RU2362605C2 - Model rocket engine - Google Patents

Abstract

FIELD: games.

SUBSTANCE: invention relates to the toy industry, more specifically to model rocket engines for space-rocket simulating toys. The model rocket engine has a nozzle, propellant charge, tracer and blow-off charge, which are made from aerosol fire extinguishing composition.

EFFECT: increased safety.

5 cl, 3 dwg

Description

The invention relates to the toy industry, namely to model rocket engines (MRJ) for space rocket modeling in technical forms of creativity.

It is well-known MRP [7] that contains a paper or plastic case in which a nozzle is mounted, a solid fuel charge from black or ballistic gunpowder, a pyrotechnic retarder tracer, which burns out with colored smoke emitting to indicate the flight path of the model after the operation of the MRP, and an expelling charge, triggered by the heat pulse of the moderator and pushing the payload from the model’s body - the next stage of the rocket, aircraft, rescue equipment, etc.

Existing MRLs, as well as sporting events and games with launches of models of various rockets, rocket planes, replica models, are potentially dangerous types of products and work. This is due, first of all, to the high temperature of the combustion engine’s combustion products, which creates the risk of burns and fires due to careless handling of the engine, the accidental fall of an emergency rocket onto dry grass and other combustible materials, as well as the possibility of explosive destruction of substandard engine engines, for example, with a solid fuel crack the charge formed during a fall, shock, detachment from the body, as a result of childish pranks, etc.

These circumstances led to the introduction of reasonable restrictions on the part of state supervisory authorities for the transportation, distribution and operation of MRPs, the organization of work with schoolchildren and athletes, which significantly inhibits the development and mass character of technical types of creativity and developmental games using MRPs.

In addition, the tendency to increase the energy characteristics of sports MRPs has led to the replacement of the charge of black powder with ballistic compositions, the combustion products of which leave a less noticeable smoke trail. The tracer, marking the trajectory of the model rocket’s flight after the charge is burned out, usually also serves as a moderator in existing MRPs, which ensures the operation of the expelling charge at a given time interval. The combination in the pyrotechnic formulation of requirements that are opposite in respect to the materials being sold - smoke-forming mixtures and low-gas compositions with stable burning rates - usually leads to compromise indicators of both the accuracy of the deceleration time and the spectacular attractiveness of the MRP, characterized by the colorfulness of the smoke plume trailing behind the rocket.

The aim of the invention is to increase security, entertainment and expand the gaming capabilities of the engine.

The goal in the engine, containing the housing, nozzle, fuel charge, tracer and blowout charge, is achieved by the fact that the fuel charge is made of an aerosol fire extinguishing composition (AOS).

AOS are fuel compositions containing an oxidizing agent, fuel, binder and processing aids, i.e. in fact, typical rocket fuels or pyrotechnic compositions that produce solid-phase aerosols during combustion are mixtures of non-combustible gaseous substances (nitrogen, carbon dioxide, water vapor, etc.) and condensed compounds, mainly alkaline and / or alkaline-earth metals (oxides , hydroxides, carbonates, bicarbonates, chlorides, etc.) in the form of micron-sized solid particles with high fire extinguishing ability. In addition to effective flame inhibition, AOS forms a finely dispersed, spectacularly plume of dense smoke during combustion. Combustion products of AOS are non-toxic, do not harm the environment, do not destroy the ozone layer of the atmosphere and are freely disposed of [1]. Having slightly worse energy performance compared to ballistic rocket fuels (see, for example, data on the heat and temperature of combustion, gas production of typical solid fuels and typical AOS, given in Tables 1.12 and 1.14 on pages 59 and 66 of the source [1]) . This is quite acceptable for MRDs used for elementary education, as well as smoke generators to simulate the operation of rocket engines in toys. AOS is fundamentally safer in terms of fire of existing fuels and propellants, and are also characterized by better smoke generation and spectacular performance.

According to the complex of intra-ballistic indicators, commercially available compositions of the PT-50 type and foundry AOS suitable for high-pressure conditions are suitable as fuels for MAJ from the AOS presented in [1];

The subsequent versions of the MRP are the development of the basic idea of creating a safe engine based on the maximum use of the unique capabilities of AOS.

To significantly increase the safety of the engine, used for the initial training of rocket-modellers or in other children's types of educational games, it is proposed to use a fuel charge from a paste-like AOS, for example [4]. Due to their viscous physical state, paste-like fuels and charges from them do not form cracks, do not exfoliate from the walls when the bodies are deformed, explosion-proof formulations ensure safety in the event of engines falling, lumbago, hammer blows, detonating impulse, heat loads and manifestations of childish pranks. This ensures maximum safety when handling MRP.

The pasty state of AOS determines the need to compensate for its thermal expansion and maintain the shape of the initial surface of the charge combustion. The use of well-known devices used in rocket engines for these purposes [2, 5] is problematic due to the complexity of their placement in the dimensions of the engine, which for the most common classes is from 10-18 mm in diameter and from 40 to 70 mm - along the length of the hulls . With regard to MRI, this problem is relatively easily solved by using elastic housings made of materials with linear expansion coefficients comparable to paste, and / or introducing an elastic compensator into the engine structure, for example, from a gas-filled chemically resistant rubber element and a perforated forming device coated with foil or film.

This synergy of pasty AOS - high fire extinguishing and smoke-forming properties, mechanical and explosion safety of charges - provides a qualitatively new level of safety of the main engine, spectacular launches and expanding the gaming capabilities of the main engine.

An engine with a tracer made of AOS is proposed.

The numerous AOCs worked out [1, 2], along with a high fire extinguishing and smoke generating effect, are characterized by stable stable combustion at low pressure in the generator, which makes them a quite acceptable alternative to the existing pyrotechnic compositions of retarders-tracers, including those generating colored smoke.

A propulsion system with a tracer located in the area of dying fuel residue is proposed.

The dying fuel charge residues, without making a real contribution to the main energy characteristic of the engine - the total impulse - worsen its output indicators, increasing the passive mass and the dispersion of the total impulse. The use of burnout residue placement zones for smoke generating AOS improves the quality of marking the rocket trajectory due to a more powerful and better visible smoke plume.

It is proposed to perform the tracer in the form of a separate component product - in the form of a washer, armored at the ends and outer diameter - and mount it on the rear end of the nozzle. In order to ensure ignition of the tracer by the combustion engine’s combustion products, the diameter of the tracer’s internal hole is made equal to the diameter of the stream of fuel charge products flowing out of the nozzle, which is determined from gas-dynamic calculation. The main advantages are independence from the manufacturing process of producing the engine, the freedom to choose the operating time of the tracer, the color of the smoke, the reduction of the range of the engine and increasing the mass production, as well as the complete and guaranteed elimination of the effect on the value of the total pulse. The latter factor leads to periodic disputes at international competitions on the comparability of the energy of various MRPs declared in the documentation of indicators of the total impulse of thrust, taking into account or not taking into account the additional increase in thrust from the tracer operating inside the combustion chamber for several seconds.

It is proposed that the MRI expel the blast charge from AOS. According to existing practice, rocket-modelers, depending on the design of the model, the mass and volume of the payload being pushed out when the outburst charge is triggered, select a charge portion of the charge experimentally, using, as a rule, black powder. To reduce the temperature of the combustion products and prevent the failure of thin-walled elements of the model (for example, dacron films up to 3-5 microns thick are used for parachutes and streamers), protective wads, cotton plugs, and powder coolers are introduced into the design. Full or partial replacement of black powder with a powdery low-temperature AOS will increase the reliability of the payload system — pushing a glider, parachute or streamer, disengaging a subsequent rocket stage, etc.

It is proposed that the nozzle of the MAJ also be made from AOS on an inorganic binder. Of the flameless AOC formulations, the highest thermomechanical and strength characteristics were achieved in compositions with a high, up to 25%, using such ingredients as magnesium carbonate, cement, etc. as binders and regulators of the burning rate. Such a composition, in particular, has SAO brand AOS used in certified aerosol generators manufactured by Nord LLC, Perm (see p. 116 of the source [1]).

Inorganic binders form a rigid spatial structure of AOS, accumulating part of the heat and stabilizing combustion processes in the low-temperature zone. When the charges of such AOS are burned, the solid residue accounts for up to 50% or more of the fuel mass. The increased height of the critical section of the nozzle from a similar AOS can be compensated by a progressively increasing combustion surface, as is realized in the well-known schemes of “non-nozzle” solid propellant rocket motors [6]. With the falling thrust-time diagram, the flaring up critical nozzle cross-section can become an acceptable design alternative to the existing thrust programming technique by changing the surface of the charge burning. Acceptable indicators of mechanical strength have AOS on organic binders, as shown in table 1.28, p.93 [1].

In addition, the scheme of the engine with completely combustible elements from the AOS is a certain ideal for improving the engine in terms of fire safety and smoke emission per unit mass, which is quite acceptable for engine engines of non-sports classes and smoke generators for children's educational games.

The invention is illustrated in the drawings, where are schematically shown:

figure 1 is a General view of the engine with tracer installed in the area of the dying residue of the fuel charge;

figure 2 is an embodiment of the engine with tracer - washer mounted on the nozzle of the engine;

figure 3 is an embodiment of the engine with a charge of pasty fuel.

The MAJ shown in Fig. 1 contains a housing 1, a ceramic nozzle 2, a solid fuel charge 3 of AOS with a bore 4 forming an initial combustion surface, installed in the zone of the remaining charge 3 of tracer 5 of AOS, a moderator 6 of AOS, and an expelling charge of powdered AOS or its mixture with black powder.

Work MRD. Before running into the cavity of the bore 4, an electric igniter (not shown) is installed, which is an incandescent spiral with a pyrotechnic coating applied to it. After applying an electrical impulse to the spiral, the latter ignites the pyrotechnic coating, the combustion products of which ignite the fuel charge 3. The gases generated during combustion of the AOS flow out from nozzle 2, creating traction and forming a thick aerosol loop behind the rocket. At the end of the charge 3 operation, when it burns out by the arch L, the tracer 5, which is installed in the zone of the remaining charge 3, and the moderator 6 are ignited. The tracer 5 when burning marks the passive part of the rocket model trajectory with colored smoke, and when the moderator 6 is combusted, it ignites expelling charge 7 and pushes a payload from a rocket model, such as a parachute.

The design of the propulsion system shown in Fig. 1 significantly reduces the risk of fire when AOS combustion products act on combustible materials, reduces the dispersion of the total thrust impulse due to the elimination of burning fuel residues, and also provides high visual performance of the propulsion system, creating a dense aerosol plume behind the flying model of the rocket during the combustion of AOS of a fuel charge 3, tracer 5 and moderator 6, corresponding to the active, passive parts of the flight path, as well as the expelling charge 7 at the end of the flight.

Figure 2 shows an embodiment of the engine with a tracer made in the form of a washer 8 and mounted outside the body cavity on the nozzle 9 of the engine. The tracer 8 has reserved side surfaces with the largest diameter, and the unarmoured surface D is made with a diameter equal to or slightly greater than the diameter D1 of the outlet channel of the nozzle 9. When the products of fuel combustion from the nozzle 9 expire, the jet ignites the tracer 8 on the surface D. Tracer 8, burning in the radial direction, it creates a smoke plume behind the rocket, first joint with the combustion products of the engine, and after burning the fuel charge 3, it’s own.

Here is also shown a design variant of the engine with a combustible nozzle 9 made of solid fuel AOS based on an inorganic binder. During the operation of the engine with such a nozzle, the inner part of the nozzle and the critical section D1 gradually burn out and collapse, providing a kind of ablation or active thermal protection for the nozzle. The critical cross-sectional area of the nozzle D1 that increases during the operation of the engine, to maintain the required thrust-time diagram, must be compensated by the changing surface and / or rate of combustion of the fuel charge 3, for example, by introducing heat-conducting wires - “leaders” of combustion (FIG. 2, solutions not reflected). In addition to achieving maximum smoke generation, an MAJ with a combustible nozzle from AOS provides the minimum of high-temperature heat accumulated in the structure, which also increases the safety of using such a design in children's games.

An embodiment of the MRP with a charge of 3 pasty AOS is shown in Fig.3. To compensate for the thermal expansion of the charge in the zone of formation of fuel residues, an elastic compensator 10 of gas-filled chemically resistant rubber is installed, and to form the initial combustion surface, a conical perforated forming device 11 is coated on the outside with a thin foil or film 12.

In the manufacture of MRI with a paste-like AOS in a heated (for lowering viscosity) state, the engine casing is filled through the mouthpiece with an installed nozzle, forming device 11 and foil 12. After cooling the charge 3, the compensator 10, moderator 6 and the discharge charge 7 are sequentially mounted (glued) into the cavity With a change in temperature and, accordingly, charge volume 3, this change is compensated by a corresponding change in the volume of the compensator 10, which keeps the charge 3 in a pressed state. A slight overpressure prevents the formation of gas bubbles and stratifications in the charge. The use of pasty charges almost completely eliminates the possibility of the transition of combustion to explosion due to such common causes of solid propellant failure, such as cracks in the charge, detachment from the body, ultimate deformation, impact, backache, etc., and thus significantly increases the safety of handling MRP.

To ignite the pasty charge, a more powerful, compared to the solid fuel composition, sample of an electric igniter is used to reliably heat and burn the foil 12. Otherwise, the operation of the propellant jet with a pasty charge does not differ from the MPD of the above schemes.

The experiments carried out on mock-ups of propulsive jet engines with nozzle diameters of 1.5–2 mm with charges of a paste-like AOS of the “Tuman 3” type [4] confirmed the non-flammability of the combustion products of gas-air mixtures of methane, propane-butane, flammable liquids, paper and cotton fabrics, and the burning effect of the skin of the palm is felt at distances of less than 10-12 cm, which characterizes such MRPs as completely safe for use in children's games.

The applicant is a small business.

Used sources

1. Agafonov V.V., Kopylov N.P. Aerosol fire extinguishing installations: Elements and characteristics, design, installation and operation. - M.: VNIIPO, 1999.

2. Alikin V.N., Lipanov A.M., Serebrennikov S.Yu. and other Gunpowder, fuels and charges. Volume 2. 3 charges of national purpose. - M.: Chemistry, 2004. P. 44.

3. Application No. 98106541. Aerosol flameless extinguishing composition. IPC A62D 1/00.

4. Patent No. 2075984 of the Russian Federation. Aerosol-forming extinguishing agent, IPC 6 A62D 1/00.

5. US patent No. 3908364. Rocket engine, NKI 60-252, 1975.

6. Timnat I. Rocket engines using chemical fuel. - M .: Mir, 1990, pp. 129-141.

7. Elstein P. The designer of rocket models. Per. from Polish. - M.: Mir, 1978, pp. 139-150.

Claims (5)

1. A model rocket engine containing a housing, a nozzle, a fuel charge from an aerosol fire extinguishing composition, a tracer and a blow charge, characterized in that at least one of the engine elements: nozzle, tracer, blow charge is made of an aerosol fire extinguishing composition. 2. The engine according to claim 1, characterized in that the nozzle is made of an inorganic binder. 3. The engine according to claim 1, characterized in that the fuel charge has a pasty consistency and is equipped with a device forming the initial combustion surface and a compensator for thermal expansion of the charge. 4. The engine according to claim 1, characterized in that the tracer is located in the area of dying fuel residue. 5. The engine according to claim 1 or 4, characterized in that the tracer is made in the form of a washer, armored at the ends and outer diameter, and mounted on the rear end of the nozzle, while the diameter of the inner hole of the tracer is made equal to the diameter of the stream of fuel combustion products flowing out of the nozzle charge.

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