooked to a standard electrical launch controller that, when the button was pushed, passed enough current to burn through the wire and allow the plug to be jettisoned out of the motor nozzle by the pressurized liquid, allowing the rocket to lift off. The parachute compartment was held on by "clamps" in a small bellows threaded onto the delay timing disks at the top end of the motor. When the motor was filled with propellant, the liquid would start to boil slightly until it reached a stable pressure... this boiled off gas would then leak up through the paper disks and expand the bellows, extending clamps to hold the parachute section to the rocket. When the rocket was launched, the nozzle would eject from the motor, and the about 70 PSI of head pressure (which is highly dependent on the outside temperature of the environment and the latent heat contained in the propellant fluid and the motor's components itself) would start to squirt the liquid refrigerant propellant out the nozzle orifice, which then released it to expand suddenly as the pressure was released and it boiled off, essentially "flashing off" into a vapor and expanding very quickly, creating thrust. This process would continue as the rocket lifted off. As the liquid level in the motor fell, the "head pressure" of the boiled off gases at the front end of the motor would be reduced as the gases expanded to fill the emptying tank, lowering the pressure inside the motor. This would then cause more propellant to boil off inside the tank, to create more gas (and thus attempt to return the pressure to equilibrium, but it can't because more liquid is being expelled out the back of the motor constantly). This continues until all the liquid is expelled from the nozzle, then the remaining pressurized gas quickly vents out the nozzle to the ambient atmospheric pressure. The pressurized gas trapped above the paper timing disks then starts to bleed down through the paper disks at a premeasured rate, which then lowers the pressure on the bellows until they finally retract (via spring pressure) the clamps holding the parachute section on, which then allows the parachute to essentially "fall out" of the rocket for recovery.

Now, the problem with these motors are that they're relatively heavy for their power levels (at most a CP (cold propellant) motor could crank out C power, on a hot summer day, and on cooler days maybe B power with the same propellant load, due to cooler conditions (less vigorous boiling of the propellant, hence lower power). If you tried to launch one in the cold of winter, it would be VERY weak, and at extremely cold temps the thing wouldn't lift off at all-- just sit there dripping/dribbling propellant out the nozzle hole! This is due to the fact that the propellant isn't undergoing any combustion, but merely a PHASE CHANGE-- from liquid to gas, and hence expanding due to that phase change. This is not a particularly energetic form of propulsion, because the only source of energy is the heat stored in the liquid itself, and the heat stored in the motor components like the tank and nozzle. The more heat, the faster it boils, the more pressure it creates to reach equilibrium (where the fluid in the tank quits boiling until the plug is released and the motor lifts off) and therefore more performance. The lower the boiling point of the fluid, the greater the performance, BUT, the harder it is to contain the fluid, and the more dangerous it is to handle. Anytime the fluid expands, some of it boils off to restore the equilibrium pressure. So, when you "fuel" the rocket, by injecting the liquid propellant into the tank, the first drops that go into the tank boil off into gas nearly instantly-- which raises the pressure and slows the boiling... BUT, it takes ENERGY to boil off these droplets, which comes from the motor tank and parts... energy which is then NOT available for propulsion (boiling off the propellant gases in flight). This is the "refrigeration concept" and is exactly how everything from you car or home air conditioner to your kitchen freezer or refrigerator works. Heat is absorbed by a boiling liquid and carried away. Of course with the small volume of the tanks on these cold propellant motors, the effect is negligible, but it does exist. If you've ever held a can of freon putting it into a recently repaired AC system on a vehicle, the can becomes quite cold from the freon boiling off inside it as it goes into the system... I've seen cans of freon completely FROST OVER on a 100 degree plus day from rapid boiloff into an AC system! A cold propellant motor essentially "refrigerates itself" as it operates, reducing its power as it operates...

So how do you improve the performance of a cold propellant motor?? By increasing the heat content of the propellant and motor structures. Painting the bright aluminum motor tank black would allow it to absorb heat from the sun. This heat would then be absorbed into the propellant, allowing it to store this heat for use to boil the propellant off during motor operation. (it also raises the internal pressure of the fluid in the motor as it boils off more propellant inside the motor while it's sitting on the pad, staying at equilibrium pressure with the added heat... so too much heat and BLAM! Same reason you don't store spray paint or aerosol cans in direct sunlight inside a closed up car! The pressure can build up til it exceeds the burst pressure of the can (tank). We can't prevent the slight 'refrigeration' of the motor when we fill it with propellant, but we can allow it to absorb heat from the environment (or the sun as mentioned). We can also "pre-heat" the propellant by sitting the can of propellant in a bowl of very warm/hot water (not too hot to stick your hand into-- again, we don't want to blow the can up!) This is the exact same reason we warm up spray cans before spray painting-- the warmer the fluid, the easier it boils off, the more heat it has to boil off, and therefore the higher the pressure and the better the spray paint works. (Plus the paint viscosity is slightly lower, which also helps, but that's another issue).

Hope this helps... Later! OL JR :)
 
Will if it was illegal which I was just thinking of rant there engines called hybrids are so

Hybrids work under a completely different principle... hybrids use nitrous oxide (which RELEASES oxygen during combustion, speeding up combustion and making it more efficient, which is why it is used in racing engines-- the N2O (nitrous oxide) is injected into a fuel grain (combustible material acting as a fuel for the rocket, with the N2O acting as oxidizer in a classical combustion rocket engine) which then burns and produces high-temperature, high pressure exhaust gas which is then expanded out of a nozzle to produce thrust. COMPLETELY different from what you're describing...

I think you REALLY need to learn about how rockets work and WHY... the SCIENCE behind it before even thinking about any such projects... because basically the stuff you're getting wrong so far is just high school physical science/chemistry/physics stuff... IOW you ain't even into the HARD STUFF yet...

Good luck and get plenty of experience with regular solid propellant rockets/motors and plenty of knowledge about how/why rocket motors work and the various propellant combinations and cycles... THEN come up with a design!

Later and good luck! OL JR :)
 
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I don't know the name of his place just that it makes and testes chemicals

Oh for the love of... PLEASE pay attention in English class... go to tutorial or something...

Google what you typed in there above and see what it tells you.

She's a nice lady and she's there to help you... LOL:) (Yeah, I'm married to an English teacher... :))

Later! OL JR :)
 
Yeah, because most people would prefer to keep their limbs and vital organs intact, which is probably what is not going to happen to you if you mess around with liquid fuels without having the proper background and a lot of help. See the earlier posts from the RRS guys, THEY know what they are doing and they still take precautions that would make a L3 RSO blush.

well one reason I want to is that I think nasa rockets burning liquid Is cooler then solid fuel second it would be awsome if. Built one from scratch third it is a challenge most people won't take on
 
Luke, my good old Vashon Valkyrie V2 was my favorite rocket when I was a kid, they worked really well here in Cali because it didn't get too cold. They made a really nice vapor cloud that would linger for several seconds after liftoff, it was really cool. I've always wondered if somebody would actually try bringing them back with "canned air" (difluoroethane) but given the EPA's regs and the much higher cost of aerosol propellants now I'm guessing that their time is pretty much gone forever.

....Basically what you're describing is called a cold propellant motor, and they've been done, decades ago...
 
when I was in the service we used LN for freeze seals. No, we didn't freeze the animal - it was used to make a mechanical barrier when the job site was not able to be isolated. (+2 points for anyone who guessed nuke). Got to learn a lot about LN and how important it was to respect (a friend got some nasty burns) One of the other things to think about is that most metals, when exposed to LN suffer brittle fracture with just a little bump (hey, liberty ships from WW2 brittle fractured, too). Could you imagine the bump from lift off causing the pressure vessels and feed lines to brittle fracture? At least there would be some cool fog in the area.......
 
It's also worth nothing that the OP seems to have mixed up and confused the properties of liquid nitrogen and nitrous oxide, which are very different things. He keeps going on about liquid nitrogen but his...diagram...states he is using NO2 (nitrogen dioxide), which is rather toxic and the "fuming" red gas bit of fuming nitric acid, but is probably meant to be N2O.
 
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It's also worth nothing that the OP seems to have mixed up and confused the properties of liquid nitrogen and nitrous oxide, which are very different things. He keeps going on about liquid nitrogen but his...diagram...states he is using NO2 (nitrogen dioxide), which is rather toxic and the "fuming" red gas bit of fuming nitric acid, but is probably meant to be N2O.

Doesn't really matter, the whole thing is still unworkable...

Later! OL JR :)
 
It's also worth nothing that the OP seems to have mixed up and confused the properties of liquid nitrogen and nitrous oxide, which are very different things. He keeps going on about liquid nitrogen but his...diagram...states he is using NO2 (nitrogen dioxide), which is rather toxic and the "fuming" red gas bit of fuming nitric acid, but is probably meant to be N2O.

NO2 is a much better oxidized, however, which is why IRFNA is a fun oxidizer :p

Also, for anybody thinking of buying RPE, buy an old edition (I have edition 3). All of the more recent advances in liquid propulsion, such as new injector designs, are all under ITAR, so they won't be published in these books.
 
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