Do-it-yourself rocket stove for the home. Do-it-yourself rocket stove

Dear visitors of the site "", today we will consider detailed instructions for self-assembly of a camping stove-rocket with your own hands without the use of welding. The jet stove appeared relatively recently and was invented abroad, but in a short period of time it gained people's love and respect in our country, especially among tourists, fishermen and hunters, and of course this stove is distinguished by its economy in consuming firewood and giving off the maximum amount of heat at the output due to jet thrust created by the furnace design itself. With its help, you can cook food in a short time, boil a kettle, which is very important in a hike.

Design jet furnace very simple - it is a vertically located pipe (it is also a body and a chimney) and a firebox adjoining at an angle, divided inside by a plate into two parts (top for loading firewood, bottom for air access to the combustion source) thus a jet draft is formed, hence the loud name « «.

The presented furnace is made with the expectation of compactness, since every gram of cargo and space in a backpack is very important on a hike. For its manufacture, a used helium cylinder was taken (a fire extinguisher can be used), its upper part was sawn off, and a technological hole was sawn on the side for installing the firebox, the design is completely collapsible and all parts are in the stowed position inside the case. We remind you that during its manufacture a welding machine is not needed, which simplifies the creation process to the maximum.

Let's look at all the stages of assembling a jet furnace.

materials

helium tank or used fire extinguisher
square pipe
metal perforated plate
bolts and nuts
metal sheet 1-2 mm

Tools

Bulgarian (UShM)
drill
pliers
heat resistant paint can

Step-by-step instructions for creating a camping jet rocket furnace.

To begin with, let's look at the drawing of the domestic Robinson stove, which is also an excellent design, but welded, and the one below is much more versatile and is rightfully considered a camp stove.

First of all, you need to find a used helium cylinder or an old fire extinguisher, bleed off the remaining contents, unscrew the valve and rinse with water, then cut off the upper part, and also make a technological hole in the lower part for installing a square pipe firebox.

We make a grate from a perforated plate.
Support legs for firebox.
We collect all the details into a single whole.

A pointed metal pin is screwed in the lower part, it is necessary so that when the furnace is installed in its working position, it stands firmly on the ground, and this stake is buried in the ground. In the stowed position, it twists. From sheet metal 1-2 mm cut out the comforter.

By the way, the pin is in the stowed position.
Also, in addition to the components from the stove, you can put a small supply of dry firewood in the cylinder, which can be very helpful in wet and rainy weather. Just imagine .. you went camping and you were caught in heavy rain, everything around you got wet, damp and disgusting, and you calmly take out your camping stove-rocket and make a fire, cook food, boil a kettle and everything is fine with you 😉
Additionally, a cable was pulled to fix the firebox.
Here is such a wonderful oven turned out, its advantage is that it is economical, compact, collapsible.

This design is made without the use of welding, which greatly simplifies the assembly process for those people who do not have welding machine or does not know how to use welding. We hope our material was useful to you. You can also watch a video of the oven in action. Happy viewing!

Let's say right away: rocket stove - a simple and convenient heating and cooking device for wood fuel with good, but not exceptional parameters. Its popularity is explained not only by the catchy name, but more so by the fact that it can be made with your own hands and not by a stove-maker or even a bricklayer; if necessary - literally in 15-20 minutes. And also by the fact that, having invested a little more work, you can get an excellent couch in the house without resorting to the construction of a complex, expensive and cumbersome or. Moreover, the very principle of the device of the rocket furnace gives great freedom to design and the manifestation of creative abilities, see fig.

But perhaps more remarkable is the "jet furnace" by the huge number of associated, at times completely absurd inventions. Here, for example, are a few pearls snatched at random:

"The operating principle of the furnace is the same as that of the MIG-25 ramjet engine." Yes, the MIG-25 and its descendant MIG-31 did not sit down near the ramjet engine (ramjet), as they say, and did not sit down in the bushes. On the 25th and 31st there are bypass turbojet engines (turbojet engines), four of which then pulled the Tu-144 and still pull other cars. And any oven with any jet engine(RD) - technical antipodes, see below.
"Reverse jet furnace". Is this a tail-first stove, or what?
“But how will she blow such a pipe?” A naturally aspirated stove does not blow into the chimney. On the contrary, the chimney pulls out of it, on natural draft. The higher the pipe, the better it pulls.
“The rocket stove is a combination of a Dutch bell-type stove (sic!) with a Russian stove bench.” Firstly, there is a contradiction in the definition: a Dutch oven is a channel oven, and any bell-type oven is anything but a Dutch oven. Secondly, the couch of the Russian stove warms up in a completely different way than the rocket stove.

Note: in fact, the rocket stove was nicknamed so because in the wrong mode of the furnace (more on that later), it emits a loud whistling rumble. A properly tuned rocket stove whispers or rustles.

These and similar inconsistencies, of course, are confusing and prevent us from making a rocket furnace properly. So let's figure out what is true about the rocket stove, and how to use this truth correctly so that this really good stove shows all its advantages.

Furnace or rocket?

For complete clarity, we still need to figure out why a stove cannot be a rocket, and a rocket cannot be a stove. Any RD is the same internal combustion engine, only the outflowing gases themselves act as pistons, connecting rods with a crank and transmission. In a piston internal combustion engine, already at the moment of combustion, the high temperature of the working fluid creates a large pressure that pushes the piston, and it already moves the entire mechanics. The movement of the piston is active, the working fluid pushes it to where it tends to expand itself.

When fuel is burned in the RD combustion chamber, the thermal potential energy of the working fluid is immediately converted into kinetic energy, like that of a load falling from a height: since the exit to the nozzle is open to hot gases, they rush there. In RD, pressure plays a subordinate role and nowhere exceeds a few tens of atmospheres, this, for any conceivable nozzle cross section, is not enough to disperse a flashlight to 2.5M or put a satellite into orbit. According to the law of conservation of momentum (momentum) aircraft with RD at the same time receives a push in reverse side(recoil momentum), this is jet thrust, i.e. thrust from recoil, reactions. In a turbofan engine, the second circuit creates an invisible air shell around the jet. As a result, the recoil momentum is, as it were, contracted in the direction of the thrust vector, so the turbofan is much more economical than a simple turbofan.

In the furnace, there is no conversion of types of energy into each other, therefore it is not an engine. The stove simply distributes the potential heat energy properly in space and time. From the point of view of the furnace, the ideal RD has an efficiency of 0%, because it just runs on fuel. From the point of view of a jet engine, the furnace has an efficiency = 0%, it only dissipates heat and does not pull at all. On the contrary, if the pressure in the chimney rises to or above atmospheric (and without this, where will the jet thrust or active force come from?), The stove will at least smoke, or even poison the residents or start a fire. Draft in the chimney without pressurization, i.e. without the expenditure of energy from the side, it is provided due to the temperature difference along its height. Potential energy here, again, is not converted into any other.

Note: in a rocket-propelled rocket engine, fuel and oxidizer are fed into the combustion chamber from tanks, or they are immediately filled into it if the rocket engine is on solid fuel. In a turbojet engine (TRD), the oxidizing agent - atmospheric air - is injected into the combustion chamber by a compressor driven by a turbine in the exhaust gas flow, the rotation of which consumes a certain fraction of the energy of the jet stream. In a turboprop engine (TVD), the turbine is designed so that it takes 80-90% of the power of the jet, which is transmitted to the propeller and compressor. In a ramjet engine (ramjet), air is supplied to the combustion chamber by hypersonic velocity pressure. A lot of experiments were carried out in the ramjet, but there were no production aircraft with it, there is not and is not expected, the ramjet is painfully capricious and unreliable.

Can or not can?

Among the myths about the rocket stove, there are not entirely absurd, and even somewhat justified. One of these misconceptions is the identification of the "racquet" with the Chinese kan.

As a child, the author had a chance to visit the Amur region, in the region of Blagoveshchensk, in winter. There were a lot of Chinese there in the villages, and then there lived a lot, who scrabbled where from cultural revolution Great Chairman Mao and his completely frostbitten Red Guards.

Winter in those parts is not Moscow, frost at -40 is a common thing. And what struck and aroused interest in stoves in general was how Chinese fanzes were heated by kanami. In Russian villages, firewood is transported by carts, smoke is a pillar from the chimneys. And all the same, in the log hut, not in a children's girth, by morning the corners were frosted over from the inside. And the fanza is built like country house(see fig.), the windows are covered with fish bladder or even rice paper, bunches of chips or twigs are placed in the kan, but the room is always warm.

However, there are no subtle heat engineering tricks in the canal. This is an ordinary, only small, stove with a lower exit to the chimney, and most of the chimney itself is a long horizontal channel, a hog, on which a stove bench is arranged. The chimney, for the sake of fire safety, is outside the building.

The effectiveness of the kan is determined primarily by the thermal curtain it creates: the couch goes around, if not the entire perimeter from the inside, except for the door, then 3 walls for sure. Which once again confirms: the design and parameters of the furnace must be linked to those of the heated room.

Note: The Korean ondol oven operates on the principle of a warm floor - a very low stove bench occupies almost the entire area of the room.

Secondly, in the very cold, the Kans were drowned with argal - dried droppings of ruminants, domestic and wild. Its calorific value is quite high, but argal burns slowly. In fact, an argal fire is already a long-burning stove.

It is not in the Russian custom to stick twigs into the oven every now and then, and our peasants abhorred cooking on animal feces. But travelers of the past highly valued argal as a fuel, collected it along the way and carried a supply with them, diligently protecting it from getting wet. N. M. Przhevalsky, in one of his letters, argued that without the argal, he could not have carried out his expeditions in Central Asia without loss. And for the British, who were disdainful of the argal, 1/3-1/4 of the personnel of the detachments returned to the base. True, he was recruited from sepoys, Indian soldiers in the English service, and pandits - spies recruited from the local population. One way or another, but the highlight of the rocket stove is not at all in the couch on the hog. To get to it, you will have to learn to think in an American way: all the primary sources on the rocket furnace are from there, and utter speculation is generated only and only by misunderstanding.

How to deal with rockets?

From our point of view, one should study the original technical documentation of rocket furnaces with caution, but not at all because of inches-millimeters, liters-gallons and the subtleties of American technical jargon. Although they also mean a lot.

Note: a textbook example is "Naked conductor runs under the carriage". Literary translation - a naked conductor runs under the car. And in the original article from Petroleum Engineer, it meant "Bare wire runs under the crane trolley."

The Rocket Oven Was Invented by Members of Survival Societies- people with a peculiar way of thinking, even by American standards. In addition, they were not bound by any standards and norms, but, like all Americans, they always automatically converted everything into money, taking into account their own benefit; a person with a different worldview in America simply does not get along. And instinctive self-interest inevitably gives rise to egocentrism. He by no means excludes good deeds, but not out of a spiritual outburst, but out of the calculation of dividends. Not in this life, but in that one.

Note: How much the average inhabitant of the greatest empire in history is afraid of everything can be understood only after talking with them long enough. And sociopsychologists go out of their way there, convincing that living, languishing in fear, is normal and even cool. The rationale is clear: intimidated biomass is easily predictable and manageable.

Without heating and cooking, of course, you will not survive. What is an oven for? For the time being, for the time being, the survivors were content with camping stoves. But then, according to the Americans themselves, in 1985-86. they were greatly impressed by two films that were released with a short interval and triumphantly went around all the screens of the world: the Soviet science fiction parody of the entire human race "Kin-dza-dza" and Hollywood's "The Day After", about the global nuclear war.

The survivors realized that after the nuclear winter there would be no extreme romance, but there would be the planet Plyuk in the Kin-dza-dza galaxy. It will be necessary to be content with the newly appeared plukans "ka-tse" in small quantities, bad, expensive and difficult to access. Yes, all of a sudden someone hasn’t watched “Kin-dza-dza” - like a match in Plukansky, a measure of wealth, prestige and power. It was necessary to invent your own furnace, none of the existing ones is designed for a post-nuclear spit.

Americans are very often endowed with a sharp mind, but a deep one is found as the rarest exception. A completely normal and with an IQ above the average, a US citizen may sincerely not understand how it doesn’t reach another that he himself has already “caught up” and how someone else may not like what suits him.

If an American has already understood the essence of an idea, then he brings the product to its possible perfection - what if there is a buyer, you can’t sell raw iron. But the technical documentation, which looks beautiful and neat, can be drawn up in fact extremely carelessly, or even deliberately distorted. And what is it, this is my know-how. Maybe I'll sell it to someone. Whether there will be a plus, or not, but for now the know-how is worth the money. In America, such an attitude to business is considered quite honest and worthy, but there a clinical alcoholic at work will never miss a stopper and will not drag a couple of bolts home to the household. On that, in general, the whole of America stands.

And the Russian breadth of the soul is also a double-edged sword. Most often, our master simply understands from a sketch how this thing works, but in the details it turns out to be careless and overly trusting in the source code: how is it for a crafty brother to deceive his own. If you don't have something, then you don't need it. It seems clear how everything is spinning there - already my hands itch. And there, perhaps, until it comes to a hammer, chisel and related literature, still count and count. Yes more important points may be omitted, veiled, or deliberately false.

Note: An American acquaintance once asked the author of this article - how did we, the really stupid ones, elect the very smart Reagan as president? And you, really smart, tolerate a slobbering senile with dyed eyebrows in the Kremlin? True, then in America no one in a bad dream would have dreamed that in the next century a black citizen with a Muslim name would settle in the Oval Office, and his first lady would dig a garden near the White House and begin to grow turnips there. Times is changing, as Bob Dylan once sang for a completely different reason ...

Sources of misunderstanding

There is such a thing in technology - the square-cube law. Simply put, when something changes in size, its surface area changes squarely, and its volume changes cubed. Most often, this means that changing the overall dimensions of the product according to the principle of geometric similarity, i.e. You can't just keep the proportions. With regard to solid fuel stoves, the square-cube law is doubly valid, because fuel is also subject to it: it releases heat from the surface, and its reserve is contained in the volume.

Note: a consequence of the square-cube law - any specific design of the furnace has a certain allowable fork of its size and power, within which the specified parameters are provided.

Why, for example, can not be made the size of a refrigerator and a power somewhere that way at 50-60 kilowatts? Because the potbelly stove, in order for it to somehow warm, must itself be heated inside to at least 400-450 degrees. And in order to warm up the volume of the refrigerator to such a temperature at a given heat transfer, firewood or coal needs as much as it does not fit in it. There will also be no sense from a mini-potbelly stove: the heat will leave through the outer surface of the furnace, which has grown relative to its volume, and the fuel will not give it away more than it can.

The square-cube law acts triple on the rocket furnace, because she is "licked" in an American professional way. With our kondachka, it is better to stay away from her. Here, for example, here in Fig. American development, which, judging by its demand, many of our craftsmen take as a prototype.

With the fact that the exact grade of refractory clay (fire clay) is not indicated here, ours will sort it out. But, to be honest, who noticed that, judging by the absence of an external chimney and the presence of transportation holes (carrying pipe), this stove is mobile with an open firebox? And most importantly, the fact that a 20-gallon keg with a diameter of 17 inches (431 mm with change) went to her drum?

Judging by the structures from Runet, no one at all. They take this thing and adjust it according to the principle of geometric similarity to a domestic 200-liter barrel with a diameter of 590 mm on the outside. Many guess to arrange a blower, but the bunker is left open. Are the exact proportions of vermiculite with perlite for lining the riser and forming the furnace body (core) not specified? We make the lining homogeneous, although it will be clear from what follows that it should consist of insulating and accumulating parts. As a result, the furnace roars, the fuel eats only dry, and a lot, and even before the end of the season, it overgrows with burning inside.

How was the rocket oven born?

So, already without science fiction with futurology, the survivors needed high-efficiency home heating stove with low-quality random wood fuel: wet wood chips, twigs, bark. Which, moreover, will need to be reloaded without stopping the furnace. And most likely it will not be possible to dry in a firewood shed. Heat dissipation after heating needs at least 6 hours to get enough sleep; getting pissed off in a dream on Pluka is no better than in America. Additional conditions: the design of the furnace should not contain complex metal products, non-metallic materials and assemblies that require production equipment, and the furnace itself should be available for construction by an unskilled worker without the use of power tools and complex technologies. Of course, no supercharging, electronics and other energy dependencies.

They immediately took a couch from the kan, but what about the fuel? For a bell-type furnace, it requires high quality. Long-burning furnaces work even on sawdust, but only dry, and do not allow shutdown with additional loading. Nevertheless, they were taken as a basis, they were very attracted by the high efficiency achieved in simple ways. But in an attempt to make the "long stoves" work on bad fuel, another circumstance became clear.

What is wood gas?

High efficiency is achieved largely due to the afterburning of pyrolysis gases. Pyrolysis is the thermal decomposition of solid fuel into volatile combustible substances. As it turned out (and the survivors have their own research centers with highly qualified specialists), the pyrolysis of wood fuel, especially wet fuel, continues for a long time in the gas phase, i.e. The pyrolysis gases that have just been released from the wood still require quite a lot of heat to form a mixture that can burn out completely. This mixture was called wood gas, woodgas.

Note: in RuNet, woodgas has created more confusion, because in American vernacular, gas can mean any fuel, cf. ex. gas station gas station, refueling. When translating primary sources without knowing the American technical, it turned out that woodgas is just wood fuel.

Before that, no one saw wood gas: in conventional furnaces, it is formed immediately in the furnace, due to the excess energy of fiery combustion. The designers of long-burning stoves came to the conclusion that the primary air must be heated, and the exhaust gases should be retained in a significant volume over a large mass of fuel, simply by trial and error, so they overlooked the wood gas.

It turned out not so when firing with bundles of twigs: here the primary pyrolysis gases were immediately dragged into the chimney. Wood gas could have formed in it at some distance from the furnace, but the primary mixture had cooled by that time, pyrolysis stopped, and heavy radicals from the gas settled on the walls of the chimney like soot. Which quickly tightened the channel completely; amateurs building rocket furnaces at random are well familiar with this phenomenon. But the survivors eventually figured out what was going on and made the right oven anyway.

Who are you, the Rocket Stove?

There is an unspoken rule in technology: if it seems that it is impossible to create a device according to the given requirements, then read, smart guy, school textbooks. That is, go to the basics. In this case, to the basics of thermodynamics. Survivors do not suffer from sick pride, they turned to the basics. And found main principle operation of its furnace, which has no analogues in others: slow adiabatic post-combustion of pyrolysis gases in a low flow. In long-burning furnaces, afterburning is equilibrium isothermal, requiring a large buffer volume, subject to the square-cube law, and the energy reserve in it. In pyrolysis gases in the afterburner expand almost adiabatically, but practically into free volume. And now - learn to think in an American way.

How does a rocket oven work?

The scheme of the final fruit of the labors of the survivors is presented on the left side of fig. Fuel is loaded vertically into the bunker (Fuel Magazine) and burns, gradually settling down. Air enters the combustion zone through the blower (Air Intake). The blower must provide an excess of air so that it is enough for afterburning. But not excessive, so that the cold air does not cool the primary mixture. With vertical loading of fuel and a blind cover of the bunker, the flame itself acts as a regulator, however, not very effective: when it flares up too much, it pushes the air out.

Further things already non-trivial begin. We need to warm up, and with good efficiency, a large oven. The law of the square-cube does not allow: the meager heat will immediately dissipate so much that the pyrolysis will not reach the end, and the thermal gradient from the inside to the outside will not be enough to transfer heat into the room; everything will whistle through the trumpet. This law is harmful, you can't break it in the forehead. Okay, let's see in the basics, if there is anything there that is not subject to him.

But how, there is. That same adiabatic process, i.e. thermodynamic without heat exchange with the environment. There is no heat exchange - the squares are resting, and the cubes can be reduced even to a thimble, even to a skyscraper.

Imagine a completely isolated volume of gas. Let's say it releases energy. Then the temperature and pressure will begin to rise until the energy release stops, and will freeze at a new level. Great, we burned the fuel completely, hot flue gases can be released into a heat exchanger or heat accumulator. But how to do it without technical difficulties? And most importantly - how, without violating the adiabat, to supply air for afterburning?

And we will make the adiabatic process non-equilibrium. How? Let the primary gases immediately from the combustion source go into a pipe covered with high-quality insulation with a low intrinsic heat capacity (Insulation). Let's call this pipe for ourselves a flame or a burning tunnel (Burn Tunnel), but we will not sign it (know-how! You can’t catch up - give money for consulting drawings! Without theory, of course. Who sells the fixed capital at retail.) On the diagram, so that not accused of "opacity", denoted by the flame.

Along the length of the flame tube, the adiabatic index changes (this is a non-equilibrium process): the temperature will first drop slightly (wood gas is formed), then it will increase sharply, the gas will burn out. It is possible to release it into the accumulator, but we forgot - what will pull gases through the flame tube? Supercharging means energy dependence, and there will be no exact adiabat, but something mixed with an isobar, i.e. the efficiency drops.

Then we will lengthen the pipe by half, keeping the insulation so that the heat does not go in vain. We bend the “idle” half up, making the insulation weaker on it; how to keep the heat seeping through it, we will think a little later. In a vertical pipe, a temperature difference will appear along the height, which means thrust. And good: the thrust force depends on the temperature difference, and with an average in the flame tube of about 1000 degrees, it is not difficult to achieve a difference of 100 at a height of about 1 m. So, while we have made a small economical potbelly stove, now we need to think about how to use it warmly.

Yes, it does not interfere with additional encryption. If we call the vertical part of the flame tube the primary or internal chimney (Primary or Internal Vent), then they will guess the main idea, we are not the smartest in the world. Well... let's call the primary chimney the most common technical term for vertical pipes with upward current - the riser (riser). Purely American: correct and incomprehensible.

Now let's recall the heat transfer after heating. Those. we need a cheap, always available and very capacious heat storage. There is nothing to invent here, the adobe (Thermal Mass) was invented by the primitives. But it is not fire resistant, it does not hold more than 250 degrees, and we have about 900 at the mouth of the riser.

It is not difficult to convert high-potential heat into medium-potential heat without loss: you need to give the gas the opportunity to expand in an isolated volume. But, if the expansion is left adiabatic, then the volume will need to be too large. And that means - material and labor intensive.

I had to bow to the basics again: immediately after leaving the riser, let the gases expand at constant pressure, isobarically. This requires heat to be removed to the outside, about 5-10% of the heat output, but it will not disappear and will even be useful for quickly warming up the room during the morning fire. And further along the course of gases - isochoric cooling (in a constant volume); Thus, almost all the heat will go into the battery.

How to do it technically? We cover the riser with a thin-walled iron drum (Steel Drum), which will also stop heat loss from the riser. The “drum” turns out to be a bit high (the riser sticks out a lot), but it doesn’t matter: we will cover it with the same adobe for 2/3 of the height. We attach a stove bench with an airtight chimney (Airtight Duct), an external chimney (Exhaust Vent), and the stove is almost ready.

Note: the riser and the drum covering it look like an oven hood over an elongated hail. But the thermodynamics here, as we see, is quite different. It is useless to try to improve the bell-type stove by building on a high loft - only the extra material and work will go away, and the stove will not get any better.

It remains to solve the problem of cleaning the channel in the couch. For this, the Chinese have to break the kan from time to time and remake it, but we are not in the 1st century. BC. we live when kan was invented. We will arrange a secondary ash pan (Secondary Airtight Ash Pit) with a sealed cleaning door immediately after the drum. Due to the sharp expansion and cooling of flue gases in it, everything in them that did not burn out immediately condenses and settles. The cleanliness of the external chimney is guaranteed by this for years.

Note: the secondary cleaning will have to be opened once or twice a year, so you don’t have to fool around with the latches. We will simply make a cover from a metal sheet on screws with a mineral cardboard gasket.

small rocket

The next task of the designers was to create on the same principle a small continuous combustion oven for cooking in the warm season. In the heating season, the drum cover (Optional Cooking Surface) of a large oven is suitable for cooking, it heats up to about 400 degrees. The small rocket stove was supposed to be portable, but it was permissible to make it with an open firebox, because. when warm, you can cook outdoors or under a canopy.

Here the designers took revenge on the square-cube law, forcing it to work for themselves: they combined the fuel tank with the blower, see Fig. at the beginning of the section on the right. It is impossible to do this in a large furnace, fine adjustment of the furnace mode as the fuel settles (see below) will be impossible.

Here, the volume of incoming primary air (Primary Air) turns out to be small relative to the heat release area, and the air can no longer cool the primary mixture until pyrolysis stops. Its supply is regulated by a slot in the cover of the hopper (Cover Lid). The 45-degree hopper optimizes the oven's auto-adjustment for standard cooking routines, but it's harder to make.

Secondary air for afterburning wood gas in a small oven enters through additional holes in the mouth of the riser or simply flows under the burner if there is a cooking vessel on it. If a small furnace is close to the limit size (about 450 mm in diameter), then an optional secondary woodgas frame may be needed for complete afterburning.

Note: it is impossible to supply secondary air to the mouth of the riser of a large furnace through the holes in the drum (which would increase the efficiency of the furnace). Although the pressure in the entire gas-smoke path is lower than atmospheric pressure, as it should be in the furnace, flue gases will be emitted into the room due to strong turbulence. Here their kinetic energy, harmful to the furnace, affects; this, perhaps, is the only thing that makes a rocket stove related to a jet engine.

The small rocket stove has revolutionized the class of camping stoves, especially camping stoves. A wood chip stove (a Bond stove in the West) will help to cook a stew or wait out a snowstorm in a one-two-man tent, but it will not save a group caught on a spring campaign by a belated bad weather. A small rocket furnace is only a little larger, it can be quickly made from nowhere, but is capable of developing power up to 7-8 kW. However, we will talk about furnace-rockets from anything we will talk further.

Also, the small rocket oven has spawned many improvements. For example, Gabriel Apostol provided it with a separate blower and a wide bunker. The result was a stove suitable for the device of a compact and rather powerful water heater, see the video below. The large rocket furnace was also modified, we will talk about this a little at the end, but for now let's dwell on more significant things.

Video: a water heater based on a rocket stove designed by Gabriel Apostol

How to fire a rocket?

A rocket furnace with long-burning furnaces has a common property: you need to run them only on a warm pipe. For a small one, this is not essential, but a large one on a cold chimney will only burn fuel in vain. Therefore, a large rocket furnace, before loading regular fuel into the bunker after a long break in the furnace and kindling, must be accelerated - fired with paper, straw, dry shavings, etc., they are placed in an open blower. The end of acceleration is judged by a change in the tone of the hum of the furnace or its subsidence. Then you can load fuel into the bunker, and its ignition will occur by itself from the accelerating fuel.

The rocket furnace, unfortunately, does not apply to furnaces that are completely self-adjusting to the quality of the fuel and external conditions. At the beginning of regular fuel combustion, the blower door or the bunker cover in the small furnace is fully opened. When the stove hums strongly, cover it "to a whisper." Further, in the process of burning, it is necessary to gradually cover the access of air, guided by the sound of the stove. Suddenly, the air damper slammed shut for 3-5 minutes - it's okay, if you open it, the stove will flare up again.

Why such difficulties? In the process of burning the fuel, the flow of air into the combustion zone increases. When there is too much air, the stove roars, but don't be happy: now the excess air cools the primary gas mixture, and the sound is amplified as the steady swirl in the riser clumps into a disorderly lump. Pyrolysis in the gas phase is interrupted, no wood gases are formed, the furnace consumes too much fuel, and carbon deposits from the soot cemented by bituminous particles are deposited in the riser. This, firstly, is a fire hazard, but most likely it will not come to a fire, the riser channel will quickly overgrow with soot completely. And how to clean it if you have a non-removable drum cover?

In a large furnace, a spontaneous change of regime occurs abruptly, when the top of the sticks drops to the bottom edge of the bunker, and in a small furnace, gradually, as the fuel mass settles. Since an experienced housewife does not leave her for a long time when cooking on the stove, the designers considered it possible, for the sake of compactness, to combine a bunker with a blower in it.

With a large oven, this trick will not work: a high riser pulls very strongly, and the air gap is needed so thin (and it also needs to be regulated) that it is impossible to achieve a stable furnace mode. It’s easier with a separate blower: the mass of fuel, rounded in section, is easier for air to flow around from the sides, a too-flamed flame pushes it there. The stove turns out to some extent self-regulating; however, within very small limits, so you still have to manipulate the blower door from time to time.

Note: for the sake of simplicity, it is impossible to make a bunker of a large furnace without a tight lid, as is often done. Due to the unregulated additional air flow through the fuel mass, it is unlikely that it will be possible to achieve a stable operation of the furnace.

Materials, dimensions and proportions, lining

Now let's see what a home-made rocket stove should be from the materials available to us. Here, too, we need to look back: not everything that is at hand in America is also with us, and vice versa.

Of what?

For a large stove with a bench, more or less reliable experimental data is available for products with a drum from a 55-gallon drum with a diameter of 24 inches. 55 gallons is 208-plus liters, and 24 inches is almost exactly 607mm, so our 200-litre is fine without additional conversion. Keeping the parameters of the furnace, the diameter of the drum can be halved, up to 300 mm, which makes it possible to make it from 400-450 mm tin buckets or a household gas cylinder.

Pipes will go to the blower, bunker, furnace and riser different size, see below, round or profiled. So it will be possible to make an insulating lining of the furnace part from a mixture of equal parts of furnace clay and fireclay crushed stone, without resorting to brickwork; we will talk about the riser lining in more detail below. Combustion in the rocket furnace is weak, therefore the thermochemistry of gases is gentle and the thickness of the steel of all metal parts, except for the gas pipeline in the stove bench, is from 2 mm; the latter can be made from thin-walled metal corrugated, here the flue gases have already completely exhausted both in terms of chemistry and temperature.

For external coating, the best heat accumulator is adobe. Subject to the dimensions indicated below, the heat transfer of a rocket furnace in adobe after combustion can reach 12 hours or more. Other parts (doors, covers) are made of galvanized metal, aluminum, etc., with sealing gaskets made of mineral cardboard. Conventional oven fittings are not suitable enough, it is difficult to ensure their tightness, and a slotted rocket oven will not work properly.

Note: it is desirable to equip the rocket furnace with a view in the external chimney. Although the gas view in the high riser seals the common smoke path tightly, strong winds outside can prematurely draw heat out of the couch.

Dimensions and proportions

The basic calculated values to which the rest are tied are the drum diameter D and its cross-sectional area along the inside S. Everything else, based on the size of the available iron, is determined as follows:

Drum height H - 1.5-2D.
Drum coating height - 2/3H; for the sake of design, the edge of the coating of the design can be made oblique curvilinear, then 2/3H must be maintained on average.
The thickness of the coating of the drum is 1/3D.
The cross-sectional area of the riser is 4.5-6.5% of S; it is better to stay within 5-6% of S.
The height of the riser - the larger the better, but the gap between its edge and the drum tire must be at least 70 mm; its minimum value is determined by the viscosity of the flue gases.
The length of the flame tube is equal to the height of the riser.
The cross-sectional area of the flame tube (fire pipe) is equal to that of the riser. It is better to make a fire pipe from a square corrugated pipe, so the furnace mode will be more stable.
The cross-sectional area of the blower is 0.5 from its own firebox and riser. A more stable furnace mode and its smooth adjustment will be provided by a rectangular corrugated pipe with sides 2: 1, laid flat.
The volume of the secondary ash pan is from 5% of the initial volume of the drum (excluding the volume of the riser) for a furnace from a barrel to 10% of it for a furnace from a cylinder. Interpolation for intermediate drum sizes is linear.
The cross-sectional area of the external chimney is 1.5-2s, where s is the cross-sectional area of the riser.
The thickness of the adobe cushion under the external chimney is 50-70 mm; if the channel is round, it is considered from its lower point. If the bench is on wooden floors, the pillow under the chimney can be halved.
The height of the bed coating above the external chimney is from 0.25D for a 600 mm drum to 0.5D for a 300 mm drum. It can be less, but then the heat transfer after heating will be shorter.
The height of the external chimney is from 4 m.
Permissible length of the flue in the couch - see next. sec.

The maximum thermal power of a barrel rocket furnace is approximately 25 kW, and a gas cylinder furnace is about 15 kW. Power adjustment - only by the size of the fuel load. By supplying air, the oven is put into operation, and nothing more!

Note: in the original survivalist furnaces, the riser cross section was taken as 10-15% S, based on very wet fuel. Then, in the same place, in America, rocket stoves with a stove bench for a bungalow appeared, designed for air-dry fuel and more economical. In them, the riser section is reduced to the recommended ones and here 5-6% S.

Riser lining

The efficiency of the rocket furnace largely depends on the thermal insulation of the riser. But American lining materials, alas, are not available to us. In terms of stocks of high-quality refractories, the United States has no equal, where they are considered strategic raw materials and are sold with caution even to proven allies.

Of our available materials for heat engineering, they can be replaced with light fireclay bricks of the ShL brand and ordinary self-digged river sand with a large admixture of alumina, correctly laid, see below. However, these materials are porous, in the oven they are quickly saturated with soot. Then the stove will roar with any air supply, with all the consequences. Therefore, we need to surround the riser lining with a metal shell, and be sure to cover the end of the lining with furnace clay.

Lining schemes for 3 types of furnaces are shown in fig. The bottom line here is that with a decrease in the size of the drum, the proportion of its direct heat transfer through the bottom and the unlined part increases according to the square-cube law. Therefore, while maintaining the desired thermal gradient in the riser, the lining capacity can be reduced. This makes it possible to correspondingly increase the relative cross section of the annular descent of the flue gases in the drum.

What for? Firstly, the requirements for an external chimney are reduced, since the outer traction pulls better now. And since it pulls better, then the permissible length of the hog in the stove bench falls more slowly than the dimensions of the furnace. As a result, if a stove from a barrel warms up a bench with a pine forest up to 6 m long, then half the size from a cylinder is 4 m.

How to line with sand?

If the riser lining is fireclay, then the remaining cavities are simply covered with building sand. River self-digging for lining entirely of sand does not need to be carefully prepared, it is enough to select large debris. But they pour it in layers, in 5-7 layers. Each layer is compacted and sprayed until a crust forms. Then the whole backfill is dried for a week, the upper edge is covered with clay, as already mentioned, and the construction of the furnace is continued.

balloon rocket

From the foregoing, it is clear that it is more profitable to make a rocket stove: less work, fewer unsightly parts in sight, and the stove bench warms up almost the same. Thermal curtain or underfloor heating in Siberian frost will heat a room of 50 square meters with a power of 10-12 kW. m or more, so here, too, a balloon rocket turns out to be more profitable, it is rarely necessary to launch a large barrel at full power with maximum efficiency.

Craftsmen, apparently, also understood this; at least some. For example, here in Fig. - drawings of a balloon furnace-rocket. On the right is the original; the author, it seems, was wisely versed in the initial developments and, in general, everything turned out right for him. On the left - the necessary improvements, taking into account the use of air-dry fuel and warming up the couch.

A fruitful idea is a separate supply of heated secondary air. The furnace will be more economical and the flame tube can be made shorter. The cross-sectional area of its air duct is about 10% of the riser cross-section. The furnace always works with the secondary fully open. First, the mode is set with a primary valve; finely adjust the hopper cover. At the end of the furnace, the furnace will roar, but here it is not so scary; the author of the design provides for a removable drum cover to clean the riser. She, of course, should be with a seal.

Rockets from anything

Canned

Tourists, hunters, and fishermen (many of them members of survival societies) soon converted the small rocket stove into a camping stove made from empty tins. It was possible to reduce the influence of the square-cube to a minimum by applying a horizontal fuel supply, see the diagram on the right. True, at the cost of some inconvenience: the sticks need to be pushed inward as they burn out. But the furnace mode began to hold iron. How? Due to the automatic redistribution of air flows through the blower and over / through the fuel. The power of a jar rocket furnace is in the range of 0.5-5 kW, depending on the size of the furnace, and is regulated by approximately three times the amount of fuel loading. The basic proportions are also simple:

The diameter of the combustion chamber (combustion chamber) is 60-120 mm.
The height of the combustion chamber is 3-5 of its diameters.
The cross section of the blower is 0.5 from its own combustion chamber.
The thickness of the thermal insulation layer is not less than the diameter of the combustion chamber.

These proportions are very approximate: changing them by half does not prevent the stove from working, and the efficiency in the campaign is not so important. If the insulation is made of wetted sandy loam, as described above, the joints of the parts can simply be smeared with clay (left pos. in the figure below). Then the stove, after 1-2 fires, will acquire strength, allowing it to be transported without any special precautions. But in general, any of the improvised non-combustible materials will do the insulation, next. two pos. A burner of any design must provide a free flow of air, 3rd pos. A rocket stove welded from a steel sheet (right pos.) with sand insulation is twice as light and more economical than a potbelly stove of the same power.

brick

We will not expand on large stationary rocket furnaces: in them all the initial thermodynamics goes to pieces, and they are deprived of one of the main advantages of the original furnace - ease of construction. We will talk a little about rocket stoves made of bricks, clay or stone fragments, which can be made in 5-20 minutes when there are no tins at hand.

Here, for example (see the video below), is a completely thermodynamically complete rocket stove of 16 bricks laid dry. The voice acting is English, but everything is clear without words. A similar one can be folded from fragments of bricks (see Fig.), Cobblestones, fashioned from clay. For 1 time, a stove made of greasy earth is enough. The profitability of all of them is not so hot, the height of the combustion chamber is small, but it’s enough for pilaf or urgently to warm up.

Video: 16 brick rocket oven (eng)

new material

From domestic developments the Shirokov-Khramtsov rocket stove deserves attention (see the figure on the right). The authors, not caring about survival in a plus, applied modern material- heat-resistant concrete, adjusting all thermodynamics to it. The components of refractory concrete are not cheap; a concrete mixer is needed for mixing. But its thermal conductivity is much lower than that of most other refractories. The new rocket furnace became more stable, and it became possible to release some of the heat outside in the form of infrared radiation through heat-resistant glass. It turned out a rocket stove - a fireplace.

Do rockets fly in the bath?

Isn't a rocket stove suitable for a bath? It seems to be possible to arrange a heater on the drum cover. Or flowing instead of a couch.

Unfortunately, the rocket oven is not suitable for a bath.. To get light steam, it must immediately warm up the walls with thermal (IR) radiation, and immediately, or a little later - air, by convection. To do this, the oven must be a compact IR source and a convection center. The convection from the rocket furnace is distributed, and it gives little IR at all, the very principle of its design eliminates significant radiation losses.

In conclusion: rocket stove-makers

In successful designs of rocket furnaces, there is still more intuition than precise calculation. And therefore - good luck to you too! - a rocket oven is a fertile field for craftsmen with a creative streak.

Ecology of consumption.Among the diversity wood stoves such a thermal device as a home-made rocket stove deserves special attention. She's different original design, which does not require expensive materials and components in the manufacture.

Among the variety of wood-burning stoves, such a heating device as a homemade rocket stove deserves special attention. It is distinguished by an original design that does not require expensive materials and components in the manufacture.

Any person can make such a stove, at least a little bit versed in the drawings and able to work with his hands. Our article should come to the aid of such home craftsmen, where we will talk about the design and principle of operation of the rocket stove. Here, recommendations will be given on its manufacture from various materials.

OPERATING PRINCIPLES OF THE ROCKET FURNACE

Although the rocket stove device is quite simple, it successfully uses two whole principles of operation borrowed from other types of solid fuel heaters:
- the principle of afterburning wood gases released during combustion (pyrolysis);
- the principle of free flow of gases through the channels (without prompting from the natural draft of the chimney).

Note. In the simplest rocket stoves for cooking, including the portable type, only the second principle operates, since favorable conditions are not created for the pyrolysis process to proceed.

First, we will analyze the design of direct-burning rocket stoves, designed only for cooking food. Here, a short horizontal section of the pipe serves as a firebox, which then turns upward. The design is simple to disgrace

Fuel is put into the pipe and ignited, resulting in an upward flow of hot gases, which tends to rise along the vertical section and go outside. Here, at the cut of the pipe, a container for food or water is installed. Of course, a gap is provided between the pan and the pipe for the exit of combustion products. This is achieved through various metal supports.

For reference. The above rocket furnace device is one of the first. It is because of the nozzle turned up with a flame escaping from it that the device was called a rocket.

Since it is impossible to heat the premises with such a unit, the design of the heating rocket furnace was supplemented with a heat exchanger and channels for removing flue gases. To keep a high temperature on the vertical section of the pipe, it is insulated with any refractory material. Further, for intensive heat extraction, the nozzle is covered from above with a cap, for example, an ordinary metal barrel. A separate channel for supplying secondary air is made in the lower part of the horizontal fire tube.

Now the principle of operation of the rocket furnace looks a little different. Firstly, at the end of the horizontal fire channel, pyrolysis gases are afterburned due to the inflow of secondary air. Secondly, the products of combustion, which have a high temperature, accumulate under the top of the cap (barrel), creating some excess pressure. As heat is transferred to the outside through the metal walls, these gases cool down and rush down.

Since the cooling gases are supported from below by a new hot stream, they cannot descend in the same way, but pass through the space between the walls of the pipe and the barrel, safely exiting into the chimney channel. The flow of processes is well reflected in the scheme of the rocket furnace

So, thanks to pyrolysis, the efficiency of wood combustion increases, and the use of free gas flow creates a self-regulating system that limits the flow of fresh air into the firebox. The air mixture is supplied as the combustion products under the hood cool down, making room for its new portion. The excess pressure of hot gases "pushes" the cooled part out, so the operation of the furnace depends little on the presence of draft in the chimney.

HEAT REMOVAL EFFECT

The gases entering the chimney are still at a high temperature. Just throwing them out is impractical, everyone will understand that the efficiency of such an installation will be too low. Taking advantage of the fact that the rocket stove literally pushes the combustion products out, the craftsmen invented 2 ways of heat extraction:
- passing gases through the channels arranged under the bench;
- installing a water circuit on the stove.

A rocket furnace with a water circuit is made without a hood, the force of the upward flow of combustion products is used in a multi-pass heat exchanger made of metal. It is not recommended to introduce a coil with water into the gas flow, it will not last long due to too high a temperature. It would be more correct to make a water jacket with metal fins inside the flue

Another way is to lay out horizontal chimney channels from bricks directly on the floor surface and arrange a chic heated adobe couch on top by connecting a rocket-type stove to it. Here, the correct selection of the length of the channels is important so that there is enough excess pressure to overcome them, otherwise you still have to take care of the organization of natural draft.

ADVANTAGES AND DISADVANTAGES

Homemade long-burning rocket stoves have many admirers, and here are the reasons:

Simplicity and low cost of installation: in order to build such a thermal device, you do not need to incur high costs for the purchase of expensive materials, fixtures and fittings. Experience in the furnace business is also required minimal;

Self-regulation and undemanding to the natural draft of the chimney;

The efficiency of the furnace - rocket is a variable value and largely depends on the design, the main thing is to maximize the removal of thermal energy from flue gases;

Fuel can be added "on the go".

Despite the attractiveness and simplicity of the unit, heating with a rocket stove has its negative points. It is a mistake to think that you can shove firewood of any quality into the firebox. Wet wood will not give the required temperature in the chamber, the pyrolysis process will not proceed. In the worst case, the smoke from the stove can pour into the room. Also, the “rocket” needs constant supervision, especially in terms of fire safety.

Do-it-yourself rocket stoves are of little use for a bath, because they give off relatively little heat in the infrared range, which is very important for a steam room. The surfaces of the stove that radiate heat are too small and it will not be possible to heat the bath properly.
For reference. A factory-made Robinson metal rocket furnace is often used as a portable heat source. The craftsmen were not at a loss here either and quickly modernized this product, having done the same, only with a grate.

FURNACE FROM A CYLINDER

This is one of the simplest options, you can use the drawing below to implement it. A propane tank with a diameter of 300 mm will serve as an excellent cap, and the role of a firebox and a hopper will play a role steel pipe size 150 mm. The internal vertical channel is made of a pipe with a diameter of 70 mm, and a chimney - 100 mm

The design is completely welded, the pipes are cut to the required length, and the upper part of the cylinder is cut off. Then the parts are welded according to the drawings, only the opening between the vertical pipes with a diameter of 70 and 150 mm is filled with loose heat-insulating material. Perlite or vermiculite can act as such, on extreme case- ordinary sand.
If there is an opportunity and desire to make a more powerful rocket furnace, then a standard 200-liter barrel is used as a cap, then the dimensions of all parts also increase. Working inner pipe accepted with a diameter of 129 mm (or profile 120 x 120 mm), and the outer one - with a size of 450 mm. It is difficult to pick up a pipe of this diameter, so they usually find another barrel of a smaller capacity and cut off its bottom

The entire rocket furnace from a gas cylinder assembly is not very heavy, so it is not necessary to arrange a massive foundation for it. When the unit is placed on the floor, legs are welded to it, and if a stove bench is subsequently planned, then the structure will have to be coated with a refractory compound, and then the outer lining should be made. Then basalt cardboard and a sheet of roofing iron are laid on the floor from below.

BRICK OVEN

In terms of its design, a brick rocket furnace is not much different from a metal one, but it requires a lot of labor. The difference is that all fire channels of the unit are made of fireclay bricks, and the cap is made from the same barrel.

The entire structure, except for the protruding cap, is recommended to be lowered below the floor level, for which a shallow hole is dug. Its bottom is compacted, and then a small concrete foundation 100 mm thick is poured along the formwork. After it hardens, laying begins, using a solution of refractory clay. After the laying is completed and the mortar has hardened, the pit is filled up, and an iron barrel without a bottom is put on top of the fire channel, the cavity between it and the brick is covered with insulation.
For all its advantages, a do-it-yourself rocket stove cannot serve as a full-fledged source of heat for heating the whole house. It makes sense to start such construction when it is necessary to organize the heating of a small cottage or other similar building, especially since the “rocket” is not afraid of periodic work. published by

This device, despite our brave space achievements, is still not widely known in our country. And for sure, only a few are interested in how to make a rocket furnace with their own hands, because they do not understand the principle of its operation.

This is a relatively new word in the domestic heating environment, which came from Germany. The key to unprecedented popularity in the homeland is a simple cheap design, coupled with high efficiency and with the slightest absence of signs of soot. Considering that it is not difficult to make equipment on your own, we will tell you how to do it, we will give drawings, recommendations from specialists, videos and photos.

Principle of operation

Oddly enough, but the very name "rocket furnace" has nothing to do with space or rockets themselves. The only analogy that can remotely remind of this is a jet of flame rising up in mobile installations.

The design feature of the furnace is the presence of a bell, where flue gases enter and where the final combustion of the sludge takes place. Under the cap, the temperature already during the first 2 hours rises to 1000 0 C, as a result of which everything burns without sediment, and the exhaust is formed only in the form of steam and carbon. In this case, gases circulate freely through the channels without forced draft, which is usually created by a chimney.

This design allows you to use the stove not only for heating the room, but also for heating food or water (on the hood). If the chimney is run through a certain part of the room, up to the sunbed, it will also heat up.

Among the main advantages of rocket furnaces are the following:

high ratio useful action - 85%;
very fast heating of the room - 50 sq.m. in 45-60 minutes;
the absence of soot and, as a result, soot deposits - at temperatures above 1000 degrees, everything burns out without residue;
the ability to use any solid fuel;
minimum flow- at the same temperature and duration of burning, a rocket furnace consumes 4-5 times less fuel than a conventional furnace.

The most simple rocket works according to the direct combustion formula - these are mobile structures that are easily assembled in field conditions literally from improvised materials and are also easily dismantled.

The simplest design from a barrel or gas cylinder

When it comes to the first stages self-manufacturing rocket furnace (see video), then acquaintance is still worth starting with the simplest design. The camp stove is presented in the form of a bent pipe section, where the fuel chamber and the ash pan are combined.

For fuel, a steel plate is welded to the bottom, at the bottom of which a hole is cut for air suction.

It is possible to use any straight cylindrical container for manufacturing - the drawing of the rocket furnace shows how the direct combustion process takes place.

Video 1 Simple construction portable cooking rocket oven

Brick rocket stove in 20 minutes

If you have 20-30 bricks on hand, you can make a simple rocket stove with your own hands in just a few minutes. Moreover, no adhesives are required for masonry.

Lay out of brick, as shown in the photo, a vertical combustion chamber. At the same time, the dishes are placed on the hood in such a way as not to impede the movement of the emitted gases

Do-it-yourself rocket-type brick oven:

For this design to work well, a warm pipe is needed. This term among stove-makers refers to the preliminary run of chips and paper so that the pipe warms up. V cold pipe there will be stagnation of gas, which makes heating difficult. And if the pipe is warm, then when the firewood is ignited, a powerful draft appears in the channel.

For reference. In the above simple designs from a gas cylinder or pipe, there is a significant drawback - the vertical loading of firewood. Each time you have to move firewood into the chamber when they burn out and only after that put it on. Stationary rocket furnaces on coal or long-term combustion already provide for a vertical bookmark, which greatly simplifies operation.

Long burning rocket stove

Photo 6 The design of a stationary furnace-rocket

Do-it-yourself rocket jet furnace scheme

In order to make such a unit with your own hands, you need to decide on the dimensions and structural elements.

How a rocket works:

As can be seen from the drawing, the diameter of the cap (D), which covers the top of the pipe, and its cross section (S) are taken as the basis.

Based on these indicators, the dimensions of the rocket furnace are calculated:

the height of the drum is 2 of its diameter;
the height of the clay coating is 2/3 of the height;
coating thickness - 1/3 of the diameter;
sectional area of the pipe - 7% of its transverse section;
blower area - 1/2 pipe section;
the flame tube horizontally and vertically must be the same;
ash pan volume - 4-6% of the drum height;
the cross-sectional area of the external chimney is a double cross-section of the pipe.
thickness of the insulating layer (adobe cushion) under the outer chimney 60 mm;
the thickness of the coating of the stove bench is 1/4 of the diameter of the drum;
outer pipe height - 4000 mm;
the length of the flue directly depends on the diameter of the drum. If for its manufacture they took metal container with a diameter of 50-60 cm and a volume of 200 liters, the length of the flue pipe will be at least 6 meters. If the diameter is half as much, then the bed should be made up to 4 meters.

If you are making a stationary rocket furnace with your own hands, be sure to pay attention to the lining of the top of the pipe. This is necessary to isolate the brazier from the walls of the furnace in order to prevent overheating of the walls. Fireclay bricks can be used for lining.

Photo examples of the original performance

It is noteworthy that not only the walls, but also the lining itself need protection. In order to protect it from combustible gases, you can create a metal sheathing and fill it with river sand. For this purpose, you can use any metal object at hand - a barrel, a bucket, galvanization.

The sand is poured into the bucket layer by layer, with each layer watered abundantly for proper compaction. When the protection is filled with sand to the top, leave for 7-10 days to dry.

The lining of the brazier is done much faster - fireclay bricks are laid on the clay mortar, and the space between the latter and the wall will also have to be covered in layers with sand - with water and drying time.

Pipe lining scheme

All further work on the installation of a jet-type rocket furnace continues only after not only the lining has dried, but also the clay protection, which is applied over the upper cut.

Before making a stationary structure, practice on a traveling sample. After the first experience, it will become clear even if you have not read books for rocket furnaces.

Disadvantages of the heater

Often this device is used to heat food or water - indeed, a huge amount of heat, a red-hot cap, why not take advantage of this idea? However, connecting a water circuit in order to heat the whole house, and not a room, is impossible. The design is so simple that any intervention, including the coil, will disrupt the course of work.
Surprisingly, such a lightweight mobile heating device is completely unsuitable for either a bathhouse or a garage. Even with its high efficiency, the camping unit will not heat up the air in the steam room to necessary minimum. And in a garage or warehouse, it is not recommended to use appliances with direct open flames.

In this article, we will give an example of a camping installation, for which no masonry or finishing materials are needed.

Necessary materials:

2 buckets;
stainless steel pipe;
river sand or crushed stone for lining.

Step 1. Cut a hole in the sidewall of one of the buckets along the diameter of the pipe at a height of 5 cm from the bottom. The height should be enough to fill the bucket with gravel or sand.

Step 2. Divide the pipe into 2 parts - a short loading section and a pancake knee-chimney.

Step 2. Insert the pipe into the hole in the bucket.

Step 4. Cut, by analogy with item 1, a hole in the bucket, but already directly in the bottom. The hole diameter corresponds to the pipe diameter. Insert the pipe.

Step 5. Pour sand or gravel into the bucket, which will act as a heat accumulator of the flame tube.

Step 6. Making legs or stands. For this, ordinary reinforcement is suitable, which is bent under pressure and the base is cut out.

Rocket stove from a gas cylinder

This is a sophisticated improved version, for the manufacture of which you will need an already used gas bottle and a rectangular tube 4 mm.

The scheme remains exactly the same with the only exception that combustible gases are discharged from the side through the hole, and not from above, as happens with marching samples.

If there is a need to cook or heat food, the upper part of the cylinder with a tap is cut off, and a flat plate is welded on top.

Video 2 We make a do-it-yourself rocket stove

The rocket stove is widely known throughout as a long-burning solid fuel heating structure. To achieve the maximum efficiency had to work hard. A liquid fuel stove is able to give all its energy, but wood is more difficult to process. To unlock the full potential of the tree, a chamber for afterburning gases was equipped in jet furnaces.

The Shirokov-Khramtsov rocket or jet furnace got its name not because of its connection with space. The point is the shape of the device and the noise that is created during operation, reminiscent of the operation of a rocket. But this sound indicates improper use of the oven.

Types of long-burning rocket furnaces:

Portable (mobile);
Stationary (for heating).

The most popular rocket model is the Robinson. It is often used on hikes. Thanks to a small portable apparatus, you can understand the principle of operation of jet furnaces. The shape of the oven resembles the letter "L".

If the oven is too noisy and hums during operation, then this mode is inefficient and expensive. Normally, there should be a quiet sound, a little rustling.

The jet furnace has a receiving hopper. This is the horizontal part of the pipe. A thrust arises in the channel itself, it is it that affects the intensity of combustion, which warms up the body. That is why it is advised to limit the supply of oxygen. Otherwise, the firewood will quickly burn out and all the heat will evaporate.

The stove is powered by jet thrust due to the natural flow of hot air. The higher the temperature of the furnace walls, the better the wood burns. This allows you to quickly heat water in a large container, which is indispensable on a road trip. If you equip the pipe with thermal insulation, then after warming up, you can burn thick logs.

Do-it-yourself rocket stove: advantages, drawings, disadvantages

If desired, the conventional design of the furnace can be improved. So the potbelly stove loses a lot of heat, but by equipping the device with a water circuit or brickwork can solve these problems. For all these manipulations, drawings are made.

Advantages of jet ovens:

Simple and cost effective design. You can use improvised materials, without significant financial costs. All work can be done by hand, special knowledge and skills are not required.
You can independently control combustion by choosing the desired intensity.
High efficiency. In general, it all depends on the quality of the installation. The main thing is to take away the maximum energy from the flue gases.

But such a simple and convenient design has significant drawbacks. So you need to select a special fuel for the potbelly stove. Wet firewood must not be used, otherwise pyrolysis will not occur. The furnace may begin to smoke profusely, and all gases will go into the house. In addition, the rocket furnace requires increased safety requirements.

The most popular portable model is the Robinson rocket stove. It was modified and a grate was added.

Homemade jet stoves are not used for heating baths. They are ineffective in infrared light, which plays an important role in the steam room. Surface structures have a small heating area, so they cannot heat the bath.

Drawings of a jet furnace from a gas cylinder and other types

Long-burning furnaces are divided into stationary and mobile. Mobile ovens used in hiking, picnics, outdoors for heating and cooking. Stationary ones are used to heat the house, outbuildings, greenhouses, garages. In this case, 4 types of structures are distinguished.

Types of jet furnaces:

Homemade camp stove made of metal pipes, buckets, cans;
Reactive design from a gas cylinder;
Brick oven with a metal container;
Stove with bed.

The portable structure is equipped with pipe sections. The only difference concerns the installed partition for the ash pan. For the lower part, a grate can be used.

A device from a gas cylinder is more difficult to build, but significantly increases efficiency. For installation of the structure, a barrel or a gas cylinder is required. Firewood in the firebox burns out due to the influx of oxygen by loading through a special window.

The gases burn out in the pipe, which is located inside the structure, due to the supply of secondary air. The effect is enhanced by warming the inner chamber. Hot air is placed in the hood, and then into the outer chamber. The products of combustion are removed through the chimney.

To create draft, the top of the chimney is placed 4 cm above the loading window.

The combined brick and metal model is a stationary structure. Due to the high heat capacity, the wood stove accumulates and releases heat for several hours. That is why this design is used to heat residential premises.

A rocket assembly with a bed is an advanced device that is able to retain heat longer. Since part of the heat exits through the chimney, we increased its length. Due to the rapid excision of hot gases and a larger chimney, this problem was solved.

This is how massive stoves with a stove bench are obtained, which are similar to a sofa or bed. These are stationary devices made of brick or stone. Thanks to its unique design, the stove is able to retain heat all night.

Do-it-yourself drawings of the Ognivo stove and other models

It is best to make small portable structures with your own hands: the Flint and Robinson rockets. It is easy to perform the calculation, and the work will require cutting profile pipes and metal welding skills. Dimensions may differ from the drawing, it's not scary. It's important to keep the proportions.

To increase the intensity of combustion, it is advised to add improvised nozzles to the design. Secondary air for afterburning will flow there.

Stationary rocket stoves are made from a gas cylinder or metal barrel. These elements act as a body. Inside, the stove is equipped with smaller pipes or fireclay bricks. From the cylinder, you can make both a stationary unit and a mobile one.

Scheme of a continuous combustion furnace:

Chimney;
Cap;
Insulation;
loading bunker;
Burning zone;
Afterburning zone.

It can be difficult to calculate a rocket furnace, because there is no exact methodology. You should pay attention to the checked finished drawings. It is necessary to determine the size of the heating equipment for a particular room.

Assembling a do-it-yourself jet furnace for heating

The construction of the furnace begins with preparatory work. First you need to decide on the place of construction. It is chosen based on the requirements that apply to solid fuel structures: wood or coal.

When you have decided on a place, you need to properly prepare it for construction. The wooden floor under the stove is dismantled. They dig a small pit and tamp the bottom.

In a small room, a jet furnace is placed in the corner. The loading bunker occupies one side, and the lounger the other.

The barrel or cylinder must also be prepared for installation. To do this, they cut off the lid and the tap. Then the structure is cleaned. Next, prepare the solution.

Stages of construction of a jet furnace with a bench:

The bottom of the dug pit is laid out with fireclay bricks. Formwork is made along the contour of the recess. Perform reinforcement.
Lay out the base and pour concrete. After a day, when the concrete hardens, further work begins.
The base of the stove is laid out from fireclay bricks. Raise the side walls, make the lower channel.
The combustion chamber is covered with brick. There are two holes on the sides. One is for the firebox, the second is for the vertical pipe (riser).
The metal case is equipped with a flange into which the horizontal channel of the stove will enter. All seams must be airtight, well sealed.
A side outlet is attached to the horizontal pipe, which serves as an ash pan.
A fire tube is made of brick. As a rule, it is square.
The flame tube is equipped with a casing. The gaps are filled with perlite.
Installation of the cap is made from the cut off part of the barrel or cylinder. It is equipped with a handle.
Equip the furnace body with brick or stone.
Equip the front of the furnace. Lay out the necessary contour.
A prepared barrel is placed on the base. The lower part must be sealed with clay.
Via corrugated pipe form a channel connecting the furnace with the street.
The pipes of the heat exchanger are connected to the lower pipe.
Install a chimney. All elements must be sealed using asbestos cord and refractory coating.

Advanced Water Loop Rocket Furnace

A long-burning cauldron can be obtained by equipping a furnace with a water jacket. Water heating may not be efficient enough. The fact is that the main part of the warm air enters the room and is packed into hobs. To create a rocket cauldron, it is necessary to give up the possibility of cooking on a stove.

Materials required for equipping a stove with a water circuit:

fireclay bricks and masonry mortar;
Steel pipe (diameter 7 cm);
Barrel or cylinder;
Insulation;
Sheet steel and a barrel of a smaller diameter than for the hull to create a water jacket;
Chimney (diameter 10 cm);
Details for the heat accumulator (tank, pipes, connecting pipe).

A characteristic feature of rocket furnaces with a water circuit is that the insulation of the vertical part ensures the combustion of pyrolysis gases. In this case, warm air is sent to the coil with a water circuit and gives off heat to the stove. Even when all the fuel has burned out, warm air will still be supplied to the heating circuit.

Do-it-yourself rocket furnace drawings (video)

Jet oven stove benches are widely known among the people. They were used even by Korea, China, England and the population of Japan. The Chinese stove differed from the rest in the ability to heat the entire floor. But the Russian counterpart is in no way inferior. Thanks to useful innovations, the stove is able to keep heat for a long time.