How to make rocket fuel at home. DIY rocket fuel How to make rocket fuel

To begin with, I think it would be wise to make a small home-made engine, get used to it so to speak. .Find potassium nitrate, where I don’t know, ammonium and sodium will not work. The spirit writes that they simply sell freely in stores in the Urals. 60% saltpeter and 40% sugar. Make homemade scales from caps, threads and a stick. Weights are copper Soviet coins (1.2.5 kopecks) corresponding to grams. About 10 grams go to the engine. Mix the components by pouring from side to side on a sheet of paper. So. Now we need to heat this economy somewhere up to 150 degrees. In principle, we heated SUCH QUANTITIES simply on an electric stove, but we need a set-up. udine mixtures are very active. THINGS LIKE NOT TO BEND OVER THE MIXTURE AND WORK ON ALMOST EXTENDED ARMS SHOULD BE INSTINCT. a handle to it, better a frying pan from a children's kitchen set. Today I tried to melt sugar on an inverted iron-melt. In principle, I’m almost sure that the temperature given by the iron is less than the flash point of the mixture. Check your iron, put a match on it, wait 15 minutes, it won’t flare up O.K. In the engine nozzle, you need to insert a stick on a cone - use a wooden children's brush, cutting it so that after it fits snugly in the nozzle, it comes out about 2 cm inward, and rub it with paraffin. So, you heat the mixture , at first it will begin to become transparent around the edges, in general, the resulting glassy mass must be pushed into the sleeve with a wooden stick, you can’t explain this in detail, you have to try it yourself. And tamp, quickly the muck cools down. As a result, there will be a charge in the sleeve with a channel somewhere up to half. I recommend doing all this with a mixture in the same proportions, but instead of saltpeter, take table salt (Warban’s thought is just five!), Then break the sleeve and see how the charge looks Are there many potholes and inhomogeneities. Fill the rest of the sleeve with paper tightly. Everything is ready, ignition by inserting a nichrome wire on the wires into the nozzle, as in the MRD. Good luck!
Only after mastering the manufacture of such engines successfully, we can talk about several large charges, otherwise it’s hard to say that a person hasn’t tried it, believing that the mixture can be poured into the engine (through a funnel). Your injuries will be on my conscience.

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Composition No. 1: 60% (9KNO 3) + 30% (9SORBIT) + 10% (9S) 9 - higher plasticity

Composition No. 2: 63% (KNO 3) + 27% (SORBIT) + 10% (S) - maximum specific thrust

This propellant is a new and much improved version of sorbitol propellant. Its faster burn rate and high specific impulse make it suitable for use in both medium and large rocket engines. It was developed by me recently, i.e. improved, because It was not my idea to use sorbitol as a binder. However, compositions similar to it have been published on some web pages of the Internet. But they never became popular with rocket scientists. And I think you know why.

The composition of the new sorbitol fuel includes sulfur, which is involved in the combustion reaction:

6C 6 H 14 O 6 + 26KNO 3 + 13S = 13K 2 S + 36CO 2 + 13N 2 + 42H 2 O (theoretically)

In fact, the reaction proceeds according to a more complex mechanism, according to the redox properties of the elements, it can be argued that at the very beginning, the reaction will proceed precisely according to a simple mechanism, and only then the reaction products will interact with each other, giving already other compounds. The correct ratio of components ensures the high efficiency of this fuel. This fuel has relatively high energy characteristics. The fact is that sulfur is involved here as a reducing agent and displaces the remaining oxygen atom from the molecule K2O, resulting in an increase in the energy yield of the reaction. Besides K 2 S does not pick up CO2 how does it do K2O. The released energy is enough to shift the equilibrium towards the formation of such low molecular weight products as CO and H2. This contributes to a significant increase in the specific thrust of the fuel. Thus, the efficiency of the engine increases on average by 15 - 20% (according to rough estimates), and maybe more. So we can say that this rocket fuel is a worthy replacement for gunpowder and ordinary caramel.

The disadvantages of this fuel compared to conventional sorbitol are: complexity in manufacturing, low ductility, impossibility of pouring the composition into the engine housing, fast solidification rate, with insufficient heating of sorbitol, the fuel quickly solidifies. Experience has shown that this fuel is well prepared and used in the cold season, since the humidity in the air is much lower than in summer. Perhaps the main problem of this fuel is the fast solidification rate and the impossibility of pouring fuel directly into the engine housing. This fuel also has a very unpleasant thing - if the mass is not compacted enough, voids form inside the fuel charge, which greatly affects the uniformity of combustion of the entire charge. Simply put, the structure becomes porous, which contributes to the formation abnormal combustion- unstable intermittent combustion caused by a decrease in heat supply to unreacted fuel, lasting from a few fractions to 2 seconds. This problem is especially characteristic only for small engines, with a fuel charge 30 - 35 grams- pressing "Powerful caramel" into such engines - the work is very painstaking and complicated, but such a thing has practically no effect on large engines, because air voids are insignificant relative to the entire volume of fuel. Although this fuel solidifies quickly, this problem can be easily eliminated by placing a container of fuel in a heated sand bath. This is a very convenient way, well, don't overdo it with the temperature, otherwise the sulfur in the fuel will melt and the mixture will become inhomogeneous.

MANUFACTURING

At first, there were serious problems in its manufacture. It was difficult to find a balance between the melting point of sorbitol and the melting point of sulfur, and when the melts of both components were mixed, the fuel was extremely inhomogeneous. A variant was considered using glycerin so that the mass retains plasticity for a long time. But the use of glycerin led to a decrease in the strength of the fuel pellet and increased hygroscopicity.

Sorbitol with strong heating and subsequent cooling does not harden immediately and retains plasticity for a sufficiently long time, which is enough for refueling 2 - 3 small engines. Sorbitol must be heated to a sufficiently high temperature (about t kip). When I heat it up to this temperature, it smokes a little, becomes transparent (slightly yellowish), and small bubbles form at the bottom, which indicates the beginning of the boil.

Before you start melting sorbitol, you should prepare all the components in advance.

1. First, weigh out the required portion of sorbitol and put it away from the place of work

2. Next, you will need to grind the potassium nitrate. Before grinding, it should be dried thoroughly, it is possible on the battery, but I dried it in the oven at t ≈ 200 0 C, more than this temperature is impossible, because melting begins and then decomposition. Dried potassium nitrate is easier to grind and sticks to the walls of the electric coffee grinder less than wet. I grinded in an electric coffee grinder for about seconds 40 . If it sticks to the walls, then it can be scraped off with cotton swabs or hands, but not bare, but using disposable gloves.

3. After grinding, weigh out the required portion of saltpeter and place in a clean jar, I used a plastic one, because. It sticks to my glass.

The sulfur that I use in fuel contains coal in the following ratio: 100% (S) + 5% (C) (by mass).
When using coal, the mass forms fewer lumps, becomes more crumbly and practically does not stick to the walls of the electric coffee grinder during grinding. However, it is necessary to grind intermittently so that the sulfur does not melt from excessive friction. After grinding, it remains highly electrified and will form lumps. As I noticed, it takes quite a long time for the sulfur to become crumbly after grinding, so it should be milled in advance. ()

5. Only after you have measured everything can you melt the sorbitol. For these purposes, I used my favorite miniature oven, but when I didn’t have one, I made do with a stove. Sorbitol is placed in a metal container, and preferably in a stainless steel container (I personally use a stainless steel mug that I purchased in a store "All for fishing and hunting") and is heated to a temperature close to its boiling point.

6. Then finely ground and dried potassium nitrate (potassium nitrate) is added to it. Before you fall asleep, shake the vial of saltpeter well so that it becomes more crumbly.

7. The mixture is stirred until completely homogeneous. With this ratio of saltpeter and sorbitol, the mixture begins to solidify quickly, so you will have to reheat the contents of the glass until the mixture is ready to stir.

8. After the mixture has cooled to a temperature that is below the melting point of sulfur, sulfur itself is added to it. The temperature can be checked by dropping a small amount of sulfur into the above mixture of saltpeter and sorbitol, if the temperature is too high, the sulfur will melt and form small, shiny droplets on the surface. Mix all the ingredients very quickly so that the mixture does not have time to harden.

10. After that, pull out the plastic mass (it is advisable to use disposable polyethylene gloves) with a knife or other metal object. The mixture should also be scraped off the sides of the mug and knead again with your hands for greater uniformity (use plastic gloves!).

I want to note that the fuel begins to solidify quickly, so I place it again in a mug and put it in a heated oven, but only turned off, because. it retained heat in itself and perfectly helps to maintain the temperature of the fuel melt and it does not remain plastic for a long time. You can also put some heat-intensive materials into the oven: clean dry sand, metal nuts, nails, lead is perfect. As necessary, pieces of fuel are plucked from the main mass and carefully pressed into the engine housing.

The fuel should be pressed in in small portions, because if the fuel is not pressed under sufficient pressure, then many air bubbles will remain inside the fuel block. As experience has shown, for pressing it is better to use a graphite stick impregnated with paraffin, and with a polished tip. For these purposes, fluoroplastic is also suitable, but the fuel still sticks to it and it is advisable to have a rag on hand with which you will remove plaque. All work should preferably be carried out in a dry room. As I already noted, this fuel is more suitable for the manufacture of large fuel charges (from 70g) for large engines.

From the author: I don't know if this fuel will become popular with rocket scientists and chemists, but after working with it for a long time, I have come to the conclusion that this is the only powerful fuel that can be obtained without much difficulty compared to perchlorate. And the lower sorbitol content makes it a little more profitable to use, unless of course your sulfur is cheaper than sorbitol. From the first time, you will not be able to cook it the way you need it, but in the course of long work with it, you will really see the difference. It may seem to you that this method of making this fuel is unsafe, but in all my practice there has not been a single state of emergency, because I strictly observe the purity of reagents and do not allow substances that ignite below 2000C. With strict observance of the cleanliness of the workplace, this method is relatively safe.

Attention! If you have any comments, questions or suggestions on this topic, please let me know.

The engine diagram is shown in Fig.1. And now the first rule:

1) do nothing "by eye".

You need a simple set of measuring and drawing tools: ruler, caliper, pencil.

The engine casing is made from 10 layers of high quality office paper. To do this, two strips 69 mm wide are cut to length from a standard A4 sheet. Next, a mandrel is taken - even, smooth and durable, preferably metal, a rod (or tube) with a length of more than 80 mm and a diameter of 15 mm. To prevent the case from sticking to the mandrel, you can cut a piece of wide tape along the length of the mandrel and roll it onto the mandrel in the transverse direction. Then strips of paper are sequentially wound onto the mandrel, which, during the winding process, are abundantly, without gaps, smeared with silicate glue. Of course, it is not necessary to coat the side of the first turn adjacent to the mandrel with glue.

It is necessary to wind, or rather, roll the paper on a hard, even surface, so that the turns lie on top of each other with little or no shift and very tightly, without bubbles. Lay down a sheet of newspaper to not only keep the surface clean, but also to remove excess glue released during the knurling process. To avoid shifting the turns, I recommend that you first roll the strip “dry” so that it goes correctly, then make a neat “rollback” to the first turn without lifting the mandrel from the table, then start rolling again with glue. Be sure to coat the initial edge of the strip so that it sticks clearly on the first turn. Of course, some experience is needed for this operation to succeed. However, do not throw out substandard cases. They are useful for adjusting the diameter of the nozzle, plug, for the manufacture of various conductors and retaining rings. After the strips are glued, you can roll the body on the mandrel with a flat board to seal the turns. This must be done only in the direction of winding.

After that, it's a good idea to drive the still raw case through the outer mandrel - a metal cylinder with an internal diameter of 18 mm. The engine body must pass through this mandrel tightly enough, this must be achieved without fail, since in the future it will be necessary to stuff the body with fuel, which cannot be done without a tightly seated external mandrel. If such a tube cannot be found, it will be necessary to make an external mandrel by winding at least 15 layers of office paper on an already finished engine case, also on silicate glue. Having slightly dried the case, it is necessary to remove it from the mandrel by first turning it against the winding. Further, until the body is completely dry, it is necessary to insert the finished nozzle on one side. For this, of course, it is necessary that the nozzle has already been prepared.
So, we make a nozzle. I recommend making two nozzles at once, then it will be clear why. It is usually easy to find a wooden rod with a diameter of 16-18 mm, preferably from hard wood like beech or hornbeam. We carefully end it, i.e. we make a smooth cut perpendicular to the axis at one end. To do this, it is necessary to cut off an even strip of drawing paper, ~ 100 mm wide and tightly wind it onto the rod exactly a coil over a coil. Along the edge of this winding, gradually turning the rod and holding the paper in place, we make a circular cut. Lightly sanding the place of saw cut, we get a clear butt. Here we come close to the second rule, which follows directly from the first:

2) for any operations requiring geometric accuracy, use all kinds of mandrels, templates, conductors.

Having tortanav a piece of wood, according to the same scheme, we saw off a cylinder 12 mm high from it. In this blank, in the center along the axis, we drill a hole with a diameter of 4.0 mm. It is better to do this on a drilling machine, at least made from a drill with a special drilling stand. It is not too expensive, but allows you to do vertical drilling. If there is no such device, you can use any simple jig, in the end, do the drilling manually. In this case, special accuracy is not needed, since the chip is in the following technology. It will not be possible to drill the workpiece in the center even on a drilling machine. Therefore, I simply put the workpiece on the M4 stud and clamp it with nuts on both sides.
Then, holding the drill in the chuck, I grind it to the desired diameter (15 mm) with a file and sandpaper. If there are deviations from the perpendicular direction relative to the axis of the end surfaces, this can also be corrected during turning. The drill for this must, of course, be somehow fixed on the table, such devices are also on sale. After such an operation, the nozzle opening is exactly in the center. On the side surface of the nozzle, also on the drill, in the center we make a groove with a square or round needle file 1.0-1.5 mm deep. Diameter adjustment is best done by having an engine case blank, which can be substandard, which you will have during the production process. Finally the nozzle is ready. It does not differ in heat resistance and during the operation of the engine it burns out to a diameter of 6 - 6.5 mm. Some call such engines even nozzleless. I would not entirely agree with this, since this simplest nozzle still provides a clearly directed starting thrust vector. In addition, such a nozzle “automatically” regulates the pressure in the engine, allowing you to forgive some mistakes of novice rocket modellers.
Now we need to make a stub. This is the same nozzle, but without the central hole. Here you can come up with different manufacturing technologies. The easiest way is to use another nozzle as a plug, only under it during assembly you will have to put, for example, a Soviet penny, its diameter is just 15 mm, or fill the hole with epoxy after installation in the case. In addition, it is useful for centering the main nozzle.

The first step in assembling the engine is installing the nozzle. This must be done while the case is not yet dry, i.e. almost immediately after winding. The nozzle is installed in the body from one end on silicate glue flush with the edge of the body.
Here we come to the third rule:

3) strictly observe the alignment of all central channels and the axial symmetry of all parts of the rocket.

Of course, this rule is intuitive, but it is often forgotten about.

There are no guarantees that the nozzle channel is directed strictly along the axis, so we make the simplest jig. To do this, on the opposite side of the engine housing, we insert another nozzle (which we prepared for the plug), without glue, of course, and connect both nozzles with a metal rod with a diameter of 4.0 mm. Consistency is guaranteed.
The pressure when working in such a simple engine can reach 10 atmospheres, so we won’t hope that the glue will hold the nozzle, but we will do the so-called “constriction”. To do this, we make a circular line on the body, retreating 6mm from the edge of the engine from the side of the nozzle, thus marking the position of the side groove of the nozzle.

Next, we take a strong nylon rope 3-4 mm thick, tie it to something firmly fixed, for example, to a weight of 20 kg, which I still hold with my foot. We make one turn of the rope along the marked line and, holding the slider perpendicular to the rope, pull it strongly. In order not to cut your hand, you can tie a stick to the end of the rope. We repeat the operation several times, turning the engine relative to the axis, until a clear constriction groove is formed. We coat it with glue and wind 10 turns of cotton thread No. 10. Coat the thread on top again with glue. It is very convenient to use a fishing knot to tie a thread. Now we can consider the nozzle fully installed, you just need to thoroughly dry the engine housing for at least a day.

Rocket modellers call a classic a fuel consisting of 35% sorbitol and 65% potassium nitrate by weight, without any additives. This propellant is quite well studied, has characteristics no worse than black powder, but it is much easier to make than the correct gunpowder.
For the classics, only potassium nitrate is suitable. If you do not find it on sale, you will have to make it yourself from sodium or ammonia and potassium sulfate or chloride. All this is easy to buy in stores,
selling mineral fertilizers. Previously, potash (potassium carbonate) was also sold in photo stores, it is also suitable for obtaining potassium nitrate from ammonium nitrate. When mixing hot saturated solutions of sodium nitrate and potassium chloride, potassium nitrate will immediately precipitate. Homemade saltpeter will have to be cleaned by recrystallization, for this it must be dissolved in a small amount of hot boiled water, filtered through cotton wool and put in the refrigerator. Then drain the solution, dry the saltpeter on a battery, and then in the oven at about 150 ° C for one to two hours. The main thing here is the observance of the temperature regime. At a higher temperature, the saltpeter will melt and become unsuitable for the further process. Sorbitol (sugar substitute] is sold both in pharmacies and grocery supermarkets. The melting point of pure sorbitol is 125 ° C, and at this temperature it can be distinguished from sorbitol monohydrate, which is sometimes also sold under the guise of sorbitol. The monohydrate melts at 84 ° C and not good for fuel.
Despite the frivolous name, caramel rocket fuel is primarily rocket fuel and should be handled with respect. The first and most important safety rule - in any case, do not cook caramel on an open fire! Only an electric stove with a closed heater and a temperature controller. If there is no suitable electric stove, you can use a regular iron, you just need to make a stand that holds it upside down, with the sole up. The three-point setting is great for making caramel.
Do not measure components by eye or by volume - only on the scales. In appearance, heaps of 35 g of sorbitol and 65 g of potassium nitrate are almost the same in volume. And this is to our advantage, since it is easier to mix the fuel. If the saltpeter is large, it will have to be crushed in a mortar or ground in a coffee grinder. But do not overdo it: the crystals should be like fine salt - if you grind saltpeter into dust, it will be difficult to work with fuel, as it will become too viscous. 20 seconds is what you need.
Now you can mix the powders of saltpeter and sorbitol and lay out a layer no more than a centimeter thick in a pan. It is desirable to stir the mixture continuously. For mixing, it is convenient to use a wooden popsicle stick. Gradually, sorbitol will begin to melt, after a while, as it is stirred, the powder will turn into a homogeneous substance, similar to liquid semolina. Part of the saltpeter dissolves in molten sorbite, so the finished fuel remains quite liquid even at 95°C. The fuel should not be overheated, because at 140 ° C the solubility of nitrate increases abruptly and the viscosity of this composition also increases abruptly.
As soon as the last lumps of saltpeter are stirred, the fuel is ready - now it must be poured into the mold. Perfect simplicity! It would be nice to make the engine as simple as possible, and such an option exists - if record parameters are not required, a nozzleless one becomes preferable. It consists only of a case and a charge. Although some of the fuel energy is wasted without a nozzle, by saving the weight of the body and nozzle, more fuel can be poured and the losses can be compensated.
For the case you will need a cardboard tube with a wall thickness of 1-2 mm. Its diameter can be from a centimeter to three, but for the first experiments it is better to take not the smallest one, since it is inconvenient to work with small engines - and the fuel solidifies faster, and it is difficult to pack it into a small tube. Its length should be 7-15 times the diameter. It is possible at 20, but it is already very inconvenient to fill in fuel.
You will also need a rod to form a channel in the fuel - in caramel engines, the fuel burns on the surface of the channel, and not from the end of the charge, there is not enough area at the end. And to center the rod, you need a wooden or plastic boss, suitable in diameter for both the cardboard tube and the central rod. The diameter of the channel should be approximately three times smaller than the inner diameter of the pipe.
Inserting the boss into the lower end of the pipe and the rod into it, fill the remaining space with “semolina porridge” from saltpeter and sorbitol. The fuel cools and solidifies, but not completely. From its remains it is necessary to roll up a sample stick - usually the size of a man's little finger. It is used to measure the burning rate of the resulting fuel - for this, it is filmed and the time is recorded on the video. Of course, the length of the stick must be measured before ignition. Normally made sorbitol caramel should burn at a speed of 2.6 to 2.8 mm / s, that is, a stick 5 cm long will burn in 17-19 s.
After about six hours - while the fuel is still soft - you need to remove the boss and rod. It remains to make a plug of epoxy resin where the boss was: stick a circle of adhesive tape on the exposed surface of the fuel to cover the channel, and make a side around the cardboard tube from adhesive tape, then pour epoxy resin with a hardener into it. The resin level should be 0.5 cm above the edge of the tube so that the resin is absorbed into the end. Sometimes they do
three or four 3 mm holes in the fuel-free part of the tube to better hold the epoxy plug.
After the glue has hardened, the engine is ready to start. Chinese “electric matches” sold in online stores are great for igniting it, you just need to lengthen the wires and insert the fuse into the engine all the way, to the epoxy plug - if the engine lights up in the middle, it will not give out full thrust.
But, having flown on the “classic”, a rocket enthusiast often feels the need to somehow improve it. This is where the invention of different compositions and technologies begins. The magic word "perchlorate" excites the hearts of homemade designers. But it will not work to directly replace potassium nitrate with potassium perchlorate - the fuel will have different characteristics. Without the third component - the catalyst - the composition demonstrates pulsating combustion up to the explosion. And it is dangerous to melt fuel with a catalyst, so you have to use heated vacuum pressing and other exotic things.