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Thread: Building A Rocket

  1. #1 Building A Rocket 
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    Out of curiosity, and love for science me and my friend are going build a rocket. Our rocket is going to be approximately 2ft tall, this size along with the diameter of the rocket will change after experimentation and calculations. It is obviously not going into space, but we are looking to get some decent altitude.

    What are some good materials to use on the exterior/interior, also, were were planning on putting flame-retartant fabrics outside of the combustion areas to stop the fuel from igniting the rest of the rocket, where can we get these materials? What are some of the basic thrust, air resistance, momentum, or any other equations we would need to know to construct and successfully operate this rocket? We are in 9th grade and have not yet taken physics so if you could explain the abbreviations that would be great.


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  3. #2 Re: Building A Rocket 
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    Quote Originally Posted by Raymond K
    Out of curiosity, and love for science me and my friend are going build a rocket. Our rocket is going to be approximately 2ft tall, this size along with the diameter of the rocket will change after experimentation and calculations. It is obviously not going into space, but we are looking to get some decent altitude.

    What are some good materials to use on the exterior/interior, also, were were planning on putting flame-retartant fabrics outside of the combustion areas to stop the fuel from igniting the rest of the rocket, where can we get these materials? What are some of the basic thrust, air resistance, momentum, or any other equations we would need to know to construct and successfully operate this rocket? We are in 9th grade and have not yet taken physics so if you could explain the abbreviations that would be great.
    You might try a welding blanket. I have one made by Havoc, it takes the heat from an oxygen and acetylene torch.
    I can take an oxygen and acetylene torch to it, and it will not burn. It is not air tight or water tight though.

    You could probably use a layer of welding blanket, and then a layer of heat treat 309 stainless steel foil wrap. They use it in heat treating and machine shops to cool metal slowly. Or to heat it, without hurting the finish.

    If you would like a piece of weld blanket, I will send it to you no charge.

    Then you could switch to glass wool or what ever insulation you are going to use.

    You could also get a sulphur dioxide kiln brick and make a very high temperature barrier.

    There are some carbon materials as well that will work. They have some carbon sponge that a fellow I know used to burn propane with. He used it like a wick to burn the propane more efficiently at higher temperatures. But that stuff could take the heat. And then cool down instantly. He did this in the seventies.

    Off the subject, one interesting thing that is nice about the Welding blanket, is that they used to use a similar material on our humidity test equipment in my school. It was a glass like, material sock, made of something similar. As you spin it in the air, it causes a drop in temperature. You did not have to wet it.

    I put a piece on a "J" type thermal couple sensor. And was able to record quite a few degrees in temperature drop when I put it in front of a fan. Regular material, like cotton will not do this.

    The way the sock works is, as moist air compresses at the sock surface, it dissipates heat. The glass sock accelerates the heat, into something not in the heat band. Now the cool air is free to move in and cool the thermometer.

    Diamonds and some phosphorus compounds use a similar method to dissipate heat. Cutters with diamonds in them, accelerate heat velocity particles back to high velocity ultraviolet, x-ray and normal undetectable radiation.

    Years ago some machinists used a phosphorous hardening compound. When you put the red or orange hot part into the substance, it would glow like a magnesium flare. The part would cool instantly because the heat rays were turned into light rays.

    The way I learned it, the higher the velocity particle the more "energy" it takes away with it. The phosphorous hardening compound simulates the closest thing to a bomb blast, that you can get to, without the explosion. It removes a massive amount of heat.

    Sincerely,


    William McCormick


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  4. #3  
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    You should probably build a model rocket like I did first to get a feel for it. 2 Feet is kinda large for a first rocket....I would suggest building a standard 1ft model first, then building your own replica of it, then maybe trying a 2 foot replica of the one that you built and hopefully successfully launched. Once you manage to replicate them, and maybe even build a few model kit variations, you could make your own based off of your own design. To do that, you could either buy a commercial engine, and put it a rocket that you designed and built for it, or you could use raw materials, either solid or liquid......though building your own engine without a very good understanding of the chemicals could be dangerous. To replicate the model rocket you could potentially use light weight balsa wood and then harden the outside and inside with a coat of hard drying epoxy; but you'll likely need a good work working shop to do that, as its unlikely you will find the exact shape you need on the market. Once you get to building your own, you have to use some physics equations that I don't have on my mind right now.....I'll search through my physics notebooks and textbooks and put them down tomorrow. The only thing is that I never learned how to build the fins, everything I did had pre-made fins. If you google it enough, you could probably find a guide to the aerodynamics of the fins and how to build them. Maybe someone on the forum knows?

    BE CAREFUL when making your own. If you screw up, it could blow up and shoot shrapnel at you, impale you, impale you and then blow up, impale you then blow up and shoot shrapnel at your friend, impale you and shoot shrapnel at your friends and cause a wild fire that you parents will have to pay for b/c you'll be dead.....and.......yeah. Stick with solid state fuel; its more reliable and is much easier to work with. To get more help with this, watch some Science channel shows, like "master blasters" (Little hesitant on that one), and other rocket shows. You will not only acquire some rocket building logic, but you will see what can happen when things go wrong. Hey, me and my physics class messed up and ended up shooting the rocket into the near by freeway! It could have killed someone! MAYBE IT DID.....!11!1!1!!!
    Of all the wonders in the universe, none is likely more fascinating and complicated than human nature.

    "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."

    "Great spirits have always found violent opposition from mediocrities. The latter cannot understand it when a man does not thoughtlessly submit to hereditary prejudices but honestly and courageously uses his intelligence"

    -Einstein

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    Use your computing strength for science!
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  5. #4  
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    Cardboard is a good choice for a model rocket body (and what almost all kit rockets use). It's lightweight, sturdy and if it explodes it won't produce shrapnel. As for the engine, I've never used anything but the commercial model rocket engines (not that I haven't thought of building m own). I'd stick with them, at least at first.

    As for other types of engines, Mythbusters showed a wax and nitrogen dioxide (or did they end up using hydrogen peroxide) engine that seemed to work really well, but it might be too dangerous to reproduce, and I'm not sure you can get a hold of the oxidizer easily. (It's, in general, kind of difficult to buy rocket fuel. )
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    You can buy 30% Hydrogen Peroxide, legally on the market. This won't work though, so you have to boil it down in order to concentrate it to 90% obove.

    The card board they use is treated with an anti flame resin; without it nothing would be left after finding it. I'm not sure about using cardboard for a 2 ft rocket......I guess you could, but making it out of wood would be cooler.
    Of all the wonders in the universe, none is likely more fascinating and complicated than human nature.

    "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."

    "Great spirits have always found violent opposition from mediocrities. The latter cannot understand it when a man does not thoughtlessly submit to hereditary prejudices but honestly and courageously uses his intelligence"

    -Einstein

    http://boinc.berkeley.edu/download.php

    Use your computing strength for science!
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    I was thinking of building it with wood, and have an aluminum foil exterior coating. For the fins, I am going to make my fin size proportional to the fin size of other model rockets and place a fin approximately every 1/3 the circumference of the rocket tube. I am going to buy a model rocket kit for the engine and flame-resistant material. I am going to build my own parachute and parachute release system with a loose, detachable top piece, on the way down it should just fall off and the parachute will come out. The parachute will be a circular piece of trash bag material with eight strings equally apart from each other that are attached to the inside of the tube.

    Would making the bottom heavier than the upper area help keep it more stable?

    What could I use as a launcher?
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    You can get a lot of what you need at a hobby shop. It might be a good idea to build one from a kit and compare it with one built totally from scratch. Estes makes some model rockets and launch pads. Google them.

    Good luck. I've played with model rockets myself when I was younger. Lots of fun.


    Cheers,
    william
    "... the polhode rolls without slipping on the herpolhode lying in the invariable plane."
    ~Footnote in Goldstein's Mechanics, 3rd ed. p. 202
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  9. #8  
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    Quote Originally Posted by Cold Fusion
    You can buy 30% Hydrogen Peroxide, legally on the market. This won't work though, so you have to boil it down in order to concentrate it to 90% obove.

    The card board they use is treated with an anti flame resin; without it nothing would be left after finding it. I'm not sure about using cardboard for a 2 ft rocket......I guess you could, but making it out of wood would be cooler.

    Some uniform cleaning companies may have a 50 pound keg of hydrogen peroxide crystal, that they use for those hard to get stains. They would probably give you a few cups for your science fair project.

    There are probably some bleaches like ox y-clean that you could use in conjunction with other chemicals.

    You can use match heads to make a very powerful rocket engine. I mean really powerful. Just watch the strength of your container. And your jet size. To strong and it can create a powerful blast. Never put match heads into anything you are afraid of getting hit with.

    You could buy enough matches to power your rocket for under $5.oo American.

    I would stay away from combinations like pool chlorine tablets and motor oil. Although you could make them into propellants easily, there is too short a time between mixing them and the ignition.

    Mixing them so that they only react at the end you want want the flame, is also a problem.

    The same is true of potassium permanganate and glycerine. All liquid fuels are going to cause you a problem. And be very dangerous to work with.

    Here is the original rocket design that the German guy, had in mind. It was going to use hydrozine.

    http://www.rockwelder.com/Apollo/frameset/apollo.htm

    To be honest you have to play around with the nozzle size and the amount of fuel you are detonating at any given time. Some will just streak a few feet, some will go great, some will blow up in a fraction of a second.

    The people who make model rocket engines, use special substances that tend to equalize the rate of burn to the pressure that is contained in the rocket. But that takes a lot of time to figure out, and a lot of tests.

    When I was younger, I bought a new model rocket, and I did not have enough money left to buy first stage rocket engines.

    So I tried two single stage engines. The rocket took off beautifully, I mean with a huge hiss and smoke cloud. Unbelievable was what everyone said. I had powerful engines in it.

    Well, it goes up almost out of sight. I am waiting for the parachute discharge charge to ignite the second stage.

    But there is such a long delay that the rocket loses momentum, and turns back at us, and just as it was aiming back at us, it ignited the second stage. Everyone ran for cover. I just watched it go right into our neighbors window. I never bothered to retrieve my rocket. Ha-ha. There was smoke pouring out of their window. Sorry Mr. And Mrs. Solina and Lisa.



    Sincerely,


    William McCormick
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  10. #9  
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    You should know that the commercial engines are built such that as they burn out, they release a jet of (hot) gas upwards to push the parachute out. You'll have to design your rockets to either make use of that, or at least prevent it from damaging anything. Lack of wadding between the engine and the parachute has caused many crashes (due to melted chute/lines/etc).
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  11. #10  
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    I was wondering how the chute was deployed.....

    Another way to do it would be to have to parachute tip of the rocket loosely secured, with ducted holes on it pointing downward. This way it will go up held together by the g-forces, but when it starts to come down the air will catch the ducts and pull the top off.

    Has anyone ever made a remote controlled rocket?
    Of all the wonders in the universe, none is likely more fascinating and complicated than human nature.

    "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."

    "Great spirits have always found violent opposition from mediocrities. The latter cannot understand it when a man does not thoughtlessly submit to hereditary prejudices but honestly and courageously uses his intelligence"

    -Einstein

    http://boinc.berkeley.edu/download.php

    Use your computing strength for science!
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  12. #11  
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    Quote Originally Posted by Cold Fusion
    I was wondering how the chute was deployed.....

    Another way to do it would be to have to parachute tip of the rocket loosely secured, with ducted holes on it pointing downward. This way it will go up held together by the g-forces, but when it starts to come down the air will catch the ducts and pull the top off.
    Yeah that was my idea, I didn't know that commercial engines release a burst of hot air so not im going to have to change my rocket in accord to that. As long as there is a decent amount of flame-retartant between the parachute and the burst of gas the parachute should not melt, right?

    Would making the rocket heavier at the bottom help keep it more aligned straight when it is going up?
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  13. #12  
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    Yeah. Normally there's a layer of wadding placed beneath the parachute. I'm not actually sure what wadding is normally made of, but I think it comes with either the kit or the engines. (It's been too long since I've done this.)

    I'm sure the point of balance is important, but I'm not sure where it should be. I do know that the fins play a big role in keeping the rocket upright, but maybe someone else can say how the two work together.
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  14. #13  
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    Fins should add effective drag to the trailing end of the rocket. If you can form them consistently (in a jig) a little twist is nice.

    I don't think it's possible to build a very symmetrical (aerodynamically balanced) small rocket, unless you spin it - as in a lathe.

    There's also the matter of balancing the rocket's mass. Think about how you would do that before construction begins.
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    In case anyone is interested, my old chemical books show the formula for hydrazine as NH2NH2, kind of odd if you ask me. Seems more like a mixture rather then a molecule.

    You could mix both liquid nitrogen and liquid hydrogen, and it would allow the hydrogen to raise in voltage more quickly, without its destruction.
    However if you do this, and you raise the voltage beyond the capability of nitrogen to raise in voltage, in a stable way. You could get a cataclysmic explosion. And atomic hydrogen welding could occur.

    Since the formula for ammonia is currently listed as NH3 and you could not burn it with a blow torch.
    I am thinking that the formula for ammonia is NO2. If that is the case be very careful if you smell ammonia while working with chemicals. Any aromatic hydrocarbon and ammonia will cause a nearly silent detonation and powerful gravity field.


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    William McCormick
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  16. #15  
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    Wow. That made even less sense than your other posts.
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    There is special wadding that you can buy from the website posted before.

    You naturally would not want the weight to be on top; the engine will likely make the bottom weigh the most no matter what. If you wanted to try to manage the inner structural weight though, I think it could be beneficial to have the weight in the middle of the rocket. This way its not so high that it will tilt over, and not so low that there is no power to prevent the wind from torquing the rocket in a different direction. If you don't have to worry about wind, just put most of the weight as low as possible.

    Do model rockets naturally spin? It seems like they do a little bit, from what I've seen from rocket mounted cameras; why do they not add a slight tilt to the wings to give it allot of spin? Bullets travel considerably straiter when they are spinning as opposed to when they are not. Would it tear the rocket apart?

    What gravity field William? I do not think we possess anything that can create gravity through a chemical explosion..... :?
    Of all the wonders in the universe, none is likely more fascinating and complicated than human nature.

    "Two things are infinite: the universe and human stupidity; and I'm not sure about the universe."

    "Great spirits have always found violent opposition from mediocrities. The latter cannot understand it when a man does not thoughtlessly submit to hereditary prejudices but honestly and courageously uses his intelligence"

    -Einstein

    http://boinc.berkeley.edu/download.php

    Use your computing strength for science!
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    If you have trouble gluing the fins on. Or if you find they break off in the field a lot and ruin your launch.

    You can glue tubes, like toilet paper roll tubes or paper towel tubes to the rocket body, instead of fins. They act just like fins, Maybe even a bit more stable. When they first came out in the late sixties early seventies I bought one.

    This is a cool missile that the company my father worked for made.

    http://www.rockwelder.com/military/Rigel.htm

    Sincerely,


    William McCormick
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  19. #18  
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    Quote Originally Posted by MagiMaster
    Wow. That made even less sense than your other posts.
    Any part in particular?

    There was a treasure-trove of information there.


    Sincerely,


    William McCormick
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    Quote Originally Posted by Cold Fusion
    What gravity field William? I do not think we possess anything that can create gravity through a chemical explosion.....
    Yes, in fact I do. Accelerating or decelerating an individual with a solid object, often crushes his body. Yet over the years during explosions individuals have been hurled by explosion only to get up, to laugh about their eye brows burnt off.

    If I said that I was going to put you up against a piece of metal and accelerate you in four or five feet to a speed that would allow you to penetrate cinder blocks. You would probably think that I forgot what accelerating a human body at those speeds could do.

    Yet you could live to tell about. The reason is that the ambient radiation that moves you, does so by electrical repulsion. Because no two particles not even sub-atomic particles ever touch we know that no matter what, electrical repulsion is going to move you.

    But when you have a gas, and very high voltages created, in the gas, it can divert ambient radiation, to hurl you like a weightless massless object. And leave you unharmed. Because you are being moved by electrical energy. That penetrates your entire body. Just like gravity.

    But if a metal object presses against you to accelerate you at a similar rate, the metal object also accelerates the ambient radiation back up to normal radiation speeds, on the side of the plate you are on.

    So the cushioning slowed repulsive penetrating gravity velocity ambient radiation cannot get to you. You squish up against the metal.


    Sincerely,


    William McCormick
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    In our town, in gas stations we used to have nitrogen fire extinguishers.

    Nitrogen will put out fires.

    Sincerely,


    William McCormick
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  22. #21  
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    Thank you all for you suggestions and help . I will begin to build this weekend when my friend comes over.
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  23. #22  
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    Quote Originally Posted by William McCormick
    Quote Originally Posted by MagiMaster
    Wow. That made even less sense than your other posts.
    Any part in particular?
    No, pretty much the whole thing.

    Raymond, good luck with the rockets. Just don't be too disappointed with a few crashes and explosions. They're pretty much inevitable.
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  24. #23  
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    Heh I really dont like the sounds of a couple of 9th grade kids building a 2foot rocket... I would definately get a few kits under your belt first and then try make a tiny rocket first. Theres a fine line between rockets and bombs.
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    Quote Originally Posted by Jimsmowen
    Heh I really dont like the sounds of a couple of 9th grade kids building a 2foot rocket... I would definately get a few kits under your belt first and then try make a tiny rocket first. Theres a fine line between rockets and bombs.
    Lol.
    Okay, but we didn't just light stuff on fire, we actually thought about our plan and used physics. We made a 1ft testing model, now were working on a 2ft model proportional to the 1ft model.
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