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General characteristics of the engine (Calculations were carried out using the SRM program, creator Richard Nakka)

General characteristics of the engine (Calculations were carried out using
program SRM, author Richard Nakka)

Engine Kn graph (Calculations were carried out using the SRM program, creator Richard Nakka)

The engine diagram Kn (Calculations were carried out using the SRM program,
author Richard Nakka)

Engine thrust graph (Calculations were carried out using the SRM program, creator Richard Nakka)

Engine thrust plot (Calculations were carried out using the SRM program,
author Richard Nakka)

Manufacturing of engine housing

Longitudinal section of the engine.

The figure shows a schematic view of the longitudinal section of the engine. From the left to the right the colors are:

  • epoxy plug;

  • cardboard wool;

  • fuel checker;

  • a ring constituting the combustion chamber of the engine;

  • nozzle;

  • the motor housing is indicated.

As you can see, the engine system is quite simple, its manufacture does not require a lot of pores.

Let us now turn directly to the manufacture of the engine. For the source, it would be a good idea to make a case, for which we take the Whatman sheet and also cut out a strip half the width of the Whatman sheet, 75 mm wide. For the winding of the sleeve, we also need glue (silicate, PVA or epoxy) and a mandrel with a diameter of 22 mm.

Wrap the sleeve so that the layers of paper as close as possible to the friend's palm to the friend, between them there would not be any interlayers of air. Adhesive should be applied evenly, with a sufficiently thick layer over the entire surface of the wound paper strip.

After winding the sleeve, we need to make a constriction at one of its ends. To do this, you need to take a fairly long and thin rope (preferably capron). Stepping back from the end of the sleeve of millimeters 5-7 we plan to pull the sleeve, in order to facilitate this task, we tied one end of the fiber to some sufficiently heavy object. We make a loop with the help of a rope and carefully squeeze the sleeve, rolling it in a loop along a rope. First, a small force should be applied, gradually increasing it by the measure of the deepening of the constriction channel. At what time the diameter on the neck of the constriction will decrease by 6-8mm, then you can calm down, rest a bit (for more details about the constriction procedure, see ). Then we take thick threads, we also wind the channel of the waist, the room where the threads are wiped off preferably with glue, the threads after winding are similar to the top with glue.

Now we need to make a nozzle (see the picture below). For this we take the usual Russian ruble of the 1997 model later also. We drill a hole in the center of the ruble with a diameter of 3.8 mm. Actually everything, the nozzle is ready. The rub is lowered to the bottom of the cartridge case (he is forced to rest his neck). We now enclose the sleeve (with the nozzle inside) on the mandrel, bend the edge of the butt (which was constricted) slightly towards the center, and also hit the flat surface with this end several times. You will get something that looks like this:

Nozzle end of motor

Now you can remove the motor sleeve from somewhere. she to us before it is not necessary also it needs 1-3 days for the filled glue drying. Now let's take the most entertaining, in my opinion, the manufacture of a fuel cell for our engine, but in parallel, the igniter for it (the igniter will be described in a single section).

To make the booking of the checkers, we cut out a strip of 53 * 230mm from the sheet of office paper. We also need a paper ring for the combustion chamber of the engine, for it we cut out a strip of office paper 3 * 297 mm. We are reeling now the armor strip, a strip for the paper ring on a mandrel with a diameter of 21 mm. Winding armor sleeve is similar to winding the engine liner, but, unlike the engine body, it does not need to make it thick. After the winding of the armor and the ring, let the glue dry (while the armor also does not tear off the ring from the mandrel!), Try inserting the ring also the armor cylinder into the engine casing. They should enter quite freely there, without extreme efforts.

The armoring of the fuel block, the paper ring of the afterburner chamber, is also an igniter (without caramel charge).

Manufacture of a fuel draft

Now let's start making a fuel saber. To do this, take 26 g of potassium nitrate and 14 g of sorbitol, both components must be sufficiently dry (moisture content <1%). Mix the ingredients and grind them. It is sufficient to finely chop the necessary only potassium nitrate, tk. sorbitol we will still melt.

We fall asleep mixture after grinding in the enameled metal bowl (or something similar), we heat on an electric tile. The mixture begins to melt at 100 degrees, after it starts to soften, the mash should be stirred, gradually leading it up to the liquid state. After the sorbitol has completely melted, fill the fuel in the cylinder. Remains of fuel will go to the igniter. After the fuel has hardened a little, it will cool down, with a nail or some other metal rod with a diameter of 5 mm, we make a through channel in the checker, strictly in the center.

For complete solidification, fuel needs 2-3 days, at this time it must be sealed in a bag.

Final assembly

We put the solidified saber into the engine casing. From the dense cardboard we cut out a circle, which we use as a wool.

Densely close the open end of the engine with the puff, bend the remaining edges of the body slightly inward and fill the remaining space above the epoxy adhesive with glue.

It remains to wait until the epoxy glue is solidified and the engine is ready for testing!

Pass to the tests!